This document is the first installment of Between the Lines. Our “Between the Lines: Preface” document contains important introduction information that will help you to understand this context and it’s objectives. If you have not already read that preface, we recommend you do so.
The most important technical editorial of 1995
Most of trend setting technical editorial of 1995 was in the pages of Personal Watercraft Illustrated. The most important of these trends was the printing of radar/computer generated graphs that showed the “on water” acceleration and peak water speeds of every stock machine test they did. These graphs, produced by a software package that interfaces with the Stalker radar guns, offer the first tangible means for readers to accurately compare the performance of different machines. Watercraft World magazine used this same computer generated graph comparison on page 53 of their October ’95 three seater test, but not in any other tests they did all year. The printing of these graphs will certainly be the standard for all the “serious” publications in 1996.
The most important single article was on page 14 of the Sept ’95 PWI. The machine itself was not that special, however the test procedures certainly were. This was the first accurately executed dyno test of an aftermarket modified machine. To the average reader, this may not seem like any thing special. However for the people in the industry, it shows that this publication is willing to verify horsepower claims that may seem a little “bold”. Conducting a test of this kind is time consuming and expensive. While it certainly won’t become an “every issue” standard for this publication, it is a tool that no other PWC magazines have used…ever.
As far as generic technical articles go, the best of ’96 was on page 44 of the December ’96 PWI. It’s impossible to make the subject of relative air density exciting or entertaining. However contributor Rick Peterson at least made it understandable and meaningful. Readers should know that this is an important subject because even a small change in air density makes a very real difference in an engine performance.
Another technical “honorable mention” goes to the aftermarket performance evaluation tests in Splash magazine done by Tom Kerker. The part of these tests that really sets them apart is the before and after comparisons of both peak speed and “on water” peak rpm. Tom measures the RPM’s with a digital tach that’s accurate within 10 revolutions. These “on water” tach readings are a definitive performance number that readers can use for comparison of tests in other articles. On-water peak rpm will soon become a standard part of quality tests done by all publications on both stock and modified machines.
A Preface about the 1996 Machines It’s important to have an understanding of the manufacturing sequence of PWC’s in order to understand what your seeing in the magazines. Most of the new model photos appearing in the January issues were taken at press introductions in October. Most of the machines in these photos are not production boats, they are “pre production prototypes”. These “pre-pro” boats (as they are called) are usually well worn, and perfectly maintained by the respective R&D departments of the manufacturers. They are used for endurance testing, fine tuning, and literature photography. As a general rule, they run a little better than the average “production” boat will run. Occasionally, they run “allot” better than the average production boat.
There is much controversy among the manufactures regarding “who is giving the magazines production boats and who is giving them pre-pros”. The truth is that most of the production units of the “new” models won’t be available to anyone until late January. With a 7 – 8 week draft to news stand time, that puts readable tests of true production boats back to April cover dates.
Since the magazines are in a crunch to scoop each other, they all want to be the first with the “new boat test”. For some magazines, this means testing a pre pro instead of waiting for production boats. As you can imagine, this makes it impossible for a reader to know what information is “real”. The reputable magazines will often do a fluff “ride impression” of a pre-pro unit followed by a definitive “ride test” of a true production unit in a later issue. If you read a new boat test in an issue that lands at the news stand before March 1st we recommend to take this information with a grain of salt. That is, unless the article goes to great length to explain how they got this “production” boat so early. Having said this, it can go without saying that most of the brand new machines in the Watercraft World “dream demo” are pre-pros. It’s no great loss since the recent dream demo issues have avoided definitive performance information anyway. You can believe it’s production when you see the radar acceleration charts in Personal Watercraft Ill. Early March maybe.
Watercraft World – January ’96
Page 97 – The article by Carl Camper offered a good overall description of impellers along with some theory. No hydrodynamic engineer (to our knowledge) has authored any articles in any other publications. Like everyone else, we look forward to other pieces by Mr. Camper. We do, however have comments regarding parts of the article. Page 99 under the heading of Impeller Design infers that most of today’s designs are not as effective as theorized. To this we ask…compared to what. Mr. Camper inferred that there is something much more effective, yet neglected to describe it. The first column on page 103 made a similar inference with “When the leading manufacturers begin incorporating more advanced pump designs…”. We hoped Mr. Camper would have either elaborated on what those designs might be, or not baited the readers without following up.
Our “on water” experience does cause us to take issue with one point in the article. The “Rake” section of page 102 stated that the Nu Jet impeller design would yield great performance on smooth water, but lacked the vacuum to keep a 60 mph craft glued to the water. Our field tests with 60 mph off shore racing ZXi 900’s have yielded exactly the opposite result. After testing many props on our modified 900’s, the Nu Jet offered, by far, the best “rough water” hook up while it caused a slight loss in peak speed on “glass”. Other conventional overlapping props yielded slightly better peak speeds, but never matched the rough water performance of the Nu Jet. Perhaps in future articles Mr. Camper may explain how the theoretical expectation of this design can be so different from the “on water” results.
Personal Watercraft Ill. – Jan. ’96
No tech items requiring comment.
Splash – Jan. ’96
Page 16 – It is unclear to us how this item relates in any way to pwc’s, racing, or reporting.
No tech items requiring comment.
WaveRider – Jan. ’96
Page 23 – While Group K does not work on any Sea Doo models, there are many items in this article worth noting. First and foremost is that the boat was never actually ridden. Like the folks at MSD, we have also been the victims of horrible weather on “the day” of a magazine test. The weather is no ones fault, however not going the extra yard to reschedule another ride day is a poor choice. Particularly when the focus of the entire article is improving the on water performance of the machine.
MSD is to be commended for providing the dyno chart information which, depending on how you read it, is as damaging as it is encouraging. Page 27 depicts a dyno chart that shows a 17.5 hp increase at 7500 rpm. However an on water test with a digital tach would have shown that the engine doesn’t ever reach 7500 rpm on smooth water. If the on-water rpm peak were at 7000 rpm (closer to reality) that would mean that the horsepower increase “experienced on the water” was actually 10.9 hp. Without the test ride, no one will ever know.
Even if the engine could some how turn the 7500 rpm that nets a 17 hp increase, the dyno chart indicates a 13hp loss at 5000 rpm and a 12 hp loss at 5500 rpm. While we have never done acceleration tests with Sea Doo hulls, every other machine we have tested comes up onto plane, and off the turns, in this rpm range. It’s possible that the combined characteristics of the hull and the hook up of the pump could mask the sensation of this 12 hp loss…but we doubt it. Here again, one pass in front of a Stalker with acceleration software would have been worth a million words (and dyno charts). Even with the test ride omitted, this article has a lot of interesting information. However since it offers no on-water performance vs. cost information, it does nothing to help the reader make a more informed buying decision. Speaking of cost, the article says that the cost is about $750 at full retail. Our calculator and a current MSD price list say that the pipe ($643), rev limiter ($80), billet head and domes ($250 & $92), adds up to a full retail total of $1065. Neither the article nor the catalog makes mention of a special kit price. We, like the readers, must assume that there is a $315 error in addition.
It seems that MSD and WaveRider missed a major editorial opportunity in this article. That is, a set of dyno runs that show the performance differences of the various chips available for the “Enhancer” cdi box. At Group K we do not use or recommend these cdi boxes because we have never found them (with any chip) to yield a significant on-water performance increase with our engine kits. However a day doesn’t go by that a customer doesn’t ask about the performance differences between the various chips. They are asking because MSD has never released definitive performance information about that subject. With the motor and dyno already in place, these tests would have been very easy and very informative. Maybe next time.
Page 63 – Besides being a very well done “general tech info” article, the clear step by step installation photos helped endlessly to make prop changes less intimidating. Our tests mirrored the speed results on otherwise stock machines. It bears noting that a ZXi 900 with any significant engine modifications will need pitches steeper than these.
This is also a good time to point out that all the impeller manufactures seem to have different methods of measuring and denoting their prop pitches. In the case of these two ZXi 900 props, the in-water engine loading (and performance) are nearly identical. However the pitch numbers are deceptively different. The unfortunate lesson here is, there is absolutely no way to accurately choose a pitch from one manufacturer when referencing from the pitch numbers of another. In fact Skat Trak now offers a line of smaller hubbed “Slimline” props as well as a new line of “Swirl” props. Both new designs have good merit, but even those pitch numbers do not translate directly to the pitches of the standard design Skat Trak props. Yes it is silly…and yes it does drive engine builders crazy.
Personal Watercraft Ill. – FEB ’96
Page 14 – To say the least, winning any of the IJSBA tour titles is no small accomplishment. Steve Royal, and his sponsor Hot Products, deserve plenty of credit and respect for their accomplishment. Having said that, we wondered how close this replica is to Steve’s tour machine. We would have assumed that his tour boat would have used a “laydown Rave” style engine rather than the upgraded 718cc HX motor. Perhaps not. No recent article (that we can recall) has outlined the performance merits vs. the costs of the Rave motor and the modified 718 HX motor. However this HX article certainly begs the question (without ever actually asking it)
The only other recent (and definitive) HX article we are aware of was page 109 of the August 95 Watercraft World. Page 117 of that item showed a stock HX at an average 52.5mph and that same boat, with a Factory Pipe, at an average 56mph. This PWI article shows a stocker at 50 mph and the race modified boat at 56mph. While the Stalker radar graphs in these two separate magazines showed the stock boat’s peak speed to vary 2 mph, both articles showed the stocker to get to 50 mph in about 7 seconds. The Royal race replica has a visibly better acceleration curve than the WW HX w/Factory Pipe. However, they appear to run nearly the same peak speeds. The PWI article makes no mention of handling modifications to the race boat that may be scrubbing off significant amounts of peak speed. None the less, it would be wise to assume that the top loader grate of the race HX does cause a slight speed loss that the WW HX would not have to deal with.
Since we don’t build Sea Doo engines, we can’t say if $7275 in engine modifications is acceptable for this kind of HX performance increase. If so…racing Sea Doos is not anywhere as inexpensive as we thought it was.
Page 24 – Karine Patrurel’s XP limited; $1504 in engine modification for .5 mph peak speed increase and .3 seconds at 50 mph…a similar story to the Steve Royal HX. Those kind of dollar vs. performance numbers will never wash with our customers.
The performance of the Pro Tec limited SuperJet seemed very much in line for the modifications it had. No doubt there are many guys out there saying “my limited radars faster than that”. To that we say “read the New Testing file in our menu A”. All radar tests are not created equal.
Page 20 – All engine builders have their own ideas about how to isolate the best ignition timing. We have no problem sharing ours. “Always run the most retarded possible setting that does not significantly compromise low rpm output.” Trust us…it is easier said than done. All in all…Rick Peterson did a good job with a difficult subject.
Splash – FEB ’96
Page 56 – This article seems to be another “replica” test of a race machine. The racers and technicians at Riva also deserve much credit for their IJSBA title. The 1100 in this test certainly delivers a huge increase in overall acceleration and peak speed over stock. Compared to the PWI HX article, this dollar vs. speed ratio looks like a bargain. However compared to what the average 1100 owner can afford, it’s still in the financial stratosphere. Definitive speed and acceleration numbers, like those shown, are defiantly important to have for a complete article. However equally telling performance numbers would have been the impeller pitch, rpm at maximum speed, and compression. These numbers, normally included in Splash tech articles, were badly needed information for this one. These numbers give a perspective on how hard the engine is being pushed, and there by a perspective on long term reliability. In addition, prospective buyers of expensive machinery like this want to know what the maintenance intervals and fuel consumption are like. The little testing that we did with triple 46 Mikuni’s showed a fuel consumption rate of almost double. That’s about 24 gallons per hour at full throttle.
As a frame of reference for 1100 owners, a Group K Sleeper kit equipped 1100 (@ $1150) delivers consistent 65 – 66 mph “spike” readings”, and 64 – 65mph “sustained” speeds, turning a Solas 15 – 20 @ 6850 rpm with 145-150 psi compression (on 92 octane pump gas). We grant that this doesn’t match the “spike” speeds of the Riva 1100. However for the 1100 Yamaha owners who have a need for speed, yet don’t have $6800, this might be important information. It’s unfortunate that the Riva people didn’t choose to also include a more affordable modification package in this article. The Riva technicians are very competent and talented people who could have easily done this. Most Splash readers, and potential Riva customers, are interested in how much speed they can get “$500 at a time”…not $7000. We think the Riva folks may have done themselves a marketing disservice by making 65 mph appear to be so damn expensive. It doesn’t have to be.
PWI – MARCH ’96
Page 14 – To say the least, this is a record setting article. This is the first article, in any publication, that has provided definitive performance information about national championship winning machines. While this article says much, there is still much omitted information.
Those who have read “About Yamaha Strokers” in menu B understand the importance of “average piston speed”. The average piston speed denotes the expected reliability of an engine. The Rius Kawasaki “aps” is 3615 fpm (@7250rpm), and the Mac Yamaha is 3690fpm (@7600rpm). As a frame of reference, a Group K 105 octane Super Jet 701 runs 55 mph with an aps of 3234 fpm (@7250 rpm). This 400 fpm difference can be the difference between replacing the pistons every 50 hours or every 50 minutes. The damaging effects of these high piston speeds can be greatly diminished by using longer connecting rods. Kawasaki 750’s that turn reliably up to 7500 rpm are very common. That is partly because the stock Kawasaki rods are much longer than the Yamaha rods to begin with. While these longer rods do not reduce average piston speeds, they do greatly reduce “maximum piston speed” (and the wear and tear that comes with it). The “short rod” Mac Yamaha, @ 7600 rpm is by far the highest revving Yamaha we have ever heard of. The article says nothing of longer rods being used, and the motor in the photo shows no sign of a thick spacer plate that would accommodate longer rods. If this Yamaha has stock length rods, the stress loads of the high piston speeds and high piston acceleration would weaken all the internal moving parts in a relatively short amount of racing time. The article says nothing about maintenance intervals. We can only imagine the those interval for the Mac Yamaha are more than most privateers could afford.
We have had the opportunity to test the peak rpm of many over the counter stroker Yamaha motors (Pro Tec and Riva included). We have never seen one turn over 7200 rpm. In most cases, they turn just over 7000 rpm. This doesn’t mean higher revving over the counter strokers don’t exist…but there doesn’t seem to be many out there.
No one expects the performance of most “over the counter” race engines to be exactly the same as the race team machines. However a 500 – 600 rpm gap in performance is more most paying customers might expect.
All of this information begs the question “When you pay for the best that money can buy over the counter…what are you getting? Both R&D and Pro Tec are very high profile companies that offer many aftermarket bolt on parts. However, of the two, Pro Tec is the only one that actually promotes the sales of their race boats and engines. The Mac replica motors cost about $7000, and the complete boats are about $13000 – $15000. The folks who have purchased these units know, by now, that their Super Jets don’t go 60 mph. Nor do the engines turn 7600 rpm. It is unclear to us why the technicians at Pro Tec would choose to disadvantage paying customers by such a margin. That may, perhaps, be the subject of many phone calls from PWI readers to Pro Tec.
Another important point regarding the Mac Yamaha is the cylinder. Page 40 of the March ’95 PWI, page 33 of the Oct 94 Splash, page 105 of the July 94 PWI, and many Pro Tec ads have promoted the Pro Tec race cylinder as a mandatory item for a competitive stroker Yamaha motor. We were very surprised to see the fastest Super Jet in the world using a modified oem cylinder instead of the Pro Tec cylinder being sold to the public. If Pro Tec is in fact selling their cast cylinders for stroker race motors, it was a major blunder to not have one on this boat for this article.
Finally the issue of the Super Jet prop. The technicians at Pro Tec must think that nobody else in the world does tachometer testing with various impellers. There are plenty of racers that can tell you from personal experience, a 12 – 20 Skat Trak prop turning 7600 rpm would drive a Super Jet around 75mph. The editors of PWI, who are not dummies, know this as well. That is, no doubt, what prompted them to visually inspect the impeller rather than accept Pro Tec’s word. We suspect the editor correctly identified the prop on this machine as a Solas I or J pitch. Either of these props, spun to 7600 rpm, could realistically net the 60 mph speeds. Here again, somebody used very poor judgment showing up for a magazine test with parts that don’t match the promotion. Besides the great disservice done to the readership and Pro Tec customers, the greatest disservice was done to their faithful sponsor, Skat Trak.
Page 24 – Rick Peterson certainly went to a lot of effort for this piece. Unfortunately it fell a little short of providing helpful information. We look forward to the follow up next month. In the meantime we stand by our timing rule posted above “Always run the most retarded possible setting that does not significantly compromise low rpm output.”
Page 62 – While this is not a tech article, this item by Jasmine Basha is an excellent editorial piece. She obviously has much experience in the area of mail order, and knows how to explain it well. If you buy via mail order, this article should be mandatory reading. The most important point she brings up is the mail order drawbacks on page 68. We whole heatedly agree that a business relationship with a competent local shop (if you have one nearby) is the best customer protection you can buy for yourself.
SPLASH – March ’96
Page 38 – The mods by Hill propellers look very interesting. It sure would have been nice to have an “on water” back to back test to illustrate the gains. Maybe next time.
Page 80 – This article was informative and the test data complete. At Group K have not yet tested the ECWI. However everyone we have spoken to that has tested it, is pleased with the results. The engines we build and sell net big increases in bottom end and midrange from the other mods we make. For these engines, there is a questionable need for additional mid range. However for limited class racers and owners of “pipey” modifieds, this modification is probably money well spent.
GENERAL OBSERVATION – This early part of the season is when potential pwc buyers are scrambling to get every available bit of information about the new 1996 machines. At the same time the manufacturers and the magazines are all making their best effort to get this information to these potential money spenders. We were very surprised to see this entire pre-season issue without one paragraph of tech info about the new machines. It’s not for us to say if this makes Splash a good or bad magazine. However, at the very least, it seems to infer that the Splash staff is okay with a “lifestyles instead of new info” format issue during the most pivotal part of the “boat buying decision” season.
WAVERIDER – March ’96
PAGE 91 – This article, by Larry Schrieb, is by far the most comprehensive carb article that has been printed in any of the magazines in recent years. The information is all correct and current.
PAGE 59 – While this article offered some good photos and a little bit of incidental info, it offered no real performance information that could help the reader to make a more educated buying decision. We also take issue (big issue) with the statement on page 60 that claims many customers report 2 – 3 mph gains. In 10 years of testing various reed petals on various PWC engines we have “never” seen gains of that magnitude. An “on water, back to back” test should have been the only way a claim like that should have been permitted in print.
WATERCRAFT WORLD – April ’96
The “Dream Demo” issue of WW is intended to be the first glimpse of what the new boats are really about. As many web users have figured out, many of the machines in this year’s DD were pre production prototypes. This fact, however, does not mean that the entire test is without any merits at all.
It used to be that the peak speed of the new boats was the “only” important information to potential new boat buyers. And that may still be true for today’s high performance machine buyers. However the greater bulk of the 1996 pwc’s are models with other marketing targets. For that majority of machines, radar acceleration/speed information is incidental…not pivotal. The info in the DD was complete enough to help make a buying decision for those boats.
However for the machines in the “performance first” category, the DD test fall badly short of giving information that is definitive enough to cement a $7000 – $9000 buying decision (this is a serious amount of money is not taken lightly by anyone). In this category, pre-pro boats have a bad reputation for running measurably faster than the eventual production units that follow. This fact is not WW’s fault. However WW does make the conscious choice to have the DD test at a time when they know production units will probably not be available. It’s nice to have the first “new model tests” before any of the other magazines. But the value of that accomplishment is lost if the information is not complete and accurate. The issue of “information credibility” vs. “scooping the other books” is part of the magazine business. Each magazine eventually makes the balanced choice that sells them the most issues. Magazine readers can only vote with their subscription dollars.
ROSSIER 720 RACE BOAT – Page 105 – This article had lots of good information about the fully modified Rossier XP 720. Perhaps the only things lacking were a radar generated acceleration graph (important for a race boat) and a price list breakdown. It goes without saying that the machine in the article would be quite expensive to build. It’s unfortunate that another less expensive package was not also included in the article. Most PWC owners have smaller budgets, and are interested in something between the $500 pipe and the $16000 race boat.
SPLASH – April ’96
Bullet Racing Sea Doo HX – Page 33 – Boy do magazine editors hate this. The April issues of both Splash and PWI have an article about this same machine. Editors don’t like it for many reasons, not the least of which is…one article will be more complete than the other. In this case, PWI apparently got greater access to the machine and tech information, hence their coverage is much better. While this Splash article has some interesting information and photos (most are repeated in PWI), it doesn’t really offer the reader (or potential Bullet customers) enough information to make an educated buying decision. That makes this article a lot less meaningful than it could have been. We can’t blame Bullet Racing for trying to get the most possible exposure from their Bonacci HX racing effort. However, getting two magazines to do similar articles in the same pre season is a poor choice that will dog them (editorially) for some time.
Rossier XP800 – Page 50 – This article carries some good, useful information about modifications and performance increases for the money spent. Unfortunately, like so many other Sea Doo modification articles, even small performance increases are portrayed as being pretty darn expensive. In this case, $2300 for about 3.2 mph. WOW! One note of confusion was the copy which denoted 190 psi compression, and the test chart which denoted 160 psi. Interested buyers should probably call Rossier for the straight scoop.
Beyond that, it’s worth noting the rpm numbers and speeds of this particular machine. As stock machines go, the XP’s have a broad range of peak speed variation (56 – 59 mph). Accounting for some of this variation, the stock XP 800s we have tested turned between 6650 and 6850, as the Splash boat did. However, among these boats, we have seen a pretty consistent trend that showed that 6650 rpm = 56 mph; 6750 rpm = 57 mph; 6850 rpm = 58 mph and so on. We have never seen a 6650 rpm machine go as fast as 58.5. Nor a 6900 rpm machine go as fast as 61.5 mph. We can only imagine that the machine used in this test has got an exceptionally good hull, or the Odessy sponsons were used in both tests and make one hell of a difference. In our tests, 61.5 mph (using a stock prop) requires a strong 7100 – 7150 rpm. This 7100 rpm also requires a rev limiter mod.
RIVA 701 Blaster – Page 80 – The intended goal of this article (we think) was to outline the construction of a “mild mod capable of speeds of 55 mph”. The back to back radar test of the ride plate was very impressive, and speaks well for the Riva plate on the Blaster.
There was nothing unusual about the parts used to construct this boat. While very expensive for a recreational mod ($3011), it seems very reasonable to believe that these mods could result in a machine that can run into the 55’s. What is unusual is that they claimed to keep the compression “down” to 190 – 200 psi. “Down” compared to what? In almost every body else’s book, 190 – 200 psi Yamaha motors are “race only” engines. Page 81 of the article also claims that “Race gas costs a little more at the pump, but that’s what you have to sacrifice when you want more horsepower.” We find it hard to believe that anyone at Riva or Splash would want to sign their name to those words. We whole heartedly disagree on both points. Race gas is not a little more at the pump…it’s triple. To boot, many shops in the business build 55 mph Blasters that can run on 92 octane pump gas.
It’s possible that Riva’s marketing people have found that most of their recreational customers don’t mind buying race gas at $4.50 a gallon. It’s also possible that Splash magazine’s reader surveys have given them that same info… we tend to doubt either case. At Group K, it has consistently been our experience that 5% (or less) of our recreational “and racing” customers are willing to spend that kind of money every weekend on gasoline. The Riva technicians might have better served themselves and the Splash readers by offering a pump gas compatible machine for testing. The Group K Big Bore Blaster in the May ’96 Splash (at $2838) runs 55 mph all day long on 150 psi and 92 octane unleaded.
PWI – APRIL ’96
Bullet Racing HX – Page 14 – This is definitely the more detailed and through of the two Bullet HX articles. The radar generated acceleration graph shows an impressive increase in overall performance. There is obviously much creative thought (not to mention blood, sweat, and tears) that’s gone into the construction of this machine. It’s unfortunate that so much of what makes this machine good…also makes it prohibitively expensive for most owners. This modification, minus graphics and carbon hull, still costs $11,955. All complete, it’s $19,725. We often wonder if pricing this high excites readers, or turns them off. Perhaps the magazine editors are the best judge of that. As someone who talks to high performance pwc owners all day (every day)…it is unclear to me who these “$20,000 pwc articles” are aimed at. At the very least, this is another article that supports the point that going competitive level, closed course, racing on a Sea Doo is currently a very expensive form of recreation.
1 MPH for $50 – Page 32 – Every item listed in this article is true and valid…except perhaps #6. The ignition timing need only be checked if you suspect it has been tampered with. Once set (at the factory) the timing of the cdi ignitions in all pwc’s will not change.
Detonation – Page 46 – The information in this article seems to be correct and technically sound, but we had a hard time relating it to our existing pwc’s. Perhaps the next installment will cover that ground.
Group K 1100 Sleeper kit – Page 94 – The caption on page 95 says that this is one the three fastest machines they have been given to radar…this is the only one of those three that you can buy. Since this article, we have developed our 100 octane 1100 big bore kit…6950 rpm…68 mph. See the page on our Triples here.
WAVERIDER – April ’96
No tech items requiring comment.
SPLASH – MAY ’96
HX pipe by Fact Pipe – Page 40 – The performance increase offered by this pipe would be impressive on any machine…much less a Rotax. Many articles have been done on full blown pro mod race boats that don’t run these peak water speeds. Factory pipe has a great reputation for doing thorough research work…and the performance of this pipe is the result of that work.
Project 900 – Page 56 – Jeff Prieur is a really nice guy…and the 900 Kawasaki he wrote about here is probably a really nice boat. However this article falls very short of giving the reader enough information to make an informed buying decision. While all the bolt on parts used can have great merits, there was no “before and after” info to illustrate what each piece could do on it’s own. Our testing showed that the Rad flywheel, Solas prop and R&D flame arrestor all have good performance increase merits. We wonder how the peak speed was impacted by the grate and plate. Our tests with other top loader grates and longer plates showed significant losses in peak speeds.
With respect to the recommended top end modifications…we take great issue with them. We think that raising the cylinder “.040” is a very bad idea. The exhaust ports of the 900 are at the brink of being too high already. Furthermore, the recommended cylinder and head mod (on a production top end) would result in about 80 – 90 psi of compression. We suspect that this test may have been unwittingly done on a leftover pre-production prototype 900 on loan from Kawasaki. The “pre-pro” 900 heads had 8cc less volume than a production unit. Someone who hasn’t seen a lot of production and pre pro heads (as these editors probably haven’t) wouldn’t know that there is a “big” difference in head volume. DO NOT TRY THIS MOD ON YOUR 900…YOU WON’T BE HAPPY. We suspect that even this pre pro my have had “soft” low speed power until the lightweight flywheel was installed.
Big bore Yamaha twins – Page 80 – It was unfortunate that weather and logistics did not permit radar generated acceleration graphs of these machines… both were very impressive. The real benefit of the big bore kits is not just sheer horsepower from the added displacement, but rather the ability to make that horse power with such low compression. Since this article, we have reduced the compression of these kits to150 psi with no compromise in the stated performance numbers. The low compression is a great benefit to increasing longevity and reducing operating temperature.
WATERCRAFT WORLD May ’96
Sponsons – Page 111 – We cannot claim to know enough about sponsons, hulls, or handling to comment on this article. Carl Camper is as qualified as anyone to write this piece (certainly more qualified than us).
Greater Yamaha Head – Page 117 – While aftermarket cylinder heads certainly do offer the convenience of no down time, they do so at a considerable cost. Milling the stock 701 head costs about $75 and performs every bit as well (on an otherwise stock machine) as an aftermarket bolt on (@$289 in this case). No doubt that the Greater Yamaha head is a well made part…it’s just overkill for this application. This article, like most other “cylinder head” articles we’ve seen, makes claims of increased cooling without showing any data or proof. If the makers of aftermarket heads make these claims in editorial articles…the publication should substantiate the claim…or omit it. There should be comparisons of total water jacket volume as well as before and after temp readings.
Our General Observation – WW should be commended for finally showing comparative radar acceleration charts. The intentional omission of the speeds on the graph is probably their attempt to not “fan the flames” of the peak speed wars. This would be fine, except that PWI prints their charts complete. It would seem that the readers who want definitive information (that’s a lot of readers) would simply buy PWI. Beyond this, the Dream Demo included so may pre-pro boats that even the “de-numbered” charts have a limited relevance to production units in the real world. However it should be understood that this pre-pro factor is only important in the evaluations of the High output” models. All in all, WW has made a big and important step towards displaying better information for readers. We look forward to more new tests done on production units after the dream demo.
PERSONAL WATERCRAFT Ill.- May ’96
Sea Doo 720 XP Factory Pipe – We have not tested this pipe, however FPP has a great reputation for doing their homework both in the dyno room and on the water. There is no reason to question the results of this test or the performance increase offered by the FPP 720 pipe. (It might have been nice to have peak rpm tach readings too.)
Read This – Page 56 – This article makes many interesting general statements and observations, however it doesn’t offer the reader quite enough information to make a better buying decision for his or her application. We are not experts on reed design or manufacturing, however we know what we want. The article mentions some thoughts that tuners have about reeds…this we are qualified to comment on. What tuners want, is a reed petal with the best flexibility to weight ratio that never breaks or fatigues. Since most thin and lightweight petals are very fragile, tuners are “forced” to choose thicker (and or more durable) reed petals. The hardest job for tuners, and recreational riders, is knowing how to choose the best compromise of performance and longevity for their particular application. We had hoped this article could have clarified that in greater detail.
One area that might have helped would have been to accurately describe the “need to control the airflow” on modified engines. We have never heard this reference before. A description of good control vs bad control scenarios could certainly make a good follow up article.
Fuel Flow – Page 62 – This article has plenty of current and accurate information. If you collect important tech articles…this is a keeper.
WAVERIDER – May ’96
No tech items requiring comment.
PWI – June ’96
Page 40 – Dialing it in – This article (like the others written by Rick Peterson) is full of relevant and good information. Reading it is time well spent
Page 52 – Riva 701 Raider bolt parts – Like all PWI tests, this one was done as accurate and impartial as possible. The performance numbers of the modified craft (57.4 mph @ 6750 rpm) seem to be in line. However we were surprised at the numbers that the machine made in “stock” form (52.3 mph @ 6150 rpm). All the properly tuned stock raiders we have seen run high 53’s to middle 54’s at about 6450 rpm. The editor mentioned that their stock Raider also ran in this range. We cannot understand why the Riva technicians would choose to do such a test with a machine that was so apparently worn out or out of tune. We feel that this discrepancy does not serve the credibility of this test well. We do not doubt that this machine ran and handled considerably better than a stocker. However it has been our experience that today’s high performance pwc customers expect allot more for $1900 than 2.5 mph and improved tracking.
Page 96 – Beyond Bolt On’s – In this article Jasmine Basha continues to prove that she has an excellent understanding of the high performance pwc business, and the ability to put to paper what she knows. No other editor or contributor (ourselves included) has written such an accurate and understandable article about machining modifications.
GENERAL OBSERVATION – When PWI released their 1995 swimsuit issue, we joined the many voices accusing the PWI editors of producing a “fluff” issue that carried little pwc related substance. We are pleased to see that the number of fluff pages for the ’96 issue was reduced and the number of substance pages was substantially increased. We still question the marketing wisdom of such a fluff heavy issue during the peak “boats and parts” buying season…that is probably why we are not editors.
Splash – June ’96
Page 18 – test of Sea Doo GTi – This test is apparently Slash’s new evaluation format for new stock boats. While there is plenty of good information, many of the comments seem more than a little subjective. The 1 – 10 type scoring system is a very meaningful measuring scale in shoot-out tests that involve several machines in the same market niche. However in the testing of a single machine, this system looses a big measure of meaning. To each of these scores we (and many readers) ask, “a score of 7 compared to what?”. Just the same, this is a big improvement on the “ride impressions” that have appeared in recent Splash issues. Splash editors will no doubt fine tune this format of testing.
GENERAL OBSERVATION – This test, like many others in other magazines, allows the test riders to make “appearance” or “styling” a tangible score. All pwc owners that we know are individuals who all have a difference definition of “style”. These people don’t need some magazine test rider to tell them what appears stylish and what does not. We would compel all the magazines to abandon the practice of trying to tell their readers what does, and doesn’t, look good. We believe that quality photography should permit each reader to make that judgment for themselves.
Page 40 – Ficshetti HX – We have not done extensive development with any 720 Rotax engines, however this one appears to be a pretty fast one. We think the most meaningful part of this test is the (new for Splash) inclusion of the radar generated acceleration and speed graph. If Splash editors make these graphs a standard fixture of aftermarket parts tests, they will be raising the quality of information for their readers by a huge margin.
WATERCRAFT WORLD – June ’96
Page 97 – Factory pipe on 750 SXi – This is a test we have seen before in other mags. The pipe obviously works well and Factory pipe has obviously done their homework on it. It would have been nice if the editors documented the increase (if any) offered by the installation of the O/P flame arrestors before the installation of the pipe. This would have given readers a clearer picture of how much they can contribute.
Page 105 – Intake Grates by Carl Camper – This article contains allot of interesting information. By far the most surprising comment is at the end of page 107 which infers that top loaders cannot “theoretically” operate as everyone presumes. Since we have no expertise in that area, we won’t touch that argument with a ten foot pole. However it would be terrific if Carl could do some sort of field test (in a future issue) to illustrate this idea in the real world on a boat. Such a demonstration test would be a trend setting piece.
PWI – July ’96
Page 124 – XP 800 Buckshot carbs – This is another case (like last issue) where the “stock” machine does not perform nearly up to normal spec. All the stock XP800’s we have tested run low 57’s @ about 6750 rpm (as the boat on page 24 of this issue does) A 55 mph XP800 is a “Slow XP”. Among the many things that could make for a slow stock reading, air density and trim setting are perhaps the most important. The text does not denote either. In a subsequent conversation with Buckshot, we were told that the trim setting was maintained at one notch below center for all tests. While this might make for better control during acceleration tests, it definitely would reduce the peak speeds of all the radar tests. It should be the job of the tester or “testee” to clarify this information for the readers. In this case, that apparently did not happen. The result is information that is hard to relate to other tests.
We will acknowledge that the XP800’s seem to respond very well to intake modification. In our tests, a stock XP with the Group K modified 40mm Mikuni’s and an R&D arrestor (total $310) runs 59.2 mph @6940 rpm (trim in center). While lower speeds might be expected from the lower trim setting, we were surprised that the Buckshot modified machine did not run up into the middle 6900 rpm range. These carbs may very likely offer a greater measure of increase on a heavily modified machine, however there is no way for the reader to forecast that from the information in this article. For $900, our customers would expect allot more power increase than this test showed.
We commend PWI for actually putting the claims of many of these inlet systems to the test. However one fundamentally important test, that should be a standard fixture, is the indication of fuel consumption. Fuel flow meters instantly show fuel consumption numbers that can be a pivotal part of this kind of buying decision. We chose to bore the stock XP carbs for our offshore kits because we found the net consumption of most aftermarket arrangements to be “staggering”. In a world where many pwc owners are concerned about fuel range, the indication of WOT fuel flow is information everyone needs.
Splash – July ’96
No tech items requiring comment.
WATERCRAFT WORLD – July ’96
Page 143 – Nozzles by Carl Camper – This is another interesting and well written item by Carl.
Page 151 – Pro Tec Off Shore 1100 – Pro Tec is more commonly associated with their IJSBA closed course racing than with the up and coming off shore style of racing. The speed of this machine is very impressive. Unfortunately so is the price tag. We, at Group K, have been one of the few performance shops to take off shore racing seriously. We are glad to see another shop of Pro Tec’s caliber take an interest. Unfortunately neither the Pro Tec riders, nor any 1100’s prepared like this one, have appeared at any 1996 region 1 events. We have seen many privateers attempt to run stroker engines like this one. All of these riders have since abandoned their stroker motors and 46mm gas guzzling carbs. Longevity and fuel economy are high priorities that their strokers did not accommodate. We look forward to Pro Tec (or anyone else) attending IJSBA points events to establish the ongoing competitive abilities of these high rpm and high priced engine formats. The current horsepower kings of region 1 off shore are the Group K 1100 Big Bore Raiders. They run 67 – 68 mph @ 6850 rpm with three 38mm carbs. For sheer speed, nothing else has even come close…strokers included.
All this aside, some of the performance numbers in this article to not add up right. The article states that stock 1100s have a limiter at 7200 rpm and a stock peak of 6900 – 7000 rpm. Every production 1100 we have tested turns no more than 6670…period. All stock limiters we have seen are at 7040 – 7080 rpm…no more. Furthermore, an 1100 that turns a Solas J @7500 rpm with the Pro Tec grate would theoretically be going about 75 mph (remember, our big bore 1100s with the same setup go 68 mph @6850). We question the performance information given for this setup, and most of all we question whether a 7500 rpm stroker can be “just as reliable as a stock boat”. While we have great respect for the technicians at Pro Tec, we do not believe that they can defy the laws of physics. This is not the kind of claim that you make…it is the kind of claim that you prove.
WAVERIDER – July ’96
Page 58 – Factory Pipe HX pipe – Articles in other magazines have also confirmed the apparent good performance of this pipe.
PWI – Aug ’96
Page 14 – Project Kawasaki 900 – This article is the result of several months of ongoing work (much of which we watched with interest from afar). We were made to understand that one of the early goals of this project was to get the most in competitive offshore power while retaining stock porting. We considered that to be a challenging goal since our own testing for the 900 Sleeper kit showed that good cylinder porting modification made a huge competitive difference. Despite what our tests have shown, we understand (as the PWI editors do) that there are a lot of owners who flat out “do not” want to port their cylinders. Besides the porting, this project hit directly on the areas that will offer the best increases.
The other racers mentioned in this piece (Walt Cadman and Dan Gunter) where the Group K off shore test riders for the development of our Sleeper kits. During the early season Walt and Dan ran their Sleeper as we had prepared them (58 – 59 mph). However later in the season they got another mph by using the Megaflow carbs (instead of the Group K bored and jetted ones) One mph doesn’t sound like much, but that’s a big gain at those speeds. Granted that the Megaflow mod is $300 more than the Group K mod…it is a mph that we left on the table.
Page 22 – Muscle Boat Shootout – This is another trend setting PWI article that the other publications will be struggling to match. We commend the PWI editors for standing the ground for credibility in this boat category that has typically been printed on rose colored paper. This test of the ’96 muscle boats is the most credible one in print because
A) They used “production” machines.
B) All the engines were dyno tested to confirm hp claims.
C) The dyno test would also expose any “ringers”. No publication has done this before, firstly, because it’s a staggering amount of work. Beyond that, some manufacturers (in the past) did not want their magazine test boats held “this close to the light”. Starting with this issue of PWI, any lesser test of the industry’s muscle boats will look weak.
Splash – Aug ’96
Page 36 – Riva Blaster 2 pipe – We have not tested this pipe ourselves, however Riva does have a rapidly growing reputation for making effective exhaust systems. The test statistics are very complete and informative. It would have been nice if the flame arrestors were radared separately before the pipe test. This would give a more accurate picture of the pipe’s ability alone.
Page 68 – Cyclone air induction – In 1995, numerous racers had told us about the great results that they have gotten with these Cyclone fans. Unfortunately these fans are no longer legal for IJSBA competition. That still leaves the recreational market wide open. There are many “high performance” recreational riders who are willing to spend what it takes to get every possible competitive edge on their buddies. For these riders, the Cyclone would be money well spent. However for the average recreational rider, the Cyclone could have some down sides. The voltage draw of the fan operating full time would definitely keep most boat’s charging system operating at full hilt. Some earlier machines, with weaker charging coils could easily go into voltage deficit that would result in a dead battery. For a 20 minute closed course race, this is not a worry. However for the touring rec rider, it would be. It would have been nice if this article covered the specifics of voltage draw and the charging ability of most boats.
WATERCRAFT WORLD – Aug ’96
No tech items requiring comment.
PWI – Sept ’96
Page 32 – Pony Express – This article, by Rick Peterson, contains plenty of accurate info. However, even for us, it went into detail that was hard to connect with the act of “riding pwc’s”. It seemed like excessive technical dissertation.
Page 136 – Line ’em up – This is a very innovative item that was very easy to over look. The rotational position of the spark plug may seem like an incidental detail, however it can result in a significant performance increase. The idea is to have the (properly torqued) spark plug, end up with the overhead electrode facing the rear transfer port, and the open end of the gap facing the exhaust port. As the incoming charge loops up the back of the cylinder towards a spark plug positioned in this way, the raw fuel is deflected away so that it cannot wet the actual plug gap. This plug positioning can often “clean up” a slight rich condition, and always allows plugs to stay cleaner for longer. The real “on water” increase can be 40 – 50 rpm at peak speed. This is a detail that Group K attends to on all our in house race machinery and magazine test boats (it’s fair). Unfortunately we have to accomplished this by torqueing a box full of plugs into each hole until we find the one with the perfect rotation for that particular cylinder (over torqueing to get a better rotational position can result in cracking the inner porcelain of the plug). With these washers, any plug can have the good rotational position. We think these washers are some of the least expensive horsepower and throttle response that money can buy … get ’em.
SPLASH – Sept ’96
Page 96 – Yamaha Race Hull – Since this hull compromises a small margin of peak speed ability for better handling, it is obviously aimed at racers…not rec riders. However, the mere existence of this “aftermarket part” has stirred controversy among local level IJSBA racers. In short terms, if you want to race competitively on a Raider, it will cost you $5000 for openers. We have seen these hulls race…and they handle great. For sponsored pros, racing on tour, it is a justifiable expense. However if a wealthy local level racer gets one, he instantly drives away other Raider owners by driving up the cost of competing on the local level. We, at Group K, will be glad to see expensive parts, like this one, made illegal in 1997 local IJSBA events. These hulls are not permitted in the new Super Stock division.
Page 109 – Haulers – Mark Dobson (lower right) is a pro level offshore racer and a Group K technician/test rider. While we have great respect for Mark’s abilities…we have no respect for his choice in vehicles. From day one…he was forbidden to bring his Oldsmobile anywhere near our building (the fire hazard was reason enough).
WATERCRAFT WORLD – Sept ’96
No tech items requiring comment.
WAVERIDER – Sept ’96
Page 59 – Rossier XP 800 pipe – This is the first of the much awaited pipe evaluations for the 782cc Rotax laydown rave motor. There are zillions of these boats out there…and the aftermarket pipe builders have done everything short of waging war over this one item that is destined to be a top seller. While this article is well written, we have some big problems with some of the information specifics. Page 61 states the stock boat as running 58.9 mph @ 6690 rpm…no way. An XP that turns 6690 is a slower than average XP. All the XPs that we have radared in the high 6600s would only run 56 mph…not 58.9. To break into the high 58’s, the rpms of an otherwise stock XP would have to be in the high 6900’s. Page 62 goes on to say that the first runs with the RE pipe (and a pair of O/P flame arrestors @ $129) were at 6900 rpm. Then some carb “dialing in” and rave valve adjustments yielded a 230 rpm improvement. We think that “dialing in” that yields an increase of this size should have been better detailed in the text. We also think that the cost of the flame arrestor must be added to the pipe “kit”. In truth, no pipe (by itself) will allow the 782cc Rave motor to turn 7130 while the restrictive stock arrestor is being used. On top of this, we were surprised that the article casually states the water speeds, rather than show the grouping of radar pass data that averaged into these speeds.
In testing done with a Rossier XP 800 pipe on a stock XP (and numerous customer’s XPs), we have never been able to achieve the 7130 rpm or the 63.1 mph stated in this article. The lack of detail and the lack of specific information makes it hard for the information in this article to add up right. Considering the $695 + $129 price tag, and the competitive scrutiny of other pipe builders/advertisers, the info in this article seems destined to become controversial.
PWI – Oct ’96
Page 44 – Dynamometers – Of all the points made in this well written article, the most important are the “more on fooling yourself” and “what a dyno can’t show” segments. As Rick infers, dynos are a priceless tool for “discovery “projects. They allow you to monitor many data inputs at once, not to mention net fuel consumption and horsepower per liter of fuel being used (an important measurement of engine efficiency) However if you simply want to do a back to back test to see what will work best “on the water”…no dyno on earth can match the accuracy of your local ride spot and an on-board tachometer. Perhaps the best illustration of this is Chris Fischetti’s nation championship 785 race boat verses the entire field of “dyno developed machinery”. Chris and his mechanics hit the water every morning and every evening to “gather information”. Their “no dyno” approach has delivered the fastest 785 machine on tour. (ask anyone who attended the final national event in Anaheim) Did Fish’s boat actually make the most horsepower?…who knows, who cares. It got consistent hole shots on the fastest factory machines on tour…that’s what matters.
SPLASH – Oct ’96
General Observation – This issue carried two items regarding Pro Tec modified Wave Blasters. Macclugage’s tour race machine (page 32), and Phil Johnson’s recreational Blaster (page 44). Both of these articles carried no performance information, no price information, nor any technical breakdown information. It seems, to us, that this is a badly missed opportunity to bring the most current information to the many faithful Blaster owners (as well as Pro Tec customers). To be sure, these “photo pieces” are easier to do than the more detailed tech items. Despite this, we are surprised that the editors didn’t maximize an opportunity to update Blaster owners with the latest offerings and technical advances from one of their faithful advertisers. The photos are nice.
WATERCRAFT WORLD — Oct ’96
No tech items requiring comment.
PWI – Nov ’96
Page 82 – Riva rear exhaust Exit – The “anti bog” effects of this rear exit kit are very real. Nearly all pre ’97 Yamaha runabouts have exhaust exits located at the right side of the pump cavity. When the handlebars are turned full left, the tail end of the steering nozzle swings all the way to the left side. In this position, there is a significant gap between the exit nozzle and the steering nozzle on the right side of the pump. A certain amount of the high pressure, exiting the nozzle, can “leak” through this gap on the right side. As this leak takes place, it gets aimed directly at the exhaust exit port at the right of the pump. This water pressure, blasting at the exhaust exit, is strong enough to back up the exhaust gases trying to exit. When this “backing up” takes place, the engine falls flat on it’s face (modified are affected more than stockers). This problem was most prominent on (but not limited to) the 701 Raider model. Installing the rear exit exhaust could often make a huge improvement in left turn acceleration. While we highly recommend this upgrade, be aware that the IJSBA limited a Super Stock rules prohibit it’s use… bummer.
SPLASH – Nov ’96
Page 30 – Kaw 900 vs. 1100 – Tearing down two complete boats for comparison photography is a lot of work. The idea is terrific, and should be done more often. It’s unfortunate that some details in these pictures were not more visible than they appeared. A pictorial like this would require “lots” of macro close ups to vividly show the detail differences. While some of those differences were not obviously visible in these photos, the intent is one worth repeating. When describing the differences in new year model machines…one picture can easily be worth a thousand words.
Page 85 – APE Sea Doo XP mods – We have tested some of these APE parts with mostly positive results (on a Sleeper kit equipped XP). The flame arrestor was a big improvement over the stocker. However it is a little more expensive than other comparable arrestors. The scoop grate works well for recreational rough water riding (as this test boat was), but may not be aggressive enough for a modified race boat (that’s okay, not everyone is a racer). The exhaust pipe performed the same as all the other “non ECWI” aftermarket pipes we tried…not as good bottom end as the stocker, with a little better top end. We suspect that the compression of this test boat was increased in an effort to regain that low speed loss. However, APE is not alone in this area. Every 785 laydown rave magazine pipe test that we have seen to date employs this same approach. It seems to be a common modification “medley” used by pipe builders on this particular engine.
The performance chart (on pg. 87) shows the stock machine to run a little slower than most we have seen. The average XP turns middle 6700’s and runs high 56’s to low 57’s in speed. A 6640 rpm XP is an uncommonly slow XP. The APE side of the performance chart shows numbers that don’t appear to be dramatically increased when compared to the cost at hand. We expect that this will be a common dilemma for many aftermarket parts manufactures who develop parts for the laydown rave motors. For these manufacturers, the laydown rave engine will be “by far” the most difficult pwc to make big (and affordable) horsepower improvements on.
WAVERIDER – Nov ’96
Page 8 to 16 – Selecting different tech specialists for different makes of machinery is an excellent idea. There is so much to know about each make of machine, no one tech editor could be expected to know it all. We think this is a format that other publications should examine closely.
Page 40 – PWC hulls – We are not afraid to admit that we know nothing about hull design. Despite that, we do know enough to realize that there isn’t anyone better qualified, than Carl Camper, to write such an article. It is informative and interesting.
Page 58 – Abaco 650 Tigershark – While Group K does make a Sleeper kit for the 650 Tigershark’s, we recognize that few shops have taken the Arctco machines more seriously than Abaco. We tested their ride plates and scoop grates on our 650’s with excellent results. We were surprised that this test showed the 3 seater 650 to run 44 mph in stock form. Our 2 seater version of the same boat (the Montego) ran only one mph faster in stock form. While getting the Abaco modified 3 seater to a speed of 52.1 is very noteworthy, were again surprised to see that come at such a high cost ($1552). Our 2 seater Sleeper equipped boat ran 51.5 mph for $519. (page 134 of July 95 Watercraft World) We grant that getting a 3 seater to 52 mph will cost more…but we question whether it should take $1000 more. During our tests, we got a much better overall increase from cylinder porting than from the dual 38’s and the Daytona pipe combined. Furthermore, once we had settled on the port format, we found that a single 46 carb (not used on our magazine test boat) would consistently out perform the dual 38’s in every way. It’s certainly possible that the combination in this article, by Abaco, could work as well as our Sleeper boat with a 46 carb…but it would do so at a cost of about $700 more money.
Page 62 – Rossier XP pipe installation – This article seems to be the pictorial bolt on process of the pipe that was tested in the September issue. The photographs show clean detail of important tips.
One very important difference between the other article, and this one, is the claimed increase in speed. That issue claimed (what we considered to be) a “very optimistic” 63.1 mph. While this article did not outline the “before and after” rpm numbers, the 61.2 mph it claims is much more in the realm of tests we have seen. Two miles per hour may not look like much on paper. However anyone who modifies laydown rave engines will tell you that there is a lot of work (and money) involved with getting from 61.2 mph to 63.1 mph.
PWI – Dec ’96
Page 16 – SLX 785 – Few machines in the Havasu World Finals display area got more attention than the Polaris SLX Pro. The Polaris folks have correctly observed that the IJSBA competition events are swarming with 60+ mph Sea Doo XPs. A machine of this magnitude was needed if they had any hopes of stemming the laydown rave “tide”. As the article mentions, the performance of true production models remains to be seen. However the Polaris folks are certainly aware that this machine can not be watered down much if it is truly intended to be the “rave killer”. While this engine employs many unconventional systems, we think the most important technical variation has been overlooked. The SLX Pro will be the first pwc (racing or not) that has the majority of the exhaust system mounted to the hull, rather than solidly bolted to the rubber mounted engine. We have no doubts that this system has proven itself well in Polaris’s own endurance tests. However we are very curious to see how such a system lasts in the hands of Joe Consumer. (Joe has a reputation for breaking the unbreakable) If the production versions of the SLX pro are as fast as claimed, and the exhaust system proves worry free…Sea Doo racers will have their hands full in 1997. (P.S. Offshore racers need not worry…the 11 gallon per hour carbs and the 9 gallon gas tank will out rule most offshore use)
SPLASH – Dec ’96
No tech items requiring comment.
WATER CRAFT WORLD – Dec ’96
Page 77 – Rossier GSX 782 – The overall text of this item reads like most other “bolt-on type articles. However we take issue with some “glaring” inconsistencies. The speed chart on page 84 shows that the stock GSX ran an average speed of 53.2 mph. All of the GSX’s we have tested (and seen tested) have run in the middle 56 mph range at about 6800 rpm. A 53.2 mph GSX is a very slow GSX. GSX’s are equipped with the most accurate digital tachometer in the industry. The WW editors easily could have (and should have) included the corresponding rpm numbers, to help GSX owners see where the discrepancies are.
The most glaring error in this article is the acceleration chart on page 79. As near as we can measure, the curve for the stock GSX shows a peak speed of about 47 mph. This huge error gives a very misleading visual impression of the gains offered by the RE modifications. An error of this magnitude seriously detracts from the credibility of the chart as well as the entire article. As we read this same chart, the RE GSX with the stock prop looks to run a peak speed of about 56 mph (the speed of most stockers), and the highest curve on the chart shows the RE machine with a “custom” Skat Trak prop. Nowhere in the text of the article is the pitch o this prop mentioned. With out knowing the pitch of this prop, or the rpm the engine turned with it, this top acceleration curve is virtually useless information to any GSX owner. As more misleading information, the radar speed chart on page 84 is “apparently” showing the speeds of the modified GSX “with the custom prop”, however the chart neglects to say that.
It bears noting that these information errors are not RE’s fault. When a publication tests your machine, you don’t get to tell the editor how to write the article. RE is a reputable shop, however the information in this article makes it difficult for that message to get through.