maximum boost???? WTF? Blowing the head gasket at 12psi??

K

kbbeckius

New member
What is the maximum boost, a SBC/90 degree V6 can withstand?? I thought we were pretty safe up till near 30lbs of boost (I don't know if I'd go much over 25) until the head gasket/bottom end let go. Were better off than the Buick guys, we have 5 bolts around each cylinder they only have 4. Check out the October issue of Hot Rod, they put a Vortech supercharger on the V6 they built last month. They got an impressive 500hp out of it, but.. lost the head gasket at 12 pounds of boost??? WTF?? It had fairly low 9.1:1 compression. They said "You really can't blame it: we were cramming 12 psi into the poor engine" WHAT? I run that on much on our stock '92 ty. The last paragraph states that "One solution would be to add copper head gaskets and O-ring wire" Is that really necessary, for 12 psi?? I don't think so!! Mabye they should have used better head gaskets.

Your Opinions??

Thx Brad :-?
 
E

Eluding

New member
I read that article. Detonation will blow a head gasket. And I believe the engine probably suffered some pretty severe detonation. Why? How about 32 degrees of timing. That is a lot more than your stock Ty will ever see, your truck will max out at about 19 degrees. Then add to that the lack of an intercooler. The intake temps were probably very high, also contributing to detonation.
Rather than copper head gaskets and O-rings around the cylinders, Hot Rod should think about cooling their intake charge and dropping the timing a bit. The engine would then be fine on 12 or more psi.
 
myclone

myclone

Donating Member
Hot Rod goes about stuff even more old school than I do...

Too much timing (old school thinking)
Too much static comp (old school thinking)
No IC (ditto)


As for the buick guys having it worse than us..... Id argue that. Id MUCH rather swap a head gasket than crank and rods ANY day. The buicks have a pretty stout bottom end and the head gaskets will let go before the rods/crank will (usually).

Ever seen a stock buick rod? Looks like the steel version of a top fuel rod.
 
K

kbbeckius

New member
Ok, I calculated the effective compression ratio for our engines versus theirs. Ours-- 8.35:1 @ 12psi =15.17:1 theirs --9.1:1 @ 12psi =16.53:1, to have the same effective compression ratio we would have to run 14.5psi boost, to make up for the difference in static compression ratio. 14.5 pounds of boost is still not that much in our applications. As for detonation, they dont mention having that problem, but with so much timing and only 100 octane fuel, that may be a good reason as to why it let go, but detonation usually causes more damage, pistons, rods, etc. As for no intercooler, while it would have helped the detonation problem (if there was one), but hot air IS less dense, so they were getting less air in the engine than if it had been intercooled. And Buick did at least do some improvements for their turbo vs standard engines like better rods, (what do we have? special pistons, and nodular main caps. why not beefier rods?) but their oiling system still sucks.

Thx Brad
 
tyndago

tyndago

New member
Carb's - no intercooler - probably not a good headgasket - and a ton of timing....


Turbo - intercooler - less revs.. Better heads - they used the old style I think something like our LB4 heads....
 
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