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Turbo Sizing for Rear Mount

Old 04-11-2011, 08:12 PM
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Default Turbo Sizing for Rear Mount

Hey guys

Been doing research and seems like the more reading I do the more confused I get. So im looking for a good place to start.

What would be a good turbo for a rear mount on a 350 LT1? Its an M6, and I would only want to run a small amount of boost 7-8psi and try and keep the stock bottom end alive.
Old 04-11-2011, 08:33 PM
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Zombie who's got a St80 rearmount said he's running full 3". If your staying on the small side I'm sure 2.5" will work.
Old 04-11-2011, 09:13 PM
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It already has LTs and a Cam, so Im still looking into what I should do. I may wrap the exhaust and just deal with a little big of lost spool time so I dont have to do another Header swap, but If the cam ends up not being a good match then Ill just put manifolds back on when I swap the cam out.
Old 04-11-2011, 09:15 PM
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I have an LT1 rearmount and tried different turbo's and I would recommend a Master Power T70 with a .68 Turbine. It is waiting to spool at ~1800 RPM on interstate and develops good power quickly.

Go with 2.5" to the turbo and stock manifolds are fine. I would recommend a T4 flange that way you can change to the .96 shell when you want higher boost and power. The .68 will pull to 6k and probably good for ~500 whp and spool quickly for the M6

Good luck

Call modular Turbo and talk to Rob thats where I got mine
Old 04-11-2011, 09:21 PM
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Originally Posted by TAEnvy
It already has LTs and a Cam, so Im still looking into what I should do. I may wrap the exhaust and just deal with a little big of lost spool time so I dont have to do another Header swap, but If the cam ends up not being a good match then Ill just put manifolds back on when I swap the cam out.
I deleted the wrong post

What cam is in the car now? Do you have a turbo now?

Last edited by boosted LT1; 04-11-2011 at 09:29 PM.
Old 04-12-2011, 07:22 AM
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Originally Posted by TAEnvy
Hey guys

Been doing research and seems like the more reading I do the more confused I get. So im looking for a good place to start.

What would be a good turbo for a rear mount on a 350 LT1? Its an M6, and I would only want to run a small amount of boost 7-8psi and try and keep the stock bottom end alive.

Do a search for Zombie chronicles. He's one of the gurus of rear mounts and has a very long thread with different ideas he has tried in the past. He and every other rear mount guy will tell you to ditch the long tubes and put manifolds on. I have read up on just about every thread on this board concerning rear mounts until I decided to go front mount a few weeks back.
Old 04-13-2011, 11:45 AM
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Originally Posted by TAEnvy
It already has LTs and a Cam, so Im still looking into what I should do. I may wrap the exhaust and just deal with a little big of lost spool time so I dont have to do another Header swap, but If the cam ends up not being a good match then Ill just put manifolds back on when I swap the cam out.
The lag difference between headers and manifolds is anything but "little". Leave the cam, swap the manifolds, don't run anything smaller than a q-trim turbine with a .81 a/r. 70mm will be fine for what you are after, but it needs to have the proper exhaust wheel and turbine housing or power will fall off hard after 5000 rpms. Make sure your valve springs are up to the task as well if you have a high lift cam.
Old 04-13-2011, 12:58 PM
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The F1-68 turbine in the TC's is just right for what you want, i would do one of those way over a MP turbo
Old 04-13-2011, 02:03 PM
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Originally Posted by TAEnvy
Hey guys

...I would only want to run a small amount of boost 7-8psi and try and keep the stock bottom end alive.
Your designing a rearmount turbo and keeping the stock bottom end is stupid ...the stock bottom end of an LT1 won't hold much boost and won't even hold low boost for long. What is ok for the stock bottom end will be terrible when you build the engine after the piston lands break.

I know I had a stock LT1 and 400 RWHP is pushing your luck but mine held until I put together a forged motor. Put 7-8 psi on a cammed LT1 and you are out of the range for any detonation--meaning you will break the ring lans if you have much of a cam.

How much power do you think the stock pistons in an LT1 can take? A friend made ~500 RWHP and it held until he made one mistake tuning and hit detonation...

Boost and stock pistons mix like oil and water

Last edited by boosted LT1; 04-13-2011 at 02:14 PM.


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