I will be FI soon and I have a question about tuning to certain boost levels. I want to get a boost controller to ride around (daily driving) on low boost 4-5psi and high boost (racing) 9-10 psi. The question is if I get tuned for 10psi will I have to get it re-tuned or a separate map for my 4-5psi setting. I have the EU waiting to be installed with my kit. I'm figuring it doesn't matter since I didn't go over my initial 10psi tune, but I could be wrong. What do you guys think?

 

Depends on the Boost controller and the tune.....Get a tune for boost instead of RPM and it shouldn't matter. If you tune for RPM you'll be totally screwed. Get a good tune and a solid 2 stage electronic boost controller and you should be good. Are you running 9 or 10 on stock internals? That's kinda pushing it. Be careful.

 

Thanks for the info. I say 9-10psi because I see that most of the ST guys are running 8-9.5psi safely with a good tune. The EM that I will be using is the EU. I haven't decided on a boost controller yet it's between Blitz and HKS. What should I look for to tell me that I have a good tune or what could tell me that I have a bad tune. Thanks

 

Any respectable shop who dyno tunes cars, HAS to use a wideband to read A/F ratios. If they are looking at your A/F ratios they will give you the safest most effective tune. It is truly the only way to know how close to detonating you are. The dyno print outs should have an A/F graph at the bottom to show where they sit through out the RPM range. With those boost levels the fear I would have would not be detonation, rather it would be bending a rod under that much pressure. The compression on the motor is already sky high, and to add 9 to 10 psi of additionally pressure is very taxing on the rods. Even with the best tune no one can keep the rods from bending under the engine pressure.

 

Thanks.. what boost levels do you think are safe with stock internals for a ST? What boost level is your TT (G35) I know the GTR can handle higher boost levels.

 

Safe boost levels for an ST would push 7.5 to 8 psi...that is on a totally stock block, no head gasket or reflash. I run high boost 8.5 and low boost of 5. I have a head gasket Aquamist and a reflash though.....I still worry about the internals on high boost all the time. 8 psi will give you good numbers and be pretty safe with a good tune. That is about the outside limit of the rods under that much pressure. I would also not run 8 all the time (to safe the life of your motor) Spend the extra $100 on a 2 stage boost controller so the engine is not under a lot of stress ALL the time.

 

the rods wont bend under engine pressure, they will bend when the motor detonates repeatedly. The shock cracks pistons and bends rods.

If you want a tune and want to run 2 boost leves, Get a tune for 10 psi and just turn it down to 5 whenever you want. The car will run fine on the lower boost leve. As far as the controller goes, if you want something simple and effective, look into the turboxs dual stage manual. Its a little price (230$ roughly) but its easy to use and works great.

 

+1 that is the easiest way to do it. Not sure of the intergrity at 10 psi or how long it will last even on a good tune. There is certainly a point where the engine just can't take anymore and will start to get frustrated with you for trying to expect too much from it.

 

I won't run higher than 8 psi with stock internals. People start creeping on those boost controllers and thats when bad things happen hehe.

 

Thanks for the advice guys. I don't plan to run at those boost levels daily just for the occasional street race or if I go to the track. I will be at low boost most of the time anyway. I just like the option of being able to adjust my power to my liking or situation. Well as far as boost controllers I might go with a EBC like the Blitz or HKS. I used to have a manual boost controller in my skyline when I lived and japan. The problem with that is that people thought it was cigarrette lighter and messed with it all the time. I know the HKS has a security feature on it to keep your settings I don't know about the blitz though. Happy New Years guys and thanks for the advice again!!