LQ4 verses LQ9

[4OfaKind]

Thanks, Guys.
So there's no huge advantage to get the better rods, heads [poss] and flat tops and running it as is?

I don't think so, No.
You said you were going to run it hard at times. To me that means start with the lower mileage LQ4, less wear already. If you are happy with the 325 hp of the stock LQ4 motor cool. I personally don't think the extra 20 hp of the LQ9 is worth the extra wear. If you want more hp, how much more? Because then since no truck motor has forged rods/pistons, even slightly stronger powdered metal is still powdered metal. So parts would need to be changed and you still have the higher mileage block. With price being the same to me lower mileage is a big advantage.

Mal

[93Polo]

I'd go LQ9 for the extra compression. My LS1 received heads and cam at 65k. It is over 90k and still running strong. The miles were not babied either.

Powdered metal rods can take quite a bit of abuse. A few 355 LT1s with blowers locally had stock crank and powdered metal rods running at ~600rwhp. The rods bolts are the weak link in the earlier LS1s not sure about the trucks. I would swap to ARP bolts since you will have the motor of the car.

[00fxd]

Good advise, Thanks guys.

"I would swap to ARP bolts since you will have the motor of the car."
Can you change rod bolts in these engines without re-sizing??

[93Polo]

Good advise, Thanks guys.

"I would swap to ARP bolts since you will have the motor of the car."
Can you change rod bolts in these engines without re-sizing??

Yes that was my understanding. The rods have a cracked beam design which allowed you to swap the bolts without resizing but also be sure that they go back together the exact same way you took them apart. Ls1tech has had some topics on it. If you can not find it in a search let me know and I will try to dig it up.

[00fxd]

I will look, Thanks Polo

[93Polo]

I was playing around on Ls1tech and http://www.ls1tech.com/forums/showth...=423651&page=2 has some info on the rod bolts

[00fxd]

Thanks Polo, good thread. It makes sense to me that because they are not interference type press fit bolt and nut assemblies, but are Lemans style capscrews that there should be no issues.