crcain

Came out of my buddies built motor. He disassembled the motor because the leak down in cylinder 1 was off a bit and he was adding a lot of oil. As it turns out the head was leaking oil and was probably the main culprit for the oil loss. But here is the number one piston:

(cylinders had scoring at the top of the bore)

evo 8 ya

iTrader: (31)

Looks like oil starvation or fuel delution. Not really sure what you'd like to know.

Mark S

Can you get some better pictures and what the bore clearance is.

Mark

crcain

I'll measure the bore clearance tonite and take some better pics.

My buddy is already running in his new engine. But basically we are curious if it was our tuning that messed up the motor or if the motor was not built right from the start. We are curious because if it was our tuning, then we may be more careful in our tuning going forward.

Mark S

After the guy who put the wrong valve springs to start with I wouldnt hold out much hope for the rest of the engine.

Mark

crcain

Yes I agree I'm hoping the culprit wasn't all the tinkering with the tuning Anthony and I did with his car and it was just a badly built motor he got. His car always ran awesome but he just couldn't put up with the adding of oil and the cyl1 poor leak down.

Mark S

Go back and copy the way the other 2 cars are mapped, You wont go wrong .

Mark

crcain

I know, I know... but we like to tinker!

Slo_crx1

iTrader: (9)

It looks like improper bore clearance to me, and a good possibility of improper ring gap to go with it. Pics of the bore would be good, it could be an issue of the piston expanding too much for the clearance of the bore once they reach operating temp, and once they expanded the ring gap might have opened up too far to keep a good seal. I kind of doubt the tune had anything to do with that, even detonation shows its marks on the tops of the pistons but the marking on the bearing surface shows some pretty heavy impacting. Maybe improper lubrication during initial start up?

crcain

Ok so I'm not exactly a natural with my mic and bore guage but I was very careful when measuring. The piston diameter measured at the bottom of the skirt was 3.3435" or 84.925 mm. Then zero'd out the bore guage on the mic and read pretty much 4 thou up and down the bore. We measure 3 thou in an area or two and 6 thou in some areas where there was scoring at the top of the bore. What do you guys think of those clearances?

I forgot my camera of course so no new pics. Will take better pics tonite.

Also, the guy that built this engine for my friend was supposed to use Arias pistons but I was just going through their catalog and these don't look like Arias pistons to me. Anyone can name the piston manufacturer? I'd like to look up the recommended piston to wall clearance.

Thanks for everybodies help.

crcain

And am I right in saying the little pock marks at the crown are signs of mild det? And if so, is that a significant amount of det to have caused an engine problem like the scoring on bores, skirts, and crown?

nitz

iTrader: (3)

you mean u like tinkering on other people's tune

crcain

They were group decisions! You were the one pushing for more timing on VP Import lol!

Here is nitz's car a month or two before we took his engine apart.

11.0 on a Green: http://www.youtube.com/watch?v=1m9ovmRspbI

One thing to note, is that about 2 years ago when the engine was first tuned on pump gas, there was a problem with the valve springs and when we pulled the head the scoring on the bores was there. So either the scoring was there before the engine came to him, or it happened in the first 50 miles on the motor which is when we pulled the head because DSM springs were installed mistakenly by the builder.

2k4EvoVIII

iTrader: (15)

Look like Wiseco.

Chris

nitz

iTrader: (3)

for pics of the bore see https://www.evolutionm.net/forums/ev...ce-needed.html which precedes this one.