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Rebuilding after chipping a piston. Need advice.

W

whitetrashgtp

New member
Hey guys, i need help on parts for this l67 rebuild.
First off, I'm boring the block .020" over and will get the rotating assembly balanced. I'm using stock crank. I need help on rod/ piston selection. I'll be running an s1x cam, 1.8 rockers, e85, and an intercooler. I'm looking for around 300 fwhp. Last dyno on the stock cam, 1.8 rockers with a 3.2 was 236 whp, 346 wtq.
Having said that, can i safely do some 9.4:1 hypereutectic pistons with n/a rods? I'll be running a 3.4 pulley on first startup. I'm looking at keith black pistons. Advice is greatly appreciated, however know I'm not spending the money on forged.
 


Those pistons should be fine. You could probably get away with stock rods, but since you're already in there upgrading, you might want to consider H beam rods. They'll be much stronger than stock.

ZZP has some for $600 a set, or you can probably get some good ones on eBay for around $200. The sloppy mechanics use ebay internals on high hp LS builds pretty often.
 
Make sure they do the whole nine yards to this engine and I mean everything because I'd say about 90% of rebuild 3800's blow up within the first 1,000 miles. It would be cheaper to just source a stock NA block unless you can get the machine work for some killer deal.
 
whitetrashgtp said:
Hey guys, i need help on parts for this l67 rebuild.
First off, I'm boring the block .020" over and will get the rotating assembly balanced. I'm using stock crank. I need help on rod/ piston selection. I'll be running an s1x cam, 1.8 rockers, e85, and an intercooler. I'm looking for around 300 fwhp. Last dyno on the stock cam, 1.8 rockers with a 3.2 was 236 whp, 346 wtq.
Having said that, can i safely do some 9.4:1 hypereutectic pistons with n/a rods? I'll be running a 3.4 pulley on first startup. I'm looking at keith black pistons. Advice is greatly appreciated, however know I'm not spending the money on forged.
Click to expand...
Those numbers seem pretty low to me, even for having a stock cam.
 
A local reputable machinist near me who has done a few 3800's before told me he'd blueprint/balance everything for 600 bucks with the .020" over bore. I only trust him because my work has 2 loaner cars with their rebuilt 3800 in it. However, i kind of have to assume a lot of rebuilt blow ups are due to poor break in.
 


no, they blow up due to crappy machine shop work, or none at all. there is no break in for a modern engine with a roller cam.

i would so save 2 grand and find a used engine.
 
whitetrashgtp said:
A local reputable machinist near me who has done a few 3800's before told me he'd blueprint/balance everything for 600 bucks with the .020" over bore. I only trust him because my work has 2 loaner cars with their rebuilt 3800 in it. However, i kind of have to assume a lot of rebuilt blow ups are due to poor break in.
Click to expand...

This comment proves you have zero idea what a break in actually breaks in. The only thing that needs broken in is the rings. That's it. If the rings don't seat then the car will still run, but just smoke and be down on compression.
 
Most rebuild failures on these are from the mains not getting line bored, and people reusing there rods with oblonged big ends.Basicly, bearing spin city. You get your machine work done properly, use aluminum bearings and you should be ok. I have 18k on my rebuild in my 5 speed gtp.
 
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