Civic EG

Let me phrase it this way. What I wanna know is, since the B20v motor is a combination of B20b and B16A, it's CR should follow the B20b specs or the B16A specs?

B20b with a b16 head is 9.2:1. With a GSR head it's 9.3:1

B20z with a b16 head is 10:1. With a GSR head it's 10.2:1

Thanks man...if like you stated, then it's suitable to go boost with that type of CR right?

There's a lot of variables when it comes to "boost"

Sure you can, but turbo type, mileage/condition of motor, tune, driving style will all determine if your B20v will go BOOM.

B20 walls aren't the strongest... not ideal for a boosted setup. So I'd use lower compression pistons or stay with a smaller/medium side turbo not pushing too much boost, if you.re keeping stock internals.

teal_dx wrote:B20b with a b16 head is 9.2:1. With a GSR head it's 9.3:1

B20z with a b16 head is 10:1. With a GSR head it's 10.2:1

great info!

Yea boosting an N/A motor can only handle so much boost, its all about the compression ratio... turbo'd cars are around 8.#:1 CR

You need to think of air as a liquid; in regards to CR's. Too much boost and too high of CR means high stress on internals. (cannot squish that much air easily)

Actually i was just kidding about going boost. I do know the risk involved. Moreover i can't find any reliable workshop here in Bangkok. But I do used to own a boosted d16 back in Singapore. A pity it's a SOHC but even so, I've surprised a fair share of Rex on the road. It's funny when you imagine their jaw dropped when you ash them...lol.

pirateEG its not all about compression ratios when boosting

an N/A motor can only handle so much boost, its all about the compression ratio

Care to elaborate bks84?


What I basically said was, an engines with stock compression can only handle x amount of boost while an engine built for boost with low compression can handle y amount of boost.

When the compression to too high, large amounts of boost put a lot of strain on stock n/a parts and do some serious damage. The air as a "liquid" is too dense for that CP and cannot be easily compressed, that strain can damage connecting rods and head bolts.

The higher compression will take less "boost" to get to a power goal but the window of forgiveness gets smaller the higher you go.

Sure the compression ratio of a given engine will affect it handles boost, but to specifically say its all about compression ratios is inaccurate. I think a good tune plays just as much of a role in a boosted applications longevity as the compression.

, What I meant by this is all about the compression ratio is still true... I think you are missing my point.

Higher compression ratios can only handle a small amount of boost safely (properly built and tuned by AMS or tinkered by a 16 year old in his friends garage), whereas a low compression engine can handle more boost... So your ability to safely boost a stock Honda block is minimal.

Compression ratios limit how much extra air CAN be compressed by the system safely; stock motor or full build race motor.

You couldn't say, build a balls to the wall engine made of all the the strongest materials known to man. Give it a 15:1 compression ratio and 40psi of boost and expect it to run. it just simply cannot be done. The air would be too dense to compress and/or the fuel would reach combustion well before TDC thus stalling the engine because it is trying to rotate the other direction.

Now with normal Honda parts you just end up breaking stuff. The physics behind this is what drives how much an engine can handle.

Strength of the components and compression ratio are the variables.

Ya, I must be missing your point.

HAHA, hey man, I am just being defensive because I know how forums works. The more posts you have the more weight you carry.

I am new to the forums but not new to cars, fixed quite a few things on my EG and am just trying to hold my ground.

There are a lot of new car owners on here because Civics are so cheap and easy to work on, again, just trying to prove my worth.

I couldnt care less about post count. I just feel like what you said wasnt 100% accurate. Thats all.

Couple years back there used to be a car that run around with a built GSR that saw 15-18 psi on (aftermarket internals of course) and had off the shelf CP 11:1 pistons with Eagle rods (stock crank, not sure if sleeved or not though). And before you assume the car blew up, it was parted out after it was totalled.