Ive being looking for a while now. There doesnt seem to be any company making aftermarket VTG turbo's yet....

Anybody know of any??

-Ben

 

i'm sure they would have a hard time adapting the vgt to withstand the heat of a rotary, but that would be very interesting...

 

what is a VGT?

 

Gods Gift for people who like turbo's

VGT is a variable geometry turbine, basicly there are small vanes that are actuated by a unicen ring which is controlled by a servo or oil pressure or in some causes as simple as a vacuum/boost dashpot which when moved change the angle that the exhaust enters the turbine from the scroll. its basically an adjustable a/r on the fly. Ive read that some of the larger diesel vgt turbo's have housings that flow the equivlent of a .8 to a 1.7 a/r's depending on the vane position

EDIT:

heres a better description with pictures (yey!)

http://www.autozine.org/technical_sc...gine_3.htm#VTG


Ive also been watching VGT technology, once the availablity of a VGT unit that can withstand rotary EGT's, i will buy it in a heartbeat

ive almost bought various GT style VGT garrett turbo's off ebay a few times just to have one and see what is needed to make it work, or just use it untill it fails just to try it out

 

Last time I checked - years ago - they only made them up to T3 sized.
So, they are too small, unless you use like a bazillion of them on a rotary...


-Ted

 

They have them in T4 and larger now. Some of the big rigs use them

 

Doesn't the new Porsche Turbo use this kind of turbo?

 

Yes, twin VGT turbos, full boost by 2k'ish iirc

 

ok that makes sense, i think i remember reading about those in maximum boost, aka the bible

 

I am sure many companies are looking to make this technology affordable.

Technology like this is the obvious choice for people who look for the best of all world... its a shame that all new technologies take so long to become normal everyday use. How long did it take disc brakes to become common? Too long.

Im sure in a few years VTG turbos will be the norm. And i am also certain that there will be better versions of VTG's, with fins that contort instead of linear vains.

...Bye bye turbo lag.

-Ben

 

this thread got me thinking, so i started to talk to some people who have run them, one person in partiular, a fellow selling his used powerstroke GT37 VNT turbo on ebay

makes it temping.. im seeing 1300deg peak egt's currently..


what do you mean by fins that contort?

 

Fins that contort are cambered vanes that are curved to have better flow characteristics. They are already used.

GT37AVNT from the Ford Powerstroke is not a good VNT turbo to start with. There are better options that are commercially used. Diesel VNT's will work, but the question is for how long. It will be inversely proportional to your pre turbine EGT's. The challenging part will be the electronic control of the VNT actuator.

The BorgWarner VGT turbos that are used for gasoline applications use highly exotic/expensive steels in order to retain strength at high temperatures, but unfortunately because of the high thermal expansion, many clearances are made excessively high. Thus, the efficiency of those units are likely not to be as high as they should be. A lot development is being done for high temp applications, but won't be available to the general public for at least a little while.

 

Good info!! thank you!!
-J

 

What apects of the GT37VGT are not very good?

Which available turbos do you prefer?

Vanes that contort sound like the old attempts that failed due to flutter...

Seriously interested; I have a GT37VGT that has been sitting in the garage for a couple of years as I waited for someone else to test their temperature limits :P

My engine destroyed 2 SS wastegate dividers (the last one being 1/8" thick and torn like paper down the middle) and melted an EGT probe as well.

Under load my preturbo EGTs are under 800C, but lean cruise puts them over 1000C...

 

Jesus christ, and i was worried about my 700c post turbine temps..

Whats wrong with using two GT37 with the 76mm (or was it 74, whatever just not the 84mm one) compressor's?

As for control, the guy i was talking too said he used a boostcontroler to control the oil pressure activated vnt unit on his turbo and said it wasnt complicated at all either.