LQ4 questions and Opinions

[paulk68]

Being my first LS swap I am looking for some opinions. I came across a LQ4 motor for sale. The info the seller has given is as follows

"2000-20004. Short blocking being freshened up. Has ls3 heads intake, custom ground cam(around 500hp). New ls2 pistons and heads machined .030" to get 11-1cmp ratio. New bearings, rings, oil pump, timing chain, gaskets, all hardware. Includes injectors and 90mm cable throttle body"

what do you guys think this is worth? I have some hesitation buying a used engine as it seems a little dicey to me. Are there other questions I should be asking about the motor?

Is the Aluminum block LS3 that much better?

Let me know your thoughts
Thanks

[OBeer-WAN-Kenobi]

The only thing I can thing of is to make sure it's a 2001 and up. 1999 and 2000 had some differences that won't be good. One of the differences is in the crank so it won't mate up properly to a T56 or quite a few other transmissions.

Do you need to save the weight, how much do you want to spend (value or max performance?) and what will you be using it for are a few questions that will let you decide if it's the right motor for you.

I actually wanted to get a LQ4 for my build because I didn't care so much about the weight savings and I figured it might take forced induction better than the aluminum blocks. I ended up with an LS1 out of a GTO that came with a T56. By themselves the T56 were too expensive and I got a great package deal. To me, value was more important.

[Che70velle]

It sounds like a total rebuild to me, from what you've posted. The ls3 heads with custom cam will absolutely make that kind of power. This is basically updating the lq4 to a non VVT version of a ly6, which is a 6.0 made from 2007 to 2010. The ly6 has the ls3 head casting, with different valves.
I'd ask him if you can contact the engine builder, or machine shop, that did the rebuild. Ask them their history rebuilding LS engines. How long, how many, etc.
Was the assembly balanced? Do they hone with torque plates?
If you get solid answers from the builder, I wouldn't be hesitant in the least bit to buy this engine, if the price is right. What's it worth? Totally depends on a lot of different variables. What's the asking price, if you don't mind?

[Bigbore500r]

What you have there is a Iron block with flat top cast pistons (factory ls2 pistons). If it really does have LS2 factory pistons installed, it would have to have the later-model rods (better) which feature better bolts and floating pins.

Iron block is stronger, carries 100lb extra weight (this is estimated and debated, some say its less than 90, others say more) For what your doing the strength of either is not really an issue, aluminum blocks go 1000hp and Iron goes more...

You can tell if the block is Pre 2004 or post 2004 by the cylinder head bolts. If they are all equal length, it is an earlier block. If they are staggered length (some shorter than others), it is a later model. Wait...i could be getting this backwards...i will check. Anyways...

Something to check for sure -
Stock l92 / LS3 heads cannot accept a cam much larger than 230 @ .050 (on a 112 ICL as installed) so if he has decked the heads .030 PTV must really be checked depending on size of the camshaft. I know a 230 intake on a 112 ICL must have pistons flycut to get minimum .080 clearance for sure. Stock LS2 pistons are a flat-top with no valve reliefs, and sit .005 - .007 out of the hole. That being said, they dont really need a cam much larger than 230 @ .050, due to the large intake port that is relatively lazy for its size.

Something to watch out for.