So driving on the freeway, full boost 4th gear, looked down to see my temp needle 3/4 way up. I put it into neutral and cranked the heater, but the engine just died.

I wasn't sure if it was a piston or just a headgasket until today.

Look at the #2 piston,



AFR was between 10.9-11.8, timing is retarded .75 degrees/psi

This happened at 15psi

Was this due to the overheating engine, or just bound to happen with stock pistons?



Setup:

Stock gsr head
stock b18a block
arp headstuds
precision 780cc/min injectors
walbro 255
garrett t3 60-1 T04S housing .63/.70
etc...

 

94 octane
about 9.7-9.9:1 compression

 

what is your timing at 15 psi?

 

15 psi on a 60-1 on a stock motor? What were you making? around 350-375?

 

i was thinking the same thing

too much boost/power for stock internals


btw i didnt see the damage to the pistons

can anyone point it out

 

Look near the intake valve pocket and you'll see that it started to melt

 

wouldnt that be piston no. 2?

 

You pushed that motor harder then you should have.

 

Now that you have the motor open, order some good rods and pistons and slap them in. My ringlands blew on me and I threw in some crower rods and srp pistons.

And that is #2 cylinder that melted. I kept looking at 3 and I couldn't see anything.

 

me too
i was looking at number 3
lol

 

WRONG....


If it was a broken ringland thats one thing.. but he has a melted piston.. Something else is wrong...

Too much power on a stock engine did not cause that

How long were you in boost in 4th? were you ripping on it for a long time?

 

looks like you had too much timing/ ran too rich or just plain and simply needs a proper tune

btw thats cyl #2 not #3

good thing ls blocks are cheap

 

X2... and added some

 

i agree , that sucker is melted not broken , so that cyl might have a injector that isnt flowing as well as the other 3

 

how will running to rich cause this?

too much heat from running too rich?

 

detenation that caused a hot spot and melted that piston. i would look at your injector for that cylinder as stated previously.

i would say you were on the freeway for a while running it like that.... maybe 20-30 mins pretty hard without a rest?

a lean condition like that can run for years without problems but soon as you put a good amont of time on running it hard for a while with out resting you run into creating hotspots that will melt like taking a tourch to it.


kev

 

I went through 2-4 gears. i might have been just into 5th at the time, cant recall for sure. I was not on it for all that long, i was driving around for like 20 min prior, but not hard.

Timing is about 15 degrees. This is on turboEDIT.


The injectors are still brand new, pretty much. How much of a percent difference could there be between new precision 780cc/min injectors?

 

You exceeded the knock threshold of your fuel. It was detonating to cause that damage.

 

This engine should operate at around 198 F right?

So if it increased from normal levels to around 220 F maybe even higher, how much does affect knock threshold and increase detonation?

I've seen lots of places that have wiseco and eagle combination deals, where is the best place(aka the cheapest)?

 

I believe this is due to the tune. It needs a professional tune, I've created a few cleff lips (never on cast piston though) and alot of broken ringlands. Probably the gear compensation, Do you know what your doing with it? There's a lot more load at those speeds, Im sure you were probably eclipsing 130mph. Werent you.

What kind of plugs you running? Hows your exhaust, lots of back pressure? Probably way to much power too.

 

I was doing 180km/h, which is 111 mp/h. What do you think was wrong with the tune? Why does it need a "professional tune"? I'm an engineering student, i'd rather do it my self and learn than pay someone else who probably knows as much as i do to do it. Plus i'm broke.

Brk7es, open downpipe.

What the hell is too much power? that statement doesn't make sense to me.

 

Cast pistons can only handle so much but I figured you wouldve broken the ringland first. Guess it just got to hot, maybe due to a lean mixture through mechanical failure or whatever it may of been. A open downpipe will throw your af ratios off.

You remember doing 111mph but dont recall weather you were in 5th? Maybe you should ask your professor

 

LS transmission, i would have guessed a ringland too. That would be from cylinder pressures too high right?
So it must have been detonating somehow, i'm wondering

Is 15 degrees too much?
Does turboedit change things in the background i'm not aware of?
An overheating engine causing the knock?
Oil vapor in the intake?

 

if turboedit is anything like uberdata/crome then it may have some issues controling timing after a certain point.

plus the fact the stock cast pistons dont like the abuse for a very long period of time. also dont belive everything you see/read about how much power the stock pistons can take.

my suggestion is to invest in a good EMS... ectune, hondata, neptune ect....and just put a set of forged pistons in.

 

x2

And learn to drain the coolant before pulling the head, tisk tisk