How much power am I making?

[85montemj]

This is for the guys who know engines. I have a 350 and i would like to know how much torque/hp i'm making. Here's what i have: 9 in air cleaner, Holley double pumper 650, Weiand Aluminum Stealth intake, I'm assuming stock heads (i haven't found the numbers), a mild cam and i think thats it for the valvetrain, stock manifolds (true duals), and i'm assuming stock bottom end (except for the chrome oil pan, +50 horses haha). Sorry for how vague it is, the only part of this car i've never touched are the internals of this engine. feel free to let me know if i forgot anything. Thanks!!

 

[JBreu]

At best 300-350 HP is all .............Not positive, just a Hypothesis :idea:

 

[megaladon6]

if you have generic non-performance heads, 250hp at the flywheel.
if you have a good set of heads and and 9.5-10:1 compression you might make 350.
unfortunately power estimates are impossible without cam specs, head specs, and compression.

 

[85montemj]

yeah i was afraid of that. would fuely heads make that much of a difference or are you talkin aftermarket?

 

[megaladon6]

there are a few dozen different chevy 350 heads.
do you know what the engine came out of? model and year if possible.

 

[84cutlass454]

i would say about 280 at fly wheel really need to look into some heads with smaller bustion chambers like 64cc to up the comp and like a 2.02 vavle would really help u out to making 350 horse. but u have a good start i have heard of people putting some old 305 heads on them with the 58 cc chambers and a port and polish and bigger vavles put in them really help and the 58cc chamber sould put u close to 10.1 i thank lol and u need some headers would really help

 

[megaladon6]

the 305 heads do up compression, but they also have small shrouded valves which destroy power. that's the biggest reason why the 305 has so little power. putting them on a 350 doesn't help.
you can have the heads milled down to up compression, but this sometimes causes intake mating/sealing problems.

 

[85 Cutlass Brougham]

In all honesty though, the heads you need depend on the cam you have or want to use and the pistons that are in the engine right now. as for power, it could be anywhere from 250 to 350 hp depending on your definition of a mild cam, the heads that are there, the exhaust, etc. Also, why are you running a 9 inch air cleaner? That is much too small for your engine. You need a 14 inch drop base with a 3 inch element at minimum.

What I would do is start experimenting using a sim program. Comp cams has a pretty good one on their site and it is a free download. This will let you model the engine on a computer and trend it. A better sim would also let you enter head flow numbers, but I forget of comp has such an input available on their site. When I sim'd my engine, I researched the cylinder head flow bench numbers so that I could get as close as possible to the end configuration. I then entered about 10 different cams using a variety of data points to model the lift curve of each cam. This took a few hours, but it let me figure out which cam offered the best area under the torque curve ( which is much more important than peak horsepower in a street engine).

 

[85montemj]

I'm not trying to say you're wrong but i never understood the air cleaner size. I mean you don't see guys with hure c.i. big blocks runnin anything larger than a 14 in. Its just less surface area right? The sim sounds cool though. i'll check it out.