bottom swap, or how i learned to rebuild the bottom end completely

[almighty]

so, i have a l36 that is in great condition but is also in a project car. I also have a l67 that is in a gtp, the motor in the gtp may be shot (still have to do a teardown) If i drop a "topswap" motor into the gtp my main concerns should be a good DP, maybe some nice porting, and a tune correct?

my other option is a bare block with a bad crank but good rods/pistons. I have been told a bottom end rebuild on these motors is not worth the trouble/money and may cause massive issues but i have access to a great machineshop guy and wouldnt mind having a "new" lower end. so what all would have to be done to the bare block\crank\rods to make them reliable.

 

[Sandman]

I would just drop in the other motor. You should put in a cam if you swap the blocks.

 

[BwolfGT]

Yeah nobody seems to have good luck rebuilding the bottom ends on these cars.
Topswap motors are faster than normal gtp motors, you've pretty much got it right on the dp and tune, porting will help. You'll also need to replace alot of little things like coolant elbows, gaskets, sparks.

 

[TorqueAutoMotiv]

I let ya know how a complete build goes in a month or so lol Pulling the engine on next saturday
I dont see why building the bottom end could be that bad specially using a good machine shop

 

[Bio248]

use the l36 block and do a small cam with it. that way you for sure wont knock with it and youll get the good driveability of the high compression block. the l67 feels like a dog all the time out of boost and always regretted not having the l36 block when i toasted my first one.

 

[99prixgt]

with a plog, d/p (i didn't knock at all with a 2.5" d/p), 1.9 rockers, and intake, you shouldn't knock at all.

With all the above and if you get a set of headers instead with a good tune you could squeeze a smaller pulley on there

 

[DanGTP]

Just for some added information:
I rebuild my engine entirely instead of just throwing another one in and couldn't be happier. It's balanced perfectly, has 9.5:1 compression with forged pistons, is slightly over-bored (not sure if that did a whole lot, though), and has been trouble-free for 6 months so far.

Price-wise it's cheaper to throw a L36 block into the car, but if you want to rebuild it and have a good quality machine shop to take it to, go for it!

 

[mikedinthecity]

bio248 i agree. knowing what i know now, mine would have got a top swap, instead of searching out an l67 and doing it that way. the things you learn after the fact. also i had no problem with the bottom end on mine, but there was nothing wrong to begin with i just did it to do it. yea there was a small amount of coolant from the intake manifold gaskets. so it was good i did do it.