I currently have CP 8.8:1 compression pistons with stock sleeves and was wondering what kind of power gains I would get switching to 9.5:1 with my setup, GT35R /T4 at 16psi? Would it be noticeable? I could have the 9.5:1 pistons put in for $1,000. I am not quit ready to fully build my motor but I could spend a $1,000 or so to keep me satisfied until then.

Or is there any other mods you would do for $1,000 to increase power that does not include fully building my motor? My current mods are listed in my sig.

Thanks

 

how about spending less than a $1000 and getting it dyno tuned for higher boost? you can make the same power while in boost and spend even less... and go for the higher CR pistons when your rebuilding?

or maybe look into methanol or nitrous injection into your intercooler...youll still need to tune.

 

At least in the V8 world that I'm used to, 1 point of compression, everything else equal, meant about a 2% increase in power. This is for naturally aspirated. The idea of raising comression is to match the rest of the setup. You want the cylinder pressure to be optimum for the profile of camshaft, flow of the heads, and other supporting parts you are running. I'm just giving you the theory as I know it. I'm not going to try to make any guesses on numbers.

 

With the setup I just sold today (T3/T4), I have had my car on the dyno for well over 15 hours and several hours street tuning over a few month period and have already paid for all the tuning that will be done with my new setup so I am covered in that area.

As far as nitrous, I don't think that would be a good choice with stock sleeves and 16psi.

And with raising my compression, I am wondering if do that for $1,000 would be worth my money or if there is something else that is a better bang for my money.

 

I would imagine that buy raising the compression to 9.5 over 8.8, will result in more usable low end torque. I think that spending the $1000 to do this on new pistons is probably the best and safest way to gain more power. You may have to drop down a psi or two but I believe in the long run you will have more power.

 

How about running methanol/water injection so that you can exceed 16 psi on pump gas?

I think you'll be VERY disappointed with the $$ you'll spend to change pistons/sleeves.

Tim

 

I don't know much about methanol/water injection. Care to explain ?

 

It's supposed to allow you to run much more boost and timing and hence make more power without knock. The Grand National and many Pontiac Grand Prix GTP guys sweat by it. Here are some links.

http://www.aquamist.co.uk/
http://www.coolingmist.com/categories.aspx...on=set&res=1280
http://www.snowperformance.net/
http://www.campbellautomotive.com/mod.php?...u=22&page_id=39

Tim

 

It is nice to have and does work, but to me it's basically like running NOS. You have to continuously fill the bottle up when empty and I myself don' t like having to do something like that all the time just for a little added power. If I were just using my car for the 1/4 mile track then I'd probably do it. But not for the street.