WTF is wrong with my engine V. A20 built engine go boom.
 

So my engine spun a bunch of bearings from the rods being effed up... so i pulled the pistons and they are scuffed on the skirts a bit after like 15 miles so what is causing that (see pics) they are forged. THe piston to wall clearance is more than adequate so i dont think that is the problem. Somebody told me it feels like the pins are too tight on the rods so they are dragging causing the pistons to rock more than they should but i need more input. They do feel a bit tight to me also but is that the only thing that can cause this? Do you think i can reuse the pistons without them being messed up

Edit: Thanks Dan!

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

[img width=800]http://www.fourgasmmotorsports.com/piston11.JPG[/img]
[img width=800]http://www.fourgasmmotorsports.com/piston22.JPG[/img]
[img width=800]http://www.fourgasmmotorsports.com/piston33.JPG[/img]
[img width=800]http://www.fourgasmmotorsports.com/piston44.JPG[/img]
[img width=800]http://www.fourgasmmotorsports.com/piston55.JPG[/img]


Copy my code :S dem pics are huge

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

shitty dude sorry to see/hear this

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

pistons look reusable to me

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

Are the wrist pins floating pressed in types? I believe that you usually have this with forged pistons but I'm just saying. See if they might've been binding, and what do you mean by more than adequate clearance? What was the spec?

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

yea to much is worse then not enuff

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

Care to explain your thoughts?

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

too much clearance, instead of too tight of a tolerance, i think is what he meant, piston/wall. unless, he meant too tight of a bearing gap

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

Dumbass I knew what he was trying to say, I asked him to EXPLAIN why.

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

too tight of a tolerance for adequate oilage. too loose is obvious.


thats my $.02

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

You fail at life, and your reply has nothing to do with what I'm asking.

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

I meant excessive piston to wall. Excessive play causes uneven piston shift, and possible scoring if the skirt dragging along the cylinder, you can check the wear in the cylinders with an inside micrometer, they'd be oval shaped as well.

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

I was referring to BAC, not you :8

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

He's been hit too many times to notice such subtly, you should have direct quoted him :S

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

maybe youve been hit too many times? he clearly qouted BAC, not sure why you would think he was talking to you.

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

What was the piston to wall clearance? How do the bores look?

The pistons look reusable, but if they are binding at all when you rotate them on the wristpins then it is the PISTON that is damaged, and not the pin. Hardened steel > aluminum.

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

It's hard to read the little text when I've been stoned all afternoon. :S

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

yup


but he said it first

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

Too little piston/wall clearance is much more catastrophic in a turbo app than too much.

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

both are catastrophic in every way turbo or not.

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

whas wrong is its an a20. upgrade man. but for the record i agree with both these two ^

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

Not equally. Say you are .005" over, not a huge deal. .005" under will scar your walls bad, quickly.

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

.005 under and the piston wont fit in the hole, lol. Jon what kind of clearance did you end up with on you're vitara's?

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

A little piston slap never hurt anyone. I would get the clearance on that block checked and go from there. You probably need more piston to wall clearance, but I'm not to sure if that's from too much or too little.

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

so if you need it to have .003 clearence and your machinest goes to .008 there will be no problem ??




you will end up scoring the wall and the skirt becouse of to much pistons shift just like waffle said.

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

I didn't say no problem, but much less of a problem than having too little clearance, which is way worse when the piston expands and contacts the cylinder wall.

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

Unless you shove about 30 psi into the engine, to make the piston swell up with 600 whp worth of thermal mass and take up clearances. I know, I did it last week. Sure, the engine isn't lasting more than 8000-10000 miles, but you aren't regularly making that power any other way.

.005 over recommened spec is a bit much, tho.

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

forged piston clearance should be .0025-.003" My cast vitaras had .0035" and the skirts got worn like yours. Not quite as bad though. Forged pistons expand more under temperature, so a tight piston to wall would ---- them up quick for sure

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

the bores are very slightly worn on the thrust sides, but not scored, i think a quick hone would clean em up. This is going to be a high boost high hp engine so im not too worried about engine longevity. I think the small end on the rods is messed up too because they dont seem to float around as much as they need to, i think the rods are the cause of all of my problems right now. BTW these were used Crower billet B18a/b rods and the big ends were screwed up as well. I have some brand new eagle ESPs with 3/8" arp 2000 bolts going in in their place. Too bad the crower billet rods had a stronger rod bolt in them, they are nice pieces, but not jacked up...

Re: WTF is wrong with my engine V. A20 built engine go boom.
 

thank you