We are straying WAY WAY off topic here, but after my great successes with twincharging, I spent about eighteen months trying to get a variable vane turbo to work, it was a miserable most unrewarding experience I eventually gave up on.
I am talking here from the perspective of someone with personal practical experience with VNT turbos.
There are two really huge problems to overcome to get even average results.
First, all the exhaust has to pass through the turbine, there being no wastegate that normally bypasses around half the exhaust volume. Sure, you can limit the boost by tilting the vanes, but the turbine has to be sized much larger than a conventional turbo turbine if back pressure is not going to completely kill top end power.
Porsche overcome this by fitting two electronically controlled wastegates.
The second problem is that, most people believe that to get an extremely low boost threshold all you need to do is close down the vanes forcing the exhaust through a very small aperture at very high velocity.
Try it and see what happens !
Close off the vanes and exhaust back pressure rises to extremely high values.
Stomping on the accelerator, at 1500 to 2000 rpm, I could see 80 psi+ exhaust back pressure, and the engine did not like that, even with 5-10 psi boost. So you need a very well developed and sophisticated control system to control the vanes, Porsche use the engine management system to do it.
If you do a lot of engine dyno testing you might be able to come up with a computer system that can control both the vanes and the wastegate to get good all around performance. Porsche seem to have managed it, but it is far more difficult to do than you might realize.
Garrett and HKS still market their ball bearing turbos as the preferred option for high performance gasoline engines, and Garrett sell the VNT turbo for high performance diesel engines.
If Garrett and HKS can't make a VNT turbo work better than a straight ball bearing turbo on a gasoline engine, do you think you can do what they have so far failed to do ?
Believe me, if it worked, Garrett would be selling VNT turbos for use on race cars !!!
VNT turbos have been around now for over thirty years on diesels, it is very mature technology, where are all the race winners and gasoline production cars fitted with VNT turbos ?
There have been a few attempts at production cars, but they have all been failures. Saab tried it and gave up. Even the genius of Honda engineering, with all their budget and resources could only make it work on their Formula one car, they gave up trying to get it to work on the original top of the range Honda Legend.
Look at the power figures they quote for their "variable wing turbo" compared to an equivalent n/a engine, they are pathetic.
It must have been a great loss of face for Honda engineering to finally admit defeat after all the effort they put into it.http://dwolsten.tripod.com/articles/jan89a.html
Forget about variable vane turbos for a Locost, unless you can do better at getting it to work than the engineers at Garrett, Honda, Saab, and HKS, and countless unknown hot rodders and drag racers that have also tried and failed to get it to work.
Even Corky Bell is struggling, and he was personally involved with the design team that came up with the Aerocharger in the first place.
I am just trying to save some of you some money and a mountain of grief.
VNT turbos have been the technology of the future for thirty years, but nobody but Porsche have been able to get it to work on a gasoline engine.
Now let's get back onto the topic of 4WD Locosts.