Reply With QuoteVery close attention to clearances, good balance and very good valve train. That sould do it regardless of engine size.
High RPM's on top end = high RPM's all the time (cruise) when running a jet pump.
what would you all think of a high rpm(7k rpm) BBC? Im sure a roller cam would help. What sort of heads whould you recommend, Im planning on using a tunnel ram with 600s.? How much if any more rpm can I reliably get out of a 396 than a 454 or 496? Seems this would be the way to go in a jet boat? Top speed is a priority of mine(so is bulletproof reliability), but I would like to maintain strong midrange-cruising power near 3000-3500 rpm. Boat is 18 ft Brendella with stage 3, mpd worked, set back Jacuzzi 12WJ. Bottom is blueprinted and will get a bottom re-work to remove the delta pad. Goal is 85-90mph.
Very close attention to clearances, good balance and very good valve train. That sould do it regardless of engine size.
High RPM's on top end = high RPM's all the time (cruise) when running a jet pump.
Do you need a forged crank and some 7/16 bolt connecting rods?
HBjet
If you want a fast and efficient jet the way I like is to build the biggest stroke/cubic inches that you can afford,then you can run a tighter pump/impeller and you will have the speed and a lower cruise rpm. The drag-car way of running a short stroke and gearing the hell out of it doesnot apply to jets. Jets love torque, stroke makes torque,so does cubic inches,but mostly the stroke.As for heads,i have tried Airflow Research,Brodix,Canfield,Dart,and Merlin. The best bang for the buck I have found so far is the Airflow Research,we don't even sell the others unless someone is brand fixated(a lousy idea to be sure)or just cheap, in which case we reccomend they go to another shop.Use a Comp Cams roller cam,the longest connecting rod you can,and ask a lot of questions! Do NOT buy a car "Crate-Motor" they aren't made for what you want!Don't expect to walk into a shop and get a quality custom engine built in 1-2 wks.,the shops that really know there stuff are all way behind,and theres a reason that the other guys can do it quicker,they probably don't have any work,think about why.Just some food for thought.......
TIMINATOR:
If you want a fast and efficient jet the way I like is to build the biggest stroke/cubic inches that you can afford,then you can run a tighter pump/impeller and you will have the speed and a lower cruise rpm. The drag-car way of running a short stroke and gearing the hell out of it doesnot apply to jets. Jets love torque, stroke makes torque,so does cubic inches,but mostly the stroke.As for heads,i have tried Airflow Research,Brodix,Canfield,Dart,and Merlin. The best bang for the buck I have found so far is the Airflow Research,we don't even sell the others unless someone is brand fixated(a lousy idea to be sure)or just cheap, in which case we reccomend they go to another shop.Use a Comp Cams roller cam,the longest connecting rod you can,and ask a lot of questions! Do NOT buy a car "Crate-Motor" they aren't made for what you want!Don't expect to walk into a shop and get a quality custom engine built in 1-2 wks.,the shops that really know there stuff are all way behind,and theres a reason that the other guys can do it quicker,they probably don't have any work,think about why.Just some food for thought....... What he said plus BOOST !!! Boost makes torque. Compression also if you do not want boost.
TIMINATOR:
Do NOT buy a car "Crate-Motor" they aren't made for what you want!I agree with everything you said, but what is wrong with a crate short block, and then just change out the cam and add a jet boat oil pan?
Then add some AFR's and intake, carb, etc?
I only ask because Cyclones motor made huge torque and HP with that type of setup!
HBjet
Here we go: 660 lbs/ft torque at 5,200 rpm on Cyclones motor. Also, from what I remember him telling me, it made over 600 lbs/ft torque at 4000 or 4200rpm and then just pretty much leveled off. And it's 9:1 comp!
Info, how much do you think it would cost to build that motor? I did some quick math in my head and I say 10k-11k givin you do just about all the work yourself, then add another 600 bucks for the dyno! What do you think?
HBjet
Very strange for a 9:1 engine to peak torque at that RPM. Torque and HP are equal at 5,252 RPM.
That price sounds about right.
I think that guy should start selling those engines immediately. It makes more HP than a Teague 509 8.5:1 engine with a B&M Mega Blower. It makes 50 HP less than a Teague 509 with a 10-71 and 50 HP less than a full race Rher/Morrison 509 14:1 engine.
[ May 17, 2003, 10:30 PM: Message edited by: Infomaniac ]
Infomaniac:
I think that guy should start selling those engines immediately.That's what I'm thinking! When it comes time for me to buy a new boat (26' Lavey NuEra) I'm going to stick on of those motors in it, or have Dave at DNE build me something. Not sure, but for the price, you can't beat it. Also, once the 572 crate motors come out, those 502's should drop in price!
HBjet
[ May 17, 2003, 10:34 PM: Message edited by: HBjet ]
Saw the dyno numbers.
Will be interesting to see where it falls on the Power charts like the Banderlog guys and other hard core jet guys have. RPM's impeller etc. they are pretty accurate.
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