LS3 Head gasket lift (Boost)

[Frankshaft]

Once you have the head sealing figured out, it will break a piston. I have a ctsv project that had small pulleys and an e85 tune that just did that. It made something like 660 at the tires.

[Frankshaft]

I would suggest biting the bullet and buying the custom aged 625 studs. They tq and clamp harder

Custom aged? Like beef? I can only imagine the price. I feel violated for what I paid for these ARP's already. 350.00 for 20 studs is ridiculous to me. But I just want this thing fixed.

Yep, just like beef. 45 days dry aged in a room lined with hymilayin sea salt. They are expensive, like $700, but they help

[CGT]

Yeah, ARP2000 studs & fresh gaskets, give the heads a light skim too.

Ramp the boost in a little slower till you're sure it's good, or reduce timing till after peak TQ - either will work, which one better suits the combo & use is up to you.

Thank you

[CGT]

Once you have the head sealing figured out, it will break a piston. I have a ctsv project that had small pulleys and an e85 tune that just did that. It made something like 660 at the tires.

I dont put much faith in chassis dyno's. But my car made 760 SAE on the chassis dyno I use when it was at 12lbs. Havent been able to redyno since the extra 3 or 4lbs because ive been fighting problems one after another since. It a 6spd manual and its not happy in anyway.
I dont think the clutch will survive in 4th gear on the dyno

[CGT]

I would suggest biting the bullet and buying the custom aged 625 studs. They tq and clamp harder

Custom aged? Like beef? I can only imagine the price. I feel violated for what I paid for these ARP's already. 350.00 for 20 studs is ridiculous to me. But I just want this thing fixed.

Yep, just like beef. 45 days dry aged in a room lined with hymilayin sea salt. They are expensive, like $700, but they help

Resized_20180209_203807.jpg

Im just gonna try aging my 350.00 studs myself

[peejay]

I wonder when we might start to see head surfaces ground concave near the bolts, for more even clamping.

[pdq67]

A , f**, "better", idea!

4-bolts per cylinder with, "MAYBE", two little ones, Seems like the old 5-bolt spacing per cylinder held up pretty good.

Or am I missing something?

And what's the strength spec differences of stock(?) 300M compared to ARP's 2000 and 625??

pdq67

[user-17438]

Seen this a lot with Subaru's, on E85 you can put enough timing into them that even without det/preignition they'll lift the heads, seal up again straight away after a pull.
It's not a tune issue, tune can be perfectly safe from a combustion viewpoint, just the pressure rise with the extra timing that E85 allows is too much for basic head clamping.
Fast pressure rise = HP/TQ, not a bad thing, just gotta hold them heads down!

With the new billet subi cases & using ARP2000 14mm head studs the tune can be pushed even further coz the heads don't lift, there has been no adverse affects (other than faster boost reponse & a buttload more midrange TQ) & teardown says everything is happy, it was never a tune issue, just a materials strength issue.

The next limitation in the line seems to be the head castings, they do lift/distort between the studs, but once the block integrity & clamping was sorted the threshold where the head castings are the limit became much higher. For drag racing it is now possible to push 40psi/1000+hp through them, but for endurance racing the reliable limit seems to be around 34psi & 850hp without going to exotic gas rings or other fancy sealing solutions.

You probably won't get away with just swapping in the studs, once the gaskets have crabon tracked they'll keep leaking under boost.
But thin head gaskets are a plus, not a minus - the less head gasket surface area exposed to combustion the better.

So how is that not in the tune? If he is running too much timing or too lean. Screw what the o2 sensor says. Or if there isn't detonation. If you can tune the problem out it is clearly a tuning issue.

[user-23911]

Look at a diesel engine.

Much greater peak cylinder pressures, typically 18 bolts on a 4 cylinder head as opposed to the normal 10.They wouldn't make them like that if it wasn't required.

The one big advantage a SBC has over a SBF. The SBF has 10 bolts per side as does the LS, the SBC has 16 or 17, I forget?
Clevelands are terrible for head seal when you've got a bad tune with boost......been there , done that.


As for broken pistons, it's detonation that breaks them. You don't get detonation with E85 and with a stock engine that's on E85 and boost and tuned bad, like a BMW 6 cylinder, they bend the rods without breaking the pistons......seen that too.

[user-17438]

Look at a diesel engine.

Much greater peak cylinder pressures, typically 18 bolts on a 4 cylinder head as opposed to the normal 10.They wouldn't make them like that if it wasn't required.

The one big advantage a SBC has over a SBF. The SBF has 10 bolts per side as does the LS, the SBC has 16 or 17, I forget?
Clevelands are terrible for head seal when you've got a bad tune with boost......been there , done that.


As for broken pistons, it's detonation that breaks them. You don't get detonation with E85 and with a stock engine that's on E85 and boost and tuned bad, like a BMW 6 cylinder, they bend the rods without breaking the pistons......seen that too.

Exactly, bent pins, bent rods, lifted head gaskets on e85 and a crap tune... good time it goes away.. but they are fastest at the point of destruction

[Momus]

Seen this a lot with Subaru's, on E85 you can put enough timing into them that even without det/preignition they'll lift the heads, seal up again straight away after a pull.
It's not a tune issue, tune can be perfectly safe from a combustion viewpoint, just the pressure rise with the extra timing that E85 allows is too much for basic head clamping.
Fast pressure rise = HP/TQ, not a bad thing, just gotta hold them heads down!

With the new billet subi cases & using ARP2000 14mm head studs the tune can be pushed even further coz the heads don't lift, there has been no adverse affects (other than faster boost reponse & a buttload more midrange TQ) & teardown says everything is happy, it was never a tune issue, just a materials strength issue.

The next limitation in the line seems to be the head castings, they do lift/distort between the studs, but once the block integrity & clamping was sorted the threshold where the head castings are the limit became much higher. For drag racing it is now possible to push 40psi/1000+hp through them, but for endurance racing the reliable limit seems to be around 34psi & 850hp without going to exotic gas rings or other fancy sealing solutions.

You probably won't get away with just swapping in the studs, once the gaskets have crabon tracked they'll keep leaking under boost.
But thin head gaskets are a plus, not a minus - the less head gasket surface area exposed to combustion the better.

So how is that not in the tune? If he is running too much timing or too lean. Screw what the o2 sensor says. Or if there isn't detonation. If you can tune the problem out it is clearly a tuning issue.

The fix was big head studs and stronger cases: a redesign to give the strength required for the tune.

[user-17438]

Or switch to q16.. better fuel. Differet tune.. I have had guys switch from e98 to q16 no longer have the same problems. 1000whp Mitsubishi to 800whp subs.

I have built plenty of subarus. But then again its not an ls v8. No need to install larger bolts on an ls. Just better.

[peejay]

The one big advantage a SBC has over a SBF. The SBF has 10 bolts per side as does the LS, the SBC has 16 or 17, I forget?
Clevelands are terrible for head seal when you've got a bad tune with boost......been there , done that.

The tradeoff is that you get some righteous cylinder bore warpage.

This is why modern engines thread the bolts in way down at the bottom of the block, not up at the deck. Clamp the engine together, not the decks. Less/no bore distortion, and because you're pulling from deep in the block, you aren't warping the DECK so much either. The head is another story, but you can't have everything.

[CGT]

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[Newold1]

You are now a LSA type engine user. Let's not over think this issue!

Simple thought here. How does GM get the LSA engines to take boost at a certain compression level, 9.1 to 1 and an engine equipped with piston oil squirters, etc?

How? It was engineered and built from the beginning to have BOOST!

Trying to take an N/A STOCK LS engine and fit it with significant boost is an exercise in futility in the long run!
You can do some things to crutch the problems but eventually Mr. BAD NEWS is gonna get you!

Band Aids don't stay on forever!

My suggestion is save your money and to lower the boost some, re-tune to lessen timing a peak pressure and just take it a little easy on the engine until you can afford and have the time slot to pull the engine and fit it with some good forged pistons and strong ring set, the correct camshaft profile, a better set of aftermarket head studs and a good tuning program and then have the power and torque you want to twist up the drive line, clutch included and smoke off the tires and make it your E-ticket ride! JMO