Turbo Tuning......Again!!
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Thread: Turbo Tuning......Again!!

  1. #1
    MIGWeb User
    Join Date
    Jan 2002
    Astra Mk3 Turbo

    Turbo Tuning......Again!!

    As i am still learning i still have a few questions about tuning the C20 LET engine. i apologise for my ignorance and am sorry if this has already been explained before. But i would still appreciate everyones comments.....

    1. Yesterday some of you highly recommended Wallace Performance who do several phase kits going up to about 315 BHP at present. Are these power outputs accurate? with these kits does the compression need to be lowered or is it just for piece of mind sake with these kits.

    2. Do the standard C20 LET injectors run out of puff at about 280 BHP if so how does the Phase 3 WP kit pull power upto 315 BHP

    3. some companies (courtney, top boss performance, interpro) in there 300 + BHP conversions swap to cosworth Managment, injectors etc aswell as changing to a ford turbo etc to get these figures. Top Boss Performance has a cav turbo pushing out 450 BHP is this realistic? what do you think of this approach compared to an upgrade kit.....other than the cost!! is it better?

    4. As a basic rule is it correct that if you raise boost you should lower compression and add a charge cooler/larger intercooler. From everybodies comments i take it that the Wallace performance intercooler is good. Would this be difficult to fit to the Astra MK3

    sorry for the essay!!!

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  3. #2
    MIGWeb User
    Join Date
    Jan 2001
    near Glasgow....
    BMW 540i....
    1. Compression does not need to be lowered altho you may want to do this to gain peace of mind.

    2. The general consensus is the orginal injectors are ok till 280BHP. An uprated FPR is used in the Phase III kit which should extend this slightly.

    As said tho, this is the GENERAL view. No real tests have been done to verify if 280BHP is correct limit.

    3. Pectel Management (which is used in Cosworths) is a better engine management than the Bosch Motronic system. If you really want to go to 400+BHP then it would be advisable to go for a good 3rd part management system which doesnt necessarily mean Pectel.

    The Garett turbos are not needed. KKK turbos are just as good. If they weren't then why would Cosworth use them in the Audi RS4 or Porsche in their own turbo'd cars ??

    The fact being, the UK has always used these methods to upgrade power. Dont mean its the only or proper way to do it. I would rather keep the KKK turbo and uprate it than have to spend hundreds on a custom manifold and ridiculously big actuator used in some Garett turbos.

    4. First thing you want to get is a front mounted intercooler altho I dont know if this would fit the MK3 Astra easily. If not you could get a custom intercooler (like me) or go for the chargecooler.

    The chargecooler gained me around 14BHP and 18lb/ft whereas the intercooler gained me 35BHP and 35lb/ft.

    Lowering compression is ok but you do lose some driveability at the low RPM end.

    Sort the car with proper cooling first.

    Hope this helps a bit
    The Cav-Turbo Resource:
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