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Hello Everyone, I am new to this forum... I have a question on an engine combo. I have a 402 cubic inch BBC, it has H.O. 454 heads, compression is in the 7:1 range, cam is around a .550 lift, and it has a 6-71 blower pushing around 7lbs of boost, it is running two holley 750's. What kind of horsepower #'s should I see with this setup. Sorry I dont have more info on the engine. I used to have a desktop dyno thing... but it dosnt account for superchargers... etc.
To be accurate, what type of block did you start with, how much duration does the cam have, intercooler? etc. It is especially hard to guess without good cam specs and since I don't know very much about it I'll assume. Roughly around 450 hp and 450 torque with the 6-71 which doesn't sound like much. IF I hadn't used the dynosim program I mighta guessed more but it usually doesnt lie and thats what it spit out. With some slight playing around I got it to around 500hp and 500 torque, but thats with cam stuff. Get some more info and I could help ya a little more.
The 450-500hp number sound about right if held to 5400 RPM or so. We have run a similar combination in the boat in the past. The way you're set up at the moment this motor will last forever and run on cat piss if it has to.
With the 7:1CR you can tolerate more boost, 10lbs shouldn't be a problem with good pump gas and copper head gaskets. The cam sound small, probably 220 degrees or less. The blower allows the engine to domesticate a pretty good size cam, don't be timid. You don't want to be building your boost in the manifold only, make sure it makes it to the cylinder.
The carbs are bigger than you need, but they're there. A pair of 600s will do fine up to 650hp or so with this combination. Make sure they are plenum referenced to avoid the lean surge issues.
If the bottom end is stout and you don't mind running to 6000 RPM you ought to be able to push this basic engine up to 625 HP or so. 10lbs of boost and a medium size roller cam should get you close. I assume you have 4 bolt caps, a steel crank and haven't used one of these damper adapters for the lower drive pulley.
Regards, Mark
Thanks for all the info guys!!! The bottom end is pretty stout, it has a steel crank, good rods... etc. I am just so used to running the drag racing stuff, this is a totally different kind of combo than I am used to running. My last motor in my drag car was a 540 inch BBC. Merlin Block, Grumpy Jenkins heads, Callies crank, 15:1 compression, on alcohol... Not really a street motor.. lol