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Greetings, just discovered LS1Truck.com and digg it already! I have 03 Chev 5.3 LM7 in a shortbed reg cab and recently purchased a LS2 6.0 shortblock. After reading forums and talking with the local GM dealer I still have no clear answer to:
Will the top end of a LM7 5.3 bolt up to the shortblock of a LS2 6.0?
Without going into lengthy explaination of why; the blending of the two engines would be a temporary solution to a $$ money planning problem.
Thanks in advance ... -Toby
all cathedral port heads will bolt to the 6.0. 6.0, 5.3, and 4.8 intake manifolds are the same.
The 862 heads from the 5.3 aren't gonna be the best thing for the LS2, but they will work. I would spend the few extra dollars to find some 243s at least.
Will the 243's work with the LS2 pistons? Won't those heads push the cr over the limit?
799 cast heads came on the Ls2 which are pretty much 243's.
799/243 heads on a LS2/LQ9 put you at 10.9:1 compression. No where near pump gas limits. Don't waste your time with those junky 5.3 heads on the bigger bore motor.
The 5.3 heads have even smaller chambers than the 243's. Not sure what it would bring you up to but I'm sure its past the limit of pump gas.
NO its NOT i ran 706 castings heavily ported heads, if i remember correctly the cr was just over 12:1 ;) it put down just over 400 on my lq9Quote:
Originally Posted by bowtietommy
12:1 sounds pretty high to me without a big cam to bring down the dynamic compression. But if it worked for you that's good to know. Also I might be wrong about this but I thought the LS2's had a domed piston and the LQ9's were a flat top
LS2 and LQ9 have flat tops, LQ4 has dishedQuote:
Originally Posted by bowtietommy
Quote:
Originally Posted by bowtietommy
tommy sorry if i sounded rude, didnt mean to, but yes with my lq9 ( flatop pistons ) i ran 706 casting heads, talking to a few engine builders we calculated CR at like 12:5:1 honestly i had no issues and i drove this truck 67 miles one way to work for a long time.. running 93 octane
Thanks for the responses guys and totally agree the truck will run 'all-choked-up'. The reasoning behind keeping the 5.3 top end is due to the truck being a daily driver wouldn't mind getting the bottem end conversion out the way. The rest of the upgrades are on the wish list. Looking to do a 402 stroker with forged internals to make way for the top end and boost.
Honestly I would wait to install the LS2 until you get the heads and maybe cam you want to go with it. You can get 317s super cheap and 243s for just a little more. If you don't tune the engine yourself you could eat up what you save getting it properly tuned multiple times, plus headgaskets...bolts, fluids etc....
Plus your 5.3 you are pulling will be worth much less without heads to go with it.
I know you might be trying to save some coin, but in the big picture I think you will only be spending more, and it's not like your 5.3 you have in there now won't do you until you get exactly what you want to go in.
No worries skeet. Takes a lot more than that to offend me. Do you have a lot of overlap in your cam? Just curious what i can get away with on my LQ?Quote:
Originally Posted by skeet