samwint77

Before this last tune it was at 829 hp / 927 tq STD. I had allot of issues with my first set of 30% over DI injectors and thought it was the tune. Found a new tuner, but apparently from the tune that had the mentioned power level it had another 6 degrees more timing and knock sensors turned down. I imagine it was a rod bearing. The engine is still in the car because I don't know what I'm going to do yet. May wind up selling it. It was on full E85 and meth

ZMC2001

That sucks. Tunes really play such a big role in these things. Hope you end up rebuilding it, I've seen some pretty good short blocks being offered from LME. If you do that, you could really turn it up. Anyway, hope you get it back up and running

bc928

The details here are important. Spinning a rod bearing (if it was a rod) is usually predicated by either an oiling issue - or more often the rod is being moved aggressively down by combustion pressure near TDC because of a detonation event. When the detonation event happens on the compression stroke, that one cylinder is now trying to hold not 1000hp/8 = 125hp but actually 1250hp - on one cylinder because of the unscheduled pressure.

This pounds out the shape of the rod bearing while also shocking the surface of the rod. These shocks also go through the mains.

the rod bearings lose shape and then spin in the rod big end.

you can make 2000hp with no detonation and then the Limits are more around physical metallurgy strength.

e85 should belay all of this if tuned properly, and I'd like to find out if this fuel was in use.

samwint77

It was e85. Talking with another shop they say that the piston rings are very thin on the lt4, and tend to fail quickly.

bc928

Fail due to what? How is that related to the bearings?

Dargo

My ‘19 ZO6 is at Vengeance Racing right now getting Magnuson 2650. I have a max effort build already with Kong x port on stock blower, ported heads, etc. For fueling I have Stage 2 cam with 32% fuel lobe, LPE big bore HPFP, 30% over injectors, and DSX low side with flex fuel sensor. In order to get 950 on e85 I had to get Fore Triple in tank fuel system and get rid of DSX low side. This is all with no meth, and Vengeance said this will get me 850-880whp on 93 octane and 950whp or a bit more on full e85. They said stock short block is good up to 1000-1050whp, but beyond that I’d need to think about a built engine. Pulley is 90mm pulley that comes with the 2650.

bc928

Again, details matter. A "built" engine may involve a different crank, (forged and basically the same), a rod type maybe from Callie's or seanz - which may be stiffer or more robust.

forged pistons with aftermarket rings - this could make a difference.

The block itself unless someone is building an LtX is nothing to drastically change. New dart sleeves are stiffer.

So what is breaking, and why, becomes very important and the old problem of that info being mixed in with what shops wish to sell is still here with us.

samwint77

They said because the car starts and runs with good oil pressure, but makes allot of noise that it may have been a piston ring. At least that's what I gathered during conversation. I was more looking to get a 416 and asking other questions.

ZMC2001

If it truly was a ring that broke, I would again suspect something with the tune caused this at that power level. Having so much extra timing could have definitely led to detonation and thus breaking a ring, although I would think something else would have given as well. Please do keep us updated with what actually broke, I am very curious. On a side note, if I were you, I would look into something with a little less displacement, 408 or lower if trying to run high boost with the new motor. 416 is the absolute highest I would go, but would still rather go a little lower for safety. I plan on eventually doing either an LTR block or billet block with 400-408 ci whenever the time comes for me to get a new motor. Also, I would stay away from Callies compstar stuff. Its not fully made in America, so I would be concerned with quality issues. Just my 2 cents and hopefully it can help you with the new motor build if you decide to go the route.