With tq being that much higher than hp (158hp, 181tq), it sounds like something was really choking the motor at higher rpms. I don't think I ever remember seeing numbers that lopsided on a BP.

I'm going to say it may have been overrevved at some point, stretching and stressing the rods a bit, which has been known to happen in our engines. The weakened rods would then not take nearly as much torque before yielding.

That's obviously not a 2.25 downpipe and log manifold. And also not normal for a 2554.

Remember, the OP is unsure which t25 style turbo he has.

I missed that part in the shitting OP. Is this a 2554? My own made the numbers in my sig. And it says 12psi, but I think it was 11 at peak torque.

So I'm 10ft/lbs down and 15hp higher, with a 1.6.

It's a 2.5" downpipe and a log manifold.

But i can see how that 0.25" could result in an extra 65hp. I stand corrected. :giggle:

My car made 160hp at less than 6psi on a stock exhaust with no intercooler on a very hot day...

Well yeah sorry what I mean when i say it ran perfect is that it seemed perfect. I.e no misfiring or anything. Obviously I have no idea if det was happening all along.

The rev limit is set to 7.5k and it saw that a lot in n/a form and even a few times in the 4 days it ran with the turbo.

Here's pics of the head:

https://www.miataturbo.net/attachmen...ine=1408987478

https://www.miataturbo.net/attachmen...ine=1408987478

Quite sooted up.

7.5k on a boosted motor and only 160hp? ouch.

That redline probably had something to do with it.

Yeah as I said I was disappointed with the numbers

is that pitting on the head or just drops of coolant?

Post the timing map.

Rain probably. It was raining when I removed it.

As i said. I can't post any mapping or anything ecu related until I've got it off my mapper. I was hoping that just by looking at the parts someone could tell what's happened but obviously that's hard after just 4 days use.

I had my rev limiter set to 7100 and it didn't need to go that high because the meat of the powerband was below there with a log manifold and stock heads. And I hated to push it too hard because I wanted it to last.

Read the thread, lol.

are you sure?

look at at the edge of the combustion chamber, see how #3 is smooth and #4 looks like it has chips in it?

or am I seeing things?

I see it too, but hard to tell considering the #4 piston came up and smacked it.

I am.. dont get why the op is saying he needs it from his mapper.. hook up the laptop and download it from the megasquirt...

As I said earlier. I don't have a laptop or even the software.

Does your "mapper" send his emails by carrier pidgeons? Or telegraph?

I mean seriously, this takes all of 2 seconds. Phone call, "can I have my map and logs", email, voila....

Or, since you said he is "well known on here" I'm guessing you meant MT? In which case he can just post it up and the included logs from his tuning session.

He's away at a festival all weekend. I'll try to get hold of him tomorrow

ohhhh...........ok lol. Shoulda said that from the beginning.

Why do i have the feeling the mapper might be TDR?

Won't be TDR. TDR maps give 135whp n/a 1.6s running with a total of 6 different cell combinations.

What Ecu do you have Megasquirt? If so, Don´t you have any friend with a laptop that can help you out? Damn, the Cable to connect to the ECU cost´s 20/25€.

Regarding the engine failure, sorry to hear that. But if I remember a few months ago you opened a thread regarding smoking from your engine?! Was this one?

Yes it was this one. It was my old heavily skimmed n/a head. Since I removed that the engine has not smoked or burnt any oil at all.

You know what else makes for TQ spikes and low HP?

Bad fuel pump or a fuel filter that needs replacing. Add to that the higher (ie- useless) redline and that could result in a lean spike up top.

Let's accept the fact that Shit happens?🙈 it's mechanical and we all know mechanicals can give anytime anywhere without notice. Pick yourself back up , get a new short block and start over. Start learning the basics of megasquirt and when ready dyno tune if needed. Me and my brother took a base e85 tune of diyauto and street tune. Last dyno was on a mustang tuned by evil genius to 231whp 10.7 afr up top on 91 at 10 psi. Even the dyno tune we started fine tuning it more on the street and sure enough was able to get a satisfying street tune by ourselves. With the e85 we tuned it ourselves and I belive the results are clear.

Skipped tooth on the timing belt?

:ughug:

Goodness! I'm just trying to figure out how you left the dyno with these numbers and then decided that it would be a good idea to beat the shit out of the engine right away??

No kidding. My 1.6 running the Greddy turbo made 168 at 8 psi. Something is amiss with that tune.

Did Faeflora tune it? Burning man is this week...

honestly I thinking the same thing. rofl.

:party:


TDR or TDR.

Meaning: Track Dog Racing or Tuning Done Right.

But OP appears to be in England (maybe around Hampshire) and I dont know of any tuners there; let alone any well known ones.

OP went to a mapper, not a tuner. :giggle:

:laugh: I atually made a joke about that but didn't hit post cause I wasn't sure if it was lame

It is lame. But, someone had to say it.

My Guess:

Stupid rich tune. Really odd tip-in settings on MS. Retarded timing. Nothing we have not figured out in the first 2 seconds of this.

Ignition cut based launch control on MS I think?

So you have a lot of fuel due to weird tip-in settings (also guessing that you can specify a throttle % in MS for those settings? I bet that % is really high on the OP tune if that's the case...) and the plain pig rich tune. And its not all getting lit off anyway due to retarded timing.

OP floors the throttle and it's both getting way too much fuel for the airflow and not lighting it well either. Not hard to imagine that eventually you get some burning fuel happening even as the piston is coming back up on the ex. stroke. Its burning at the tailpipe, not hard to figure it might be burning at the head under these conditions. Couple that with the fact that suddenly that crank really wants to increase revs as it launches and you have a rod caught between a piston that's got force resisting its upward travel pretty strongly just after BDC and a crank that's not going to just stop turning.

This would explain why the piston does not look as bad as you would think, the bearing is probably OK, yet the rod is utterly destroyed. And why it made crap power.

Yes, with spark cut it is possible to have fuel ignited at an inopportune time.

Once again, launch control is for competitive drag cars that get rebuilt relatively often, not street cars.

But flames and brap brap noises....

you guys are putting way too much faith in the mapper to blame the launch control.

Just to note, OP is in the UK. It's not TDR that tuned it.

We know, just having fun with "mapper" vs. "tuner," "aluminum" vs. "aluminium," etc.

And "tuner" vs. "TDR."

A similar comparison would be "Barista" vs. "Starbucks."

So, launch control is a no no on the Miata? Glad somebody else lost an engine before I tried it! Sort of a normal thing to use in the Mitsubishi world, so sort of surprised that it is not good on the Miata.

So much to learn!

Keith

Its a no-no for OP and other n00bs that have no idea what they're doing on a super questionable tune and everything else.

Tons and tons of other people use it without too many failures like this.

The risks are obvious, and not any more dangerous on a BP than any other car.

I have launch on my car. Must have used it total 3 times. After that the fun wore off. maybe it's a drift0r thing.

160rwhp from 13psi. I can manage that on my own, no need to pay anyone...

I used launch control every time I autoxed.

It is common for cam timing to be off a tooth or two in our cars if done by inexperienced hands. Cams in an advanced position could help to account for the 181ft lbs below 5000 rpm and the reduced power above 5000, along with a stifling of flow by an inefficient exhaust tract.

The inadvertent increase in cam overlap coupled with the intentional misfire induced by the launch control may have allowed the reversion of the flame front from the exhaust manifold back into a cylinder that was in its intake stroke. The reason the gasses were still expanding in the exhaust manifold was because of incomplete combustion in the cylinders due to the launch control. So the gasses have already begun burning as the valves are closing and the compression stroke begins. The piston is trying to compress gasses that are already expanding and trying to push the piston back down. Cylinder pressures go through the roof as the crank is trying to push the piston up and the pressure is trying to push it down. The rod is suddenly stuck in the middle and resists momentarily before saying "Fuck this!" and he quickly makes a window to jump out of...

The moral of the story is that intentional misfires are always bad for an engine.
But only occasionally do they create spectacular and catastrophic failures.

Too bad we all convinced him to take the head off before checking the cam timing.

NVM

I'm not.

I am blaming the tuner for the launch control malfunction more or less.

I did a number of stutter box launches on my DSM without issue. Done properly IMHO it's fine. But with a crap tune that's puking fuel, it can be an issue. Sort of like boosting something with a crap tune. Not the turbo's fault.

Many stock cars have the same basic system in place anyway to prevent overrev due to keeping your foot in it too long. Works great and I see many guys bouncing off the limiter in 1st as a sort of traction control analog at the strip without issue. Doing the same at lower load and RPM is fine....unless its all messed up....

Actually, that's a fuel cut and not a spark cut and it is completely safe for the engine. Overboost protection in MS1 uses a fuel cut, too, although with batch fire it's a bit harsh. You MS2 and newer guys proabably have something more sophisticated.

The problem with the launch control is that it is designed to make the fuel/air charge expand in the exhaust port and exhaust manifold to spin up the turbo. The engine is not designed for it. The exhaust isn't designed for it. The turbo isn't designed for it. It is a backyard engineering trick to try and make the system do something it has not been designed to do.

Right update

I got the spare engine in today.

I took the engine with the snapped rod apart. Turns out there were more holes than i thought. Guess I won't be using that sump then.

https://www.miataturbo.net/attachmen...ine=1409427753

Now for the interesting bit. All the rods are bent! Now bear in mind this is a freshly rebuilt bottom end that has only done 3k ish since it's rebuild. It ran perfect when the car was n/a then 4 days with a turbo and this happens. I think it's safe to say something is wrong and this wasn't just a dodgy rod. All the bearings looks brand new (well they are only 3k old) the bottom end appears to be in perfect condition aside from the bent rods.

https://www.miataturbo.net/attachmen...ine=1409427753

I've spoken to the mapper and he's checked the map over on his computer and he can't find anything wrong at all. He tried to explain how the launch control couldn't be firing on the up stroke but it went a bit over my head tbh. Apparently the car actually has a lower rev limit since the turbo was mapped so it should have actually been safer from a revs point of view. What the actual fuck is going on? I'm scared to even the the fucker back on.

I don't want to name the mapper as I still think there's a chance this isn't the mapping but I am struggling to see what else it could be now tbh. I have asked him to check this thread to try to figure out what's going on.

Did the launch control bend the rods or were they bending as soon as I picked it up from mapping and the launch control just finished is off?

Bent ALL the rods at 181 RWTQ. Gosh, I wonder what it could be?

Your mapper owes you a motor.

Learn to tune yourself.

You are useless.

No one is gonna help you if you're this useless.

Good luck with blowing up more engines. Keep trusting the "mapper".

You need to go to the mapper and watch him pull the tune file from your MS and the email it to you. Then you can upload it to this site and we can take a look at it for a sanity check. If you don't do this then you don't actually want help and you're just in denial not wanting to accept the fact that you may have paid someone to blow up your motor.

Maybe I'm giving the benefit of the doubt a bit too much....?

Can anyone think of any way this couldn't be mapping related? I do appreciate the help everyone. I've asked for the map to be emailed and a different local mapper has said he will check it over for me.

Also I did a compression test just after I fitted the turbo (but before it was mapped) and it was even across all 4

the only way it wouldn't be mapping related is if somehow your injectors stuck open and flooded the engine, or your boost controller got stuck closed, overboosting like crazy, or your timing belt skipped a few teeth, or your car unbolted itself and advanced timing like crazy, or something drastic happened.

everything else points to tune

Here's what you do: download map directly from your ecu. Without letting anyone touch anything, upload directly to here. We will figure it out.
Don't let any "mapper" touch anything. Just download/upload. Done.

Otherwise, you're wasting time.

no. post the tune and we can put this to rest.

Or better yet could someone please explain how this could happen with no signs of det?

I'll post the tune as soon as I can