LLY: How much can a stock bottom end LLY take?

Chevy1925

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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TheBac said:
Bet you aren't. Stock CP3 can put out enough fuel to bend rods. Done that.

I'd love to know just who has been selling all you guys this line that these stock engines can take so much. Its complete crap, but heck, it's your money so good luck.
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built trans, lift pump, exhaust and intake, and a CP3 that will hold rail with GOOD tuning is hard to bend rods from what ive seen (this is stock turbo, stock injectors, 1 cp3, stock motor). doesnt mean it dont happen though. I think tuning has come a long ways in making these trucks live. i know i beat the piss out of mine on a 3200uS and 32* of timing for 4 years before twins went on. then reality struck

you start adding more air or fuel and all bets are off.
 
SSchmi5519

SSchmi5519

LLY Cult Leader
Oct 19, 2008
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I think a lot of it has to do with the natural characteristics of mass producing parts.

Of all the OEM connecting rods that GM has produced there is one rod out there that is strongest and one that is weakest. Then there is a span between them where most rods fall.

If your set of eight are towards the higher strength end, you get the guys running ~700hp on them and are ok. If you even had one rod which was toward the weaker end of the spectrum, that is the one that will bend on you. No two pieces can be perfectly identical.
 
Ne-max

Ne-max

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Nov 15, 2011
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TheBac said:
Bet you aren't. Stock CP3 can put out enough fuel to bend rods. Done that.

I'd love to know just who has been selling all you guys this line that these stock engines can take so much. Its complete crap, but heck, it's your money so good luck.
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I'm referring to post 8. My rods are the reason I went with a 366 instead of a 475.
 
J

jkholder09

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Jan 8, 2012
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SSchmi5519 said:
I think a lot of it has to do with the natural characteristics of mass producing parts.

Of all the OEM connecting rods that GM has produced there is one rod out there that is strongest and one that is weakest. Then there is a span between them where most rods fall.

If your set of eight are towards the higher strength end, you get the guys running ~700hp on them and are ok. If you even had one rod which was toward the weaker end of the spectrum, that is the one that will bend on you. No two pieces can be perfectly identical.
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What about if you bend all 8 just a scoch and all evenly such that compression is lowered and now it lasts forever:hello:
 
SSchmi5519

SSchmi5519

LLY Cult Leader
Oct 19, 2008
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jkholder09 said:
What about if you bend all 8 just a scoch and all evenly such that compression is lowered and now it lasts forever:hello:
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It has happened, but I would assume that according to the spectrum of strength, that those 8 rods are all nearly equal in strength.

Usually doesn't happen like that as once the rod is bent a little bit, the leverage of the piston on the rod is changed so that it bends easier.

Kind of like you can stand on a soda can, but once the side is dented even slightly the whole can crumbles under the weight.
 
05smoker

05smoker

I'm officially done!
Mar 30, 2007
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My brothers LB7 didn't bend a rod at 600 hp. It pulled the rod out of the bottom of the piston and proceeded to window the block. Twins and stock cp3 and injectors. Adult driven at all times. ;)
 
hondarider552

hondarider552

Getting faster
May 28, 2008
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Hell, I bent my single cab rod with 2500us and a S475 within 3 weeks... so anything can happen.


I think it's pretty safe to say ~500rwhp on LB7/LLY, and 550-600 on LBZ/LMM. Course there is a +/- HP to that, but to me, that's the limit. Paint has been over 700 for years, and I was at 500 for 2 weeks..
 
SSchmi5519

SSchmi5519

LLY Cult Leader
Oct 19, 2008
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If youre trying to go for longevity best bet is a properly timed EFI tune with stock or slightly less than stock fuel quantity.
 
D

Drewsdmax

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Jul 16, 2012
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I run the II s366 on my stock bottom end and stock studs with no problems @ just over 500HP and 900Ft/Lbs). I'm throwing a set of 45 overs in this spring which may make things a little more interesting. If you have a stock (original) CP3 it's unlikely you would have enough fuel to break the 600hp mark anyway (although if its healthy enough it can be done).
 
catman3126

catman3126

Ehhh?.... You don't say?
Jul 24, 2012
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Drewsdmax said:
I run the II s366 on my stock bottom end and stock studs with no problems @ just over 500HP and 900Ft/Lbs). I'm throwing a set of 45 overs in this spring which may make things a little more interesting. If you have a stock (original) CP3 it's unlikely you would have enough fuel to break the 600hp mark anyway (although if its healthy enough it can be done).
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Yeah care to take a look at my dyno chart? and there has been guys a fair bit higher then mine and relying on a less adequate CP3 pump to protect a bottom end is not a good idea. I have no doubt theres more in mine with tuning also. my cp3 maintains good near desired rail pressure with what I'm running now.
 
mike diesel

mike diesel

I'm alright.
Sep 6, 2012
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I've dynoed over 600 hp on my lly with 30% injectors and stock cp3 with my s472. Stock cp3 is plenty capable of over 600hp.
 
MAXX IT OUT

MAXX IT OUT

<<<IT WORKS
Mar 1, 2013
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All this talk makes me wish i would of save for another couple of mouths and got rods.:mad: I have the air and fuel for 750+ HP and the engine for 600 HP reliably.
 
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