When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Freshly built motor, it's a iron block 5.3 punched out to a ls1. The motor had 60 miles on the rebuild when pulled. I'm running my turbo kit on it but only saw 2-3 psi of boost once to,make sure the gate opened. Truck never made a sound till around 40 miles, I'd started making a pinging sound in the bottom end. We tried I know the truck was running a little lean but wasn't to bad. We were trying to put a few miles on it to break it in before I took it to get tuned. The motor was being ran on the boosted 5.3 tune. Nothing changed set up wise besides the block was bored to the ls1 specs.
I primed the system up and as soon as the truck started oil pressure was good. It has a brand new mellings pump.
To my knowledge it's a stock crank, gen4 ls1 rods, and gen 4 ls1 pistons. From what I'm told. The rods should be the same length as stock 5.3.
The 2 pistons came from the passengers side # 2 and # 3 I believe. If not #3 and #4.
The truck did get a little hot on the first drive, apparently had air still in the cooliant. Was cursing about 45 saw it climb pulled over and let it cool down. Wouldn't think it would do it tho? Espically to just those 2 pistons? As far as I know everything else is perfect in the motor. Rods are fine, bearings look new. Heads look great
Do you guys think it was a tuning issue then? Or possibly a wrist pin? Or maybe even a issue from the machine shop? The builder said the only think wrong from the whole ordeal was the 2 pistons.
The truck was never put past 1/2 throttle. I was using the old 5.3 turbo tune to try to break in the motor just putting it to work and back about 5 miles round trip. The old tune had the exact same set up only thing swapped out was going to the larger bored pistons. Cam, fueling everything was the same. Would you guys think it could of done it even though I kept the motor out of boost? The wideband was a little lean but wasn't anything I would think to worry about
Do you guys think it was a tuning issue then? Or possibly a wrist pin? Or maybe even a issue from the machine shop? The builder said the only think wrong from the whole ordeal was the 2 pistons.
The truck was never put past 1/2 throttle. I was using the old 5.3 turbo tune to try to break in the motor just putting it to work and back about 5 miles round trip. The old tune had the exact same set up only thing swapped out was going to the larger bored pistons. Cam, fueling everything was the same. Would you guys think it could of done it even though I kept the motor out of boost? The wideband was a little lean but wasn't anything I would think to worry about
This is not a tuning issue.
A tuning issue, if bad enough, would have busted a ring land or left little dimples in the top of the pistons.
As stated above it does not appear to be a tuning issue. I would also like to know what the clearance was in the cylinder. Does the bottom of the cylinder have a sharp edge from the machining? Where did those pistons come from? It seems weird that the scuffs aren't in the center of the piston. I would also check to see if the piston skirts are round down there. If someone placed them in a vise to drive out a pin it could have made them oval. Just a couple thoughts going through my head.
May 18, 2017 | 01:59 AM
What do you guys think?
