Is it because there's too much boost pressure? Timing?
Are trucks running on no.2 alone more prone to blowing up than ones using drugs? Thanks

I think the bearings go bad and thats what starts the break down of the crank...I could be wrong tho.

--Ben

BTW I might have to visit you guys at Fine Tuning Transmissions sometime! I go to school in Canton, NY which is about an hour and a half from Montreal...

Sure, come on down anytime! We can shoot the breeze and show you a few projects we're working on.

Mods could you please put this thread in the Power and Performance section please. Thanks, Nick

Oil not changed often enough and not enough oil!

How many cases have been heard of? I have never heard of this until lately, would injector failure be the major contributor due to washing of the bearings also internal coolant leaks.

I believe rcr1978 is correct. I have had my injectors replaced 3 times and the last set we installed had were edm'ed and we know we had a problem with one. Thus, after the engine went down and disassembled we found three spun bearings, cracked crank and a burnt piston.

Oil changes were every 8-10,000 miles with bypass system and monitored quit frequently. If I was not getting oil, I would believe that could cause it as well.

Mike

The block is weak. Don't tell anybody I let the cat out of the bag.

Isuzu has beafed it up in the LBZ motor but they also added HP/TQ so who knows.

I agree with Hoot, the block is weak, but I dont think that was the cause of Silverado Man's truck. I dont ever recall seeing fuel in the oil and all the other bearings looked brand new. His old block is at the machine shop being checked out as we speak so we will find out if its cracked as well.

--edit--
To clarify the injector problem mentioned above, the injector that was faulty was a used injector that was supposed to be modified purchased elsewhere. After replacing it, we then installed EDM'd injectors.--edit--

My roomate in college spun a bearing in his supra but that was do to way too much boost they found.

I think hoot is correct also but I dont know if it is the weak block distorting or the weak clamp load on the crank. For most of the destroyed blocks on here I would say high or spiking cylinder pressures were the culprit. Generally high boost isn't nearly as detrimental as N20 and propane injection spikes. It can beat bearings out after prolonged use just the same but it usually takes much longer.

Do the LLY and LBZ block direct interchange?

Probably not, but who knows? ...the LBZ has a lower compression ratio and a buncha other things different...

Great so do I have to worry about my engine going boom if I ever use Nitrous? Ill NEVER touch propane, and I really mean that...im too scared to have a tank of it riding around with me. But maybe down the road I might want to experiment with Nitrous...Im not looking for anything better than like mid to high 12's, (on nitrous). Could this really be bad for my engine...?

Im not going to disagree with hoot on the block being weak, but we are asking it to hold up xxx horsepower than it was designed to, right?

--Ben

I think the block is plenty strong for 100hp adders. Over that you are asking for decreased life due to flexing of critical parts. Stock engines should last forever.

I have a great deal of R&D into making a stock block better...

In the failed blocks, is the #4 cam bearing spun?

The block is plenty strong for those not pushing above the -500 HP range.Once you cross the threshold your on your own IMO.

You should and could expect a failure after all you have gone well above it's design.

In the failed blocks, is the #4 cam bearing spun?I've yet to see that in ANY of the engine's I've torn down

I think hoot is correct also but I dont know if it is the weak block distorting or the weak clamp load on the crank.

Eric???

Mac when you say 500 hp, you are talking about 500 Rear Wheel horsepower, right? Cause you can make more than 500 crank hp with the PPE Hot alone...

---Ben

Eric,

I asked about the cam bearing because talking to Dale, he thought that is where the problems started on his. Though he didn't break the block. IIRC

mine by faulty injectors overfueling ruined bearings and one piston.

Eric???

Nope hoot said the block was weak and I agreed as did Eric.

So how many members here have grenaded a motor ???

magu grenaded his and posted, who else ???? and what were they running at the time ????
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The cam bearings spin as a result of a cracked block up through the no 4 web. This can happen un noticed on a stock engine because the motor will still operate fine, the blocks are overbuilt for stock power levels. The crack does cause a problem with the no 4 cam bearing though. When its cracked, it cant hold the bearing securely and it spins. The first notification of a failure would be turbo failure from lack of oil, or repeat turbo failure. Oil goes to the turbo through the no 4 cam bearing. When we start pushing it hard, that small insignificant crack gets stressed and causes ka-boom. That being said, I have still NEVER seen a spun cam bearing.

There have been a few theories on how to improve the block strenght and of the few I know of, I think GM's solution (other then casting a new block) is the most BS. I have a block cut into scrap to prove it (IMO) My team and myself have spent literally hours and hours inspecting every square millimeter of this engine and spent a ton of money on R&D with out even making anything yet. We have come up with a viable solution that we believe will be the best way to improve the block and it will be much stronger then any LBZ block could ever hope to be.

dont tease, elaborate.

So then it's the block that is flexing and that is causing the crank to split in two?

Mac when you say 500 hp, you are talking about 500 Rear Wheel horsepower, right? Cause you can make more than 500 crank hp with the POE Hot alone...

---Ben

Rear wheel that's what I'm saying. Looking at what's been done it is my opinion that the block will take all the #2 alone that it can make power with.Once you introduce alternative air and drugs things can go bad and that's what has been written/reported here.

As far as bearing wash for injector failure that is a different story other than it's hasn't seemed to be a problem on a stock Duramax engine .

More then what's been posted here on the board. I'm sure they will post when ready. It's served as smelling salt for me.

So how many members here have grenaded a motor ???

magu grenaded his and posted, who else ???? and what were they running at the time ????
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How many blocks have vented themselves? I think if you look back almost every one has had a broken rod/piston that has vented itself. Now look where the blocks are vented. Again, most everyone are in the same places. So the question is what happened first? Bearing spun, crank damaged, Rod broke, piston broke, camshaft broke, pushrods bent............ Once you find the root cause the answer is simple. I will tell you it's not in the block from the several blown motors I've gone over.

Rod(s) bend ...causes piston lower in cyl ... piston skirt hits crank counter weight ...in turn blasts stuff out the side of block ... just a theory :)

At least the holes in the block are large enough to fit a Coleman lantern inside to take a look around :)

Has anyone seen the changes to the LBZ block yet?

Hmmmm. Wonder if there is any connection here to the infamous tick?

What percentage of the grenaded motors ran propane?

I know that a high percentage of the engines I have seen fail had propane on them at one time or another.

I agree with Diesel Tech, finding the root cause is crucial and while the block is weak, its being stressed from other sources. There are lots of potential weak spots in the engine and at this point, I wont go public with my findings. I am still learning on this engine everyday and will continue to do so. I do suspect that Diesel Tech and myself have likely the same findings.

Hmmmmm.....wonder if its more the pistons trying to send themselves into orbit with a lil valve float?

Nathan. I was asking the same question as you. Caps not able to keep a good grab or what? Girdle the answer?

Dont want to make people let the cats outa the bag if they arnt done with R&D yet;)

I know of at least 2 that have NEVER run propane...but other drugs were involved.

Harmonic flexing of the crank should be maintained at < 1/3 of a degree throughout the firing circle or you can cause flex or vibration induced stress cracks to the crank or block in short order. Additionally with increased tortional loads associated with Propane and NOS (not as common in naturally aspirated engines) I'm not surprised.
I hope this doesn't become widespread but we all know that when you continue to add power you will soon discover the next weakest link in the chain. This can't be good for those who are pushing the limits with drugs. It all goes back to the ole saying. ---> YOU PLAY YOU PAY.

On Edit: Is the Duramax harmonic balancer rubber or liquid filled? My reason for asking is that liquid is more suited for a wider RPM window.

I know of at least 2 that have NEVER run propane...but other drugs were involved.

Anything that substantially increases peak cylinder firing pressures would likely be the culprit of tortional flexing beyond safe limits. I'm sure both Propane and drugs.

I would almost bet that #2 alone failures would be little to nothing. Even in the high HP ranges.

Has anyone ever looked into using billet cranks. In alky motors the crank is usually the reason the block gets ruined. Even in gas motors, I have seen a crank fail and then ruin the block.

I'm not that fimiliar with diesel engines, but I would think if your problem would be with the crank and then it transfers to the block.

Determining the origin is the key. Sometimes the problem we see visually after the event may not be the actual cause. It can happen with any related componets being pushed beyond design limitations and then transfered to the next thing in line.
It can very well be that running more tortional load on the crank via propane or NOS may require stronger connecting rods, more efficient harmonic ballancing, a stronger crank and better crank support from the block. If I was looking at big HP I would not want to change one segment only to have something else follow shortly there after.
We could be reaching the point with the DMax where design limits are now being exceeded and where HP will become more expensive........
Personally I'm not that much into HP and competition so I don't plan on going further than what #2 will provide.
That should be all I need for a little street spankin of the competition. ):h

Just venturing an educated guess here, but I think the relatively high compression ratio (for all the additional power we're adding) is not helping the fact that the rods aren't the strongest available. They are a powder metal preform, which is then hot forged to full density. This is done to achieve the ability to fracture split (FS) the main caps. That saves a ton of cost while maintaining a medium strength material. The cost savings can be 25% or more by FS vs. machining. There are also some stiffness advantages (in the area of the bolts) that are gained with FS.

The thing is, to get them to FS requires an alloy with a certain metallurgy. That metallurgy is quite different than one you would apply to a forged or billet rod with a design goal of high yield strength and elastic limit (resistance to failure from fatigue).

Get the cylinder pressures down and get some whoopass rods, and then see what happens.

I agree with the whoop ass rods, but then you just move the problem down the line...next weakest component is....?

I agree with the whoop ass rods, but then you just move the problem down the line...next weakest component is....?
the block

man oh man I have posted this so many times it is the weak leak unless you inject liquid which can not be compressed (bad injectors) GM themselfs test our lb7 blocks at cylinder pressures excedding 3500psi no bent rods none but lots of busted blocks i also have the solution which was given to me by an engineer who is top brass in developing the lbz block, eric is concerned with this method do to the main bearing cap bolts location in the oil passages. i was assured by GM that it was not an issue and that a fairly simple strengthing method exists Hopefully i will get this done to my block this winter and will be able to prove a simple fix works, sorry guys but i have to lean towards the general on this one after all there is no one else who has tested the block such as they have, nobody.

I agree with the whoop ass rods, but then you just move the problem down the line...next weakest component is....?

Isn't that engine building in a nutshell? ):h

Dale and I have talked alot about the GM fixes and I see what they are trying to do, but when you partially restrict an oil passage to something as critical as a main/cam bearing...... Its one thing if the passage was smaller which the LBZ's are supposed to be. If you take a hole that is X dia then put a bolt in it to interupt the flow of oil then that is bad IMO. Not saying it wont work, just goes against conventional wisdom.

I know that GM tests the hell out of these engines, but are they pushing them as hard as we do/are/will? I guess I dont know the ins and outs at GM, but I guess you need to decide if your building a competition based engine or one for running 300k.. I can assure you that GM is looking for longevity in there designs over anything. That is fine for 95% of us. When you step it up to the next level, I doubt you would put more then 10k a year on the engine and likely not even that. It's gonna come down to your intended use of the engine I guess. Part of the reason for overkill is you wont know if a small machining process on the block dont work untill after you spill the crank on the ground. Then you need an engine and they still dont give them away

I guess you need to decide if your building a competition based engine or one for running 300k.. I can assure you that GM is looking for longevity in there designs over anything. That is fine for 95% of us. When you step it up to the next level, I doubt you would put more then 10k a year on the engine and likely not even that. It's gonna come down to your intended use of the engine I guess. Part of the reason for overkill is you wont know if a small machining process on the block dont work untill after you spill the crank on the ground. Then you need an engine and they still dont give them away

agreed

With a LBZ due in a week or so you guys have me second guessing my purchase. Blocking flow through an oil port can't be good. How long is that bearing suppose to last. Just past warranty. :eek:

Eric, I wonder if Banks' approach of redoing the oil system would get around the problem.

Is there a way to fillet the stud in the proper location to allow flow around it? I think it could be a valid workaround.

With a LBZ due in a week or so you guys have me second guessing my purchase. Blocking flow through an oil port can't be good. How long is that bearing suppose to last. Just past warranty. :eek:

they are not blocking flow thru a oil passage the lbz actually has smaller oil passages because it had more then enough atleast thats what i have been told also you are only tapping the holes 2mm deeper, believe me after getting this info and talking to people who know whats involved with building engines the dmax is being tested far further then it needs to be so it lives as long as you drive it and i am very impressed by what they are doing.

nwpadmax your pms are full.

For some reason I can't put all this together. How is tapping the main bearing cap hole 2mm deeper interupting oil flow?

Tommy, I have pics and a cut up block that explain it perfectly. I think with the LBZ and the deeper holes, its all good. Like Dale already mentioned, the oil passage holes are smaller by about 1.5mm depending on how accurate my calipers are. I've not given up on GM's theory yet, just makes me nervous that its not enough. I guess it needs to be tested. I think we can do lots of gains with out going deeper threads, just utilizing the threads that are there.

With a LBZ due in a week or so you guys have me second guessing my purchase. Blocking flow through an oil port can't be good. How long is that bearing suppose to last. Just past warranty. :eek:

They may be addressing the "Tick". It was reported to be excess oil pressure of flow to the bearings. I can't see how making a hole smaller would save them money so I don't believe they would do it to cheapen the engine.

I don't know exactly what GM has been doing with their oil passages and why but I know when we build a gasser race motor and we restrict the oil passages it's to create more oil pressure in the most vital area's of the motor. The way you acheive this is if you wanted to provide more oil pressure to the rod bearings you would restict the oil flow up stream and thus create the oil pressure to rise in the area of the rod bearings. You can do this in several area's of the block to create more oil pressure in key area's of the motor.

So once again I don't know if this is GM is doing but I would imagine that if they are restricting oil passages in certain area's this would be the reason. Am I way off base here?? Just my .02

Cheers,
Wade

They may be addressing the "Tick". It was reported to be excess oil pressure of flow to the bearings. I can't see how making a hole smaller would save them money so I don't believe they would do it to cheapen the engine.

From a spectators stand point I'm not sure what they're trying to accomplish. Maybe both enhanced metal strength via the smaller hole (retaining more metal) and reduced oil flow. I'm still not clear on exactly what was done and why. The strange thing about the tick is that it was patternless. If that was also targeted that would be good. Dale and Eric says it's all good so I don't think theres any reason to worry. Wish we had those pics. :)

I don't know exactly what GM has been doing with their oil passages and why but I know when we build a gasser race motor and we restrict the oil passages it's to create more oil pressure in the most vital area's of the motor. The way you acheive this is if you wanted to provide more oil pressure to the rod bearings you would restict the oil flow up stream and thus create the oil pressure to rise in the area of the rod bearings. You can do this in several area's of the block to create more oil pressure in key area's of the motor.

So once again I don't know if this is GM is doing but I would imagine that if they are restricting oil passages in certain area's this would be the reason. Am I way off base here?? Just my .02

Cheers,
Wade

Good Point! That thought entered my mind as well. Guess it depends on if any other areas were lacking lubrication.