ToxicWS6

lets say u have one engine, being a 402 and another engine being a 347 both have with forged rods/pistons, 243 heads and 9.1 CR and running same boost levels, say 20psi, assuming turbos were both equally proportioned per engine and everything else, fuel tuning etc were, how much of a power diff would u see between the 2? basically same engine just diff cubes?

friends and i were debating this so i thought id see yalls opinions

Blackpanther99

iTrader: (8)

402 is Bigger cubic inch motor, which could mean it could hold more HP

Drednot

iTrader: (1)

Would it depend on how the extra cubes were obtained (bore or stroke)? I know Gen 1 engines are very different between bored engines and stroked engines and bored AND stroked engines like the 350,355,377,383,400,406, etc.

ToxicWS6

I know more cubes equal more power but say a N/A 347 makes 380hp and a N/A 402 makes 420, would be a diff of 40more hp cause of the 55more ci, but if u ran 20psi on them would it still be roughly 40more hp or would the ratio/scaling go up and it be more of an 80hp diff? If u know what im getting at

And im curious on the bore and stroke part too

Drednot

iTrader: (1)

First off, I am no engine builder. That being said, I think the bigger engine would exponentially increase in power with the boost. I think it would be more than the 40hp. But hey, I am an idiot so.....

redtan

iTrader: (5)

It would be more than just the power created by the extra cubes. To run the same 20psi in a 402 will take a lot more air then 20psi in a 347. So not only do the extra cubes provide some power and torque, but the extra air will also put down more power.

badamn

well with boost you multiply the power of the engine so lets say you double it.you get 40 more hp with the bigger block at the same pressure.

ToxicWS6

so yes, with the more air mass for the bigger block, and the multiply the boost and N/A power (heard some were its roughly 20-25rwhp per psi, give or take of course)

347=380hp + 20PSI X 20HP(low end of scale via the air mass part) = 780hp

402=420hp + 20PSI X 25HP (higher end of scale..etc) = 920

780 - 920 = 140hp diff

if that makes sense then cool, if not i have a feeling i just put alot of bs but i think i got the main idea lol

Drednot

iTrader: (1)

Sounds good to me.

bww3588

iTrader: (49)

Not quite.

20psi is 20 psi. Regardless of engine size. Yes, volume of air increases with more cubes to achieve the same pressure, but that is solely because of the larger cubes.
The volume of air will not help or hurt power output over the added cubes.