how high of a compression do you think is still safe for a daily driven b18c with a built block? im thinking of going 12:0:1 but 11:5:1 sounds alittle safer. although i'll lose some power from the compression, but making a motor last a while is pretty important.

anyone here knows someone thats driving with a 12:0:1 daily and isnt detonation at low end or when starting up the call while its hot?

 

im not talking from experience... just knowledge, but everything is a compromise, u want a high cr, naturally ur gonna lose reliability.
but to answer your question, there are lots of people with built motors running a 12.0:1 cr or higher and its reliable... but remember this, the higher the cr, the more critical the tuning becomes. gl duuu

 

well there are some honda & acura motor that comes 11:5:1 stock. for example, jdm k20a there compression is 11:5:1 stock and we all know people who builds honda engines know what there doing rite?

since you brought up reliabilty, what wears out when you raise up the compression and rev the engine alittle futher then we suppose. for example, like taking it to 8500-9k rpm.

 

it will be fine, i ran 12:3:1 for over a year i just made sure i used 91 or higher, im innj so i had regular access to 93 octane. Make sure your fuel pressure is bumped up a bit and get to a dyno st tune it

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by allmotorbeasteg6 &raquo;</TD></TR><TR><TD CLASS="quote">well there are some honda & acura motor that comes 11:5:1 stock. for example, jdm k20a there compression is 11:5:1 stock and we all know people who builds honda engines know what there doing rite?

since you brought up reliabilty, what wears out when you raise up the compression and rev the engine alittle futher then we suppose. for example, like taking it to 8500-9k rpm.</TD></TR></TABLE>

In Japan, they have 98 octane at the pump. Increasing compression really doesn't increase wear to any components, but the motor will become VERY sensitive to fuel differences. You may be able to do 12:1 but 91 octane will be a VERY certain limit and you'll have to retard timing more than you would with lower compression, which hurts peformance.

I've heard of people who went to 12:1 but had to retard timing too much and actually made more power at lower compression and advanced timing. Also, when you run a high compression, you are placing a lot of trust in the gas companies to actually give you fuel with the stated octane. The increased wear comes from the increasing minor pings which take their toll eventually.

 

dude my timing was 18 btdc and i had no problems

 

Ignition timing is only one piece of the puzzle. Valve timing, fuel timing, and fuel mixture can also result in detonation.

What I was saying is that there are SOME people who have made more power with less compression, namely because they had more freedom in tuning the above.