420A 420a fully built motor long gone

[lxeclipsegsx]

i'm guessing my piston melted it was running to rich for awhile dint have the time to tune. dont know if i should return to stock buttom or just replace piston.

 

[totaleclipse_05]

How does your piston melt if you are running rich?

 

[Talonracn50]

Richness could cause cylinder washing (removing the oil film and causing premature wear), but it was likely something else that caused only one piston to fail.

 

[InfiniteGSX]

but it was likely something else that caused only one piston to fail.

+1

Nothing against xeclipsegsx or whoever built it... but since it was only one cylinder... I'd say it was a defect on installation. And whoever did the installation of the pistons/rings/rod's/rod bearings is to blame for either not catching the defect, or purposely doing it (asuming you aren't the one that built it). It could be a defect on the Cylinder Walls or the rings which caused premature wear, Inproper installation, Defective parts used...... But I wouldn't blame it on the Engine Managment. Cause I'd have to say all 4 cylinders would have failed if that were the case....

Right?

 

[BigRand]

well I half agree with the notion that all four would have failed, however the reason I say that is because maybe the other three haven't failed yet.

I'd say take them to a machine shop, and have them inspected, (or take pics and post em up here) of all your pistions. If you notice the same wear patters then maybe richness could have caused it.

I wouldn't bother returning the whole set back to stock, as you might have noticed pistion prices have come down a lot lately. You could probably pick up a set of pistions w/rings for about 350bucks. Check out the prices for stock pistons?

 

[lxeclipsegsx]

350 where could i get it for tht price? and i'll keep you guys posted on what happens. one more thing all the oil came out. before it was shooting it out throw the breather.

 

[bullettdsm]

350 where could i get it for tht price?

Stockers? For example;

http://www.store.partsdinosaur.com/product100.html

one more thing all the oil came out. before it was shooting it out throw the breather.

It will shoot out the breather if you burn a piston or ruin your rings. Basically, you are pressurizing your crankcase by compression going by the rings/pistons. Where is it coming out from now?

As for it being installation or tune. Could be either. Gotta take her apart and see. You will not have all four pistons go at once. If your tune is bad (I'm just talking about lean here) you will burn one piston first. If you are running pig rich you stand the chance of washing out your cylinder walls and ruining your seal on the rings. If that happens then you get fuel in your crankcase and start ruining out bearings.

MB

 

[Slo2gen]

Could have had the rings installed upside down.?

 

[4UH8ERS]

I melted just one piston. It was melted on the top edge by the ring lands so bad you could see straight through it like a peephole. while all the others were perfectly fine with good compression and all. I originally blamed it on a failed injector in that cylinder because I couldn't really find any other explination for it, but just to be safe I did a complete rebuild and replaced all 4 injectors which definately fixed the problem.

 

[lxeclipsegsx]

lets say i did get fuel in my crankcase and started ruining the bearing will the car still start because after i changed the spark plugs it started dint want to stay on though
spark plug were broken as well

 

[bullettdsm]

I melted just one piston. It was melted on the top edge by the ring lands so bad you could see straight through it like a peephole. while all the others were perfectly fine with good compression and all. .

Typical too lean situation. Could have been injector. Could have been tune. Pretty unlikely install error.

lets say i did get fuel in my crankcase and started ruining the bearing will the car still start because after i changed the spark plugs it started dint want to stay on though
spark plug were broken as well

Bearing breakdown will generate knock, noises, low oil pressure, flakes of in the oil.

What do you mean, spark plug broken?

MB

 

[lxeclipsegsx]

how much boost can a stock 420a motor hold? was it 8-12psi?

 

[VelocitàPaola]

The stock bottom end can withstand upwards of 14psi if carefully and properly tuned. The main limiting factor with stock bottom ends and boost is detonation. If detonation occurs at more than 9-10psi, your engine is pretty much done for. Additionally, the 12:1 FMU really isn't good for more than about 8psi or so of boost, which is where the "no more than 8psi" myth comes from.

 

[lxeclipsegsx]

so about 14psi well tuned what about the head? well i have the portfueler keep around 12-14 keep it safe?

 

[BigRand]

so about 14psi well tuned what about the head? well i have the portfueler keep around 12-14 keep it safe?

Well you know we can't call it SAFE, Your going to want a very conservative tune.

AFR's at least around 11.5 or lower, and probably want an EGT to monitor the exahust temps under boost to make sure nothing is melting

AWDdynamyite I believe had a porterfueler setup tuned for 16psi on the stock bottom end, but eventually ended up building it.

What size secondaries do you plan on using to get the requrired fuel?

 

[link16]

Go for the stage V...That is what I am rolling with now, and it is great. Way too rich without tuning it though.

 

[lxeclipsegsx]

thats what i'm running i believe they are 550cc i already have a fully built motor something is wrong i have a extra stock motor that i just bought for right now i dont want to have the car just collecting dust brand new paint job that why i was asking about a stock motor

 

[link16]

IIRC they are only 500cc injectors.