Lb7 limits

LSxBakakos

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May 29, 2022
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Hey guys, been doing weeks of searching and finally decided to register, hopefully I'm positing in the right spot

From what I've gathered I've seen guys leaning on SBE and them living from 650-750 at that level, but most the posts have been from years ago and technology has come a LONG way since then. I don't know what the true limits are or how long I can expect this thing to last so figured I'd ask you all

I've got an 03lb7 that's my toy/only comes out on weekends, usually to only get beaten like a redheaded step child.
It's built drivetrain, stealth 67, LDS Sac65s, PPE dual fueled, and almost every bolt on offered. Suncoast stg5 with goerend R etc. Ive been on tune 4 and have held off clicking it into 5 just because of the "unknown". 4 made 650rw, and wont keep traction under 40mph. Tune 5 i was told makes about 725+ and to use it on "reserve". Out of respect for my tuner I'd rather not say their name, they are one of the biggest most reputable in the industry so it's not some backyard b.s. they have detorqued it on 4&5 under 2100rpm to keep things alive. Considering I'm in the market for a house I'm paranoid of this things longevity bc it'd be an expensive paperweight lol. Is my tune 4 safe-ish to keep beating on? Is it gonna nuke itself if I turn it up? I'd really like to touch 11s this year but it's always in the back of my mind on when it'll banana rod itself. How often are you 650+ guys laying into em? And how long have they been running at that power level?

Went 12.80 last year with the 67mm draining 6k of rail on stock sticks, hoping after I installed 65s and 2xcp3 it'll touch 11s, curious on your opinions as well

Thanks in advance!
 

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LSxBakakos

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I definitely won't disagree with that mike, was just hoping with the maybe 5k a year I put on it that I could enjoy the power for a year or two without having to worry about forking out 15k on building a short block
 

TheBac

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"Ignorance is bliss" comes to mind.....

Technology and knowledge may have changed, but LB7 rods havent. As Mike said, buy the house, turn the tunes down, save for rods.
 
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gmduramax

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"Ignorance is bliss" comes to mind.....

Technology and knowledge may have changed, but LB7 rods havent. As Mike said, buy the house, turn the tunes down, save for rods.
100% if this reputable tuner has a chamber pressure monitor and is keeping the truck in a safe range it could live. But don’t these motors make peak torque around 2400? It’s all a gamble either way.
 

LBZ

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"Ignorance is bliss" comes to mind.....

Technology and knowledge may have changed, but LB7 rods havent. As Mike said, buy the house, turn the tunes down, save for rods.
What he said…….
 

LSxBakakos

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I'm unsure on how to highlight how you guys have but gmduramax I'm unsure wether they have a chamber monitor. The guy who tuned it told me he pulled torque out of it and it very well could've been a typo on the rpm. It's detorqued and sloped in as he said. Considering their one turbo is max on a SBE they advertised 640 was the limit. I don't want to give up racing, was just trying to see how long some have been running 650+. I'd just like a year or two out of this short block and an 11sec slip in my hands
 

2004LB7

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do you have any dyno graphs you can post? that should help see if, and how much torque was pulled
 

LSxBakakos

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Unfortunately all I have is the number from the tuner and no graphs. Maybe that's their guesstimate with how many they've done? I can't say for sure. I have a buddy out in Colorado with less fuel same charger and tuned by the same place and he made 687rw. I can always ask him for a graph considering I'd imagine timing and pw being somewhat similar between the two if that helps any? Both of our tune 4s were set to be 650, tune 5 was setup as a max effort for both as well. His peaked 687 on 5, and I was told mine was 725+
 

TheBac

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Dont take what I said as an insult. The 12.80 at the track tells me you're closer to 530rw than 650 being claimed, though..... at least with the info you've given.
I bent rods at 580rw, but was running 12.20s at the time. We've all been there.....

If you want it to live, turn the tunes down until you can build it properly. Physics is physics. The rods cant handle over 550rw for very long, I dont care what anyone else says. You can still have a very fun, useful street truck at 500rw
 

LSxBakakos

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Thebac no insult taken, as far as your truck making 580/bent rods did it just show as a compression loss? And 08lmm is correct on that. Stock injectors, stock cp3 and being down 6k on rail netted a best of 12.80 in 4wd. I have yet to run it since the fueling corrections or new trans, and I'm pretty sure my last converter was "blowing through" in lockup considering the low trap speed. After the fueled tunes my built trans bit the dust, so it's fresh and coupled with a goerend R now which seems to hold and couple MUCH better
 

TheBac

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Initially showed as extra whitish smoke and slight shake on cold start, balance rates on multiple cylinders were well off when warm. Did compression check, 2 cyl were way off, with the others all within 10% or so. On teardown, 2 rods were noticeably bent, 4 were tweaked. That was stock turbo/sticks with a very big tune. Rebuilt it with LBZ rods and +30 injectors, still on stock Cp3 ran 12.teens. I was lucky I caught it early.
 

LSxBakakos

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Well I do appreciate that feedback and glad you mentioned that so ive got something to reference off of. Also good to know that balance rates will show c.r. loss and I actually just ran one on Friday. I can feel how much they detorqued it, but I guess that outcome is inevitable for me too lol. With my luck though I'll probably have a window in the block vs having something show prior much like yours. Did they pull a lot of torque out with your tuning? Or was it in full?
 

TheBac

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That was before "detorquing" tunes was a thing. Rods will surprisingly take a LOT of abuse before they wipe out the block, but when they go, they go. There's an old pic of one of Finger's rods from his truck bent almost 30* and the truck was still running, but banging.
 

LSxBakakos

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With that being said you don't think with moderation I can continue to run tune 4? it's definitely felt in the butt dyno where the power comes in at. Ive seen quite a few catastrophic failures over the years from working at an engine shop so i get what ya mean lol. But the fact it bent 30* and didn't let loose is just mind blowing, but id imagine the skirt was making contact with tht crank. Most of the time we saw rod bends due to a hydro'd cylinder, overrevving or in forced induction application when cylinder pressure was too high. Not so much torque related like these things. Definitley wish I had more knowledge with diesels and got into them at a younger age, up until 6 years ago when I got this thing I'll I'd ever known was small blocks big blocks and LS engines and these have been a huge learning curve to say the least
 

LSxBakakos

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Buddy that has the identical build(smaller sticks/10mm stroker)just sent me this. Considering we're both on a 32" tire I'd imagine full power comes in between 2800-3k? Judging by the wheelspeed. Both tunes done by the same place if that helps you guys any
 

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darkness

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You’re not going to get the answer you want to hear. If you’re worried about your shit blowing up I’d suggest keeping the power down.
 

LSxBakakos

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You’re not going to get the answer you want to hear. If you’re worried about your shit blowing up I’d suggest keeping the power down.
Im literally asking if it'll live for a year or two at that level before it scatters itself. I do plan on building an engine in the future but don't want a paperweight for a while. So if you guys really think it's just gonna blow itself I'll either play with fire or turn it down and be bored with the power level again