can any one tell me the best compression ratio for a turbo set up on a b18 engine please.pistons will be forged but am trying to decide how high compression ratio i can keep so off boost is still good

 

my new motor is 9:7

 

9.5:1 here

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by john54321 &raquo;</TD></TR><TR><TD CLASS="quote">can any one tell me the best compression ratio for a turbo set up on a b18 engine please.pistons will be forged but am trying to decide how high compression ratio i can keep so off boost is still good </TD></TR></TABLE>

http://www.evans-tuning.com/fo...=1612

Yeah, go run 10:1 compression so you can have 3 WHP more off boost but sacrifice lots of top end. It doesn't really make sense to me, and I'm so much happier with my low compression street motor.

 

theres probably a couple billion threads on this, just ask whoever is tuning your car, tell them your goals, your setup, and they will tell you what they feel comfortable tuning. Higher is better, there is no doubt about that. But there are many stipulations, do a search.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DaZman69 &raquo;</TD></TR><TR><TD CLASS="quote">Higher is better, there is no doubt about that.</TD></TR></TABLE>

Care to elaborate? BH's sheet shows no gains in spool, barely any gain off boost, and a marginal gain while boosting that is more than made up for the additional boost you can run on pump gas. Earl and basically every other engine builder I've talked to recommends 9:1 for a street motor because it's so much more street gas friendly, and you really don't notice any benefits from 10:1 on a street car. On a race car where you can pour C16 or VP Import through it non stop, sure, go 10:1 and get as absolute much out of it as possible, but for a street car 9:1 is the best.

He asked for what compression ratio is better, so I'm laying it out for him.