for those in the know: vatn turbochargers

[saxman]

For those of you experienced in turbo systems, what are your opinions of the vatn(Variable Area Turbine Nozzle for those of you that don't know) turbo chargers? Does anyone besides the once fabled aerodyne make any of these?

[ProECU]

Sax,

can you point me to any research papers, links etc that you have been looking at?

[saxman]

lots of info on the vatn turbo's can be found in corky bell's maximum boost

seems that garrett is producing a line of "vnt" turbos that show some promise. in the late 80's, early 90's a few chrysler vehicles came out with a garrett vnt-25 turbo, using a variable a/r set up. this goes over the basics of it
http://www.thedodgegarage.com/turbo_vnt.html

apparently garrett also supplied audi witha vnt15 and vnt20 line.

seems holset has a vgt turbo which follows the same principles.

All in all, it's a fascinating concept. Variable a/r ratios allow the turbo to also be at peak efficiency, allowing lighting fast spool, but the top end of a big turbo. And due to the potential size of a/r available, boost can be controlled entirely with a/r ratio, so there is no need for a wastegate, and as such, all of the exhaust gas is used to spin the turbo.

[saxman]

seems the biggest disadvantage to them is that over time, the vanes start to stick. I'm sure there are ways to maintain them to prevent that though.

Really makes me wonder why these aren't more popular... seems like all the big name companies make them, just aren't commonly used.

[ProECU]

sounds like vtec for turbo's, i'll look into.

[superR]

sounds interesting....i cant find any for sale though.... just for a rough price comparison

[Weq]

VNT 25 also. they are quite popular in euro/germany and used on turbo desils alot. This makes them quite cheap and inexpensive over there.. I have seen a few dynos of SOHC's with them, and they make impressive torque right through until redline. Very versatile turbo and i think they will be used alot more int he comming years.

ps. hond a had a twin turbo legend and accord backin the mid 80's with Vairible vein turbos :)

[saxman]

sounds like vtec for turbo's, i'll look into.
I would compare it more to a cvt tranny than vtec, as it's not really bipolar like vtec, switching between two a/r's... it's a constant variation.


I'm halfway tempted to sell my t3, and set up a vnt-25 set up. Sounds very cool, very promising, and quite different... and the vnt turbos aren't that much on ebay... $250 or so... not bad at all.

[ProECU]

yeah, I was screwing around with that vtec comment, but yes, point taken.

Sounds like a very interestin concept.... i'll need to do some more reading.
There must be a reason these arent more widely used.

[saxman]

sounds interesting....i cant find any for sale though.... just for a rough price comparison
http://cgi.ebay.com/ebaymotors/Turbocharger-Turbolader-Garrett-VNT-Turbo-for-2-5-Van_W0QQcmdZViewItemQQcategoryZ33742QQitemZ8037654 008QQrdZ1QQsspagenameZWDVW

http://cgi.ebay.com/ebaymotors/Dodge-CSX-Shelby-Daytona-VNT-Garrett-T25-Turbo-89-91_W0QQitemZ8042738973QQcategoryZ33742QQssPageName ZWDVWQQrdZ1QQcmdZViewItem


sounds like the perfect turbo for a stock internalled engine... all the ones I've came across so far seem to be a bit on the smaller size, so power wise, they're not going to support much more than 250whp or so, but for a stock internaled car, I think it'd be awesome.

[saxman]

i'll need to do some more reading.
There must be a reason these arent more widely used.
I'm not sure why they're not more commonly used on the aftermarket market, but it seems they're pretty common on the small displacement engines in europe. Apparently the next generation porsche 911 is going to be using them.

I think part of it is they're different, and the earlier models were plauged with some issues.(the chrysler motors using them apparently had head gasket issues due to overboosting problems, the aerodyne units had oiling issues... but then self contained oiling systems on a turbo have that potential)
Also, it seems the cars that came with them stock eventually had issues with the vanes sticking closed from carbon build up, but apparently there are modifications that can be done that cause the vanes to open full whenever you release the throttle, and leave it open for low load driving. This prevents the vanes from sticking as easily, and also allows for better gas milage off boost, etc.

All in all, I'm seriously starting to think about ditching my t3 for one.

I love the fact that wastegates aren't needed. Suddenly 100% of the exhaust energy is going to the turbo instead of the 80% or so you get with a wastegate set up. Means more efficiency, lower iat's, less chance of detonation, etc. Can't go wrong there!

[poid]

yeh i looked into these a couple of years back...bit hazy now but it was issues with vane reliability that hasnt seen them used on high-horsepower applications and restricted to smaller/low boost turbo's.

Its a fascinated concept and surely companies like garrett are still trying to develop these things, as the advantage of quick spool and huge top end would give the manufacturer that brings a reliable model to market a big advantage.

[saxman]

seems like for a lower power set up, there are a few options out there and that there is the manufacturer support. Maybe the problem with them right now is that they aren't made in a size that would properly support big power numbers with just one turbo and that a lot of people looking to add a turbo to their car don't want to be content with being limited to 250hp without changing turbos... but then, there are an awful lot of turbo hondas running t25's and such that would really benefit from a bigger top end.

Interestingly, I was reading something about the turbos making full boost at like 1500rpm... can you imagine never being out of boost unless you wanted to? good times!

[JasonGilholme]

apart from buying the turbo would you need a special sort of engine management unit?? So that you can control the ratios of the turbo?? Or can you control them manually via the turbo itself??

[ProECU]

I'm guessing the A/R is mechanically controlled, not electronically.

[saxman]

the a/r is controlled via a boost and a vacuum signal to what looks like a wastegate actuator. my understanding of it is that basically there's a set boost level at the controller, and as engine load increases, the boost slightly goes up, which opens the vanes more, increasing the a/r, balancing the boost, keeping it constant.

So basically, instead of a wastegate bypassing more and more gasses to keep boost constant, this just opens or closes this vanes, adjusting the a/r to keep boost constant.

to give an idea of how it mechanically works...

http://img147.imageshack.us/img147/5821/vwgarrett149pr.gif

[saxman]

well, I found myself a source for a few vnt25 turbos... waiting ona final price, but shouldn't be too bad, so I think I may pick one of these up and see what she can do.

[ProECU]

excellent illustration.

Keep us updated with its performance & your experiences with it

[terroristone]

i believe nissan were playing with the idea a few years ago, i think you can find them on some older 300zx's. they are hard to find, a bit like rocking horse shit.

[saxman]

you can get them off a lot of cars... hell, even honda offers a car with one... just a matter of finding the right one

[adza33]

are you guys basically saying that you can strap this type of turbo to your honda without needing any extra engine re-inforecements??? I know very little about this but yeah, what kind of KW boost u lookin at on a civic for example??

Adam

[saxman]

are you guys basically saying that you can strap this type of turbo to your honda without needing any extra engine re-inforecements??? I know very little about this but yeah, what kind of KW boost u lookin at on a civic for example??


this turbo isn't going to behave any different in that aspect than any other turbo set up. I'm going to be trying for about 220-230whp or so(170ish kw at the wheels) on a stock block d16z6. The block is capable of handling this, with a good tune. This doesn't mean that everyone can go out and run it without a problem, and doesn't mean that you should go out, strap a turbo on, and crank the boost up until you make 170kw.

[adza33]

hmmmmm food for thought....170KW at the wheels, it'd be great...i guess once it becomes more popular and more ppl do it, then the more problems we'll know about and how to go about them... Sounds awesome though, civic turbo... although it would be pointless doing it on mine cuz its only a SOHC VTEC, normally on these setups thay use the turbo's for the lower rpm and let VTEC take care of 5400 on.. Am i right?

Adam

[Mr_will]

hmmmmm food for thought....170KW at the wheels, it'd be great...i guess once it becomes more popular and more ppl do it, then the more problems we'll know about and how to go about them... Sounds awesome though, civic turbo... although it would be pointless doing it on mine cuz its only a SOHC VTEC, normally on these setups thay use the turbo's for the lower rpm and let VTEC take care of 5400 on.. Am i right?

Adam


kind of, from the point of view of drivability what youre saying would be right, just getting some more torque in the lower range would make the car more enjoyable to drive normally, however if youre wanting big power then turbo + vtec for teh win. thered be nothing wrong with having the peak efficiency of the turbo within the vtec range

[aStRooo]

anyone read Wheels magazine, there is a little info on the new turbochargers there. the new porsche runs them.

[saxman]

hmmmmm food for thought....170KW at the wheels, it'd be great...i guess once it becomes more popular and more ppl do it, then the more problems we'll know about and how to go about them... Sounds awesome though, civic turbo... although it would be pointless doing it on mine cuz its only a SOHC VTEC, normally on these setups thay use the turbo's for the lower rpm and let VTEC take care of 5400 on.. Am i right?

Adam
170kw at the wheels is more of a limit of what the stock block can take, not so much of somethign that only that turbo can do. there are plenty of other turbos that can make those power numbers as well... most can.


mine is a sohc vtec... it's a great motor, very capable.

turbos are used for making power. VTEC is nothing more than something that allows better air flow for the motor. To say somethign like most people use turbos for lower rpm and vtec for higher rpm really underestimates the power of the turbo and several overestimates the difference vtec makes. Don't really think of them in the same context like that, they're not. Think of vtec as nothing more than something that allows better air flow for the motor. Despite both having an impact on the air flow of the motor, they're pretty much unrelated and shouldn't really be thought of in the way you're thinking of them.