here is the story

I build up h22a engine, cp forget pistons 9.0:1cr , darton sleeves and so on

i did over 1000 miles without any boost,I was braking the engine, no problems after that, it was running perfect

then of course it was time to tune it which i did, 350bhp for about 300-400 miles and that what happened, see yourself on the pics

the question is why i did happen

here you go

 

looks like detonation...if it was one side i would say a bad piston but something detonated enough to crack it...

 

all four are cracked,the most damaged are pistons 1 and 4 and all of 4 are cracked on the intake side

so I guess detonation = really bad tune ??

please guys I need more input

 

bad tune for sure

 

yea bad tune....did u read your plugs to check all 4 cylinders were burning equaly..

 

very bad tune

 

There were some threads about CP pistons cracking just like you describe...I dont believe its a tuning issue since Ive heard of this happening before (CP pistons in turbo builds).

https://honda-tech.com/forums/showth...stons+cracking

 

if u notice thats the sharpest(hottest) part of the piston....usualy its good too deburr them...so detonation was the cause...sometimes you just get bad gas....my sleeve cracked 6 months later a day after i put gas...

 

Well there is definitely some fuel issues going on, do you have a picture of the plugs? Also, possible headgasket blown too. Look at the endges of the piston in the first picture, see how clean it is almost all the way around? The a sign of coolant in the cylinders, or just no fuel at all.

Definitely a botched tune, what A/FR are you running at while under boost?

 

Pictures of the plugs, they seem to be a bit to dark for me ??



the head gasket, a bit bend and scratched but its only because I was straggling with it while taking the head of, besides looks ok



I also noticed that on the cylinders, all 4 look like that can you see spots just in the middle, does that give any clues??



I didn't quite make fitting wideband yet so I cant't tell you that, I can't remember what was the A/R during the tune either, I know that would be useful info

 

looks like its running a lil rich lol. looks like theres significant scarring on the sleeves too. who did the motor? p2w clearance may be to tight. this makes sense since this happened after you added boost. there wasnt much thermal expansion on the motor alone. also, they look like stock sleeves to me...

 

Who tuned it?
What were the a/f ratios like? Cruising? WOT?
What was your ignition timing looking like in boost?
If you post your maps, Im sure someone here would lend their opinion...
Does anyone else not remember the string of CP pistons cracking on the intake valve reliefs for no apparent reason? Some were even tuned by VERY reputable tuners...
The general concensus was that it was somewhat of a design flaw since no other mfgs seemed to have this issue....

 

I built it up by my self not including sleeving to motor of course, these are dartons 200 on 100%, I knew what I was buying

PyroProblem, I'm complete noob if we're talking about tuning, I trusted the tuner and let him to do his job, I can't remember what A/Rs were like

I'll try to get a chip burner and dump maps

 

If the tuner is experienced and reputable, I wouldnt point fingers at him just yet...
If you search for "pistons cracking" or "CP pistons", I think youll find that there were quite a few others running CP pistons that had them break/crack in the exact same spot...Lots of debate and good support on both sides of the argument, but I think you agree its a little more than just cooincidence...
In any event, good luck with the rebuild.

 

the problem with cp pistons were on b series pistons and that was years ago. they've revised it since.

 

ahhh, ok...I know its been a while and all I remember is this was kinda an issue back in the day...Thanks for the heads up!

 

it is interesting that you had this problem on so many cylinders. what was your piston to wall clearances or do you not know?

 

X2^

like i talked about before, what were your p2w numbers?

 

What are your rings gapped at?

 

haven't done anything yet, was too busy with uni work, I should get more time this weekend

so how do I check p2w now ? I guess gap filler gauge wont be enough

 

Im going to have my fuel maps by tuesday, so I put them in here

 

take out the pistons and mic em', then measure each sleeve wit a dial bore gauge and mic it.

 

ok i have the bin file dumped from my ECU but I can't open it with CROME for some reason

 

any idea how to open that bin file??

 

bump

will anyone help with this fuel map???

I took pistons out today, didnt measure anything yet but that is how they look like
was p2w too tight ??? or that could be caused by detonation ?
I put some numbers soon