Are there companies producing VATN Turbos? I hear Garrett has some turbo setups. Here is a link with a small amount of info: http://superstreetonline.com/techart...bo/index3.html
Another reference:
http://www.honeywell.com/sites/ts/tt...3115213640.htm

It would be interesting to see these turbos on a 4banger. It would love to see 600hp with almost no turbo lag.

 

I would like to hear about this as well. I watched about 10 minutes of Extreme 4x4 on Spike TV today & they had Gale Banks on explaining a turbo he designed with the help of Garrett.

It used an electronic device to change exhaust wheel in some manner to in his words, "Completely eliminate turbo lag on larger turbos". He explained it would spool up larger turbos significantly faster.....

I would love to hear more about this from the turbo experts......

 

LOL. I was watching the same episode and posted this question.

 

VNT turbos tend to not work very well with gasoline engines due to the much higher EGTs that the gassers produce over, say, a diesel engine (where you find 99% of the VNTs).

 

My dumb question is what causes the higher egt over diesel?

 

Ignition variables

 

Yep, plus diesels are somewhat more efficient that gas motors, which means more energy goes to doing work on the piston rather than making heat. Also, diesel fuel isn't nearly as explosive as gasoline and it burns more slowly as well (which is why diesels can't rev like a gas motor b/c the piston can literally out accelerate the flame front).

 

Me too and I was thinking the same thing I wish someone would make one for the Evo

 

VNT's described in good detail : http://www.thedodgegarage.com/turbo_vnt.html

 

No, at the same compression ratio a diesel is less efficient -- they make up for it by running 22:1. Combustion extends much later into the power stroke in a diesel, thus less of the available energy goes into useful work. In the simplest model gasoline engines are combustion at constant volume, diesels at constant pressure. You'll find all this stuff in any basic engine text.

In a diesel fuel is injected during combustion, there's isn't really a flame-front like in a gas engine. Combustion occurs at the surface of the fuel droplets.

Diesels aren't throttled, so at low load you have lots of air in the cylinder that's just along for the ride giving a high volume, low temperature exhaust. VNT helps extract more energy. VNT doesn't change anything about the turbine wheel, just the nozzle geometry. It's the nozzle that does all the magic of turning heat and pressure into momentum which drives the wheel. Turbines are literally rocket science.

Dave

 

Well diesels won't exactly be diesels at gasser compression ratios, so they are more efficient at doing what they do with the CRs they have. A lot of the highly turbocharged diesels of today have CRs of 18.1 and even slightly lower.

"Flame front" might have been an inappropriate word, but the actual process of burning is much slower and thus, the piston can outrun it.

 

Interesting reading.

 

this is correct, and diesels are also less efficient becuase they're not throttled as mentioned above, at low rpm or high rpm and high load (if you ever notice a diesel truck going up hill)... all it can do is push more fuel, it can't push more air so you get these puffs of black smoke which are basically puffs of unspent/unspendable fuel. this is also the reason that turbo charging a diesel engine is a natural route because since the damn thing can't get more than enough air and since you can always just mash more fuel, more air is just obviously better.

this i also agree with. because with such great compression is how diesels can sometimes get such good gas mileage. and since lots of diesel truck engines are hugemungous the torque is easily produced and you get lots of air in such a big cylinder.

however on the subject of vatns why wouldn't it be good on a gas powered engine, at least for the torque benefits that could be extracted at low rpms and with quick spool while all at the same time giving you plenty of tuning capabilities for high horsepower on the high end. higher egts... does this make the constricting motors and what not more difficult to make durable?

 

Hate to rain on your parade, but the new BMW M5 engine is not throttled. The valve timing and direct injection control engine power. I think it is called Super VANOS.

It's only a matter of time, til all gas engines will use diesel technology.

Mitsubishi has had GDI (gasoline direct injection) for almost a decade in asia. MIVEC, New ECU/Software, and GDI would elliminate the throttle butterly.

I would speculate the turbo would spool earlier with the GDI/MIVEC technology.

 

yes but see there is air control and fuel control. you don't see an m5 spitting out gasoline cuz you mashed the pedal up a hill. you certainly see that in a diesel truck... why? because there isn't even a fuel control... it's the pedal and if you press it more... it gives you more gas that's the only control... how is that technology? my ****in' bicycle uses something more complicated than that... my leg modulation.

oh yes and also the m5 is ignited... it's not diesel... that also makes a world of difference. and wait... you're wrong again... the m5 engines use individual throttle butterflies.... so yes there is air control. vanos merely is a type of variable cam timing and lift.

oh yeah and di or cdi or gdi is not diesel technology... cdi is a technology regarding fuel atomization using high pressure injectors so you can spray the fuel right into the cylinder and not against the head of the valve to pulverize the fuel. you want a fine mist of fuel so you have more surface area to combust, hence a more complete and clean combustion. this has nothing to do with diesel. although it is well applied in diesel engines. which i think is what the mercedes diesel cars use.