VGT or VNT???

[Niebs]

Just curious if anybody here has tried playing around with VGT or VNT set up on their rotary. I know they are mainly for diesels, but I think they would be perfect for a gasser as well. If they can take the heat that is.

[RETed]

Last time I checked - this was YEARS ago - the Garrett VNT's only came in (small) T3 sizes.
You'd need two to handle a 13B.
Not worth the headache...

Only real plus is the fact that you don't need a wastegate.


-Ted

[Raksj04]

what is VNT and VGT??

[Niebs]

Yeah. I know Garrett has some. Most of them are for diesels tho. I heard something that they can't take the heat from gasoline engines very well. I believe they are trying to work out the kinks but i wasn't sure if anybody has found one out there or made a small diesel work for them.
Ive been toying with the idea of setting one or two up on a gasser and see if there's any good gains or not.

VGT-Variable Geometry Turbo, VNT- Variable Nozzel Turbo. In simple form, allow the area around the turbine to increase or decrease in volume. When the turbine area decreases, it spins the turbine fast. This allows you to be spool up and give good boost very quickly at lower RMPs and then at cruising speed/when little boost is needed the volume around the turbine increases. So that you do not over spin the turbo or overboost your engine.

[TitaniumTT]

Yeah. I know Garrett has some. Most of them are for diesels tho. I heard something that they can't take the heat from gasoline engines very well. I believe they are trying to work out the kinks but i wasn't sure if anybody has found one out there or made a small diesel work for them.
Ive been toying with the idea of setting one or two up on a gasser and see if there's any good gains or not.

You need to think very large diesel to use in a rotary application for both the exhaust flow and for the compressor map to make any useable hp.

The Garret VNT's don't last too well in the marine industry. I've seen them fail after less than 100hrs. Clogged with soot. In fact, Volvo Penta (who does some cool things with their diesels including twin charging) suggests in their regular maintenance to lube all the external components to prolong the life of the VNT operation... which is a simple actuator run off the vacuum pump.

VGT-Variable Geometry Turbo, VNT- Variable Nozzel Turbo. In simple form, allow the area around the turbine to increase or decrease in volume. When the turbine area decreases, it spins the turbine fast. This allows you to be spool up and give good boost very quickly at lower RMPs and then at cruising speed/when little boost is needed the volume around the turbine increases. So that you do not over spin the turbo or overboost your engine.

More importantly it decreases the EMAP which leads to a happier more efficient engine.

[Raksj04]

thank you. I figure it was variable *something* Turbo

[Niebs]

Thats true, I guess you would need to use a fairly larger VNT for a rotary. I just thought it would be an interesting thing to play around with. and see if there are any good gains from it or just a waste of time and money.