Anybody seen one of these on an RX-7?

http://www.evoxforums.com/forums/showthread.php?t=22515

Bell Engineering/Corky Bell has a shop here in San Antonio. I went by his shop years ago when I had an FC and saw one of these variable vane turbos sitting on his desk.

Seems like it would be a nice solution for quick spool and plenty of volume in the higher RPMs.

I'm still going to stick with the stock twins but this seemed like it could be useful for some of you guys.

 

that sounds great, the problems i see with it is maybe it couldnt withstand a rotarys hot exhaust, maybe the vanes would shear off or possibly stick causeing problems?

 

Inconel turbine wheel, vanes and exhaust housing. That issue has been addressed for decades!

 

well :P i see no problem with these it would be interesting to see what kind of numbers they would put down on a fd

 

they are ridiculously priced

 

I wonder what determines the position of the vanes at any given RPM? Is there some sort of electronic controller that uses sensors to determine when to move the vanes and to what position or do the vanes just move from an "impact" angle to a less aggressive angle as the RPMs rise. It would be nice if it were a simple mechanical system and not something that requires a bunch of electronic crap. It sure seems like it would solve a lot of problems if the cost were not out of the question.

 

older holset turbo's used boost pressure. The newer ones are all electronic.

 

SEARCH THE INTOR-WEBZ... This information is all over the place.

http://www.autozine.org/technical_sc...gine_3.htm#VTG I could give you some SAE stuff but this'll due.

-J

 

Looks like the system would not be able to handle the rotary heat if none of the VTG turbos (other than Porsche's) can handle a normal gasoline engines heat.

 

If I remember correctly... Borg Warner was manufacturing the VVT's for Porche, but the manufacturer exclusivity agreement is now up.

Prices have dropped in the last year substancially.

The only issue I could see, would be reliability in direct relation to the turbo's size.

The smaller, the shorter the life span.

Seems likenin the past, the VVT's that were lasting long enough to pay for themselves were fairley large.

 

Honda uses them on a gas application on the RDX SUV just like Porsche. Cummins/Holset uses them for diesels. Ford uses Garrett variable vane turbos on F series diesels:











Besides some of the reported reliability issues, I think they're great on cars that were actually designed for them in terms of the plumbing and the control system. A variable vane turbo is designed to be used without a wastegate. The A/R should increase so much with the vanes open that boost will no longer rise, and yet no exhaust is "wasted" by bypassing the turbine blades. In that way they are much more thermally efficient.

But good luck finding one off the shelf that will work well like that on a rotary. And if you're going to run a wastegate with a variable vane turbo you are losing much of the benefit. You might as well stick with the proven twin scroll turbine housing and divided manifold that even Mazda was using back in the series 5 turbo FC3S.