V.G. turbos and why we don't use them?

[shauno]

I have a small but intersting question that came to mind just recently. I don't know why just now, considering I've been doing diesel engine reseach and testing for three years. It involves the use of variable geometry turbos.

If you're not familiar, they have a compressor that changes position depending on load, speed, and rpm. It has an electric motor connected to an arm that actuates the movement of the compressor wheel (similar to a wastegate), by doing so it creates a smaller hosing to wheel area or a larger passage for air to travel through, generating more boost or less turbo speed.

Thinking now, it could be used to compensate for lag and top end losses.

I also have a counter thought (not being an engineer here) that it could not be used because diesel engines run at lower rpms.

My experience with sitting in front of window watching an engine run for hours on end tells me that these could work with the proper controls. I've seen them spool up to 95k rpm for long periods of time.

Has anyone had any experience with these or am I a loner?

As far as I know, they are being used on the cummins diesels, probably more but I only did cummins work. I have witnessed homemade controls capable of controlling these units very well with the right fuel and ignition controls for long periods.

I am ranting here but I thought I would share my thoughts.

Any replies would be cool.

Later.

[evildky]

I think that new cheby and ford diesels come with them, the dodge has not yet joined the ranks, Banks Power, uses them for all their big power diesle mods, guessing bullydog either is or will be, I have no idea how well they'd work on an gas engine, pretty neat stuff

[spork]

A few of the turbo dodge cars in the 80's /early 90's used a variable geometry turbo... I can't remember exactly what years they were.

[george.bryant]

theres heaps of ppl here using vg turbos on ls and rbs they run awesomely.