Compression Ratio
Thread Starter
Joined: Jun 2003
Posts: 27
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From: Boynton Beach, FL
Compression Ratio
i know that with a lower compression ratio you can boost more safely. And most people are running like 9.0 but my question is doesn't a higher compression ratio produce more power under boost? say i get a 9.6cr i would have a reasonable high C.r and low enough for safety. is the .6 extra compression worth running the risk?
and i know you run the risk of knocking but still if you tune it right you can be safe. by the way this question is basically for a B18C i am building for 450whp, and i plan on doing it right w/ good parts and what not
and i know you run the risk of knocking but still if you tune it right you can be safe. by the way this question is basically for a B18C i am building for 450whp, and i plan on doing it right w/ good parts and what not
Honda-Tech Member
Joined: Aug 2003
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From: P0rnfield, Iowa, USA
Re: Compression Ratio (B18C Hatch)
The main reason that it is wise to lower the compression on a car with a turbo is that it also lowers the risk of detonation. The more compression you have, the hotter the intake charge gets when it's compressed before the spark plug goes off. Add some boost and the extra heat the already compressed air brings with it and your engine is likely to have a rather short life. However this is where High octane gas comes in. The higher the octane, the more compression (and heat) the charge can take with out going off premature(to a point). This is why most people who go turbo run 91 or better gas. And to run more boost, lower the compression.
Honda-Tech Member
Joined: Apr 2002
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Re: Compression Ratio (B18C Hatch)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18C Hatch »</TD></TR><TR><TD CLASS="quote">i know that with a lower compression ratio you can boost more safely. And most people are running like 9.0 but my question is doesn't a higher compression ratio produce more power under boost? say i get a 9.6cr i would have a reasonable high C.r and low enough for safety. is the .6 extra compression worth running the risk?
and i know you run the risk of knocking but still if you tune it right you can be safe. by the way this question is basically for a B18C i am building for 450whp, and i plan on doing it right w/ good parts and what not </TD></TR></TABLE>
i ended up going with 9.1. if i could do it over again, i would have probably chosen 9.8. higher CR does give better numbers given the same boost level, faster spool.
what else will you be doing the the block ?
for 450 whp i would hope you are getting sleeves, pistons, rods.
if i were you, i would make sure i do EVERYTHING RIGHT the first time to avoid the risk of blowing anything up. also, it gives you piece of mind knowing your block is pretty much bulletproof.
if i could do it all over...
9.8 cp pistons
full race/manley rods
and its your choice on sleeves, there are lots of good ones.
and i know you run the risk of knocking but still if you tune it right you can be safe. by the way this question is basically for a B18C i am building for 450whp, and i plan on doing it right w/ good parts and what not </TD></TR></TABLE>
i ended up going with 9.1. if i could do it over again, i would have probably chosen 9.8. higher CR does give better numbers given the same boost level, faster spool.
what else will you be doing the the block ?
for 450 whp i would hope you are getting sleeves, pistons, rods.
if i were you, i would make sure i do EVERYTHING RIGHT the first time to avoid the risk of blowing anything up. also, it gives you piece of mind knowing your block is pretty much bulletproof.
if i could do it all over...
9.8 cp pistons
full race/manley rods
and its your choice on sleeves, there are lots of good ones.
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