Staff Edit: This is a spinoff from another thread.


Pistons are the weak link in the LBZ. The piston will crack or have other issues prior to the rods giving. The pistons are stronger that previous versions but they seem to still be the weak link. The block has a mutitude of improvements over the LLY and so does the crank and rods. I think I found the limits of the LBZ but that is being discussed between a few experts and myself to determine the root cause of failure at this point. Lets just say at 750HP or so, things get real interesting after multiple pulls at that power level.

So I take it that another LBZ piston bites the dust? Sorry to here that Tazman.:(

How many dyno runs/pulls/miles on the engine?

Didn't crack a piston but there is issue with it that we need to address. I will know more when we get the piston out.

Oh, well at least the block and everything is still intact. Keep us posted on your findings.:)

Not sure if the block is usable in it's current state, I have a backup or 2 but there will be some research on this issue prior to rebuiding it. I haven't decided if I'm going to build a race motor or just detune it a little to make it live. I was very conservative on the timing so I'm confident that was not the root cause of the issue.

Just out of curiosity, how do you know that it is a piston issue if the engine is still in the truck? What are the symptoms?

The only thing in the truck is the short block. The compression and the cylinder wall tell the tale. I just need to pop the piston out to look at it. I know what happened but until I have the proof, it's just speculation at this point. No big deal other than labor to fix it. I may put a stock motor back in until the big motor is ready or I may just step up the production of the big motor. My accountant (Wife) hasn't returned my request for additional funding!!!;) Just kidding, everything is in place for a race motor but I haven't decided what to do yet. I don't think a 800HP LBZ is out of the question!:D To do it right takes a lot of time and effort by several people so I can't say it will be put together this week or not?

Just for the record, it did not crack a piston on top, as some have mentioned but I might have wished it did by the time this is done!!!:eek:

Ric

Give me a call when you get that piston out of the hole. From the pictures we can make several guesses but once it's out and you can look at things overall I think we can get to the bottom of what has happened. It's safe to say that trying to get the power above the 650 RwHp level just is not going to make a stock motor life long. The LB7 and LLY are pretty much done around 500 RWHp if you want to keep it alive for long periods we now get some information as to what a LBZ may take once Ric get's it apart.

That's exactly what I was going do. Once the piston is out then I will have a better understanding of what happened. As Steve pointed out all of us are speculating as to what happened to cause this. I didn't intend on this getting started yet but this is a new issue that I don't think any of us have seen yet. Whatever the damage is, it is not on top of the piston. No pictures will be posted until the research has been done on both the block and the piston. To me.....this is not a huge deal other than a lot of labor for me. I have some really good support in this deal and I will build it bigger and better for the next go around. The LBZ is still a great engine and this may have just been a fluke deal but I will get to the bottom of it in the next couple days.

Kyle from CrankitUpDiesel will be coming over to assist us with interpreting what happened but I can tell you that I think we found the limit of what the stock short block will take. I think we can make the stock engine live at this HP level but we need to make some adjustments to control things a little better.

For those of you that have asked, the truck will be running and ready in under 2 weeks with a improved configuration.

So what did you find out Tazman? What pistons did you decide to run?

crack start in the oil galley....?

i think i was told no crack

Sounds like a thread of speculations? Are we gonna see pics or just draw them in our minds? LOL

main bearings,no oil to rods,rod sized to crank,good by piston ????

The goal was to get the piston out tonight but the winter storm has slowed progress for us. We will have it out by the end of the week. I'm sure it scuffed the side but I'm not sure what the extent of the damage is. I can tell you the top of the piston looks like new and so do the rest of the cylinders. I will have all the parts to repair the damage by the end of the week.

We will be building the engine to with stand more punishment but I will caution everyone as to how much power these engine will take. You are on borrowed time at these power levels and it's very expensive to repair these engines.

I know there are a lot of people that have opinions on this but if I didn't have the resources and support to do this, I would not go above a 550HP tune up. Based off what I have seen from several engines, 600HP seems to be the starting point of issues. McRatt, Keith, myself, and may others have leaned on these things pretty hard and we have all found the limits of the engine in one way or another. I'm only posting this so others can see how much time and money it takes to repair one of these engines. You can have a lot of fun at 500HP and not break the bank.

Thanks to ATS, PPE, TTS, SoCal Diesel, Danville Performance, Tony Burkhard, Mike L, CrankItUpDiesel and many others, we will have one stout LBZ when the project is complete next week. You can see by this post how many resources it takes to do this so my point is, how about we not tell everyone these engines will live at this HP level. I think we can better serve a lot of Diesel Enthusiasts by posting some of the limits so they have a better understanding what it takes to get one of these to live! I'm sure I will get flamed for this post but I personally know some people who are trying to duplicate a high HP truck because all they hear is how cool it is to have the power but they don't have the technical or financial resources if they damage the engine. This is just my opinion but I would rather help someone make reliable HP at a safe level than push it to limit and break it. I was preparred for the damage to my engine, some people are not!:(

I previously posted what it would take to duplicate my truck, what I should have added was what it can take to maintain the truck!:eek:

Guess thats why they say you have to pay to play. I like most other hp junkies would love to have as much hp as I could afford but I think your right, most don't look at what happens if it self destructs. As I learn more about these trucks and the power they can handle, posts like these are great ways to learn at others exspense. I was on the quest to in the next year to have a low 12 to high 11 second truck but I can say now that I'd rather have a low 13 to high 12 second truck that will live alot longer life and not hurt my wallet as much. Thanks to all for the great info!!

Curious, is this a stock C.R. uncut piston?

BTW, there is some great advice here on building too much power with stock internals. I know:( .

Stupid question but if the cylinder is scuffed wouldn't that mean there is a problem with the piston or ring? Because if it was a bent rod i would think it would toss the crank first. Or i guess i can stop being a speculating A## and wait tell you get it torn down.:D

The piston is scuffed on the side. There is minor transfer on the cylinder wall. It may have collapsed a ring but I won't know until the end of the week when I get it out. I can use muratic acid and recover the cylinder then put a new slug in it.

The rods are not bent, the piston protrusion is with in .002 accross the deck so I'm cofident there is no rod issue. The parts are arriving dailey to build a stronger peice and I hope this give's people some insight on what it costs to do this. In my opinion, if you are running a high HP tune up, you are on borrowed time. I will post some pictures at the end of the week, there are a few guys that have the pictures already so we have a pretty good understanding what happened. Luckily my wife has a good understanding of what it takes to run this hard so she has given me some latitude to build this thing right but if I break it again, I'm sure her understanding will diminish at a high rate of speed!!:eek:

Well, the piston issue has been resolved and to my surprise the piston looked great but someone at the assembly plant owes me some money. There was a 1/2" peice of the oil ring missing on the #5 piston. It scratched the bore but I was able to hone it and resuse the block. The ring was broken in half also and the spring is what was transfered to the block. There was no sign of the missing piece of the ring so it appears this happened during assembly. The rest of the motor looked great and the rods were perfect. These motors are tough but this was a issue that could have been avoided in my opinion.

Anyway, the build is complete and running so I will put some miles on it and retorque everything then see what happens. Kyle, Mark, Jason, DJ, and myself performed a 35hour build on the motor and transmission to get it ready and we are paying for it today. We fired the engine at 5:15AM on Sunday morning. What a project!:eek:

Congrats on the build! Maybe the LBZ is tougher then we thought.

Glad to hear that you got it sorted out Tazman!

Thanks for keeping us in the loop Taz. I've been wondering about this for a while. Congrats on the quick turn around.

thats awsome glad everything worked out for you guys

Thanks for posting the updates Tazman.:)

I have not had time to really look at the ring lands of the piston to determine if there is any unseen issues with it but I will probably send it to Steve to have him check it out unless GM wants it to see what happened. The engine sounds completly different and it appears the heads helped the turbo spool up a little quicker which helped over all drivability.

I must say the Trippin heads looked awesome and the attention to detail was impressive so we will put some miles in it then see what kinda power gain (if any) we got from just the heads and cam shaft.

Nice work!

Good news. Glad to hear it all worked out. Sounds like you had the "A" team on it.

So are you running the "street" heads/cam?

Did you notice a boost drop with the new heads?

I haven't put any power in it yet so I don't know the effect of the heads just yet. I want to put a few miles on it before we lean on it.

Slick,

The heads are the full race set up and the cam shaft is a design for streetablility and racing. I don't know if it is available to the general public just yet but it may be we would have to ask Trippin. I know we are going to do some testing this week to see if we gained any noticable power. Do to the BS of the dyno #'s from everyone, I will not post the #s or exactly how much gain there was unless everyone can agree to take them at face value for tuning purposes and not start a bunch of crap about the #'s. If we can all agree to do that then I will be happy to post all the #'s compared to where we were at. We have a great base line to see if there is any gain from just bolting on the parts but I have almost stopped posting because of the nit picking. I don't run a business and any one that knows me can tell you that this is just a hobby that I enjoy so I have no ill intentions toward anyone or there goals. I try to help in any way I can and although I have had some disagreemnts with some people on here, I still respect their opinion and I don't hold anything against them. After all the BS about the dyno day, I'm sure you can understand my reluctance to post any #'s. I have no doubt, the parts we put in are capable of 750-800HP with the right tuning. Possible more but I don't have the data to support anything YET!!!:D

I know I've said it before but words can't express the thanks to ATS, PPE, TTS, Tony Burhard, Kyle (CrankItUp), Danville Performance, and especially Trippin at SoCal diesel for the quick turn around of this motor. We also used the Cometic Head gaskets to complete the build thanks to Trippin for supplying them. We made the engine compartment look as close to stock as we could and we double and tripple checked everything as we went together with it. I really don't care to pull a all nighter again anytime soon but the group of guys who helped me, made it a lot of fun. Just for your entertainment, Kyle starts dancing when he get tired!!!;) :help2: :grd:

Thanks for keeping us updated.

Dont see how anyone could argue with you on If your using the dyno as a tunning tool showing what you have gained. The exact numbers dont mean crap IMHO but the change is what matters. If you roll the same dyno the same way and get different numbers you know your either making progress or losing it. Be cool to see em. Hell, just overlay the grafs of before and after and wite out the numbers from the side. :D

I hear you on that TAZMAN10:( . I get tired of certain people on this site taking the what kind of Dyno did you use question way too far. Or as you would say other kinds of nit picking. Not just at me. I feel similar to you just a consumer tryin to spend his coin right and hopfully only once:) . Your info has helped me out lots you'll be able to tell by my LBZ sig in about two-three weeks. Anyway keep up the good work and I hope nothin breaks:cool: .

Just for your entertainment, Kyle starts dancing when he get tired!!!;) :help2: :grd:

:nopics:

really more like tapping a foot....

really more like tapping a foot....
Don't even try and deny it Kyle, you were doing some funky irish jig!):h
Yeah, i have to thank Kyle and Jason for making the trip to help out with the build as it made it goe alot easier. I don't know about anybody else but I don't want to do it agian for at least a week or two! We took it for a SPIN last night and it is AMAZINGLY stupid! It should be illegal to have that much fun with four people in a truck in 4wd!:eek: I don't think I will ever buy another sports car in my life!