I am wanting to run 9psi but I have read that some people get the new pistons, new head gasget, or nothing at all. at what psi are the pistons recommened?

 

Well, that really matters on what turbo your going to run. wink1.gif a larger turbo at 9psi could be 14 psi on a smaller one.

I do get you point though, 9 psi should be alright. If you want to go safe and get them, that's cool. A lot of money but, it'll keep you on the safe side. I would rather suggest spending the money that would have gone to pistons on a piggy-back like E-manage, or the SMT6. Both are similar with the SMT6 gaining a little more respect as of late.

Keep in mind that with proper tuning and keeping the AFR in check, Tim (Speed-Factor) was running 17psi on stock internals. With only a GSX fuel pump as an upgrade to the fuel side.

 

Don't mislead the dude, Tim was running much larger injectors @ 17PSI. Use a little sense, stock injectors don't support 300whp tongue.gif

PSI is not the only factor that comes into play when buying lower compression. Power does as well. Stock pistons won't hold up to much when you start to get around 12PSI on a medium-sized turbo. I've heard 250whpish numbers of when the pistons start to break with mildly aggressive tuning.

Although forged is not necessarily better, a good forged 8.5:1 compression piston like Wiseco should be able to handle anything a street tuner can throw at it.

You don't want to get too low of a compression piston, even though its safer, running 7:1 or 7.5:1 makes city driving hell. I'm running 7.5:1 on the GSX, and its a slug around town. Give me an open road though, shizzam! tongue.gif

 

if its only a small t3 you might even be able to keep everything stock. anything larger you'll need new pistons to run safely.

oh man, yea definately dont want to run anything lower then 8.5:1 or it wont be streetable.

 

Ok thanks guys I am going to use the smaller turbo eventually so I don't have to mess with the interneals

 

If your going to run a small turbo like a T3, be sure to run an intercooler and to really keep an eye on heat. 10.3:1 stock compression and a small turbo don't mix very well.

 

Yea I am going to buy the speedfactor extream kit probally over the summer, don't like the idea of that hot of air going into the intake

 

Go with pisons OR the head gasket. NOT both. Its not what psi you're willing to run.... its how safe you want to be at any boost level!

 

Running 8.5:1 compression at anything under 9-10PSI is going to make you lose a lot of power. Lower compression = less power. If you put 8.5:1 compression pistons on a stock Tibby with no turbo, chances are that 3 cylinder Geo Metro you see around town would own you. On a Turbo Tibby running say, 6-7PSI, you would lose 10-15whp. Doesn't seem like a lot, but 1PSI is around 8-10whp usually. Thats like running 2PSI less than what you are running.

Running 8.5:1 on a car means you lose low-end drivability on a 4-cylinder. If your using a small turbo, which spools relatively fast, its not so bad in your case. Thats why you don't see 4-cylinder cars running large turbos like T88s, etc. They wouldn't be able to drive around town.