MONTE CARLO "COPO" Monte Carlo SS - Turbosaurus Build (Swinging Dick Racing's c*ck got bent... she bounced a little too high & hard, & came down awkwardly)

[motorheadmike]

My god, the pics of your daughter helping out are priceless. You should be proud of her (I'm sure you are.)


Regarding your headgasket, you'd be better of with the additional layers of the LS9 gasket and not worry about the increased bore of it. The little bit of compression lost is miniscule and not note worthy. And the concern of too large of a bore is an NA issue, not boosted.

Regarding the port job, your setup needs the most possible even flow too all cylinders because of the meth and what you need it to do. You need every cylinder to receive an equal amount of your Mike's Boost Juice, otherwise you're running a cylinder lean and hot. I'd strongly urge you to leave the General's work alone only for distribution purposes only.

My two cents. Take them for what they're worth.

p.s put a 125-150ml meth nozzle pre-turbo to help.

It, the significance of it, will make more sense to her in 10-15 years when she starts intuitively applying these lessons to other seemly unrelated things in life.

Supply chain issues and budget limitations dictated what I got, and when. Could have got some LS9s through Amazon from BTR for the same money... but, got them in October.

As for the heads, balance and distribution: you worry too much. I keep my tunes in the smart range. Cylinder to cylinder variations are higher stock than most would want to believe. And the inconsistency between ports as cast is pretty astonishing... I mic'd the bowls and have a pretty decent eye for detail. I doubt the variation is going to be more than a few CFM port to port.

The water/meth is fully atomized once it leaves the compressor housing. Meth fully vapourizes at 72*F. So it isn't getting any more or less distributed than the air it is suspended in. Water is a bit harder to gauge. It starts to vapourize at 212*F, but begins evaporating before that point (anything above freezing).

All that to say I'm...

Still considering gapping the rings. Hmmm...

 

[Northernregal]

Gap the rings. It's more important than head gaskets on pump gas.

 

[motorheadmike]

Gap the rings. It's more important than head gaskets on pump gas.

The Procharged stock-ring gapped LS2 in my TBSS would like to have a word about that.

Not sure I want to drop another hundo on a cheap gapping tool, ring pliers, and a ring compressor.

 

[Northernregal]

The Procharged stock-ring gapped LS2 in my TBSS would like to have a word about that.

Not sure I want to drop another hundo on a cheap gapping tool, ring pliers, and a ring compressor.

Gap is cheap insurance. Angle grinder and some 4" exhaust seal clamps. You got this improvised solution man.

 

[Tony1968]

Hand file would work for the rings. Not busting chops here but did you find out what the damage was originally? Maybe I missed it.

 

[64nailhead]

Worry wart here - gap the rings or check them. Anywhere from .022 top /.024 bottom to .030/.032.

You do like to live life dangerously 😉

 

[motorheadmike]

Here are the factory ranges for a stock, new, LR4 4.8L:

Top	0.23-0.44 mm (0.0091-0.0173 in)
Second	0.44-0.70 mm (0.0173-0.0276 in)
Oil	0.18-0.75 mm (0.0071-0.0295 in)

That's a pretty broad range, definitely tight toward acceptable with mileage/wear in a JY turd.

For comparison here are the factory gaps for I believe an LS2:

Piston Ring End Gap - First Compression Ring - Measured in Cylinder Bore - Production
0.20-0.41 mm
0.008-0.016 in

Piston Ring End Gap - Second Compression Ring - Measured in Cylinder Bore - Production
0.37-0.69 mm
0.015-0.027 in

Not a huge difference. Lots of high mileage stuff out there getting boost stuffed at it, like my LS2 - which may already be benefiting from the far end of the range plus 160K miles of use. Or just dumb luck and decent tuning.

All this to say I am not opposed investigating and investing the time and effort to avoid catastrophe. So I have the tools enroute... guess I can start knocking out some pistons.

 

[Tony1968]

Those gaps are very very tight. Usually. 004 times bore diameter for stock builds
Going blown it should be minimum .0055 but preferably .006 to .007
So a 4 inch bore would be .024 to .028 top ring.
Every ring manufacturer has specs for their individual products

 

[motorheadmike]

Those gaps are very very tight. Usually. 004 times bore diameter for stock builds
Going blown it should be minimum .0055 but preferably .006 to .007
So a 4 inch bore would be .024 to .028 top ring.
Every ring manufacturer has specs for their individual products

Yeah, I am with you. However, there are lots of direct bolt on forced induction kits for LS and LT engines where no internal modifications are required and lots of longevity to support their use. Again, my educated guess for my failure was extreme cylinder pressure below MBT. A programmed progressive boost curve (with RPM and TPS thresholds/safeties) would have been ideal to prevent the "over boost" condition.

 

[81cutlass]

My 6.0 has unknown ring gap.

Pandora's box!! You don't know until you blow up!