Variable Geometry Turbochargers

[Lev_96_240sx]

Everybody knows that the worst part about any turbo setup is the dreaded turbo lag. Well while browsing through various car sites, magazines and whatnot, I came across these variable geometry turbos. They are currently used on the Cummins Dodge trucks, most Porsche cars, and the new bmw twin turbo 3 series engines. Problem is, I haven't been able to find anyone that sells them. I think something like this could be a godsend for the tuner market and definitely something worth exploring. I mean who wouldn't want a turbocharger that acts like a supercharger at lower revs and very much like a turbo at the top end?

Does anyone know of a company that sells these turbos? And more importantly, sells them in a variation that would be viable for the S-chassis?

[ELEMENT692121]

borgwarner supplies the ones for porche look and see if you can find any on there website
Modified by ELEMENT692121 at 6:23 PM 2/10/2008

[IanS]

This is a very good question, I knew of the existence of VG turbos on diesel engines, but for some reason I never thought of utilizing that technology for my own means. I will do some research on the subject, but my first thoughts about why its not more widely used would be, price, complexity, and reliability. Im guessing these three things have kept VG turbos out of the mainstream, but with technology expanding the way it is, and their use on regular cars like the BMW, that may be about to change.
Modified by SideWays=smiles at 9:39 PM 2/10/2008

[ELEMENT692121]

sorry i didnt realize the caps lock was on i wasnt yelling at anyone .. i fixed it i appoligize .. it is a very intersting subject .. from what ive read so far its a very hard piece to make and keep working well over a long duration .. wikipedia has a nice write up on them ..

[ELEMENT692121]

also check out garret they are working on what they call a hydra charger works like a power steering pump very low effort into makin a good amount of boost .. they are also running twin in line turbos very small turbo feeding another small turbo .. 2 10 psi efficiancy range turbos run back to back create 30 lbs of boost with hardly any lag .. there using this set up on some new tractor trailers ..

[IanS]

sorry i didnt realize the caps lock was on i wasnt yelling at anyone .. i fixed it i appoligize .. it is a very intersting subject .. from what ive read so far its a very hard piece to make and keep working well over a long duration .. wikipedia has a nice write up on them ..

Hahaha, ok.

Ive read all the VG stuff on wiki, and Im pretty sure Ive read every article on Garrets website. There is some really cool info there, and I foresee some very interesting times in our futures.

[Lev_96_240sx]

Definitely. From what I've heard and read, they are fairly new as pertaining to gasoline engine applications. As far as the concerns with them, yea, price and complexity would definitely be big ones, but reliability imo won't be a problem. Remember, the trucks that these things have been running on run 1-2 million miles. I don't know how often they get replaced but I'm guessing not too much. At any rate, we can look at the reliability of the turbos on the new BMW 335s since they each run 2 VG turbos. I'm really curious to see whether anyone has done a custom VG-Turbo application.

[Bronze MFP]

pretty sure the new GT-R uses VGTs as well.supposedly HK$ is looking into them and there was some teaser setup at one of the parts shows not too long ago. Who knows how much an aftermarket turbo would cost, but the performance would have to offset the cost if they are crazy expensive. which might be the case, as the gt-r makes ~90% of its torque by 1900rpms!

[Lev_96_240sx]

Well going by the example of the pricing on the Skyline and now the GT-R, most of their cost is in the electronics since we can buy the engine out of a 60+ thousand dollar skyline for 3000. It shouldn't be too much of a stretch to imagine that the new skyline will have most of it's production cost in the electronics and computer gizmos that skylines are known for.

That being said, I think that if you can get those torque numbers at that low rpm level, even if the VG Turbo costs twice as much as a comparable BB turbo it will be well worth it for any performance application.

[240_SeX]

I think that Vgt's will become very popular as soon as they can perfect a reliable and cost effective way to create and control them. I wrote a short research paper on them in college and found a considerable amout of info on them, they actually arent that new. They have been used on deisels for some time now i beleve that were introduced in the mid 90's. anyway i found some cut-away pics of them and a short write up that motor trend did on the 07 Porshe.

http://www.motortrend.com/road....html

[wishihadas14]

I have been thinking about this myself for quite some time and have looked into a fair amount. Porsche has been using twin VGT's for awhile on their flat-6's, but I don't know what size or if it could push enough psi to produce high hp numbers since I couldn't find any compressor maps. Acura's new RDX uses what they call a Variable Flow Turbocharger that does essentially the same thing, through a different method. It has a variable flow nozzle inlet instead of the many vanes needed in a regular VGT, which cuts down on the complexity and moving parts required. I like this in theory too, but that turbo was designed to produce near-instant boost on a 2.3L and produces 13 psi. max (in stock form) but only 8 psi. after 4500 rpm. Again, I have been unable to find compressor maps, and as the displacement is relatively close I assume it is reasonably sized for a KA or SR, I doubt that the cost of buying an OEM Acura turbo for a brand new model would be prohibitive and the chance of not producing enough peak boost would outweigh the advantages of quicker response for full race applications. IMO, until we see some aftermarket turbos, these will just not be plausible because anyone who wants to spend that much on a turbo probably wants high hp/tq numbers and the truth is that a properly sized turbo will not lag all that much for the intended application and that a twin-scroll setup or v-mount intercooler (two also very costly options) can reduce lag by a significant amount. Sorry this post is so long. What I concluded after my research is that right now VGT/VFT is just not worth it as an aftermarket build, but that if these big-name turbo suppliers start to produce VGT/VFT's in sizes for all types of motors and applications, then we will likely see this to be advantageous, though cost prohibitive.