GMT900 6.2 PPV Build Log

[ls3_ppv]

Hi, I am car enthusiast or perhaps a professional idiot. Either way, I have a 2010 Tahoe PPV and I wanted to start a build log to share with the class my journey with this vehicle and perhaps shed some light on GMT900 ownership in the good and bad ways. I believe the forum format lends itself well to a build log and while I have had the PPV for a minute now, its in a place where I want to share the process.


In June of 2021, I was having some issues with my daily driver. At the time, I needed something with a hitch and decent tow capacity. Having two dogs to haul around and needing a hitch makes an SUV a logical choice for me. I happened across a dark gray PPV that was in decent shape exterior-wise with a very clean interior AND an LS3 already dropped in it. This really scratched that itch for me to have something fun and unique to daily. With an LS motor even souped up should make for a reliable daily. Here it is the day I bought it and brought it home.



Plasti-dipped stock wheels aren't my favorite but I bought this car for the spec and drivetrain. We can fix that later...

 

[ls3_ppv]

With the chassis having nearly 200k miles on it, a refreshed motor already dropped in and running was a welcome part of the purchase deal I made. Seller had pictures of the work and enough receipts that I was convinced and drove out of state with a buddy to bring it back home.

Proper LS3 shortblock w/flat top pistons
BTR 225/238 cam
BTR pushrods
BTR springs
LS9 head gaskets
Speed Engineering headers
Tick performance oil pump
5364 heads
Circle D converter
Upgraded kolene clutch pack
Corsa intake
AFP poly engine mounts
ARP head studs
Spintech mufflers

PPV goodies included:
Dual batteries
Uprated alternator
Integrated wiring for accessories throughout
Rubberized flooring
140mph certified speedo
Transmission temp readout in the cluster
26gal fuel tank
Lowering springs
Power steering oil cooler
no third row, no onstar and no tow mode button

But some of the cop red/white lights still worked so that's cool. This PPV only got a 3.08 rear gear open diff housed in a basic chevy 10 bolt rear end. I'd later come to realize how a hog ass cam, high stall coverter, LONG highway gear and heavy vehicle are not well matched together.

Documentation on the GMT900 PPV: LINK

Seller advised me that the 6L80 needed a tune, engine needed an upgraded valley cover and better catch can. (Oddly specific recommendations, hmmm...) He tried to do a burnout but with an open diff it just boiled one tire. I paid for the vehicle and headed back home 4 hours away without incident



Sweet idle video seller sent over:

Me behind the wheel somewhere near Atlanta on the drive home

 

[Joseph Garcia]

Very nice project truck. Time to put a blower on it.

 

[Marky Dissod]

This PPV only got a 3.08 rear gear open diff housed in a basic chevy 10 bolt rear end.
I'd later come to realize how a hog ass cam, high stall converter, LONG highway gear and heavy vehicle are not well matched together.

Time to put a blower on it.

Instead of a blower, far more value would be achieved as follows:
3.73 and whatever limited slip of your choice (3.42 if the highway is that much more important to you than metro / urban / city)
NORMAL stall converter (a 6L80 with 4.03 1st gear makes a higher stall converter dumb in the context of better gearing)
Shifter with 'Tow / Haul' mode, for 2 different shift modes after you get it tuned, instead of just the one (who doesn't want two shift modes?)

Before you put the engine in, is the LS9 gasket thicker than a normal (non-supercharged) gasket?
Because if the gasket is thicker than normal, not only does it take away from the quench and RAISE the minimum safe octane,
it also makes that hogass cam even more ill-suited to your heavy vehicle than it already is.

I'll always prefer an SSV. That said, your PPV is proof that GM should have put a 6.0L or 6.2L in every PPV.

 

[kbuskill]

Instead of a blower, far more value would be achieved as follows:
3.73 and whatever limited slip of your choice (3.42 if the highway is that much more important to you than metro / urban / city)
NORMAL stall converter (a 6L80 with 4.03 1st gear makes a higher stall converter dumb in the context of better gearing)
Shifter with 'Tow / Haul' mode, for 2 different shift modes after you get it tuned, instead of just the one (who doesn't want two shift modes?)

Before you put the engine in, is the LS9 gasket thicker than a normal (non-supercharged) gasket?
Because if the gasket is thicker than normal, not only does it take away from the quench and RAISE the minimum safe octane,
it also makes that hogass cam even more ill-suited to your heavy vehicle than it already is.

I'll always prefer an SSV. That said, your PPV is proof that GM should have put a 6.0L or 6.2L in every PPV.

Just curious, why/how would a thicker head gasket "RAISE the minimum safe octane"?

A thinner head gasket would raise the compression ratio and require higher octane, wouldn't it?

 

[ls3_ppv]

Before you put the engine in, is the LS9 gasket thicker than a normal (non-supercharged) gasket?

Too late, the 6.2 was in it before I bought it. LS9 head gaskets are thicker than normal LS head gaskets. I didn't get the machine shop build sheet on this 6.2 rebuild from the seller, its hard to say what effect the LS9 head gaskets had. Block could have been decked, heads could have had a lot of material removed too. It ran and drove me home.

 

[Marky Dissod]

Just curious, why/how would a thicker head gasket "RAISE the minimum safe octane"?
A thinner head gasket would raise the compression ratio and require higher octane, wouldn't it?

Little known fact:
LS/Vortec combustion chamber shape depends on the piston crowns sticking out ever so slightly above the bore at Top Dead Center.
Reducing the compression with a thicker head gasket reduces the effectiveness of the 'quench'.

Our combustion chamber designs are made less effective by lowering the compression with a thicker gasket.

Quench: Unlocking Performance Squished Between the Piston and Head

Quench is the clearance between the piston and cylinder head at TDC. It can affect engine effeciency and performance, if you truly understand it.

www.enginelabs.com

 

[kbuskill]

Little known fact:
LS/Vortec combustion chamber shape depends on the piston crowns sticking out ever so slightly above the bore at Top Dead Center.
Reducing the compression with a thicker head gasket reduces the effectiveness of the 'quench'.

Our combustion chamber designs are made less effective by lowering the compression with a thicker gasket.

Quench: Unlocking Performance Squished Between the Piston and Head

Quench is the clearance between the piston and cylinder head at TDC. It can affect engine effeciency and performance, if you truly understand it.

www.enginelabs.com

So you are saying that the thicker head gasket, reducing quench/compression, will be less efficient at keeping the engine from detonation and therefore require higher octane to compensate for the increased chance of detonation, if I am understanding you correctly.

 

[ls3_ppv]

I had the PPV for about a month before I started to mod it. I found it needed some new front brake pads and well why not just do new calipers? Its got 200k on them, probably original anyways. From these forums I discovered the 4 pot bolt on brake upgrade from the 2019+ silverados. I ordered a set, powdercoated them and put them on along with a new oem brake booster. Very nice improvement in pedal feel, definitely more confidence inspiring than the "heavy duty" gmt900 ppv brakes. Not bad for less than $500 all in!

2019+ 4pot brake upgrade

Brake Swap List
Caliper Front Right 13536580
Caliper Front Left 13536579
Splash Shield Left 84080138
Splash Shield Right 84080137
Front Rotor 13514522 ....13.5" rotor
Front Rotor 13514522
OEM Pads 84847749
Disc Brake Pad Pin Kit 13513399
Disc Brake Pad Pin Kit 13513399








As I previously mentioned this thing was on tow duty, brake upgrades are always a good idea for a tow pig.


And towing a trailer to go collect another shitbox.

 

[ls3_ppv]

I sadly cannot find pictures of the exhaust that came on the PPV but what a pile of crap it was. I smelled fumes big time from day one driving it anywhere and initially chalked it up to the headers, aftermarket mufflers and piping. Turns out the flanges at the collectors of the speed engineering headers were chopped off for some reason and the previous owner had some crazy ideas for booger welding in a crossover pipe and the spintech mufflers. The chopped off collectors were fiberglass wrapped after booger welded to try and get them to stop leaking on the top side of the collectors because the PO welded the entire exhaust together in the car. There were no sections and I realized any further exhaust mods meant cutting out what I had and starting over. This was the first indication that the previous owner was not the performance guru he was trying to convince me that he was.

Well its getting into the end of August now and I wanted to take this thing to LSfest East. So I chopped off the section after the header collectors, swapped the spintechs out for some magnaflows to quiet it down and take out some rasp. Here you can see the spintechs with the turndowns have been replaced with some straight tips off the magnaflows. I also replaced the rear trunk emblem that was missing and hit it with a few coats of black and clear. Off we went to Bowling Green, KY!




I get a timeslot for the dyno and got some data on where the car stood.

I though this seemed low for a 420bhp 6.2 with a big cam but maybe that 6L80 really is sapping a lot of power. I expected at least 400whp with the cam and exhaust.



Cleet even made an appearance at this LSfest, I was stoked!


At LSfest, I approached one of the guys at the HPtuners vendor tent and had some questions. I knew the PPV was running like shit, would die sometimes coming to a stop and had some general drivability issues. Guy asked if the PPV was at the campground, grabbed his laptop and walked over. A literal quick & dirty campground tune would be flashed and run on this vehicle for about 10 months more. Drivability and shifting was much improved, still only 6-7MPG though. Yikes! But I craved more, LSfest gave me some ideas that i couldn't shake and they were followed by some poor decisions. Ideas were great but the execution was bad.