Stehu

Ok, first of all my car used an european 1996 model 1.6 l that had 90 whp. As we all know, not having turbo on a miata is really boring. And especially after Inglar took me out for a spin in his previous car(he had an MSM with the Big enchilada), I was on fire. Only 2 months later I found an MSM engine on ebay with the transmission on, turbo, downpipe and wire harness for only 3000$. And it had only traveled 33 000 miles. Bought the Hydra 2.6 aswell too to make room for further upgrades(soon garret 3071 on vvt engine).

But, 3 months ago something wierd happened. I was at 3000 rpm and changed gear, went straigt up to 4500 and WOT. And suddenly, BAM! I heard very loud knock that changed with rpm. I guessed a rod, but I was in the middle of nowhere, and the knock sound stopped so I went driving the rest of the way home.

Just abou a mile before I was home I heard a bigger bang and the oil pressure went down to 0. Stopped the car asap and opened the engine bay. I quickly saw that the rod had been shot out through the block and the baffle pan making the piston move freely inside the cylinder.

Does anyone have any ideas of what could of have happened? And, is it possible that the pistons have destroyed one of my rods?

18psi

iTrader: (76)

Yes. You do too:
Why? Not sure. How hard were you pushing it? boost? timing? afr?
You need to post more details.

As for rods: definitely replace them with stronger ones. Even if they're in ok condition. Stock miata rods are one of the weakest links in the powertrain, no reason not to upgrade them.

hustler

iTrader: (6)

I don't see any detonation on those pistons, I suppose you were unlucky enough to find the limits of the stock rods.


On a side note, #4 is the fattest, #2 is the leanest.

Savington

iTrader: (31)

Need to see a full dissection of the motor to give any more info. It could have been a straight rod failure, a bearing failure, or a rod hardware failure.

bbundy

What compression ratio are the MSM's? Those pistons look really domed up to me for turbo pistons.

Bob

phillyb

iTrader: (8)

low end torque is what does this to mazdaspeed3's.

sixshooter

iTrader: (12)

I agree that they look domed and I expected dished.

18psi

iTrader: (76)

IIRC same as the 99-00 nb which is 9.5:1

Stehu

Of course I was forgetting some details.

Turbo: stock msm turbo with original DP
catback: some random 2.5 "
Intake: Custom made.
Map: FM's map. Stock timing table
Pressure: 14 psi.
Fuel system: Rebuilt from retourless to retour.

I was driving a while ago with some knock on high rpm, but I got it adjusted quick.

Could the valves have been damaged? They looked fine too me. Btw, the block itself is totally broken. The rod was located in cylinder number 2 from the radiator.

Savington

iTrader: (31)

What did the wideband say?

The valves could be damaged, they could be fine. Depends on whether the piston hit them or not.

It's obvious that you threw a rod, but in order to give you any more info than that we need to see the inside of the motor. Pull it out, pull the pan/mbsp, and snap some photos of the big end of the rod, condition of the rod hardware, etc.

flounder

Isn't anything above 10-11 psi kinda pushing it for stock rods?
You're at 14.

Savington

iTrader: (31)

Stock MSM turbo at 14psi is well within the range of safety for a stock motor.

People who use boost levels to describe the capability of the stock motor do a huge disservice to this community. Not directed at you, just people in general.

Stehu

The stock MSM turbo is very small, I don't know how many whp that should be, but not more than 200. I had fuel cut a couple of times so I

I guess that there might be valve damage then, because there's a very big chance for that the rod would have rotated and shot it up, and there are very small marks on the exhaust valves.

I will pull the block apart in about 4 weeks(got a broken wrist atm) and show you more leet photos

chicksdigmiatas

iTrader: (11)

Welcome to the party, lol. Mine failed in the exact same fashion, although with more boost.

Savington

iTrader: (31)

If it's marked, it's bent. Expect to replace the entire longblock.

chicksdigmiatas

iTrader: (11)

Yeah, what sav said. Mine had piston contact on the valves (like everyone said it wouldn't). It is either time for oversized valves, or a new head. I chose VVT. I did manage to sell my HLA's and exhintake cam to offset the cost of the steal I got on a "needs some work" vvt head.

curly

iTrader: (25)

Is it possible the last few thousand miles were extremely abusive and ended in a crash? Might be why the engine was being sold. An aquantience had nitrous oxide dumped in the tank and raced until it exploded when his accord was stolen.

codrus

Head casting & cams should still be fine, no?

--Ian

nitrodann

It depends.
If the piston smacked the valve then I doubt it. Pull it apart and find out.

Dann

Savington

iTrader: (31)

If he's going to build a motor, sure - otherwise the cost of a head gasket, four new valves, installation, seals, etc. is going to outstrip the additional cost of a longblock vs. a shortblock.