please help 408 turbo ?????

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May 12, 2007 | 09:50 PM

turbo408stroker

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From: ocean city

please help 408 turbo ?????

i am installing a hp stage 3 76mm turbo kit on a built 408 with 75lbs injecters with a sump tank with new lines magna fuel pro tuner pump rated to 2000hp fuel rails i will be using ls6 intake and stock 6.0l heads and a duel nozzel elky control meth injection kit my comp is 9.0:1 what kind of power sould i be able to get out of this setup trying to get to run 20 lbs of boost at the most

May 12, 2007 | 09:53 PM

bboyferal

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That's a twin kit, right?

May 12, 2007 | 10:08 PM

turbo408stroker

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From: ocean city

no single kit

May 12, 2007 | 10:35 PM

Ed @ Late Model Speed

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I'm currently finishing up a similar setup on a customers 408 Corvette, with a custom single turbo setup using a T76. Our goals are 12PSI and 700-750HP.
I think 20 PSI out of that setup may be a little too much for the single T76 to supply. I think you may need to move up to a T88 to see 20PSI. I would have used a T88 on this one, but we already had the T76.

Hope this helps,
Ed

May 13, 2007 | 12:04 AM

Turbo Tech

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A T76 at best if the turbo system/intercooler can support it should be able to support 700 to 750 rwhp. With the meth another 50 to 75 rwhp.

May 13, 2007 | 09:55 AM

NA$TY-TA

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Quote:

Originally Posted by turbo408stroker

no single kit

Never gunna get there with 408 cubes....
I couldnt do it with 38 cubes less then you....
I told the same thing to a local buddy of mine with a 408 and 76mm turbo and they couldnt even get to 11 psi.... so he's going bigger now...
For a 408 id say 91mm would be a perect match...
Meths gunna help with the fueling some but to get those 75# injectors to push enough fuel your going to need to Boost ref the FP Reg. and let FP rise with Boost to make them larger... Cause 20psi on a 408 will be around 1K HP.

Kyle

May 13, 2007 | 10:03 AM

engineermike

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Quote:

Originally Posted by NA$TY-TA

Your experience is definitely WAY different from mine. We made 930 hp on an engine dyno with 377 cid and a T76 at 18 psi and there was more left in it. Also, I'm at 17 psi from a T76 on my 388 with the 40 mm wastegate WIDE OPEN (no spring) making 700 rwhp through a TH350 and loose converter. I've been as high as 22 psi on my 388.

I'm not sure what was wrong with yours or your buddies.

Mike

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May 13, 2007 | 10:07 AM

engineermike

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. . . and to the thread starter. . .

Just make sure you minize piping losses in the setup. A 3.5" downpipe, 3.5" or 4" exhaust, no cats, straight through muffler (like Magnaflow) would help keep backpressure/boost under control. Also, make sure you use little or no piping upstream of the compressor, a huge air filter, 3" mandrel bent cold side piping, an intercooler with a low dP, etc. . . All these things will improve the backpressure/boost ratio, which is usually a problem on these large cid, T76 combinations. On our 377/T76, we optimized all these things and were getting 18 psi boost and 26 psi backpressure, which is outstanding considering the turbo and cid.

Mike