6g72 SOHC to DOHC swap

[phantomrt]

That sounds the most logical to me. One should also note that each of the two center mains have two oil jets in them... even more demand on the oil going through them. Is there any chance that someone has tried drilling out the center main bearings' oil supply passages another 1/32"?? It would, in theory, take away from the two outer bearings and increase oiling to the center ones.

The detonation theory sounds flawed-- as though pistons 1 and 6 have a much lesser chance of detonating.

How does the flywheel have an effect on the center mains?

[Ondonti]

The detonation theory is just that detonation causes MUCH greater cylinder pressure which pushes the rod down on the crankshaft and when this is happening on all 4 center pistons the center of the crankshafts starts to flex downwards till it bottoms out on the bearing.

Detonation at 700whp wont do this but near 900whp the forged crankshaft can no longer cope.


I think the biggest problem is just that the center mains are too small.

The 6g74 and 6g74 have much larger mains and can hold a lot more power not to mention that with those larger mains comes a beefier crankshaft. So the cheap but difficult fix is going to a 3.5L 6g74 motor and the more expensive but easier (since no need to adapt things to the larger block that has some different stuff as far as the oil filter outlet goes) option is to get a billet crankshaft (which is available now).

[phantomrt]

to know. Thanks. It would be very cool to go with a TT 6G74 setup. A lot of work, but greater displacement.

My all stock TT was down to the copper on just one of the center mains and an adjacent connecting rod is what spun out. The rest of the bearings looked okay, but not great. The day I first went to look at it, we started it up (knowing it had a really bad engine noise), and it had a loose oil filter so oil spewed out of the oil filter gasket immediately. Lost probably 1.5 quarts in the ~6 seconds we ran it. Got it home, drained the oil, and found probably another 1.5 quarts in the oil pan. hmmmm Pretty dirty oil, too. Crankshaft rebuilder said the crankshaft was cracked as well. I never asked where.