How much compression could I run on 91 octane pump gas????
I will be going Hondata if that makes a difference with tuning

 

I have heard 12.5:1 is the limit with really good tuning.

I personally won't go above 12:1 just for safety.

 

I heard 12:1
anyone else know the limits of tuning with 91 octane

 

i have heard 11.5:1 .... maybe 12:1 if you are running 94 octane

 

if it has knock sensor, I'd say 11.0:1

 

I run 11.5~ on hondata

jdm itr pistons, gsr head, flat faced valves, stock headgasket

I wouldnt go higher than 12.2 or so.

 

Blackbeautyitr runs 12.3:1 on 91 octane JUN(cosworth) pistons and 91 octane w/ both a jun ecu and now a hondata ecu. but they are forged pistons.


Modified by eh2666 at 7:56 AM 4/14/2003

 

I do plan on running Hondata so maybe 11.5:1 is possible.
anyone else have any insight on this

 

How much power increase do u get from bumping up the compression. For example, what gains would you most likely get if i were to raise your compression from 10.5:1 to 11.5:1?

 

maybe about 7-10 HP gain if you tune properly. You will notice and increase in torque. Worth it in my opinion.

 

I live in San Jose and 12:1 is what they are saying around here. Although some peeps that run 12:1 have premature combustion with 91 octane while some don't. Just to be on the safe side...I would recommend 11.5:1 if the highest octane you can get your hands on is 91.

Peace

 

I would recommend 11.5:1 if the highest octane you can get your hands on is 91.

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Exactly!!

 

I run about 12.3:1 using 91 octane. There's a shop out here that build an ITR with 13.1 running on 91 octane also. From what I heard if you tune it right you'll be ok with it.

 

I would say the limit is 11.8:1 - 12:1 with great tuning with no combustion chamber work and stock pistons, I would think that an experienced tuner with a good standalone could take it closer to 13:1 on 91 octane if the motor was built properly.

But for safety, I'd say 12:1 is the max, after that the risk versus return isnt near as great.

 

safest I would say on 91 is 11:5:1 (that's what Celica GTS c/r is at if I'm not mistaken)