What can they handle??

[06gmc]

So I know that as soon as you start to throw more fuel and air into these motors you are starting the clock on something breaking. And even built motors have failures. I also know a lot of it depends on how hard you beat on the skinny pedal. But I am wondering what each series of motor can handle in HP before you start to really getting prepared to build the motor.

The reason I ask this question is sometime this spring I am wanting to throw a turbo and built trans in my LML and I am wondering if it will handle it. Truck is my weekend driver and id like to run it at our local midnight drags every so often, But I am not really wanting an all out race truck.

 

[Bdsankey]

So I know that as soon as you start to throw more fuel and air into these motors you are starting the clock on something breaking. And even built motors have failures. I also know a lot of it depends on how hard you beat on the skinny pedal. But I am wondering what each series of motor can handle in HP before you start to really getting prepared to build the motor.

The reason I ask this question is sometime this spring I am wanting to throw a turbo and built trans in my LML and I am wondering if it will handle it. Truck is my weekend driver and id like to run it at our local midnight drags every so often, But I am not really wanting an all out race truck.

The LML will handle just about any drop in turbo on the market right now and be fairly safe.

01-05: ~650hp before failure
06-10: ~675-725 before failure (depends on if you won the piston lottery or not)

These numbers are just what I've seen from trucks in my area with good tuning and upgraded turbos/injectors to help keep everything in check.

 

[2004LB7]

Personally I would say about 450-500 hp for upto the LMM. The LML maybe 550 hp. The LB7 can probably do the upper end of the estimate better then the LBZ/LMM

I think anything above on a stock bottom end is reducing reliability a lot. A big part of it seems to be if your pistons will pop or not. Early years had better pistons so can take a little more

But, tuning plays a big part in reliability too along with driving style

 

[06gmc]

The turbo would be a drop in replacement, along with what's already in my sig. So from what I have gathered the sportsman pump would probably be a good limiter in HP to remain at a safe level. Does that sound right?

 

[2004LB7]

Use your tune to limit HP not the CP3. You are better off with good fuel pressure and shorter PW then letting you CP3 run low and running higher PW

 

[06gmc]

What I meant by that is the sportsman can only supply enough fuel to support 650HP. The tuning will be a reputable name in the biz its over my head lol

 

[Ne-max]

HP is NOT what destroys stuff. TQ is what does. You can make high hp on a stock bottom end by keeping tq numbers low. Torque is what makes these heavy trucks fun unless you're a dyno queen or less then 5k.

 

[2004LB7]

^^^ 2x

 

[Bdsankey]

HP is NOT what destroys stuff. TQ is what does. You can make high hp on a stock bottom end by keeping tq numbers low. Torque is what makes these heavy trucks fun unless you're a dyno queen or less then 5k.

I can confirm my stock motor was fine until I started letting it run to 4700-4800rpm sled pulling on 32" tires with 3.73 gears. Bent 7 rods in my LLY.

 

[SSchmi5519]

What I meant by that is the sportsman can only supply enough fuel to support 650HP. The tuning will be a reputable name in the biz its over my head lol

Is their "sportsman" pump still just a stock LBZ pump/regulator?

FWIW, I bent all 8 rods in my 2005 at 541hp. Would have never known it without tearing the engine apart. Thing still ran great, no haze or anything...thought it was healthy. I was wrong.

 

[Bdsankey]

Is their "sportsman" pump still just a stock LBZ pump/regulator?

FWIW, I bent all 8 rods in my 2005 at 541hp. Would have never known it without tearing the engine apart. Thing still ran great, no haze or anything...thought it was healthy. I was wrong.

Essentially thats all it is (stock LBZ pump/reg) but they open up the fuel feed ports from the gerotor pump off the back of it to the main body to remove the fueling restriction that is seen above 3000rpm.

 

[TheBac]

Stock engines? My opinion is:

~550rwhp for LB7/LLY
~600rwhp for LBZ/LMM


As NeMax said, tune it to keep tq low, that'll allow the rods to live a little longer.
Less pulse/timing by using larger injectors helps, too
Better turbo does help....the stockers are hurting at those higher hp levels.


Have no idea what an LML/L5P can handle stock. I dont think anyone here has tried to kill one (or done it accidentally :hehe like we used to do with the older engines.

 

[Chevy1925]

Everyone gets concerned with hp, it’s torque that is the concern.

1200ft lbs and up, lb7/lly will have short rod issues.

1300ft lbs and up, lbz/lmm will have short rod issue

Lml is all over the place. Their rods and pistons seem to range below or above any older engine.

L5P has seen 1500ft lbs and still held stock compression.

You can run large injectors to keep pulse width very low and keep pistons alive HOPING it’s a good set but if they have been abused under high pulse width and timing for miles before, waste of time to push it. At some point, you will not be able to de-torque the engine to keep making hp. You will become rpm limited due to top end parts and/or bearing issues.

Cranks breaking has no consistencies behind them.

 

[frankenstien]

Everyone gets concerned with hp, it’s torque that is the concern.

1200ft lbs and up, lb7/lly will have short rod issues.

1300ft lbs and up, lbz/lmm will have short rod issue

Lml is all over the place. Their rods and pistons seem to range below or above any older engine.

L5P has seen 1500ft lbs and still held stock compression.

You can run large injectors to keep pulse width very low and keep pistons alive HOPING it’s a good set but if they have been abused under high pulse width and timing for miles before, waste of time to push it. At some point, you will not be able to de-torque the engine to keep making hp. You will become rpm limited due to top end parts and/or bearing issues.

Cranks breaking has no consistencies behind them.

are those numbers at the crank or tire? what is it exactly with the timing and pulse width that hurts the pistons? I have Max Effort tuning on my truck, with stock injectors, iirc its about a 3200us pw, have about 25k miles on that, kinda waiting around for a rod to bend, but was thinking about getting larger injectors to help bring down the pw, but if there's no point.. run it til it don't.

 

[2004LB7]

To advanced timing or large pulse width creates large amount of cylinder pressure

Large PW also can cause the injection spray pattern to be outside the bowl

 

[Chevy1925]

are those numbers at the crank or tire? what is it exactly with the timing and pulse width that hurts the pistons? I have Max Effort tuning on my truck, with stock injectors, iirc its about a 3200us pw, have about 25k miles on that, kinda waiting around for a rod to bend, but was thinking about getting larger injectors to help bring down the pw, but if there's no point.. run it til it don't.

This is all at the tire.

Running big pulse width increases cyl pressure but also adds a ton of undue heat to the piston and makes it very hard to cool back down before the next cycle. Just like heating a piece of steel up over and over, it becomes brittle in the weak areas.

So if you have already started to hurt the pistons, adding bigger injectors to bring pulse width down won’t really save you because we don’t know how far gone the pistons are.

None of this is “the Bible” because you will have those that challenge the norm.


I’ve wanted to take a stock lb7 bottom end, throw some high flowing heads on, nice cam, big single, big injectors in and spin the thing to 5500rpm to see what kind of power it could make and what it could take. That would be low torque but high hp. Drop it in a light car or truck and it would be fun. Hell I’d even mod some thing to just put l5p heads on it to keep cost lower assuming heavy valve springs from older years works. This obviously with all the extra money I have laying around

 

[PureHybrid]

are those numbers at the crank or tire? what is it exactly with the timing and pulse width that hurts the pistons? I have Max Effort tuning on my truck, with stock injectors, iirc its about a 3200us pw, have about 25k miles on that, kinda waiting around for a rod to bend, but was thinking about getting larger injectors to help bring down the pw, but if there's no point.. run it til it don't.

I'd be surprised if Mark set it to run that much pulse. I've been running his tunes since 2011 at 500+hp, close to 80k miles. Don't sweat it

 

[PureHybrid]

I’ve wanted to take a stock lb7 bottom end, throw some high flowing heads on, nice cam, big single, big injectors in and spin the thing to 5500rpm to see what kind of power it could make and what it could take. That would be low torque but high hp. Drop it in a light car or truck and it would be fun. Hell I’d even mod some thing to just put l5p heads on it to keep cost lower assuming heavy valve springs from older years works. This obviously with all the extra money I have laying around

IIRC Mark has a stock lmm block in his white truck with big injectors, stroker pump and his 72mm charger. Thought it made over 800hp

 

[Chevy1925]

IIRC Mark has a stock lmm block in his white truck with big injectors, stroker pump and his 72mm charger. Thought it made over 800hp

I don’t think he ever got it down the track. Wanted to see what that sucker would hold up to. Iirc he swapped the built motor in not long after the dyno pulls to continue turbo testing without fear

 

[frankenstien]

I'd be surprised if Mark set it to run that much pulse. I've been running his tunes since 2011 at 500+hp, close to 80k miles. Don't sweat it

The tunes are locked, so I cant look at them.

I got his tuning, drove it for a couple of days, asked for more on the Max Effort tune, so I'm not sure exactly what it is, but i want to say I logged it at some point, and saw 3200 or 3250? I could be mistaken.

I would like to not bend the rods, but if it happens, it is what it is, from what ive read the LLY doesnt have the piston cracking issues the LBZ's seem to, just the short rod syndrome

I have also been thinking of seeing about raising the max rpm, as sometimes i hit the rev limiter before it will shift, not sure if thats a good or bad thing for the motor, it stops at 3500rpm now, or maybe i need to have my tcm tune adjusted