9.0:1 questions or go 8:3.1

[AK_4g63t]

I bought a set of Wiseco 9.0:1 pistons along with a ton of other things when I first got my car with a blown motor. I'm now about to start the build again (1st time some things didn't go so smoothly) and I researched 9.0:1 compression and there are still some unanswered questions. In the future I want to run the FP3052 or FP3065 and I don't know if the higher compression pistons are going to do me more good than bad. This car will be a street driven car that will see the track only a few times a year (since it's 600 miles away). The bad thing is we only have 90 octane gas up here. I want to do a methanol set-up in the future. I guess my real questions are: (plan on 400whp)
-at what psi will I start to see knock with 9.0:1 compression?
-what octane will I need to run at 5psi, 10psi, 15psi, 20psi, 25psi?
-right when i get this car driving (everything stock except internals) will it be knocking with 90 octane at the stock turbo psi?
-should I sell the 9.0:1 and go with the 8.3:1 pistons instead?

All of everyones input would be MUCH appreciated!!! I just don't want to have to run my methanol kit 24/7 just to boost taking off from a stoplight because the kid in the stocker wrx next to me thinks he has something special...
-Donny

 

[95tsiawd6blt]

actually shep runs 70 psi

 

[GVR4592]

actually shep runs 70 psi

Since when?

 

[tkelly27]

http://www.shepracing.com/racecar.php

Says 55 to me.

low compression FTW!

 

[GVR4592]

http://www.shepracing.com/racecar.php

Says 55 to me.

low compression FTW!

http://www.dsmtuners.com/forums/showpost.php?p=151074692&postcount=62

I'd say it's high compression FTW!

 

[AK_4g63t]

Alright guys... I'll go 9:1. If Shep runs 10.5:1 at 60psi+ then there's no reason that 9:1 at 25-30psi can be that bad. My DSMlink should be here before the motor is finished so I'll be able to tune and watch for knock. I also am buying a new knock sensor and a Greddy profec B spec II & turbo timer tonight. I'll run this set-up at a low boost with my sidemount and stock fuel system and I'll add the FP3065, Dejon Tool big race interooler, 1000cc injectors, and all of that good stuff after I get some more $$$. Thanks for the help everyone and I'll let everyone know how it's going. GVR4592, thanks for pushing the issue of keeping the high cr.

 

[tkelly27]

"Asa general rule of thumb a methanol car will run better with higher compression."

Lower compression stays FTW when you're running pump gas, at least as far as I'm concerned

You shouldn't have any problems with 9:1 and a good tune though.

 

[Chriztopher]

I was in the same position as you. I bought a 2G in need of a rebuild. I went 9.5:1 but I have a high power goal and want a street car. Broke it in on 93 octane pump gas. No issues so far. As the name of the website implies it is all about the tune. I made one mistake tho…The real forehead slapper is that I bought pistons and rods but did not do a stoker kit!! I was such a rookie.

Since this thread is mostly about fuel and tune… Next, I am going to tune it for E85 and get the AEM 2, which has a sensor to detect the fuel in the tank and adjust the tune to the fuel type on the fly. I will be applying for the alternate/flex fuel tax credit and make 10-15% more power. This way if I ever end up on E in bum f*** nowhere with a car tuned for E85, no sweat I can go pump gas and still be threat to V8s all the way home.

 

[JusMX141]

Did we just go back in time?