LQ4 Rods vs LQ9 Rods
01-10-2012, 01:03 PM
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LQ4 Rods vs LQ9 Rods I have an early LQ4 and am wondering what the hp limit of the rods is. Is it a hp limit or is it a boost limit? I am planning to run between 8 and 10 psi maybe as much as 12 if I run e85. The setup will be EPP cam/LS3 heads/pt76gts/4l80. If I made between 600 and 650whp would that pass the limits of the lq4 rods? Don't know what other information is necessary so if I am missing something let me know.
01-10-2012, 09:17 PM
#7
Some years 6.0 came with different type of connecting rods
Early lq4 came with gen3 "ls1" type pressed wrist pin
Later year lq9 came with gen4 "ls2" type bushed floating wrist pin connecting rods which are significantly beefier than the ls1 type.
All the later model ls motors use the ls2 type rods.
My 08 4.8 has the longer floating wrist pin connecting rods.
Ive seen em in even 05 5.3 motors, but the 6.098 length.
Early lq4 came with gen3 "ls1" type pressed wrist pin
Later year lq9 came with gen4 "ls2" type bushed floating wrist pin connecting rods which are significantly beefier than the ls1 type.
All the later model ls motors use the ls2 type rods.
My 08 4.8 has the longer floating wrist pin connecting rods.
Ive seen em in even 05 5.3 motors, but the 6.098 length.
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01-10-2012, 11:02 PM
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So 650 whp through a 4l80 with a good tune will be ok you guys think? Down the road I plan to build a motor for it, but for now I am leaving it as close to stock as possible. I have found some LQ9 rods/pistons to buy. Is the bump in compression worth having the strength of the rods?
01-11-2012, 04:49 AM
#9
Problem with those early rods isn't only that they are weak, but they break when they bend. The lq9 rods are stronger, and usually bend without breaking. Prob with the lq9 piston and rod installed in early engine is the balance on the crank. The lq9 rod is ~40grams heavier which will require the lq9 crank or heavy metal to balance the light crank. You could get a set of scat I beam pressed rods and run them with the stock lq4 piston. They are at least as strong or stronger than lq9 rods, same exact weight as early lq4 rod, and under $300.
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Homer_Simpson (09-06-2023)
01-11-2012, 11:13 AM
#10
I am in the same boat and looking at picking up a lq4 motor. Everyone is worried about the rods bending/breaking. what about the pistons? the stock cast pistons handle it with out an issue? i'd think any kr and those things would fail quickly.
01-11-2012, 02:08 PM
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Also a good question. If the stock internals will be good enough for 650 then they will stay. I don't want to have problems with it, but if everything is likely to hold up it will stay stock.
01-11-2012, 02:28 PM
#12
Yes any KR and the pistons will let go above 600hp. Hence the reason everyone used to say these engines are only good for 500rwhp. That is what they will take while detonating from time to time. RPM is not the issue I have seen above 900hp as the rods bend and do not spin bearings. This is my experience at 900hp and 7200rpm max.
01-11-2012, 04:27 PM
#13
We'll be doing some testing this year, I think we've figured out a big key to keeping the rods from bending this last year, we pushed the lq4 rods to well over 900rwhp and have my l33(newer style rods) at 855rwhp dyno proven, I'm sure well over 900rwhp tho off the dyno and on the street. 
If I keep my rx7 we'll be putting twins on it and shooting for 1000+ rwhp later this year, all will come down to if we can get time to work on it, right now just too busy working on other peoples cars. I will say I don't think rpm is the issue, at least not at 6500rpm shifts.
If I keep my rx7 we'll be putting twins on it and shooting for 1000+ rwhp later this year, all will come down to if we can get time to work on it, right now just too busy working on other peoples cars. I will say I don't think rpm is the issue, at least not at 6500rpm shifts.
01-11-2012, 04:29 PM
#14
We'll be doing some testing this year, I think we've figured out a big key to keeping the rods from bending this last year, we pushed the lq4 rods to well over 900rwhp and have my l33(newer style rods) at 855rwhp dyno proven, I'm sure well over 900rwhp tho off the dyno and on the street. If I keep my rx7 we'll be putting twins on it and shooting for 1000+ rwhp later this year, all will come down to if we can get time to work on it, right now just too busy working on other peoples cars. I will say I don't think rpm is the issue, at least not at 6500rpm shifts.
If I keep my rx7 we'll be putting twins on it and shooting for 1000+ rwhp later this year, all will come down to if we can get time to work on it, right now just too busy working on other peoples cars. I will say I don't think rpm is the issue, at least not at 6500rpm shifts.Leaves me scratching my head....
