blufke

I have a b18b and when i do my in car rebuild im considering bumping up the CR with a thinner headgasket. I can bump it up to around 9.4 or around 9.6(about as high as i want to go), but would this be a bad idea? the highest octane gas we have here is 91 and my tial has the .45 bar spring. im considering putting together a water injection kit which will help greatly, but without that what do you guys think? is it worth it?

PrecisionH23a

id stay around a 9.0:1 for compression... thats just me though.

ekb18c

I would bump up the compression. You would still be fine at 10:1 compression on 91 octane for moderate boost.

blufke

the problem is the gasket would be very thin, if i took it to 10:1. anyone else?

moderate boost meaning 7-10 psi?


[Modified by blufke, 10:15 PM 11/13/2002]

ekb18c

Well then why not use a stock or comestic head gasket then? I dont understand why you need to use a thinner head gasket. If you use flat top pistons, there is no reason why stock head gasket isnt good. Since you are goign to rebuild then go with 10:1 compression pistons(flat tops) adn then use stock head gasket or comestic. You will be safe for the street as long as you have proper fuel management. If your using a stock ecu then the ecu will limit the amt of boost you can run safely(proper fuel delivery). So therefore if you are using a stock ecu then i would only go as much as 7-8psi on pump gas. If you are using a fuel management system then you can run up to 14psi on pump gas. Compression is your friend esp. when it comes to spooling bigger turbos.

blufke

im doing an in car rebuild with stock stuff, except rod bolts and rings. so bumping the compression would be done with the headgasket. i dont want to worry about a good seal though, by using a thin gasket.

blufke

anyone else? the highest i can get it with a cometic at .01" thick is right around 9.7:1.

boostaholic

Just leave it at stock LS motor compression and run more boost. B18b's can take 10-12psi no problem with the right tuning.