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TurboKraft TurboKraft is offline
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Join Date: Mar 2005
Location: Phoenix, AZ
Posts: 2,540
Originally Posted by matty74 View Post
So I could run 1.0 bar boost on a twin plug 3.6 efi, 8:1 CR on 98 octane gas? Could I go a bigger turbo charger? like a T40?
With a good intercooler and good tuning, yes.

GT40R -- sure you could, if you're after even more power. And with 8.0:1 compression, I wouldn't worry about this engine being lazy.
Un-cork the B&B headers by modifying (enlarging) the secondary pipes and make them flow smoothly into a divided T04 flange, and add 2 small external wastegates, one for each secondary. Now you have twin-scroll headers (no not equal length, but we're not starting with expensive new ones, either). This is similar to what we're doing to Tom's 1984 930:
2010: An EFI Hot Rod Odyssey

Lest you worry about a GT40R spooling up late, either, we had a worn-the-#$%&-out 1978 930 racecar come into the shop once. Tired 3.3L 7.0:1 compression (or less), GT2 cams, Carrera manifold, poorly ported 930 heads, old EFI, twin-plug 964 dizzy. Big intercooler, but really poorly plumbed, lots of backpressure. GT4088R with largest A/R turbine. Dump pipe. Cobbled headers in an attempt to convert to T04 flange, with major restrictions. Doesn't make desired 17psi boost until 4,635rpm, and creeps up to 19.5psi. 485rwhp/458rwtq, and feels like it's going to blow any second.
Fast forward a few weeks and we've built new twin-scroll headers with twin wastegates, re-plumb the inlet & outlet of the intercooler, add a race muffler to quiet it down, and minor ECU re-tuning.
Same worn out engine now makes 515rwhp/528rwtq at 17psi, no more boost creep.
And full boost by 3,500rpm.
Chris Carroll
TurboKraft, Inc.
Tel. 480.969.0911
email: -

Last edited by TurboKraft; 05-17-2010 at 05:02 PM.. Reason: posted before finished typing (ctrl+enter)
Old 05-17-2010, 04:19 PM
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