Turboed 408 Questions ??
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Turboed 408 Questions ?? Well, fixing to pick up a 98 Z28 with a built 408 with a T76 turbo. I've been reading up on the subject of forced induction for a few days now. I know I still have a lot to learn (first turbo car). What I have been reading so far is that a T76 turbo on a 408 motor can start giving you back pressure issues once going over 600+ HP. Is this true? (T88 has been recommended)
My goals for the car: Build a reliable/streetable 700 - 750 HP car (RPM range 3500 - 6000) with at the max 15lbs boost on pump gas.
So, will I be able to reach my goals with the current T76 turbo that is on the car? Or will I be pushing it?
Right now as the car sits, I have a lot of work ahead of me. Stock cam, stock heads, stock rear, and the stock 4L60E 3/4 clutch packs took a dump. Just trying to plan out my future spending with this car and try and formulate a time line. Thanks a bunch. I'm sure I will have tons of more questions before this build is over.
Patrick
My goals for the car: Build a reliable/streetable 700 - 750 HP car (RPM range 3500 - 6000) with at the max 15lbs boost on pump gas.
So, will I be able to reach my goals with the current T76 turbo that is on the car? Or will I be pushing it?
Right now as the car sits, I have a lot of work ahead of me. Stock cam, stock heads, stock rear, and the stock 4L60E 3/4 clutch packs took a dump. Just trying to plan out my future spending with this car and try and formulate a time line. Thanks a bunch. I'm sure I will have tons of more questions before this build is over.
Patrick
With your goals, if you stick with them, you will be ok. I am in the same boat as you but I am not going for max effort and mostly street car. You should be able to put down 700-750rwhp no probelm with a well set out build. Back pressure will be up there but if you don't try to max it out you should be ok. you can always upgrade the tubo later but for the street and your goals you'll be jsut fine. You would also make some nice time slips too don't forget!
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Thanks Websy! I was hoping someone would say I was okay for now. My main goal is to get the motor setup for the turbo. Right now with stock heads/intake/cam I'm sure its bottlenecking a bit. Maybe get the suspension/rear/transmission setup for the power too before I turn up the power. Right now, its setup on 4psi. Thanks again.
Patrick
Patrick
With that size turbo and running through an auto, I think you will be close to your goal if you do some good flowing heads (ETPs or AFRs), a decent size cam and a good convertor. Good luck man.
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Reading up on heads now. The unfortunate thing is not a lot is known on this build. I'm pretty sure it has stock 6.0L heads on it. Tons and tons of research to come. Whew! Already have a built 4L60E in mind (want to keep overdrive for street use) and I'm pretty sure I'm going to go with a 9-in. Car as 3.66s in the rear now.
Last edited by Pat-Man; Jan 11, 2008 at 04:17 PM.
I'd definetly change the heads and get some dual springs, etc. 6.0 stock heads will be fie for FI. They flow nice and are cheap. I'd also get a cam, doesn't have to be custom or the best. A basic blower cam will do and had proven itself many times. In my 408 I will be running a comp 224/228 .581/.588 114LSA for more than one reason, one being I already had it. If you do some MORE searching, since you said you already are, you'll see that its hard to pick the perfect cam for a turbo application. Many use small ones, easy on springs, street friendly and will still make gobs of power. For you and for me a basic cam like I mentioned should do the job. Speed Inc has used the 224 a few times I've seen in 402/408's for one. If you are worried about it than call up a few shops and get a custom one grinded. I promise you that they all will have different answers though as it would be a different story if you were running a blower cam.
