Thread: Should I go 9.5 or Stay 8.5

As I'm waiting for Mr. Keo to bring me my block back I've been pondering on what fun things I can do to it.

I am tempted to install the 9.5 pistons into it, that way I have more low end power, and more overall power on lower boost settings. Today I found out the amount of crap you have to go through to pull the head and then resurface, etc. etc. Plus the cylinders probably will need to be honed for the new piston rings etc.

I don't plan on running more then 12 psi of boost, probably will keep it at 7psi for the daily. External Gated, with O2 induction intake manifold. What I'm worried about is blowing it up with 9.5's, especially with the increased flow with the intake/exhaust mods.

Is it worth the trouble/costs to go to 9.5's?

I say if you NEED to rebuild, go 10:1. If not, for me it is worth the trouble, but it is not worth the costs.

However, I cannot see much fun in a heavy ass car running only 7psi with 8.5CR

Yeah, the cost is just a little high to justify it, but I also don't want to run too much boost. I need the car to be able to take crappy 91 gas too I guess .

What all would have to be done if I do decide to install 9.5 pistons?

Remove head/clean/resurface
Clean/Resurface Block
New Head gasket
New Piston Rings / Rehone the cylinders? What if I reuse the rings from the same cylinders that I currently have, would re-honing be needed?


Here is a great read about Compression Ratio vs Boost Pressure

10:1 on 7lbs on a t25 is safe. then throw a 50 shot in it for when u need to say bye bye to that reli bad ass civic

I can source you a UK 10:1 block!!

I am going turbo on a rebuilt 9.5. If you are installing different pistons I would get new rings and hone the cylinders. Also check the clearances of rings.

good read and i also found an arodynamics link u posted up wich was a good one too thank

http://www.sr20-forum.com/turbo/14467-10-1-boost.html

I wonder what percent of efficiency is lost outside of boost between 8.5 and 9.5

Just read up on honing, doesn't seem as bad now: http://www.ehow.com/how_4727370_hone-cylinder.html



NP , which aerodynamic link was that? The one in my build thread? I would stay 8.5 if I cared to make over 300whp, but loosing the low end torque is killer for me .

the one with the prius and the undercarge aro stuff