Hi,

Is anyone out there running the mkturbo kit on their Miata for HPDE weekends and having good success? Just want to check in since that's my plan. I usually try to make it to between 7-10 HPDE weekends (2-3 day events each) per year. I want to see what prep work you did specifically for the MKturbo setup to make it reliable. I realize that a big portion of the reliability will come from the tune so I plan to leave plenty of time between the first event and having things completed so I can shake down the car and have the tune finalized on a dyno by a pro in my area.

Really just looking for what stuff I need to do so that I don't have a mechanical failure on day one of a three day HPDE weekend.

The things I'm assuming that need to be updated are:
- Inconel studs w/ locking hardware
- Upgraded clutch
- Turbo brace
- Turbo heatshield or blanket
- Ceramic coated downpipe & manifold
- Wrap all the junk around that turbo area with reflective heat shielding

And for general track use, the typical things apply which I've already done:
- Coolant reroute
- Bigger radiator

Asking this because my car (99 Miata/stock engine/upgraded suspension, brakes, cooling) has been very reliable at the HPDE events so far and very competitive. I'd like to get the car up to around 200whp and I'd be stoked to leave it there and have a reliable setup for street & on the track.

Thanks,

Chris

 

You got all the big things.

My big concern is manifold cracking. No idea how long or when it will happen. Solution for that is coming later this year with the cast manifold.

 

Makes sense RE: manifold concerns. I was thinking the same thing so that's why I figured a turbo brace with some helm joints would do the trick. I've heard some guys end up cutting reliefs in the manifold as well so that's another area that I may need to add to the list just in case.

 

Don't cut reliefs in a fabricated manifold. That is only for cast manifolds.

And under no circumstances should you use a turbo blanket.

Do not use IAT based spark retard.

Do shield the exhaust from the transmission, the fuel tank, and the differential.

 

I’ve got 10-12 track days and 30-40 sessions on my 1.6 setup. The only issue I’ve had was stretching turbo studs, which inconel fixed. Manifold seems to be holding up fine with no brace, fingers are crossed. As six pointed out, heat shield the hell out of everything. My brake fluid was boiling in the first few sessions until I shielded the brake cylinder and descending hard lines. Check my build thread for more details on the heat shielding.

 

I got lots of good track weekends in on mine. Basic heat shielding and checking the bolts from time to time kept it going. I eventually blew the turbo, which seemed to be due to a lack of restrictor on the oil feed, which are now standard. The replacement turbo is cheap. Would buy again.

 

Can you go into more detail on not using IAT based spark retard? I want to learn and I didn't find a decent answer that made sense to me on google.
Does retarding spark on high IAT's increase EGTs leading to something like stretching studs?
What should be done instead? Increase fuel with high IAT instead?

 

Probably decrease boost...

 

I'm in the opposite camp as curly. Add boost and fuel, remove timing. Let the boost make the power, timing is what makes things hot, raises EGT and cracks pistons.

 

I’m pretty sure that adding relief cuts stopped cracking on my log manifold.

EDIT 12-June-2019: New crack at weld between 3 & 4. See Six's comment below????

 

Relief cuts are good for cast but not welded manifolds.

Retarding timing causes EGTs to skyrocket because the fuel does not have time to finish burning before exiting the combustion chamber. I cooked two turbos, numerous turbine inlet and outlet studs, IWG flappers, and all kinds of things trying to track the car. Exhaust manifold and turbo were still glowing red even after a full cool-down lap. Excessive doesn't really do it justice. It had been set to pull timing more aggressively after some discussion in one of Hustler's threads back in the day.

I finally figured it out and drastically reduced the settings after much money and hardware was destroyed and time lost.

It isn't turned off because it wasn't possible to turn it off. But I did have it set where it only pulled half a degree for something like every 40 degrees of temperature rise above whatever the maximum set limit was.

 

@sixshooter Maybe we should take off-line. But, why do you say this? Again, I am not CERTAIN, but my experience has been that my welded (Schedule 40 Steel) log liked to break the welds until I cut the flange. Maybe our welds were bad? IDK.

It appears to me that between hot and cold, I can see the cuts open and close a bit.

Sure, I get that cast iron (not TSE cast steel) has low tensile strength, whereas a welded steel should be much stronger in tension, but are there other aspects that you are referring to?

DNM

 

What I meant was reduce EBC duty for high coolant temps to reduce power. Not reduce boost and increase timing to make the same power. Like decrease EBC to drop 50hp. That'll help substantially with heat. And if your answer is "I don't want to decrease power", then maybe try different material designed to withstand high horsepower track conditions!

 

Thanks for all the replies. I am not looking to go nutty with horsepower either. I figure if I get to around the 200whp on the track, I would be more than excited. I really just want to try to keep some speeds up into the straights more than anything. If I go in for tuning and we safely get to something higher than that it would only be for street use.

That's good to know about the relief cuts. I will pull that off the list.

Regarding the turbo blanket, thanks for the input. I've never really had issues running a blanket in the past but I have heard that people have run into moisture and rust issues as a result of running them. I think a heatshield is more my speed though only b/c then i can box in a portion of the downpipe too.

 

Relief cuts turn cracking (cast iron) manifolds into (eventually) warping manifolds. Still not good, but at least it lasts longer. No experience with fabricated or stainless manifolds.

Agreed on the effects of retarding timing. I've broken many things tracking a 300+ rwhp Miata, but the power-producing hardware has not been one of them. I attribute this partly to using fuel with enough octane that I can run MBT to minimize EGTs. Race gas only seems expensive until you start breaking turbos and engines.

--Ian

 

Yes, cast manifold will warp when relief cuts are made and will have to be resurfaced after so many heat cycles, especially if you overheat the **** out of them like I did. Fabricated manifolds need the flange structure much more than the thicker cast ones do to remain true when abused by track use.