Hey Jetdriver-
I have a 19' jet and wanted the same hole shot improvement. (I have a BBC,and the orig motor was/is a very stock version). I started with a blueprint of the pump and the inducer. These things helped, but what made the biggest difference was the new intake manifold and electronic ignition. I also had the carb tuned. I experienced a very noticeable change with the combination of mods. While my setup is different, my goal was the same as yours is--and hopefully my experience can give you a little direction. Good luck!
Jetdrive,
CORRECTION.......... I meant to say everything forward of te bowl is Volvo (suction, intake grate, shaft, etc.). Bowl is all Legend and so is the impeller.
Welcraft molded the hull to accomodate the Volvo intake. It's an interesting design, as it differs from the normal set up with the longer shaft.
Also, it's crucial that your impeller is true as is the clearance between the impeller & wear ring.
Hey Got River?
Glad to hear there is more of us Scarabies out there with jet drives (so far three of us, U, me and Scarabjet) As far as I am concerned jet drive is the only way to go, I don't think I could ever be sold on an I/O or an outboard.
Any rate, furtunately, my Mercruiser came with the HEI Thunderbolt IV electronic igniion, unless you are talking about upgrading this to another electronic ignition.
Now, I am interested in knowing what combination intake manifold and carb you have. Since mine is just the two barrel stock rochester, I'll be moving up to a 4BBL with the intake.
Thanx in advance...
KIWI,
That Subaru motor you're running, you say is a flat 6, is that the H-6 (2.7) that they used in XT-6's? I have an 88 XT6 and the engine just went on it, but since it can turn 6000 revs without a prob, I was curious how it would do on a small 16' or under jetboat? They don't have much torque at all, but they could do well in the rpm range. One major drawback is that a rebuild on those Subaru motors is approx. $3000. One great thing I can say about them is that I got 260,000 miles out her before the oil pump let go sending the rest of the motor starving for oil like Ethiopian kids looking for food in Afghanistan.
Jetdrive & Volvo Pump- both you guys are fighting the same problem-
A Legend Pump & Volvo I think you will find came from the tooling same source and are much the same design.
I think, Larry Smith (Scarab) Aquired the second set of tooling and spent several years trying to develope it for his little sixteen footer.
Aggressor was asked by Mike Myer President of Wellcraft in 95/96 to Design & produce a Drive for V6 4.3 motor as Wellcraft had tested most other manufactures with little or no luck in obtaining speed or performance requirments setforth by Wellcraft.
Aggressor designed & built the JR Drive for this program. Units was tested both in Calif and Florida. Volvo a stock owner in the Genmar Group (which owns Wellcraft & 17 other Boat Co's) made the decission to produce a Jet Drive of there own. Ala the JPX
which came from the second tooling set. The JPX has a bigger problem- as the Volvo 4.3 has a higher shaft centerline 10.2" and not 9" - So the intake was raised to meet the motor not the motor lowered to meet the intake.
The Problem you are facing is a 9" Impeller requires such a large cut to make it perform, you loose your hole shot.
You might call Hi Tech Performance-Dwayne as he had us make some special impellers for the JPX - Not sure of the outcome.
We also have been testing v6 motors since the 95 period as that size motor is the future and a good way to bring new boaters into the market. Also pay note to some of the inputs you are receiving on the board about motor improvements.
Dave Aggressor
Thanks for the input Dave Aggressor. You're absolutely right! I did my research 2 years ago & did forget to mention that Volvo has a longer suction piece, causing problems on the holeshot. Don Bowers' cavitation reducer helped a little but as I mentioned in my previous posts, the Legend C-cut was even more noticible on holeshot improvement.
Any chances of a phone number for High Tech Performance?
Actually, I was recently toying with the idea (with my local boat performance shop), to test a three bladed impeller. Any thoughts on that?
Thank you!
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