GMT900 6.2 PPV Build Log

[ls3_ppv]

April 2024, the PPV is chugging along. I am working on the back and forth revisions and datalogs with the remote tuner and trying to iron out some minor shifting issues during various throttle loads. But of course, you can't sleep on the deals. I was crusing FB marketplace and happened upon a VSracing 78/75 billet gen2.5 series turbo. .96AR T4....well uhh thats exactly the upgrade this PPV needs. That 64mm ebay turbski is choking this 6.2 motor out in the upper rpms, guy wanted $200 for it with less than a dozen 1/4 mile passes on it before he upgraded. He already tapped it for a boost reference push lock fitting at the outlet and oil fitting came with it. Even offered to deliver it to me, buddy how could I not!?

So anyways, its time to get serious about some power...



Also a good time to heat wrap that downpipe. This stuff really sucks to work with but its a big difference in under hood temps.


I also take a quick peak under the valve covers and make sure things aren't going sideways on me again. She's mint bud!

 

[ls3_ppv]

Retune the PPV and with a new motor and turbo I just want to rack up some miles on this thing. We head back to LSfest again in September 2024 as the PPV has been trouble free since April and about 8000 miles now. Some interesting match ups on the track at Beech Bend raceway lol


PPV makes the trip there and back but I'm noticing that the oil pressure is tending lower. About 18psi at hot idle now when it used to be closer to 30psi. I change oil and send out for a blackstone oil analysis, lead levels are slightly elevated.... for tracking here were lead levels all 8000 miles.

Mileage / Lead PPM
300 / 5
2200 / 2
5211 / 3
8039 / 7

Blackstone flagged the 5ppm and 7ppm reading which indicated it was higher than universal averages and we needed to keep an eye on it as lead is from bearings.

Disaster strikes....again in December 2024. Different failure mode, same headache. Before I pull the motor again its confirmed with a mechanical gauge. 14psi cold idle, 4psi hot idle.


Out she comes, yea PHQ is right lol.


Camshaft bearing #4 has left the chat...


I also mic'd out the oil clearance on the other bearings and they are all above the service limit of .005" and consensus is you really want something in the neighborhood of .002-.003 on new cam bearings. A little self-clearancing by the lifter on that #4 bearing.


I am not going to lie, I am pretty disheartened at this point. I consult with the machine shop on wtf has happened here but at 8000miles there is no warranty. If you have been following along, you will remember that the only thing I reused was the camshaft and while its journals were the proper size I didn't trust it any more. Also found that the rear oil galley barbel slid aft and an O-ring on it had failed. A momentary drop in pressure when this happened I suspect caused the mayhem. This oil pump was fighting for its life to save this motor, that camshaft bearing sliding aft but staying partially in place allowed oil to keep things lubricated enough to prevent a bigger disaster. Cylinder bores, lifter bores, all bearing surfaces otherwise have zero damage. I'm not excited to spend two Christmas seasons rebuilding this turd, its certainly not my preference. But the story doesn't end here...we must keep going!