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-   -   turbo reliability on track (https://www.miataturbo.net/race-prep-75/turbo-reliability-track-52179/)

hustler 10-08-2010 08:08 AM

This also happened to me once on the street but I never found the problem, I thought it was something under the dash.

ScottFW 10-08-2010 10:11 AM

Can I assume these cable melting events happen primarily near the exhaust parts, or are they more randomly distributed? Looks like I get to add more thermo sleeve to my shopping list, bonus for more under-hood bling.

CoralDoc 10-08-2010 10:29 AM

On my friend's car, the cable did not melt, but it did bind up pretty well. We dissected the failed cable and determined that the outer housing had warped enough to bind the inner cable in the region closest to the turbo housing/exhaust manifold. Insulating the throttle cable from heat coming off those units would be a good start on a solution.

emilio700 10-12-2010 11:35 PM

Interesting post on the MotoIQ blog about Sierra Sierra having turbo stud failures.

http://www.motoiq.com/magazine_artic...fr-turbos.aspx

SKMetalworks 10-13-2010 12:07 AM


Originally Posted by emilio700 (Post 642364)
Interesting post on the MotoIQ blog about Sierra Sierra having turbo stud failures.

http://www.motoiq.com/magazine_artic...fr-turbos.aspx

Indeed, those exhaust housings look completely mutilated.

JKav 10-13-2010 01:06 AM

Those T04 housings are made of pot metal. It's no wonder they're pitching turbine wheels.

hustler 10-13-2010 08:51 AM

Its too bad that Sierra Sierra is a budget team and can't afford V-bands.

edit: I'm getting a real kick out of $sierra $ierra dealing problems that peasants on this board solved a long time ago. We really are great. The 3rd paragraph reads like my life with the old set-up.

Look at this safety wire job
http://photos.motoiq.com/MotoIQ/Colu...20_8xoh3-M.jpg
Notice which side of the top bolt the wire lies.

JasonC SBB 10-13-2010 12:11 PM


Originally Posted by bbundy (Post 640315)
That is what I thought too. But I could run down a long hill in high rpm vaccume for a long time and not see any oil smoke. Floor it from a steady cruise on flat ground and leave a smoke screen after it came up to full boost.

Whoa. Is this with an FM stroked/bored/honed and assembled block?

bbundy 10-13-2010 12:15 PM


Originally Posted by JasonC SBB (Post 642546)
Whoa. Is this with an FM stroked/bored/honed and assembled block?

Yep. And Vent to atmosphere on the valve cover and oil pan doesn’t change it I don’t get excessive blow by in the vent system anyway. Motor still shows good compression. Install stock internaled motor keep everything else the same including boost level and problem goes away. Just had to back the fuel down a bit it and it makes slightly less power and torque.

Bob

Trackwhore 10-13-2010 12:17 PM


Originally Posted by hustler (Post 642446)
Its too bad that Sierra Sierra is a budget team and can't afford V-bands.

That's because the'd rather run a twin-scroll exhaust housing and manifold.

JKav 10-13-2010 12:43 PM


Originally Posted by bbundy (Post 642550)
Yep. And Vent to atmosphere on the valve cover and oil pan doesn’t change it I don’t get excessive blow by in the vent system anyway. Motor still shows good compression. Install stock internaled motor keep everything else the same including boost level and problem goes away. Just had to back the fuel down a bit it and it makes slightly less power and torque.

Bob

In my mind, the only thing that explains this is ring flutter. Have you or FM checked with the piston manufacturer on what you're experiencing?

hustler 10-13-2010 01:36 PM


Originally Posted by Trackwhore (Post 642552)
That's because the'd rather run a twin-scroll exhaust housing and manifold.

...and look how well that's working out for them.

bbundy 10-13-2010 01:48 PM


Originally Posted by JKav (Post 642567)
In my mind, the only thing that explains this is ring flutter. Have you or FM checked with the piston manufacturer on what you're experiencing?

The new pistons I got are compleatly different design and also have longer skirts. We will see. I got two more weekends then things start coming apart again.

Bob

Trackwhore 10-13-2010 05:36 PM


Originally Posted by hustler (Post 642611)
...and look how well that's working out for them.

...and look how well it worked out for you. It got you to a better solution. I'm surprised you are making comments about the evolutionary process of building a reliable race car. ;)

Twin-scroll has obvious benefits in this application.

hustler 10-13-2010 06:02 PM


Originally Posted by Trackwhore (Post 642744)
...and look how well it worked out for you. It got you to a better solution. I'm surprised you are making comments about the evolutionary process of building a reliable race car. ;)

Twin-scroll has obvious benefits in this application.

Yes; its quite strange but this is also a space-car and nothing like my peasant heap. I learned a lot from looking through a bunch of cars at RLTA last year and incorporated the ideas I could afford into mine.

sjmarcy 10-13-2010 06:06 PM


Originally Posted by curly (Post 639205)
I would be flabbergasted if more than 4 cars on this site could survive 7 track days in 14 days…

Pretty common sentiment. Bring spares, tools, cash, and friends if you boost a lot.

JasonC SBB 10-14-2010 12:17 AM

The link from the Sierra Sierra blog deserves to go in here:
http://www.cogneusa.com/img/prodotti/steel6a_eng.gif
http://www.cogneusa.com/img/prodotti/steel6a_eng.gif

hustler 10-14-2010 08:53 AM


Originally Posted by sjmarcy (Post 642763)
Pretty common sentiment. Bring spares, tools, cash, and friends if you boost a lot.

Several of us managed to anticipate weak spots and been successful with reliable turbo cars. Its not easy, take money, and takes extreme attention to detail.

JasonC SBB 10-14-2010 02:16 PM


Originally Posted by bbundy (Post 642621)
The new pistons I got are compleatly different design and also have longer skirts. We will see. I got two more weekends then things start coming apart again.

Bob

With whose pistons did you rebuild it? Does it do away with the gas port thingy that may have contributed to your problem?

bbundy 10-14-2010 03:24 PM


Originally Posted by JasonC SBB (Post 643154)
With whose pistons did you rebuild it? Does it do away with the gas port thingy that may have contributed to your problem?

Wiseco redesigned the pistons for the stroker. They still have gas ports but less of them, 6 instead of 10. They also have longer skirts and a different shape to the structure underneath so they look quite different. They also come with ceramic coating on the top now.

edit: I'll add that they are not compatable with the stock oil squirters.

Bob


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