Horton what Turbo are you running? It seems like your exhaust is ok. Do you have a way to measure Turbine Inlet Pressure (ie TIP)? This will confirm or eliminate the turbo as a source of the problem. I suspect your TIP is going to be sky high. It should be less than 13-18 psi at that boost pressure. I bet yours is 25+

A 2554 I think.

And no I don't have a way of measuring that

What size exhaust are you using?

I'll write a technical reply when I find 5 minutes - for those who haven't read my intial reply above please do.

The exhaust is without doubt part of the restriction at the top end.

Connor please stop saying what boost it makes peak - some of these people genuinely think it's making 13PSi @ peak power still.

Might be worth you plumbing your boost gauge up to a pre-intercooler port connor, try and see what kind of pressure drop you've got through the IC.

are you sourcing boost pre-intercooler?

the dyno plot suggests it's peaking boost at 4K and then dropping off significantly at redline.

I mean... is it dropping to like... 1-2psi at redline?

it's making 140-150rwhp at 7K. a stock 1.6L on that dyno would be making like 70-80.

Yeah but how many torque curves have you seen look like that? I can think of some diesel ones, or some subaru's :giggle:
I mean even stock exhaust cars still don't drop that hard.
And his tune looks ok. I didn't see anything wrong with it.
I dunno.

Boost for dyno & ECU are inlet manifold sourced.

Which is why I suggested to Connor to source his boost gauge from the pre-intercooler source and see what it reads - if his intercooler is shit then the turbo could still be making over 1bar and be running out of efficiency. I didn't pursue this on the dyno because his IAT's didn't look bad at all.

Dan

a lot.

He's asking where the boost control reference point is.

on a miata?
interdasting. maybe it looks more drastic because the curves are separated.

Either the turbo inlet is a garden hose (WRC anybody?).
Or the cam timing is off.

With everything that has happened in this thread, just saying "the cam timing is not off" does not satisfy me.

Pretty sure Dann posted a dyno plot just like that...motor blew up in a similar fashion :)

cars with restrictions don't make that much torque in the first place.

im assuming the boost plot looks exactly like the torque plot.

Correct

so you disagree with me that the plot looks problematic, then point out that the last one like that blew up?


Make up your mind Scott :giggle:

Sorry mate it's all a bit over my head. But yes as dan says it doesn't hold at 13psi.

Even if the car should make more power or the torque curve is weird or whatever I'm not fussed. The car drives great and I just want it to last more than 4 days.

As long as it's safe I'm happy

Well, what happens when someone starts to choke you? I mean, they haven't fully closed off your trachea, so you should be fine.

I don't think he understands the meaning of the word "safe".

I think he understands "safe" to mean "low power, and hasn't blown up yet"

if it's just a boost controll issue it's fine. if not, it's not.

it would actually be exaggerated over those, since it's probably 10-12% lower than a dynojet reading.

but what you really need to plot against is the torque; which would show how much it's spiking over the "norm" albiet those plots are from 2007-08

That makes sense. I was wondering how it was making so many mad torques.

EDIT:
Brain, Do you know all the specifics of that old chart comparing the 3 turbos?
I saved it a while ago but didnt name it properly so I dont remember if its a B6 or BP, etc.

How is the lowend THAT much stronger than other small turbo setups? Weren't there some questions about what turbo is actually on the car? Could it be something so tiny that it really is just choking out?

He thinks its a 2554

Boost

Attachment 184702

omg

Now take the torque curve and boost curve and it all makes a lot more sense.

The car made noticeably less torque with a flat torque curve, and even with a "slight" hump didn't get near matching the figures it currently runs.

IAT's remained mid 40degrees at the end of a long pull too.

So it drops from about 13psi at its peak down to about 7psi in the top end. That's quite a dropoff. I guess you aren't going to blow anything up at 7psi with a tiny turbo at the top of the rev range. That is a very unusual boost plot and is why everyone was worried as hell. If the boost curve had been 13psi to redline with that torque curve then you would have been in serious trouble, but as it is it is just an amusing quirk.

It's still a good 50-60ftlbs under my car with a 2554 only doing 8psi at redline...

But if this is normal, then ok then.

You have a '99 head IIRC, 3" exhaust, and perhaps more aggressive timing?

2.5" downpipe, doubt the timing is more aggressive.

If this dude is losing that much from the exhaust, then it needs to be fixed, stat.

... different dynos, different places/elevation/humidity?

That would affect the whole curve, not cause an obscene drop like that.

Truth.

Dis is jacked.

This is why plotting tq/MAP vs RPM is useful. Alas, it doesn't seem like any dynos offer that as a display option.

--Ian

That is because his turbo is WAYYYYY out of it's efficiency islands even making 8 psi at 6800. If the OP turned the boost down to 5 psi peak, it would make what we consider a "normal" looking graph and peak around 150 WHP on a dynojet.

I think the designation for this turbo would be "T-to small". It looks like a TD03-9b or there about in size.

Keith

Or maybe the IC has a terrible pressure drop and he's sourcing the wastegate signal before the IC.

if that was the case with 2554's, not only would all the plots we have for them look pretty much like that, but 1.8 owners and 99+ owners would see an even bigger drop

fortunately, that's not the case at all.

because a 15g and T3 Super 60 isn't a small turbo. The 2554 setup was a very mild, untuned, build as well.

yes, it completely normal for 1.6L motors to make shit power.

it's also normal for dynapack dynos to read 10-15% lower than the dynojet you probably dynoed on.


hey remember that time i said it's probably boost drop? that was cool.
https://www.miataturbo.net/attachmen...1&d=1410436005

Are you suggesting that his turbo is so small it can barely support 150rwhp at 7psi? Even considering that 150rwhp on a dynapack on a 1.6L is a very common number on almost ever sized turbo thrown at it?

I am saying that I don't think he has a 2554. He doesn't seem to clear on the issue, and I think he has something smaller than the 2554.

Braineack, I really want pictures of his turbo, so we can see if it is really a 2554. I specified that it looks like a TD03 9b because that turbo would only support around 150 WHP on a 1.6. This would explain the boost drop, and the low power. I dynoed a 3000GT on stock 9b turbos (3.0 liter with twin 9b's) on a dynapack dyno and had the same boost drop with a MBC sourced on the intake manifold.

Keith

Oh I see what you're getting at. I wouldn't be surprised. I mean it took us 4+ pages to get basic info from OP, it will be another 20 before we actually have his turbo's specs.


By the time we get all the information about this car/build/setup, ND's will be stanced clubricer rust buckets and we will be waiting for the NZ unveiling.

Here's raw rota-dyno numbers from Shueinds last dyno with his SR20 T25 on his 1.8L

https://www.miataturbo.net/attachmen...1&d=1410455286


and and here's one of my dynos:

http://i46.photobucket.com/albums/f1...97_22_full.jpg

My car is a 1.8 by the way.

I'll get a picture of the turbo

Holly fuck!

Looking at the results, everyone was thinking it was a 1.6 even though you probably already said it was a 1.8

Now I am even more convinced he has a tiny turbo smaller than a 2554... or the blades are bent to shit.

Keith

https://www.miataturbo.net/attachmen...ine=1410457156

Here's the only pic on my phone showing the turbo. I'll get a better one when I can be bothered to go to the garage.

The blades all look fine and there is no evidence of any damage to the blades or the housing. There's minimal radial play and no in or out play at all.

looks like a 2554 to me, so explain the similar power output as the one I compared it to.

Just how bad is this exhaust, exactly?

Edit: I haz the dumb. What boost control are you using? Is the wastegate tight?

Indeed, 5 psi begi basic, very little timing, no intercooler, no MAT sensor, stock exhaust, 100 degree weather.

https://www.miataturbo.net/attachmen...ine=1410488090

...on what?

That was the first run i did with my car when i first installed the begi kit.

So.. did this one ever get sorted out? I think I actually have a similar problem

Could be the angle, but the intake cam looks advanced in the pic in post 227. That would explain all of his issues.

Hi,

i see this is a quite old thread,but did it ever been solved? I got into similar situation with a turbo 1.6. Car ran great,put put 235 to the crank,TQ was kept below 300Nm (~ 1 bar peak boost). Car ran fine,but after the owner took it home and made "some launch control sessions for the pals",ticking noise was coming from engine. After dissasembly,the rods were bent,they needed to be replaced.

I am not as experienced as the tuner of the car in this post,but i tuned lots of cars from NA to supercharded/turboed cars,low power to 600+. I had never have any issues with launch control on any cars,except this 1.6 miata.
After this car,i tell every miata owner to be cautious on the launch control.

So,i am after a logical solution,what happened,how could be the rods overstessed by launch control,whereas other cars does not have issues like this.I personally had the feeling, internet rumours about stock rod safe limit was not correct and the rods simply could not handle more than the double TQ they were designed for,but after reading this post,i feel we just fell into the same situation as Horton did.
https://cimg6.ibsrv.net/gimg/www.mia...06bc0e4ea2.jpg

My guess is overboost because of -30 degrees of timing as soon as launch control goes back to normal timing.

In my case,overboost protections was set to 1.1 bar,so it is unlikely. Yesterday i did some search,found similar case on a supra where 5 rods were bent from launch control. My bet is,its not the launch control which is the issue,but the hard launch. I mean engine is at full boost,and when the clutch is released,the power is instantly jumping up,but it needs to move the car,so the rods are momentarily overstressed.

Also found some VAG 1.8T cases,where the rods were bent due to launch control. I know these rods are weak anyway and can bend with any more torque than 350-400Nm. I also had one of these engines and i bent the rods with mid size turbo and big torque low down. I was running E85,so definiately no knock occured.

Ive got nothing. But I enjoyed reading through this old thread. I even found a new signature.

I would not say Launch Control per se, but possibly implementation. Since you mention full boost at clutch release, are we talking about extreme retarded anti-lag type settings? Then you're getting everything hot, so detonation can become an issue.

From an article about setting up all the pops and bangs type Launch Control:

"Now before I scare you too much, let me say that like all things, this only happens if it is abused. Be sure to not stay on the 2step limiter too much. I suggest to people to never be on the 2step longer than two seconds. This way the exhaust pressures and temperature never build up for too long. As long as 2step is set up properly and not abused you will be fine. The times where I hear of it becoming a problem, is with owners that think all the loud popping and backfiring is so cool, that they do it all the time for long periods of time, and then are all confused why the motor blew."

Just a thought. DNM