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Forum Rules (Click Here) -> Ontario Rodders -> Tech -> Supercharging vs NA Compression ratios
Post Info TOPIC: Supercharging vs NA Compression ratios
Nickeleye


COURTICE, ONT

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Supercharging vs NA Compression ratios
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Good Morning Everyone,

I've been reading a lot lately about superchargers. I have a question.... Is compression just plain compression and doesn't matter how it got there?.

Does a bottom end know in which way the compression was achieved?

For example if you have a blown motor with a static compression of 7.5:1 and with boost have an effective compression of 9.8:1 and you have an NA motor that's 9.8:1 can the bottom end tell thedifference between the two?

A blown motor is only 9.8:1 at peak horse power and less compression with less rpm - the NA motor is always 9.8:1 - is the NA motor harder on the bottom end overall especially street driven?

thanks,



-- Edited by Nickeleye on Wednesday 20th of March 2019 10:37:48 AM

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GLHS60


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This is a very complicated issue, compression ratio vs effective compression ratio vs boost.

I try not to even consider the term effective compression ratio in regards to boost.

While my experience is with Turbochargers there is some similarity.

In a nutshell, I run 24 psi with pump gas on a stock bottom end with forged pistons and no issues.

If one looked up an effective compression ratio chart mine would be well over 20 to 1

Obviously there is no gasoline that would tolerate 20 to 1 so this is the basis for my view.

Boosted Engines don't make more power due to more compression but the density of the air compressed.

As the air compressed is denser, additional fuel is needed to maintain a proper air/fuel ratio.

Durability problems, boosted or not, are mostly caused by detonation.

Thanks
Randy





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There's no logical reason to call an Engine a motor

Sherwood Park, Alberta Canada
Nickeleye


COURTICE, ONT

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Thanks for you input

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GLHS60


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Any time, also, think of it this way, if your compression ratio is 9 to 1, it's still 9 to 1.

You're just compressing denser air 9 to 1

Atmospheric pressure is approx 14.7

If you boost your Engine another 14.7, it performs like its double in size.

Thanks
Randy



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There's no logical reason to call an Engine a motor

Sherwood Park, Alberta Canada
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