high rpm BBC

[BrendellaJet]

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.

[Infomaniac]

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.

[HBjet]

Do you need a forged crank and some 7/16 bolt connecting rods?
HBjet :D

[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.......

[Infomaniac]

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.

[HBjet]

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

[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

[Infomaniac]

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 ]

[HBjet]

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 ]

[Infomaniac]

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.

[BrendellaJet]

okay, now im confused! Why would 5200 rpms be better than 6500+? Seems like the more rpm = more speed. It would still be a big block and its not like it wouldn't have any torque. If one could turn the same impeller faster than the other-wouldn't that be best? Im not worried about the boat running higher operating rpms-if it is built with good parts you think it would be happy to run at 3500 - 4500 rpm, and occasionally up to 6500+-where it is designed to make most power and generate more speed. Is there a reason why Cyclones motor is a better build up for a jet boat? What am I missing?
[ May 18, 2003, 12:36 AM: Message edited by: BrendellaJet ]

[BrendellaJet]

anyone?

[revndave]

YOU NEED A BLOWER.
I RUN 475 CHEVY.MERLIN HEADS,BABE ERSON ROLLER,SCAT BOTTOM END,1071 MOONEYHAM AND BIRDCATCHER INJECTION.8.5 LB ON PUMP GAS AT WESTECH IT MADE 915HP AT 6800RPM.AT 10.5 LB IT MADE 1013HP AT 7200RPM.STEVE SAID MOST POWER HE HAS SEEN AT THAT CUBIC INCH.COULD OF RAN IT HIGHER BUT NO SHAFT ROCKERS.

[Blown 472]

HBjet:
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 vroom, completly missed that one.

[Bow Tie Omega]

Bri, I think you should be placing these funds towards your "project", instead of a rev motor. I have a simple equation that most can understand: RPM's = $$$$$. Money that could be used in "other places".

[v-drive]

in talking about the other project are you referring to the el camino? :cool: v-drive

[Bow Tie Omega]

When trying to get more rpm, I know that some racers go with larger diameter rod and main bearings to free up the rotating assembly. My question is how much are they opening up the internal diameter of these bearings and what is considered safe before you start having problems (loosing oil pressure and damaging bearings).

[BrendellaJet]

Bow Tie Omega:
When trying to get more rpm, I know that some racers go with larger diameter rod and main bearings to free up the rotating assembly. My question is how much are they opening up the internal diameter of these bearings and what is considered safe before you start having problems (loosing oil pressure and damaging bearings). Its not the bigger bearings that gives more r's-its the smaller diameter journal. If you have more questions-start your own damn thread and get off mine.

[Bow Tie Omega]

[ May 20, 2003, 07:00 AM: Message edited by: Bow Tie Omega ]

[Bow Tie Omega]

[ May 19, 2003, 06:47 PM: Message edited by: Bow Tie Omega ]