LS3 Head gasket lift (Boost)

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KnightEngines
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Re: LS3 Head gasket lift (Boost)

Post by KnightEngines »

What effect do you think gasoline like av gas would have on it? Is this an E85 thing soley?
Late reply!

It's an alcohol fuel thing, E85 & meth, both are very det/preignition resistant so you can keep banging in timing till the power/tq starts to drop off (ie, tune for max HP/Tq), but when you do that the cylinder pressure rise gets pretty fast & they can lift the heads if they aren't held down pretty firm.

Petrol type fuels will rarely allow enough timing to see the fast pressure rise, so don't make as much TQ & don't lift the heads as readily.

The heads almost always lift around peak TQ rpm.
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Re: LS3 Head gasket lift (Boost)

Post by peejay »

n2xlr8n wrote: Wed Feb 21, 2018 3:37 pmI'll defer to KnightEngines, but I've tuned alot of E85 blown (turbo) engines. Many folks tune E85 like race fuels. I don't. I like to keep the timing conservative and throw the boost at it.

I bet you'll be disappointed with the avgas tune up.
I'm green when it comes to E85. My book-learnin' says that even though the octane rating is good, you still don't want very much ignition advance with E85 because, while it does take longer for the flame to "take", once it burns it burns more rapidly than gasoline, so you end up with ideal timing around what you had with good ol' pump gas.
KnightEngines
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Re: LS3 Head gasket lift (Boost)

Post by KnightEngines »

With aspirated engines you'd be right, timing usually ends up much the same.
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Re: LS3 Head gasket lift (Boost)

Post by rebelrouser »

Not built any boosted LS engines, but nobody mentioned the old school fix of a copper gasket and o-ring? I had some issues with a mopar LA 410 stroker and a procharger, they only have 4 bolts per cylinder, and the copper gasket and o-ring fixed it right up. I blowed the gasket into the lifter valley at 16 lbs of boost with 8.5 to 1 static, the 02's and exhaust temps looked good at the time.
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Re: LS3 Head gasket lift (Boost)

Post by CGT »

KnightEngines wrote: Thu Feb 22, 2018 1:25 am
What effect do you think gasoline like av gas would have on it? Is this an E85 thing soley?
Late reply!

It's an alcohol fuel thing, E85 & meth, both are very det/preignition resistant so you can keep banging in timing till the power/tq starts to drop off (ie, tune for max HP/Tq), but when you do that the cylinder pressure rise gets pretty fast & they can lift the heads if they aren't held down pretty firm.

Petrol type fuels will rarely allow enough timing to see the fast pressure rise, so don't make as much TQ & don't lift the heads as readily.

The heads almost always lift around peak TQ rpm.
Its got 16 degrees in it at and around peak torque now. Maybe it'd be worth backing it down some after the studs. Ill most likely be buying a smaller ring for the balancer to lower boost a bit as well. Thanks for the input.
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