So today i yanked my Sr20det head, and to my surprise...

[Chuki hears all]

Piston #2, on the intake side, was either bent in or melted. I realized something was wrong once i changed turbo manifolds and smoke was pouring out of the exhaust. So i yanked the engine and both manifolds and began to put the engine in tdc, and exhaust port 2 released oil during each rotation. Then i removed the head and discovered my piston was essentially ruined. I believe its due to overheating, actually im pretty positive. Also I think the cylinder wall is okay, i didnt feel any ridges. So my question is do you think the head and or block are warped. And do you think its worth taking to a machine shop and getting straight edged? Yes, i did search but i couldnt find any similar threads or post. Also, consider the head and the block are aluminum.:duh:

[HalveBlue]

Pics or STFU.

Seriously though, take off your head and start measuring. The FSM lists the clearances for both the block and head. You'll need a good straight edge and a good feeler gauge.

Or you might just bring it to a machine shop and have them check it for you.

But yeah, melted piston = very bad. I'd be surprised if your engine as a whole didn't suffer.

[sr20boostn20]

sounds kinda like you detonated the shit out of it,

but pics please this would be so much easier

[civilized_drifter]

today i'll get some pics of it, he lives 10 minutes away from me

[Chuki hears all]

Sorry i have yet to get pics, i have no camera. But around 7:00 o'clock tonight. thanks

[daryl337]

regardless, you are going to have to re-hone the cyl for your new pistons, get them to deck it while they are at it.

[civilized_drifter]

pics
http://i78.photobucket.com/albums/j91/STidragster/logans%20240sx/DSCF1569.jpg

http://i78.photobucket.com/albums/j91/STidragster/logans%20240sx/DSCF1570.jpg
http://i78.photobucket.com/albums/j91/STidragster/logans%20240sx/DSCF1571.jpg

[SimpleSexy180]

time for new pistonzzzzzzzz

[HalveBlue]

Fuckin' eh boy.

The fun has just begun.

So are you going to rebuild your engine or just get a new one?

Good Luck!

[Chuki hears all]

well, i plan on rebuilding it. Ill have a Build thread once i get some money up. I broke the entire engine down in two days, :bigok: so im excited to finally build my first bottom end.

[Sileighty_85]

Nice! If you got any Q's PM me up I just built up my SR a few moths ago.
I know where to get alot of good parts if you wanna go all out.

[daryl337]

LOL.. brings back memories.. *sigh* :D

[Petrol]

Looks like det to me. The thing is, what caused it? Have you upped the boost?

[Chuki hears all]

The cause is unknown for now, my head and block are betting cleaned measured and inspected i should know by Monday. IMO overheating and daily abuse; I bought the car from one of my friends, his name is matt paul. To elaborate on abuse, I'll inform he's a NOPI am. So constant Drifting. but anywhoo.

How does this sound for a set up? Cp pistons, ER spec rods (Oem lightened by enjuku) Race prep my CrankShaft. And of course bore and hone. Im thinking about New oem bearings? Good idea?

[Z U L8R]

ACL race bearings ftmfw.........*speculation* and get rid of your manual boost controller, that's what did it <_< >_>

[k's_silvia2.0]

Gluck fixing it.

[TonKpilS14]

u should see my stock pistons... they are FUUUUUCCCKKKEDDD up.

dont throw them away, use them as ashtrays ^_-

[orion::S14]

The cause is unknown for now, my head and block are betting cleaned measured and inspected i should know by Monday. IMO overheating and daily abuse...

That is damage form detonation...has nothing to do with overheating, unless the overheating caused the detonation.

Stupid high cylinder temps from heavy detonation = melted pistons, at the edges.

How was it tuned?

- Brian

[infinitexsound]

harbor freight engine cleaner gun, simple green, big tub..and hot hot water... some brake clean... be sure tro keep all ur parts in order...#1-4.
new pistons... send the block to a machinist have them check it out, bore it and hone it and measure for what size rings... then start assembling.. i suggest redline assembly lube... measure for bearings too..

[DOOK]

i say ditch the SR and get yourself an LSx :D

[pEcHeP]

OMFG

Detonation = Over Heating

It gets hot, then pre-detonates! Cummmmmon peeps!

[burnsauto]

id have both the block and head checked out by a machine shop. good machine shops will pressurize the head, make sure it didnt crack due to overheating. if you're going all out to rebuild the bottom end, you might as well make sure everythings nice and flat when you bolt it all back together. Good luck though, looking forward to seeing how the build comes together :)

[homegaragespl]

one word....amazing! How the fuck did that happen I wonder...

[Omarius Maximus]

That is damage form detonation...has nothing to do with overheating, unless the overheating caused the detonation.

Stupid high cylinder temps from heavy detonation = melted pistons, at the edges.

How was it tuned?

- Brian

+1. Keep in mind that running low octane gas + upped boost is usually a recipe for disaster. Especially when you run it hard for long enough periods of time where you heat soak the intercooler.

If I were to purchase an SR, the first thing I'd do is knock base timing back by a couple of degrees. Pump gas is garbage, and every tank from every gas station is different, regardless of what their octane numbers tell you.

[Chrischeezer]

running very lean
cylinder temps go through the roof..

[Petrol]

Hope this helps you out, I ran 1 bar of boost on my SR20DET without any problems. This is what I did to help prevent det
Uprated fuel pump - the stock pump delivers less fuel as it gets old
Catch tank - oil vapour reduces the octane rating of the fuel
Colder plugs - slightly reduces the charge temps
Cold air guide for the induction kit - again to keep charge temps down.

Forged pistons won't help you if you have det problems, they will melt in the same way. You really need to sort the root cause of the det :)

[Chuki hears all]

Wow, i havent visited my thread in a while. However i had a aem tru-boost, not a mechanical controller. I believe the Majority of Zilvians are correct. When i got the engine it always sounded like the Timing was f*cked, my guess it was firing at wrong time which is obvious. But the block and head went to the machine shop last wednesday. And should get it all back by this thursday.
Im planning on using CP pistons, ER spec oem rods, Racing bearings, get my shaft machined to "race spec" and full oem gasket set. I have no idea about head modds, ill worry about that once my block is built. I cant wait to start assembly. Oh yeah i have always ran premium fuel and i have a Walbro 255.

[tiresmokes13]

The cause is unknown for now, my head and block are betting cleaned measured and inspected i should know by Monday. IMO overheating and daily abuse; I bought the car from one of my friends, his name is matt paul. To elaborate on abuse, I'll inform he's a NOPI am. So constant Drifting. but anywhoo.

How does this sound for a set up? Cp pistons, ER spec rods (Oem lightened by enjuku) Race prep my CrankShaft. And of course bore and hone. Im thinking about New oem bearings? Good idea?

One word

detonated .

[daryl337]

oh god.. I coulda told you that.. I didnt know this thread was still at the "what caused this" stage... haha....




What a waste of a week for this poor guy.




Go get the block checked out and honed.. because if your cylinder walls look like mine did... you are gonna need it. :D