best guess on my LMM damage
- Thread starter camcojb
- Start date
Not really sure on that. Seems if LBZ/LMM engines survive a year or two, they have a much lower failure rate. I've got an LBZ piston that is cracked cleanly in two pieces with no indictions of heat or pressure. It came out of a stock engine. Looks like someone dropped it and it broke like a coffee cup.
When I see LLY or LB7 cracked pistons, they are melted where the crack started.
I really think its a crap shoot and the grace of god when its going to go mine had 56k when it went and 46k of tht over 500+ rwhp. i beat the heck out of mine every day and ran mega pw and around 30 degrees of timeing. mike mmlmm on the other hand was runnig a simular tune and his lasted 12k or so and basicly identical trucks. Mine didnt break however untill i put a evil lift pump on thoe. I still belive thts the cause
Really seems to come down to a roll of the dice. Too many across the board failures to be able to pin point it to one reason. My main guess is low oil pressures and lack of cooling to the base of the pistons.
I've seen the pistons out of a LLY hotshot rig that had a hole punched in one piston and a crack started in another, just like the LBZ/LMM ones. The LLY issue was high work load, high heat and low oil pressuse.
I've seen the pistons out of a LLY hotshot rig that had a hole punched in one piston and a crack started in another, just like the LBZ/LMM ones. The LLY issue was high work load, high heat and low oil pressuse.
I would think if cylinder preassure is high you would notice it more on the main bearings when you are tearing the motor down. Pics of these piston failures might help as well if anybody has any pics that they could share would be helpful
25-30 psi at idle, no idea what it was at wot. It's never changed since the truck was new.
That makes me feel good!
I ran a Bullydog for about 40K, Extreme loaded the whole time.
These pistons are really something else.
Food for thought, and consider crappy castings. In a performance gasser with cast pistons if you end up detonating, thata split your slugs bigger than Dallas! And a diesel is essentially a "detonation factory" right? Throw some more timing (load and heat) at it and it is all that much worse! IMO, theres lots of varibles to consider on the sum of piston falures, prolly some of everything. In all actuallity, cast pistons are very resiliant and will take a hell ova beating but the foundation, the cast quality, has to be spot on. IMO, piston quality is the main contributor to the failures. Can explain the randomness of problems too, most are good enough to survive but theres "bad eggs" mixed in with them during manufacturing, no two are cast "Exactly" the same. If QC is bad, well theres an open door for trouble, have 7 good slugs in your motor and 1 sucks an fails? Seems locical to me