Was This The Result Of Detonation?
 

Examining my head I noticed my #3 looks a little chewed up. I'm assuming this is the result of detonation? Thoughts?

http://boostedmiata.com/headwork/Coo...oute%20013.JPG

http://boostedmiata.com/headwork/Coo...oute%20014.JPG

Holy hell Scott. I'm starting to wonder if you have some sort of fetish involving continually having to rebuild your car.

I take that as a yes? The rest look perfectly fine.

Yeap, detonation city. Get out a strong magnifying glass and take a look at that area and others. Looks like little specs of aluminum in the carbon built up on the exhaust valves. Maybe you guys will start tuning a bit richer in boost like you should. :)

Also get a file and some sand paper and smooth those edges out. Though unlikely, they could be the source of the problem.

You were one step away from:
Attachment 207852
Attachment 207853

Been there done that...was n/a when that happened.

this forum would have a lot less interesting pictures if it weren't for Braineack and his misadventures

That would be my guess. Any little flakes of metal on the spark plug's electrode?

nope, everything else looks fine, i just went back over it. Oh wellz.

Yes detonation, it looks like my friends 350Z head, just much better, check your oil pan for fragments of metal as well as make sure u clean ur oil pump, change oil.

you obviously don't know how I roll.

I'm beginning to wonder if it wasn't some FOD from a part of this screw:

http://boostedmiata.com/headwork/Coo...ute%20ZOMG.jpg


or when my HG blew on #3 soon after I had put this head on last year. I was forced to drive 25 miles with the coolant temps constantly spiking above 220 and coolant leaking into #3...

It's odd it's only in #3, no other cylinders show any damage, you can see similar pitting in #4 in that photo above, but I'm pretty sure that was from the screw dancing around. The injector I put on #3 and #4 flow more fuel than #1 and #2 as well. Good thing I'm doing a coolant reroute, I'll just richen my tune slightly and stay conservative with my timing.

god damn I feel bad for you. I also feel great about my decision to pull 2* out of my spark table last night.

You made the spark table of doom less doomy? Did something happen? I mean besides this thread.

You honestly think I'll do anything besides take a 1 degree out and add a few points of fuel after it's back on????

If the block fails I have another and two spare heads...

Nah, nothing happened...just thinking about conservatism and "what if." Yeah, I'm now running 25-28* fom 4k-7k at 14psi, lol. I was tuned at MBT, I followed everyone's advice and backed off 2* especially considering I have new ignition in the car.

Brain, what's wrong with fattening up and pulling 1*? Its the labor I sympathize over. I haven't' touched the mechanical bits of my car with a wrench since the install.

Nothing wrong. I'm just saying, I had the head off for unrelated issues and noticed it. I'm going to smooth it down a little and slap it back on and forget all about it.

I blame ur FMIC dude if you had a good WI setup ur shit would still be running right :D still bad luck indeed. Seems like the more we push em the more stuff we find in em to fix.

My FMIC is huge and I've never logged over 110*F.

^^^ holy crap. and i was gunna use your maps as a solid base map for my turbo install next week


I have now taken 1 degree of timing out from the whole map, maybe ill even do 2!!

Not a good idea unless you have lower compression pistons, and im not sure if hustler had headwork done either, but that would make a difference also.

Using someone else's dialed in timing map to "try" is a bad idea.

for the record i was talkin about scotts map, not hustlers. and its just to get the engine going and tune from there. u cant tell me all of you guys made all of your maps from scratch.

I did. :fawk:

But yeah most grab someone's. Most maps suck. I'm not surprised Brain had detonation with his tuning. He ran mid 12 AFR's IIRC and his timing was a bit agrressive IMO.

I made my fuel table from scratch. Its not that hard. The spark table was a DIY copy that was stupid retarded. lol@people using my spark table.

yeah my NA maps were basicly from scratch. i started off with diy's but then ended up re-scaling everything for NA and just said screw it and started from scratch. Its not bad.. but id basically like to start with a drivable map and tune it asap.

then use diy's map.

If you don't have det-cans, you will fail.\
/thread

I cleaned off the carbon and look at it closer, it really looks like the FOD that matches #4. Without seeing the piston in front of me I'm speculating. But it looks like a piece of something pressed its imprint in the squish area, hopefully not parts of a piston. But I didn't notice anything when looking at them initially.

The last two blocks that let go from detonation had no head damage what-so-ever, in fact this is the head of my first replacement motor whose ringlands failed.

My spark map isn't much more advanced than DIYs (16-17* @ 13-14psi) and I run between 12-12.3:1 in boost. It ran great everyday for 10 months straight as a DD with a couple autoxes and dyno runs for abuse.

Scott, can you post your latest datalog?
__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote

To me that looks like damage from a foreign object. Before installing the head though take some 400 grit sand paper on the tip of youre finger and debur the sharp edge of each combustion chamber, a .020" or .040" radius does wonders for reducing detonation.

Yeah, I've pretty much sided with that hypothesis. I've already smoothed it down, then hit it with 2000 grit. Will be going back on Monday.

sure: