Swapping LS2 Pistons into LQ4
02-23-2010, 01:06 PM
#1
Swapping LS2 Pistons into LQ4 Hey guys, I just picked up a set of stock LS2 pistons that I plan on swapping into my '02 LQ4 to bump the compression up for the motor. I was just wondering if it's just as easy as taking the LQ4 pistons out, and putting the LS2's in, and use the stock LQ4 rods, or if there's anything else that will have to be done. Also, will the rotating assembly need to be rebalanced with the LS2 pistons?
02-23-2010, 09:24 PM
#4
I'll try and see if I can find the newer rods for a decent price then. I've heard the newer rods are a little better anyways. I planned on trying to pick up some pistons and rods together, but couldn't find a good enough deal, so I just got the pistons by themselves. Will the newer rods work with an older crank just fine? And I should be able to just use the piston rings from my LQ4 pistons, couldn't I? They're still brand new. The motor was never ran after the rebuild.
02-23-2010, 10:24 PM
#5
most lq9s have the floating pins, and anything 04+ should as well. they will work with an older crank just fine, as they only changed the reluctor wheel to the 58x on the newer cranks. The rings should swap right over, just make sure they back on the right way.
02-24-2010, 12:36 AM
#7
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Be careful. I believe you need to use a LQ9 crank as well. The full floater rods are heavier requiring a heavier crank to balance. Also, I believe the pin diameters are different on the LQ9 and LQ4 pistons because of the floating arrangement. Research it, see what you find out.
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02-24-2010, 03:17 PM
#8
Be careful. I believe you need to use a LQ9 crank as well. The full floater rods are heavier requiring a heavier crank to balance. Also, I believe the pin diameters are different on the LQ9 and LQ4 pistons because of the floating arrangement. Research it, see what you find out.
02-26-2010, 11:22 PM
#10
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It can be done, but at high RPM's there will be some harmonics going on that may shorten the life of your rotating assembly without it properly balanced. If it were me, I'd pop for a set of 243's for around $400. CR problem solved. No swapping out of the rotating assembly. Alternatively, you could mill your heads if you're not running a wicked cam. That's my $.02.
02-26-2010, 11:26 PM
#11
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^^^^I believe he is referring to converting the non-floating rod to floating without bushing the small end of the rod, which would be pricey. It can be done without a bushing, just have a reputable machine shop fit the pins and insert an oil hole.
02-27-2010, 02:35 AM
#12
I think I'll just end up sticking with my LQ4 pistons, and just have the lower compression. The 9.4:1 compression doesn't bother me all that much. Makes it better for boost later on down the road. There's no way I'll get rid of my L92 heads for LS6's. The extra flow is worth the drop in compression. With the cams I'm looking into, I should be in the high 400's at the wheels with those heads and an LS3 intake.
02-27-2010, 08:10 AM
#14
you can get the ls2 pistons put on the press fit rods. Same way the stock pistons are on there. Just dont put the circlips on the pistons after. The only part that could be of any concern is a weight difference between the dished and flat top pistons, but I cant see that being much. If you can weigh your lq4 piston/rod assembly, subtract around 610 grams, youll know how much the stocker weighs.
03-01-2010, 10:57 PM
#15
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I believe the pin diameters are different. .945 for press fit, .943 for floating. Check Carcraft archives, I think they put LQ9 pistons on press fit rods. If I remember, they had to modify the small end to get it to work.
