Garage Storage Organization and Garage Cabinets

william · **How is a VNT "controlled"?**

I have been fishing around to determine how a VNT is controlled. I understand that the wastegate portion to control the boost level is the same as a standard turbo, but is the variable nozzle portion controlled by a computer, can it be controlled manually, or does it take care of itself? I am wondering if I can use a VNT (actually two VNT's) with a standalone engine management (such as MSII) and a manual boost controller. Thanks for any info...
william

**Will Martin** · 03-31-2007, 11:42 AM

William,

All aspects of the VNT is controlled by the computer (unless it's cool outside lol). You can controll the boost of a VNT, and actually use a G-valve or some sort of MBC to controll boost.

I've never used a standalone engine management system before, but I'm sure you can get it to work with on a VNT (twin VNT's would require a bit of fabrication but is possible), although there are cheaper options....and owning a TD is all about being cheap! lol

tkelly27 · 03-31-2007, 04:22 PM

http://www.thedodgegarage.com/turbo_vnt.html

AFIK there is no wastegate on a VNT. You can control the vanes using a MBC.

Twins on a 2.2/2.5 or twins on a ?

william · 03-31-2007, 09:05 PM

That link is perfect, thanks. The idea is for a TT 3rd gen 3.5 v6 going into my 74 cuda. Not sure if a couple t25s or maybe one t28 would be enough. Only looking for about 7-10 psi to support 350ish hp. I thought the VNT would help keep the torque up.

tkelly27 · 04-01-2007, 04:35 PM

Just a wild guess, pair of T25's should work, 1 T28 is going to be to small. You may also need to keep the option of an external gate for the turbo's open. Like the link says, when you are crusing around it's one thing, but when you have a big load on it, there could be problems.

Aren't there some diesel trucks that have VNT's? Those might be a better idea for a single. Just some ideas, a TT 'Cuda sounds like a cool project!

**Will Martin** · 04-01-2007, 07:06 PM

There are so many variations of the "OLD" VNT technology being used today as "NEW" tech. Audis, Mercedes, VW's, diesel trucks, etc use some sort of VNT/VGT. When I was pushing the limits of my S60 VNT, I was going to get a bigger one, but didn't feel like messing around with trying to control the boost.

IMHO, if you're using those on a 3.5l v6, you might want to have like a t28 for the low end and a slightly bigger on up top. I say this only because the t25's 'might' run way out of steam by then, although I've seen VW guys run them up to <gulp> 30psi and live to tell about it. lol In any case, if you put them on a 3.5 v6, you're gonna have some fun!

william · 04-05-2007, 09:31 AM

Thanks for the input guys.
I will have to look very closely at what the VNT's will support. I am still on the fence as to whether it will be a 3.5 or a 3.9, but with that displacement, it will be critical to get the correct turbo setup. I thought the VNT might give me an edge in the heavy car, keeping the available torque at a lower RPM. The 3.9 would be a lower static compression, and a less efficient design, so I would need to run significantly more boost, perhaps 10-14psi. The 3.5 might support the HP I need at a modest 6-8 psi, which means less work for the turbo.