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2015 GMC Sierra "Ol' Bue" Sleeper Turbo Build

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Posted (edited)

Just an updated pic with the exhaust removed.


** There's something hiding under there behind the axle **



Edited by Regan Menzies
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Onto the turbo portion. Here's where it gets really fun... Many hate on rear mounted turbos but hey to each their own. I prefer to have the heat out of the engine bay and no clutter in case I need to work on something. A few random parts.












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Just about done with turbo. My divorced oiling system is complete, purged and tested with constant 40 psi.
Ran out of titanium wrap and had a extra spool of fiberglass wrap for the muffler. Figured why not.. Now I just have to coat it all with the black silicone coating once it dries to help protect it.
I just have a couple more welds to finish the other half of my 4" piping from the turbo back to the 5" tip and pipe my wategate back into the exhaust after the turbo. Then weld my MAF & wideband bungs. Then back to the dyno.




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Fitment of the 4" piping was pretty tight but the spare tire still fits just like factory. I kept the drain simple by making it gravity like any front mount turbo. Can't go wrong there. No need for check valves or 2 pumps.




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2 Breather tanks and 1 catch can setup. May seem overkill but it beats not being good enough!
1/2" hose to each valve cover.
1/2" hose to 2019+ oil fill tube w/ an10 180 fitting.
3/8" hose to gutted PCV valve tapped with a 1/4" npt 1/2" barb.





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Turbo setup is done for the most part... few things in the tune need dialed in. Completed the 4" stainless exhaust with 2 mufflers and 1 resonator, all coming to a 5" tip. I wanted her quiet and it surprised me how quiet it is!



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Very nice build.  I have the same TSP cam in my L86 with some porting on my heads.  I hope to have boost soon but I just had to pull the engine mysellf from two spun rod bearings.  So I had to spend my boost money on pistons and rebiulding the engine.  It's almost back together.  It's just hard to get parts right now.


But hey now I have a new crank with Forged Diamond pistons on stock rods.


I'm curious how you like that cam with boost?

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  • 2 weeks later...
Posted (edited)
On 3/30/2022 at 2:54 PM, pokismoki said:

cant wait to see your dyno numbers..


With the VS Racing Billet 75/65 turbo, it made 505 WHP at only 7 PSI. The graph showed how restrictive the turbo was in the higher RPM's due to the smaller turbine so I swapped the turbo out for a On3 Billet 78/75. I plan on putting the truck on the dyno again this weekend.

Edited by Regan Menzies
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On 3/30/2022 at 2:54 PM, pokismoki said:

when will you dive into the transmission?  I hear the 8 speed is the hot set up if you can source one... otherwise you got some upgrades and beefing up to do on the 6l80

I don't plan on doing transmission work for now so I am keeping it in its safe limits around 500 WHP. I plan on keeping the 6L80 for now. Other than the huge cooler, external filter and the lower temperature thermostat, I'm going to leave it alone for about a year or so. 

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