spyro

egt's
i have seen people using vnt turbos but with low boost 8 psi max

98ctr

due to the egt's that gas cars put out, VNT's are not used much. Porsche is comming out with its first variable vane turbo in the new 911's. the way it works, it varies the exhaust turbine's speed for the best power at different rpm's.

trucks have been using them on the disel engines for quite sometime. wish we could use them on gas cars, it would give us a flat torque curve all the way to red line from like 1500 rpm's.

91efate

yea no lag at all, my friends shadow csx has full spool at like 2k all the way to redline, i think we'll be seeing more of them

web

Funny reading this question, I was about to ask a similar one.

A VNT20 is a pretty large turbo though, capable of quite a bit of flow. I do believe the 2.5 Audi diesels came with a GT2052V which is a VNT17, not a VNT20. Bit confusing nomenclature, that. Similarly, the GT1749V I'm looking at is a VNT15, off a 110HP VW TDI 4cyl.

I agree it's rare on petrol engines, but the Shelby CSX used it... are these troublesome?

Geometry failure is also seen a lot on diesels with these turbos, but that's mostly due to carbon buildup.
So that extra 100c EGT really does 'em in then eh? There's really not THAT much of a difference between diesel and petrol EGT's...

BTW the Peugeot 405 T16 used a VAT25. A VAT25 has a much simpler single vane mechanism AND an internal wastegate. VNT's do away with the wastegate completely although it is said some large applications use an external wastegate. Never seen one though.

Marcel

norwegian cRxXx

yoco:

here is my audi 2.5 v6 tdi 150hp turbo (the 180hp versions don't have the exact same turbos)..

web

Just found out many modern diesel VNT's are vacuum controlled through ECU modulation. rather than boost controlled like the old VNT25's were. Looks like that Audi turbo is one of the vacuum controlled ones. Probably difficult to control when slapped on a car without such controls.

spyro

you can modify the turbo to be controlled by pressure many people use them on diesel engines without electronic control

and regarding t16 i know that its not a vnt turbo
what was the turbo used on the shellby , possibly custom made to that model

91efate

i don't remember the exact model on the shelby csx, but you can look it up if you want. all i can tell you is its a garrett vnt and its about the size of a td04-tdo5 and uses vacuum controlled vnt. my friend hasn't had a problem with his turbo to date but i don't see what egt's have to do with use on petrol engines its irrelevant i think that its the production cost maybe, because these are bit more detailed than a normal turbocharger and they consist of alot more parts. just my .01 cents though

BUCKETHEAD

it explains it all in the maximum boost book. there alot more expensive