RKD in OKC

The newest Porsche Turbo uses Variable Geometry Turbos. There is a huge difference in exhaust gas temperatures between desiel and gasoline. That is why there has not been much longevity on gasoline engines with VGT designs. I suppose since Porsche in now using them they have solved the longevity issues if not with expensive materials.

Bullwings

The Acura RDX is using the same technology now too.

And also I remember reading that the problem was the temperature of exhaust gases generated by gasoline engines.

Technically if you wanted zero lag, you could use an anti-lag setup like they do in rally cars, which provides better response and less lag than VGT. Granted, the turbos don't last very long, but if it's purely for a track car that you race competitively and have the money for, I don't see why not. You'd even rival push rod V8s torque at low rpms.

There's been some recent developments making them practical to use in everyday street cars (Prodrive P2 is a prototype car using that technology). I'd rather see an anti-lag system developed for the 951 before VGT.

anders44

antilag really kills the turbo, the swedes usually use cheap truck turbos as they can take a beating and are cheap. as for antilag I will test it out, and you can do different versions, from mild to wild. launch + als + 944 = broken drivetrain I think.

personally I would love to see 997T turbos on a 944....

I know many people with 997T's and some are going to upgrade to the GT2 turbos, so I am hopeing to score a pair that way.

gt37vgt

i've got 2 of them I'm looking at setting one up on a 2.5 and one on a 3.0 I'll be making longer secondaries in hope of shedding some exhaust heat and maybe water injection . my biggest problem is the size of them my 400 hp vgt is as big as a 700hp turbo and the 550 hp unit is is an outrageous size must be 10" or so it is 37lbs of course i will post a massive story when it all happens . i will make it happen but i sure as hell don't recommend it at this stage . I wonder what ever happened to that twin turbo 3.o that in the pictures . also i'm kicking around different ways of controlling it maybe use it to control exhaust pressure maybe still use waste gate . have an override set up for open cruse and be able to close the vanes to quietly cruse by the cops

Geneqco

Aerocharger turbos are now made by Hiperturbo:
http://www.hiperturbo.com/technology.htm

They have just released a new bigger model rated at up to 380 hp - they got 400 hp from a 930 using this. It develops its peak boost somewhere around 2000rpm from memory. They have a bigger one in development but were not able to comment on its size at this stage.

I have spoken to the Garrett guys about their diesel turbos... they do test them up to 700C (around 1300F) after which they start to have problems... I think the normal temperature is closer to 600C. The issue (for petrol engines) is the cast iron hotside doesn't allow the heat to dissipate very well. They can deal with this problem using high tech materials but these materials are quite costly.

gt37vgt

yeh i really wonder what parts exactly apparently cant handle the heat perhaps the soliniod as the vgt vains are not as delicate as as the turbine

Geneqco

I get the impression from talking to them that they just seize up.

DanG

You guys are right on with the temperature issues. There are some new VGT units out there that can handle the higher EGTs of a hi-po gas engine, but the diesel turbos on trucks aren't them. The new 911 turbos are VGT, I believe.

gt37vgt

yet the 997 has 2 of the magic little suckers i imagine either one of them would cost more than my car. if garret test them to be approved for an OEM application they would have to last 300 000 km (a k26 does) 30 000 is enough for me

KuHL 951

Don't mention Aerodyne to any Miata tuners or you will strung up and tarred. They were an abject failure costing many people complete engines as parts were ingested from seized blades. Hopefully Hiperturbo does a better job with their equipment. The concept is great, it's the real world execution of the idea that sucked.

DanG

Temperature isn't entirely a mileage/wear thing. Its a do not exceed thing. Once you start gooifying turbo internals, you can't ungooify them. Yes, gooify is a technical term. So the mileage limit on a diesel VGT turbo used on a hi-po gasoline engine would be however many miles you drive before exceeding the melting point of the lowest heat-resistant material. If you don't actually exceed that temp, you can still bet that wear will be greatly increased at temps slightly below this level.

So while some things in a turbo are qualified based on a specific amount of cycles or run time, the metal bits in the VGT mechanism also have a do not exceed temperature level. Diesel VGT turbos can't meet gasoline EGT levels, we're talking a few hundred degrees.

gt37vgt

so it wont last but how long will it take ??? nothing is going to melt something is just going to be weakened by the heat and break or wear perhaps i need to convert my car to menthanol thats heaps cooler . tragicly i cant get 85 on pump here i'm sure that would be somewhat cooler .

sawood12

As far as I know the 997 turbo is the only petrol engined production car that uses varible geometry guide vanes. All the other cars that claim to use something similar actually use an orifice that changes size ahead of the turbo - a bit like putting your thumb over the end of a hose pipe. It is nowhere near as an effective solution as a variable vane turbo. Expect big improvements to come when Porsche marry up this technology to direct injection in the facelift 997 turbo (probably).

Porsche reckon that due to the exotic alloys they use in the turbo that the turbo will last as long as a conventional one. I'm looking forward to the aftermarket ones hitting the streets in a 951. I'm sure it will be out of my price range though.

anders44

and yes... the turbos of a 997T costs more than our cars :|

gt37vgt

either one of them.

at the moment i would say a high end twin screw blower is a better solution . Like auto rotor sprintex lysom.
my turbos were cheap but i think i will do 3 or 4 days fabricating so not cheap and the big one is as big as a blower