90turbohatch

These are race engineering 8.8:1 forged pistons made by wiseco. I've been having overheating problems for a while. You can see I have a block guard. Some say this can cause the car to overheat, but my car was fine with it for a month before I encountered any overheating problems. I don't drive the car much but when I do it overheats. I've had a wideband on the car ever since I put the turbo on the car a few months ago. I've never had the thing perfectly tuned. The afr seems irratic at times but most of the time pretty good(12's in boost, 13-15 crusing, 14.7 idle). It goes lean when cruising or at idle at times. Sometimes 19:1 afr, but not for long. I'm always watching the wideband and if i see this i just alter the throttle. Never goes lean in boost. Leanest its ever been was for one pull at 12 psi. Afr was 13.3:1 for about 2 seconds. I run 8 psi boost on a mitsu big 16g on an a6 engine. Anyway the car overheats even when just crusing. Sometimes the lower rad hose does not even get warm. Seems like a flow problem like thermostat not opening. I've changed the thermostat and tested the old and new one. Both good. The lower rad hose has got warm-hot only a few times but if it does then i expect the water pump is working. Also replaced the rad cap and bled the cooling system several times. Water pump is honda oem with very low miles-approx. 5000 mi. I removed the radiator and flushed and checked flow-that was good. So I said the hell with it I'm gonna pull the head and check the hg and most likely replace it. So I pull the head and look what I see. OMG! Nice pistons! This engine has less than 6000 mi. 3000 mi boosted.

The car ran good. Pulled like a raped ape. It never ran different. It also had good compression the day before I pulled the head. I tryed to think what the ---- happened and where the pieces are. All 4 pistons are damaged. This is the worst one(cyl.4). I think I made a horrible stupid mistake. I remember checking and reseting my ignition timing about 2 months ago when i changed my crank pulley. I had a pm5 crank pulley installed from my old motor for some reason(I think because i had a pm5 alternator belt or something). So when I put on the pm6 pulley and belt I reset my ign. timing. Now here is where i fucked up. I believe I had my timing light set to 16 degrees btdc and I used the red mark. The reason I thought about this was when I checked and set my timing 2 days before I pulled the head I realized that I had previously done this wrong. My light should be set to zero and line up the red mark. It would be correct I believe if I had my light set to 16 and used the tdc mark(white mark). So I believe that I had my base timing set to 0 degrees at idle. Well 2 days before I pulled the head I set the timing the right way and I drove the car. It still overheated and didn't feel any different somehow. My spark plugs also look fine. Maybe a little rich. The cylinder walls look good as well as the combustion chambers. No damage or marks on any of the valves.

I also never heard detonation. I always run 93 octane gas. I'm running a zdyne ecu with .75 degree retard per lb. boost. So why does my car overheat? Timing? It still overheats with the timing correct. It actually runs fine. It just overheats. Why are my plugs fine and wtf happened to my pistons? I wonder how long they were like this. Why is everything else fine? Where are the pieces and what should I do?

HMT-Admin

Wow, talk about a freak accident.

1. Get rid of the block guard
2. Check the sleeves for any cracks
3. Replace all 4 pistons
4. Reset your base timing and make sure its dead on to match your map.

Why it blew up was probably a combonation of the lack of coolant on the top of the cylinder, and too much timing.

Sorry for the breif response, but I had 2 big paragraphs for you and it ------- erased because I wasnt logged in.

Jeff

B16MIKE

damn,that looks bad.

90turbohatch

Thanks for the response Jeff. You said it blew up because of too much timing. I believe I had it set with not enough timing. Please correct me anyone. My plug was firing when the cylinder was at tdc. Isn't that much better for a motor than being too advanced and the mixture ignites before the piston gets to tdc and forces it back down before it is up. Is there any reason why my spark plugs look fine. Was the timing causing the overheating? I just can't understand why the engine ran fine and my plugs looked good. I'd like to remove the block guard, but how. Its welded in. I thought I would need it with with my plans to run 20 psi at the track. But now I don't think I will need that much boost to run 12's. My car is much faster than I thought it would be even at 8 psi. So I may only need 12 psi. to run 12's. I'll just have to find out this summer.

Spenser

lol, maybethe fact that you had the block guage welded in had something to do with all of this

90turbohatch

I don't know how the block guard being welded in has anything to do with it. And how the ---- do I get it out of there? Also my car was not overheating at all for the first couple thousand miles with the block guard installed like this.

accordepicenter

you guys keep melting pistons, you should sand down the sharp edges of the piston face (using like 200+ grit sandpaper, ending with 400 grit at least) itll prevent you from getting hot spots in it and melting or causing detonation...

HMT-Admin

Man.. that thing really is welded in good. I assume the block was decked after it was welded? Have you checked to make sure your head is true? (straight). Are you using ARP head studs? I bet the head gasket just wasnt sealing good.

As far as your timing, there is no way you can have a 0 degree base timing, ---- as soon as you gave the car any power it would fall on its face big time. I think your timing was tooo advanced. Forged pistons just dont break like that. The car had to been beat pretty hard with a agressive timing map. You may not have ever heard pinging, but obviously it did

Jeff

MikeJ-2009

At the end of my motor's life, it was misfiring because I had so much fuel going to it, but my pistons ended up just like that. 3 degrees retard at 19psi don't work.


Question, are the pistons all messed up on the same side? I saw that my pistons were all fried on the intake side only, which was kind of interesting.

Xgenturbo

You mean the outside edge of the top of the piston?