What would be an advantage to running lbz internals over my lb7?

IMO, no.

The LBZ piston and rod are stronger parts than the LB7. For a stock application both are fine but when you start running the power up you will be better off with the LBZ units. The rest of the lower end I would call a wash between the two. If you plan on doing a rebuild why not start with the better parts.

What makes the LBZ pistons stronger? At the same compression as a LB7 piston, will a LBZ piston be better?

The LBZ piston and rod are stronger parts than the LB7. For a stock application both are fine but when you start running the power up you will be better off with the LBZ units. The rest of the lower end I would call a wash between the two. If you plan on doing a rebuild why not start with the better parts.

I do not want to get to a knock down drag out with you Steve. :rolleyes: The rod is stronger but not strong enough. Crower's or the new Carrillo rods are the way to go. As far as the pistons. LBZ has a lower comp ratio but IMNSHO it is not stronger. Your better off enlargeing the bowl of a LB7 to get what you need for comp. ratio. But it still may not be strong enough for huge power. Forged pistons are out there but pretty much track only use.

My best advice is figure what you want for power and work with what you got.;)

Merry Christmas!

The LBZ piston and rod are stronger parts than the LB7. For a stock application both are fine but when you start running the power up you will be better off with the LBZ units. The rest of the lower end I would call a wash between the two. If you plan on doing a rebuild why not start with the better parts.

but for "roughly" the same price you could have billet rods no?

IMHO, with the amount of $$ LBZ rods/pistons cost, you're not getting THAT much more strength for the $. I think I remember LBZ rods and pistons being really expensive for what they are :confused:

Has anyone bent LBZ rods? How do we know they're not strong enough?

LBZ rods are about 1k less than aftermarket.

Has anyone bent LBZ rods? How do we know they're not strong enough?

LBZ rods are about 1k less than aftermarket.

What was BigD running?

What was BigD running?stock rods that had been shot peened and cryo treated. Stock LB7 rods.

Be interesting to see how the LBZ stuff holds up, nothing out there for the LBZ yet to push them that hard, or at least not many built. Guys with the LBZ bottom ends?

I would guess its all up to where you want to spend the money. For me I've got a heavy foot and I say 100 Hp adder is fine but then I get use to it then it turn it up some more. So if you have better self control you might be fine with the LBZ rods, but at this point no one knows what they will hold for sure. We do know the LB7 rods fail around 500 -550 RwHp of prolonged use. I do not know what it would cost to buy factory LBZ rods but a set of our billet rods are $2750 so you can compare cost from that. If you switch to the LBZ piston you also need to switch the wrist pin as it takes a different pin than the LB7 piston. The LBZ piston is stronger as it is reinforced in the pin area and has a slightly lower compression rate to start with which is good for those of us with a heavy foot. If you would like a second opinion on the strength issue maybe MMS will chime in. The LBZ piston failures have been tracked down and it was not a piston problem but a machining problem with what was done to them. So until I see a problem I'm sticking with the LBZ units.

I would guess its all up to where you want to spend the money. For me I've got a heavy foot and I say 100 Hp adder is fine but then I get use to it then it turn it up some more. So if you have better self control you might be fine with the LBZ rods, but at this point no one knows what they will hold for sure. We do know the LB7 rods fail around 500 -550 RwHp of prolonged use. I do not know what it would cost to buy factory LBZ rods but a set of our billet rods are $2750 so you can compare cost from that. If you switch to the LBZ piston you also need to switch the wrist pin as it takes a different pin than the LB7 piston. The LBZ piston is stronger as it is reinforced in the pin area and has a slightly lower compression rate to start with which is good for those of us with a heavy foot. If you would like a second opinion on the strength issue maybe MMS will chime in. The LBZ piston failures have been tracked down and it was not a piston problem but a machining problem with what was done to them. So until I see a problem I'm sticking with the LBZ units.I asked Eric just that and he gave the nod to the LBZ units over all, both have pro's and con's, but it was his opinion as well that the LBZ's are a bit better overall.

We do know the LB7 rods fail around 500 -550 RwHp of prolonged use.

:rolleyes:

Be interesting to see how the LBZ stuff holds up, nothing out there for the LBZ yet to push them that hard, or at least not many built. Guys with the LBZ bottom ends?

Should be tested by spring. Big twins, dual pumps, etc. Although with the exception of dual pumps my LLY showed no signs of failure.

This is one of the reasons I went with a new truck and not just a built engine, guess only time will tell.

I would guess its all up to where you want to spend the money. For me I've got a heavy foot and I say 100 Hp adder is fine but then I get use to it then it turn it up some more. So if you have better self control you might be fine with the LBZ rods, but at this point no one knows what they will hold for sure. We do know the LB7 rods fail around 500 -550 RwHp of prolonged use. I do not know what it would cost to buy factory LBZ rods but a set of our billet rods are $2750 so you can compare cost from that. If you switch to the LBZ piston you also need to switch the wrist pin as it takes a different pin than the LB7 piston. The LBZ piston is stronger as it is reinforced in the pin area and has a slightly lower compression rate to start with which is good for those of us with a heavy foot. If you would like a second opinion on the strength issue maybe MMS will chime in. The LBZ piston failures have been tracked down and it was not a piston problem but a machining problem with what was done to them. So until I see a problem I'm sticking with the LBZ units.

Is it not true that Jim chambers truck split 5 LBZ pistons and that his LBZ pistons had no maching work done to them, and in fact Eric used a completly different machine shop for his build. Is it not also true that Jims truck was barely over 600hp?

3 out of 4 LBZ piston trucks that I can think of split there pistons. to high of a failure rate for me its obvious that something is being missed here or not being considered the LBZ pistons may in fact be stronger under the right conditions but out side of those conditions apperently they go down hill fast.


If I was building an engine there is no way I would use LBZ pistons, i would definatly use cut or stock LB7s.

Is it not true that Jim chambers truck split 5 LBZ pistons and that his LBZ pistons had no maching work done to them, and in fact Eric used a completly different machine shop for his build. Is it not also true that Jims truck was barely over 600hp?

3 out of 4 LBZ piston trucks that I can think of split there pistons. to high of a failure rate for me its obvious that something is being missed here or not being considered the LBZ pistons may in fact be stronger under the right conditions but out side of those conditions apperently they go down hill fast.


If I was building an engine there is no way I would use LBZ pistons, i would definatly use cut or stock LB7s.

Jim had Crowler Rods in his motor. I think the stock rods are weaker than the pistons. Put crowler rods in and the pistons are the weak link. Your LB7 pistons might not of lasted if you hadn't bent your rods.

Is it not true that Jim chambers truck split 5 LBZ pistons and that his LBZ pistons had no maching work done to them, and in fact Eric used a completly different machine shop for his build. Is it not also true that Jims truck was barely over 600hp?

The only thing I did on Chambers was clearance the crank and rods. Then the rotating assembly was balanced. We never had his block nor did we do any assembly on it. His pistons were not touched other then just a nitch on the bottom for balancing purposes.

Jim had Crowler Rods in his motor. I think the stock rods are weaker than the pistons. Put crowler rods in and the pistons are the weak link. Your LB7 pistons might not of lasted if you hadn't bent your rods.

i drove mine on the street had a sheet load of hooks and drag way passes and i had a broken glow plug, it didnot start acting up till itwas below 32out. That and thier are a ton of lb7s out there running high hp in comparision to LBZs.
I guess we will find out next season if they keep splitting.
Also remember Jim was down on power.

You can kill anything if the tunng is off, sooner or later people will figure it out but until they do parts will continue to get broken. Just turning numbers up and down without knowing what's going on internal to the engine is makeing the parts guys happy.

I have had both pistons on the CMM. The LBZ may be stronger overall but there is a lack of material in the areas it needs to be. My vote is the LB7 unit.

:exactly:
I have cut them apart. Measured and I think the LB7 is more robust where it is needed. LBZ is beefier from the center of the pin down. But it has to be as there is no steel reforcements cast into it.

Not to get in a long drawn out thing again about pistons but the steel insert does nothing for the strenght of the LB7 piston, it's there to control piston growth. When the engineer from the piston manufacture recommends us the LBZ is the unit to use when they can pull the LB7 units off the shelf should tell us all something about which is which.

I PMed him as you said. But I as of yet have not received anything to that chances my mind. Or anything at all for that matter.

Are you saying I should beleive everything I read on the internet?

Or maybe I should just buy some canned tuning and pay a maintence fee to keep it upto date. So that way my truck will not blow up. Which canned tuner would that be?:rolleyes: Last I knew canned tunes have hurt pistons also.

Not to get in a long drawn out thing again about pistons but the steel insert does nothing for the strenght of the LB7 piston, it's there to control piston growth. When the engineer from the piston manufacture recommends us the LBZ is the unit to use when they can pull the LB7 units off the shelf should tell us all something about which is which.

Who manufactures the pistons?
I was told from GM engineers they came from Japan along wiith the heads? aren't they stamped Isuzu?

Johnboy
Check with Eric Merchant as he was told what pistons were recommended to use by the engineer and has posted it in the piston thread as well. You disagree and that is fine but the facts are the facts.

BigD

Mahle was the OEM factory supplier for all the LB7 pistons. There were made in the Mahle Brazil plant.

The inserts DO increase strength if they bond well to the aluminum. Stronger than the LBZ? That is another question.

Johnboy
Check with Eric Merchant as he was told what pistons were recommended to use by the engineer and has posted it in the piston thread as well. You disagree and that is fine but the facts are the facts.


Eric from Mahle, when asked specifically by me about which are better, gave the nod overall to the LBZ units. He mentioned that both have pro's and con's, but the overall vote goes to the LBZ units, according to MMS anyways.

There have been reports from guys who have chowed LB7 pistons at levels were other guys are fine. GMCsled chucked a piston didnt he? IIRC he was running a Xtreme and WAY less N2O than I and others did but his(and others have chowed) He is the one guy I remember off hand but there are others.

Regardless what I went with i would have the SOB's inspected in depth becasue it seems like some live better? Eric, Steve and other builders.....what do you do to em into the motor?

Eric from Mahle, when asked specifically by me about which are better, gave the nod overall to the LBZ units. He mentioned that both have pro's and con's, but the overall vote goes to the LBZ units, according to MMS anyways.


I know he gave the nod to them in stock form, but what about after you cut the compression down to say 15:1?? Maybe the lb7 lends itself better to this app. I don't know if this would make a difference or not??

You need to remove less material from the LBZ piston then you do from the LB7 piston to lower the compression since the LBZ is lower to start with. So depending on how much you are trying to remove there might be some point that the LB7 could be better but IMHO the LBZ will be better for everything above 14.5:1

Eric is building a LBZ short block with Crowers for me right now. My LB7 decided to divorce a piston (short/bent rod) and the small end of the rod beat a nice hole in the side of the block. The LB7 piston seems to be very strong even at extreme power levels, Just ask Kyle and he has probably cut the crap out of them. I hope the LBZ piston will hold up as well as the LB7. Isn't the major issue here to keep the Rod's straight and the correct length? Most piston failures have been attributed to a rod issue. I do think there is some credibility to the therory that shortened rods may help the pistons live a little longer, when piston fracture is the cause. I've got a gut feeling that I was running on short rods for a while before it came apart. I would be willing to bet that there's a lot of high hp truck's that have some ugly rods inside. I hope not. Maybe the tuning parameters can be adjusted to eliminate a lot of this issue. I'll be testing the combo soon. No mercy..................

You need to remove less material from the LBZ piston then you do from the LB7 piston to lower the compression since the LBZ is lower to start with. So depending on how much you are trying to remove there might be some point that the LB7 could be better but IMHO the LBZ will be better for everything above 14.5:1


It takes less to go from 16.8:1 to 14.5:1 than does to go from 17.5:1 to 15:1 No kidding? Had not noticed. The volume of the bowl will be the same for both if they are both made 14.5:1. Yes you have to remove more from the LB7 piston. Like 1.6CCs worth. Removing the material is not the trouble. The material that is not there is. The LBZ piston has a larger and higher positioned oil gallery. This is where things go to heck. To lower the Compression ratio you must make the bowl deeper, wider or both. Deep is not a good option because it changes the distance from the injector to the dome. That will cause poor burn. At least according to those I have discussed this with. So that leaves widening the bowl. In the LB7 piston this can be done without decreasing the distance from the top inner corner of the oil gallery. The same can not be said for the LBZ. The larger raised oil gallery prohibits this. These pistons where designed to work with boost levels below 30psi from GM. When we raise the boost levels over that we need to lower the compression ratio accordingly. Just like gas engines as boost goes up comp. ratio must come down. I have talked to more than a few performances diesel shops about his and they agreed. The LB7 piston is better suited for this. I have discussed this with the engineers I work with. Gave them the two sectioned pistons. They all agreed. Enlarging the bowl of the LBZ piston compromises it strength because the section distance from the bowl to the oil gallery is reduced far more than it would be on the LB7 piston. The only real strength advantage of the LBZ piston over the LB7 is the longer wrist pin and the added surface area it provides. But LBZ pistons are still failing in spite of that so is it really worth swapping out your LB7 pistons? I say no. I do think that a stronger cast piston is needed then we have right now. But from the sounds of things that will be six months at best if at all. So we must make do the best we can.


Know another note. Please do not underestimate the intelligents or resources of any of the individuals on this board or any other. I do not doubt your tuning prowess. Nor do I give or sell my thoughts on tuning on this or any other forum. I only will discuss things that I feel I am knowledgeable enough to help others. I am very knowledgeable in metals and machining them. Machining them is what I do for a living. I could list the companies I have worked for and some of the interesting projects I have been a part off. But I see no need to bore the members of this board.

I have managed with help to tune my truck with some impressive results. That is the one in my sig. Only my trucks will be in my sig as if it not mine than it is not my place to brag about it.

Eric is building a LBZ short block with Crowers for me right now. My LB7 decided to divorce a piston (short/bent rod) and the small end of the rod beat a nice hole in the side of the block. The LB7 piston seems to be very strong even at extreme power levels, Just ask Kyle and he has probably cut the crap out of them. I hope the LBZ piston will hold up as well as the LB7. Isn't the major issue here to keep the Rod's straight and the correct length? Most piston failures have been attributed to a rod issue. I do think there is some credibility to the therory that shortened rods may help the pistons live a little longer, when piston fracture is the cause. I've got a gut feeling that I was running on short rods for a while before it came apart. I would be willing to bet that there's a lot of high hp truck's that have some ugly rods inside. I hope not. Maybe the tuning parameters can be adjusted to eliminate a lot of this issue. I'll be testing the combo soon. No mercy..................

Are you getting Alimony to help pay for the new build?):h

Are you getting Alimony to help pay for the new build?):h
:funnypost

Are you getting Alimony to help pay for the new build?):hLOL........ no alimony, but I could use it:rolleyes: . I might be paying alimony if it pukes again. Actually, My wife is very supportive (thank God) and knows how much I enjoy playing with my truck. I probably should not push it though.:Nonono:

sorry to get off topic but, what about lly internals?

The LLY and LB7 pistons are the same I believe.

It takes less to go from 16.8:1 to 14.5:1 than does to go from 17.5:1 to 15:1 No kidding? Had not noticed. The volume of the bowl will be the same for both if they are both made 14.5:1. Yes you have to remove more from the LB7 piston. Like 1.6CCs worth. Removing the material is not the trouble. The material that is not there is. The LBZ piston has a larger and higher positioned oil gallery. This is where things go to heck. To lower the Compression ratio you must make the bowl deeper, wider or both. Deep is not a good option because it changes the distance from the injector to the dome. That will cause poor burn. At least according to those I have discussed this with. So that leaves widening the bowl. In the LB7 piston this can be done without decreasing the distance from the top inner corner of the oil gallery. The same can not be said for the LBZ. The larger raised oil gallery prohibits this. These pistons where designed to work with boost levels below 30psi from GM. When we raise the boost levels over that we need to lower the compression ratio accordingly. Just like gas engines as boost goes up comp. ratio must come down. I have talked to more than a few performances diesel shops about his and they agreed. The LB7 piston is better suited for this. I have discussed this with the engineers I work with. Gave them the two sectioned pistons. They all agreed. Enlarging the bowl of the LBZ piston compromises it strength because the section distance from the bowl to the oil gallery is reduced far more than it would be on the LB7 piston. The only real strength advantage of the LBZ piston over the LB7 is the longer wrist pin and the added surface area it provides. But LBZ pistons are still failing in spite of that so is it really worth swapping out your LB7 pistons? I say no. I do think that a stronger cast piston is needed then we have right now. But from the sounds of things that will be six months at best if at all. So we must make do the best we can.


Know another note. Please do not underestimate the intelligents or resources of any of the individuals on this board or any other. I do not doubt your tuning prowess. Nor do I give or sell my thoughts on tuning on this or any other forum. I only will discuss things that I feel I am knowledgeable enough to help others. I am very knowledgeable in metals and machining them. Machining them is what I do for a living. I could list the companies I have worked for and some of the interesting projects I have been a part off. But I see no need to bore the members of this board.

I have managed with help to tune my truck with some impressive results. That is the one in my sig. Only my trucks will be in my sig as if it not mine than it is not my place to brag about it.



I agree 100% with this. Took the words right out of my mouth:cool:

Johnboy

You have your opinion and I have mine and that's fine. Do not think that I haven't been building motors just because I do tuning too. When asked the Mahle piston engineer recommend the LBZ piston to be used over the LB7 piston. I also have recommended the same thing all along. We both agree that a stronger piston would be nice but as of now that's not a choice. I hope your build works out for you. The ones we have built with LBZ pistons are working just fine and have over 12K miles with plenty of drag racing and pulling on them so they have been proven to work when properly machined and assembled.

:rolleyes:

Sorry about not having a chance to chime in sooner. Just to clarify my position on the pistons, part of which has already been stated by others here, there are definitely advantages and disadvantages to both designs. For the guys that have called and spoke to me in depth about their applications, there are various reasons why I would recommend one piston over the other. And depending on those circumstances, there have been cases where I would have suggested one particular piston, or vice versa.
From what I've seen (which is admittedly limited because we depend on customer feedback), there hasn't been enough evidence to write-off either design completely. With time, that may well change, but generally speaking I would still give the edge to the LBZ. It obviously has a few things that could be improved, but I have yet to see a failure that I would attribute directly to those weaknesses.

But LBZ pistons are still failing in spite of that so is it really worth swapping out your LB7 pistons?

How many modified LBZ pistons have failed? I know of Keith's but that's it. I have a hard time keeping up with things anymore so I'm trying to figure out how many LBZ piston failures are out there...

Eric is building a LBZ short block with Crowers for me right now. My LB7 decided to divorce a piston (short/bent rod) and the small end of the rod beat a nice hole in the side of the block. The LB7 piston seems to be very strong even at extreme power levels, Just ask Kyle and he has probably cut the crap out of them. I hope the LBZ piston will hold up as well as the LB7. Isn't the major issue here to keep the Rod's straight and the correct length? Most piston failures have been attributed to a rod issue. I do think there is some credibility to the therory that shortened rods may help the pistons live a little longer, when piston fracture is the cause. I've got a gut feeling that I was running on short rods for a while before it came apart. I would be willing to bet that there's a lot of high hp truck's that have some ugly rods inside. I hope not. Maybe the tuning parameters can be adjusted to eliminate a lot of this issue. I'll be testing the combo soon. No mercy..................


Eric should be able to slap these LBZ short blocks together like a champ:D . 2007 will be a new year to see where the next failures start showing. I know that almost all of my stock rods (lb7) were bent. With all the new mods and stronger parts, there always will be the next weakest link.... lets see who finds it first;)

Failure free year