gtred

This is the second race day that this car has run... and the second time I had turn-workers shaking fire bottles at me as I passed the turn stations. The first time they pulled me off because they saw my brakes were on fire... just when I was hooking up really well...

The second time was a bit more intense. At about lap 6 I began to notice an exhaust leak... I didn't pull right off, but continued around the track toward the hot pits; noticing a little bit of a burning oil smell. By the time I arrived at the hot pits it was smoking pretty well. I got positioned at a fire station and waited for the workers to stage before I pulled open the hood and it flamed up pretty good.

It seems that it wasn'tjust an exhaust leak, all of the locknuts had backed off the turbine outlet flange and the downpipe had actually pulled away from the turbo. Now how do you miss something like that in your pre-race check!?!


It seems that the heat had melted off the plastic pull portion of the dipstick. When it fell away, it allowed windage to push oil out onto the manifold and the heat wrap around my heater hoses. It lit it up pretty well.

Lesson one: pull off immediately when you smell smoke
Lesson two: replace the hood cable with hood pins, or you might not be able to open your hood at the next fire.
Lesson three: find a better locking hardware for the turbine outlet flange and a better way to run the heater core hoses.

hustler

iTrader: (6)

Why are you running a heater core in a racecar?

Didn't we all tell you to get Inconel hardware?

gtred

I live in Oregon, not Texas!

They call the first race of the season "icebreaker" for a reason. In April, you'll usually have iced up windows. The next several races are rain races. Those without defrosters use a rag-on-a-stick to swipe the passenger side of the window just before the turn it point!

By the first week in July you've got a 50-50 chance of a dry track.


I did use inconel + resbond + stage 8 fasteners for the manifold-to-turbo inlet, as you all had recommended. The threads here at TM.net said that it wasn't necessary to use incolel for the turbine outlet-to-dp flange... do we need to revise these? I'm not sure if a stage-8 type locknut assy would fit on the separated gasses DP as the pipe and welds get in the way of seating area. Seriously, I don't see how the steel crimp nut I used could have backed all the way off the stud; let alone all 5 of them! There must be some amazing shakin' going on!

I agree that I need to remedy these problems with a more reliable solution; it is hard to inspect this area as it's covered by a bulky heat shield. I wonder if steel or Cu heater core piping would suffice? What fasteners do you use for the DP flange? Do any of the other year miata (or similar) use an all steel dipstick?

Handy Man

no OEM all steel dipstick... might be able to find one aftermarket.

I made a head shield for mine out of some AL angle after I melted my last one, its worked so far.

I used the left over Resbond from my TSE turbo stud kit on my DP studs and nuts, its worked so far.

gtred

Wow, you melted yours too? It could be a real fire hazard if it uncorks that crankcase tube, like mine did. It opens up the windage right onto the manifold and turbine housing.

I found a dip stick that shouldn't melt! http://www.bellengineering.net/produ...roducts_id=687

Savington

iTrader: (31)

You don't need a metal dipstick, dude - you need to stop driving the car when you hear an exhaust leak that massive. You can't expect anything to survive when the turbo is blowing directly onto it with ~1200*F exhaust gases.

I've been using plastic dipsticks in all of our cars and I've never had one melt, but I've also never done full sessions with the downpipe completely de-attached from the turbo.

hustler

iTrader: (6)

My turbo hardware is broken, I blame the dipstick.

gtred

Ha! That really is bad isn't it! The car is so noisy with the open exhaust that I didn't notice it until it completely came loose!

It was all together when I started the 3 day event. I suppose it is just good practice to pull off the heat shield and re-check the bolts after a run.

Seriously, Hustler/Sav what hardware do you run? Inconel on this flange also? or, double nut? drill the stud and safety wire?

Braineack

iTrader: (62)

then you havent lived.

VanMSM

There is an OEM all steel option: Mazda dip sticks - MiataRoadster - High-performance customer service...and parts for Roadsters

18psi

iTrader: (76)

yup, 99-00 california nb's come with that

TimM

Did you clamp your downpipe to the bellhousing yet? If not, it's a good start. It stabilizes the whole turbo assembly by relieving the weight of the exhaust system.

Savington

iTrader: (31)

Find me a race car with heat shields, please.

Take off the stupid heat shield, wrap/sleeve anything that needs to remain cool in that area (heater hoses, lower coolant hose, brake MC reservoir, etc), and throw the heat shields in the trash. This is how race cars are built, and this is how you should build your car.

curly

iTrader: (25)

Careful what you ask for.


They have your place, but I get your point. Turbo heat shields with covers don't make sense, you have your hood above it, so there's no point. With my greddy system it covered up some issues I didn't know about.

Why my new side mount setup, I just put them along the side to block the multiple coolant and brake lines, and left the top open. There's a science to heat shields.

Handy Man

Tell me more. How is this done?

hustler

iTrader: (6)

I have a heat-shield around my hot-bits, to help keep me from melting.

hustler

iTrader: (6)

I safety-wired the CHRA with Inco wire, I have v-bands in and out of the turbo, and I have a ghetto exhaust brace thingie attached at the rear subframe to a "U" shaped clamp. It works.

curly

iTrader: (25)

Pretty easy:

Flyin' Miata : Turbochargers : Parts and upgrades : 1990-97 2.5" FM exhaust brace

It's an exhaust clamp with a sturdy bracket bolting it to a couple of the engine-tranny bolts. Just like stock.

Handy Man

How have I not heard about this until now?! I need that yesterday!

Thank you Curly

TimM

Easy & pretty effective. I did my own with hardware store angle aluminum & muffler clamp before the FM unit came out. Bought the FM later because it looked sturdy - didn't fit....