Right I've taken the head off and removed the piston through the top by super glueing a little sucker on the top of it.

Here are pics.

Pic of no:4 straight after I removed the head. The piston has hit the valves in the head.
https://www.miataturbo.net/attachmen...ine=1408965497

No:1
https://www.miataturbo.net/attachmen...ine=1408965497

No:2 & No:3
https://www.miataturbo.net/attachmen...ine=1408965497

Mangled rod:
https://www.miataturbo.net/attachmen...ine=1408965497

The bit of rod left on the crank spins perfectly smooth so I don't think this is bearing related.

Once I've got the block out I'll remove the sump and take a look at the bearings in what's left of the rod.

Here's the launch in normal speed.


I held it on launch control until I saw the boost rise on the gauge the let it go and released the clutch. I'm pretty sure it was a full boost when I let it go or at least very close.

So maybe it just couldn't take a full boost launch? And there's nothing wrong with the tune?

define full boost. did you post the tune yet?

can you show pics of the head in a similar manner?

Looks like a big chunk of piston is missing on #4 on the intake side and some det on the exhaust side of it. And maybe some contact with valves.

Lots of compression getting past the rings, but unsure if that was before or after boom. Probably will find a cracked ringland on the piston.

All four show it was running pretty rich, as the pistons are steam cleaned from the fuel.

Full boost as in I watched the gauge get to just under 1 bar before I let it launch.

Can't post the tune until I get it off my mapper

The head does have marks on the valves where the piston has hot the head. The engine made good compression a couple of weeks ago.

Also I have the no:4 piston out and there are no signs of cracked ring lands or anything that I can see

Really interested in hearing more feedback/opinions and seeing that tune.

I'm certainly no expert, but those pistons don't look bad to me at all, definitely not like I've seen from other motors that met an early demise. I assume we can ignore the valve marks on piston #4, none of the other pistons show any damage and with an exploded rod it seems pretty inevitable that there would be a collision.

The problem is, it still could have been knocking badly, and you wouldn't see it too much since he's only had the car running 4 days. So while I agree the rest of the pistons don't look too bad, we still can't rule that out.

But for all we know it could have even been a seized injector that flooded the cylinder and hydrolocked it.

Sitting on the 2 step and building just under 1 bar is putting some serious stress on the engine. Even built engine cars I've worked with don't do that.

Serious heat and load from sitting on the 2step + possible flood from cutting fuel and spark = boom?

Really it doesn't matter without knowing the state of the tune (probably garbage), but really this is pretty cut and dry, due to numbers.

1) The motor was fucked before it was even turbo'd.

or

2) The tuner sucks.


Or a combination of 1 and 2.

The motor made great compression and ran perfect before the turbo. It also ran perfect with the turbo. No smoke, no rattles, no knocks. I had my local engine builder (who built the bottom end) take a look at it and he said the pistons look great. The tune appears ok but hard to tell from just 4 days. He thinks the rod simply couldn't take the stress from the launch control simple as that.

I personally think the tune is fine and that the launch control was just too much. I am still confused as to why it made such lower power for the psi the turbo was producing though.

rods break from torque

your engine doesn't make much torque.

the only thing that could have spiked compression through the roof like that is a bad tune or failed injector or something

until you post the tune, I'm betting everyone will just say its the tune

These statements are contradicting.

Are they? I mean it appeared to run. Perfect and I was told its running perfect just not making great power.

If it was running perfect, it would have made more power.

Whether it was running like dick due to the tune, or due to a shot motor, we don't know. But it wasn't running well.

You're gonna get seriously flamed if you keep saying stupid stuff like: " It didn't go up in a burst of fire on startup, and I was told it was tuned good by the guy I paid to tune it, therefore it ran perfect and was tuned perfectly"

I mean seriously.......stahhp

*edit: and I keep forgetting to mention that if you really have a 4.65 Final drive, your 1st gear is semi-truck long, meaning you probably didn't load up the engine that bad after you actually launched it.

Right.

No tuner is going to say "Thanks for the money! I did a fucking terrible job for you, have a nice day!"


At least... not to your face.

Also see: TDR.

if your going to ask for help you need to keep an open mind. don't be an ask hole or you'll need a flame shut....



Shamess plug--> fire suits available at OGracing.com :P

I don't know much about BP motors, but if you messed up a rod it happened from pre-ignition. Ie two cylinders firing at once. things that can cause this, too lean, excessive spark advanced, elevated cylinder temp, faulty coil wiring ect...ect...ect . post pictures of the cylinder head and spark plug. that will have evidence of Pre ignition.

Exactly my point. 160hp for 13 psi is nothing. Should have been in the 220-230 range.

LOL

But gaiths, the car ran perfect. It didn't blow up for a whole 4 days. That's like...forever :party:

So how much timing and fuel enrich was it running for the launch control?

OP, just as a reference point...

Here's a 2554 on 10psi.

https://www.miataturbo.net/attachmen...ine=1408979180


For another anecdote, that car has run for at least FIVE days.