horsepower increase with cubic inch increase?

[35racing]

With all things equal on an engine what would an increase of 5 cubic inches add to the engines horsepower?

[DANNY]

Like a 350 to 355?

[DaveBauerSS6]

If the 350 was making 350 hp, which is 1 hp per ci, then 5 more cubic inches would be 5 more hp.
Assuming all variables are relative.

[usafracer]

Depends are you increasing displacement by bore or stroke?

Truth is there is no way to tell. You say all things equal but its never equal especially when you add extra 5 CI.

[dirty white boy]

theres more power to be found in your tune-up than in 5 cubic inches...

[keeks]

You could just do the basic math for a ball park. For example, 350 makes 450hp, equals 1.28hp/inch.
355 = 456hp. Certainly not accurate.

I would say if possible, spend that machining money on a dyno with a carb guy. $1000 here will get you a day on the dyno with a sprint motor. Prob less for a carb setup.

[hot_rod]

According to a dyno program on my laptop, Dyno2000. Adding 5CI by increasing the stroke from 3.48 to a 3.53, will net you 1 HP at 6000rpm. Adding 5CI by increasing the bore from 4.030 to 4.060 will net you 2 HP at 6000rpm. This is keeping everything the exact same except whats mentioned above. But if you increase CI by bore, then your compression ratio will be slightly different. Which could be made up by different head gasket thickness. But from what the program is saying, is that the difference is negligible. I agree with Dirty White Boy, your more likely to find HP and Torque gains with the proper tune up and carb setup.

Hope this helps answer the question. If you want to PM details about your engine (i.e. cam card, compression ratio, valve size, head flow, etc.) I can put everything into the Dyno2000 and give you a close estimate of your HP/TQ increases.

[35racing]

Thanks for the feedback.... my situation was a choice of bore size. wasnt sure how close .30 over was to .60 over ballpark figures. might as well go .30 from looks of things.