DivineE

These ideas have been discussed recently at length here in the UK and it was eventually decided that a 3.0 16v with a large BB turbo was the best combination. You can get decent boost from around 2500 to the red line. It seemed that the real world benefits to building a heavier, more expensive, more complicated dual charger car outweighed any gains so we took the easy option.

That said if you wanted to build one as a technical exercise I would be very interested to follow, I think re-locating the alternator to where the air con compressor sits and sitting a charger where the alternator used to be was the only real option we thought of.

gt37vgt

well yeh if there is no budget sure 16v 3.0 bb huffer

JDS968

I've got another idea, but it would involve some pretty crazy fab-work...

Short version (gotta leave in a few minutes, sorry)...convert a large turbocharger into a part-time supercharger. You put a large pulley on the crankshaft, running a belt to a very small pulley on a shaft connected to the impellor wheel (essentially extending the shaft connecting the impeller and turbine wheels to a much greater length, sticking out the front end of the turbo). The small pulley on the turbo has an electromagnetic clutch, like an air conditioning compressor. The clutch is wired to respond to the tachometer signal so that it disconnects at whichever RPM you choose (say, 3000 RPM). That way, under 3000 RPM, the crankshaft is forcing the turbo to spin, much like a centrifugal supercharger. Above the 3000 RPM, the pulley on the turbocharger disconnects and spins freely, reducing parasitic drain to almost nothing, and the turbocharger spins under "free" exhaust power.

There's one unknown factor here...unlike a centrifugal supercharger, the turbo is still connected to the exhaust piping while it's being belt driven. That means the crankshaft is pulling the belt, which is spinning the entire shaft, both the impeller AND the turbine wheels. Because the turbine is now being mechanically driven, it theoretically will cease to be a turbine and act as a compressor, pulling vacuum on the exhaust manifold. I've never heard of a 4-stroke engine operating with vacuum on the exhaust ports, so I have no idea what this would do, if anything. Maybe it would be good, help clear exhaust gases better?

Chris White

So - when does your kid go to college?!!

Willard Bridgham 3

If what you're looking to do is to increase the range/decrease the lag of the turbo, sequential turbos will do the same thing if properly sized.

Turbos don't require belts and all that other stuff.....less space.

beebone

Here u go, thats what VW does on Golf GT, the ele. mag. clutch control by ECU and disengage on rpm that barely turbo kick in.

beebone

Yes, twin seq turbo that Jap cars use.
Or simple install a V8 engine.

944obscene

Actually, blowers (being the old style roots superchargers) make less power than turbochargers, mostly based on application, and the fact that they are incredibly inefficient in adiabatic comparison. While a "Blower" supercharger is at about 60% efficiency, the turbo is somewhere over 80%. Looking at heat production, the supercharger is turning a lot of that air into desert heat while the turbo isn't. Then looking at the application side, most people don't take the time or money to install some sort of after-cooler or intercooler system on a supercharged car so they're running on HOT boost.

As far as parasitic loss, a more modern supercharger blows the older designs out of the water. When looking at a Twinscrew, the parasitic loss is incredibly close. And turbo's don't give free power either. Most turbochargers on factory cars take 10-15 hp from the power that they're helping the motor create. Most people just don't think about it, because A: it's not something that's been mentioned often, and B: Where do you readily measure power-loss with a turbo? Well sir, that would be in the exhaust and intake strokes, with internal pumping losses, rather than mechanical belt-drive loss.

Twinscrew superchargers are so close to turbochargers in overall efficiency, that running one would nearly negate the need for a turbo. The only exception being top-end numbers. If you wanted INSANE whp, then you'd want a turbo, but if you're realistic and have the money, there is tons of reasons to go with a twinscrew.

DivineE

Hmmm perhaps you misunderstood my reply. Do you feel that a twin charged car would be faster, more usable?

toddk911

Or just relocate the turbo to the exhaust side and run twin sequential turbos.

toddk911

opps! didn't see your post before posting mine.

Agree 100% with twin seq. Small turbo that spools super quick by 2K and runs to 4K or so, and then a bigger top end turbo that will come into full boost (20psi) right at the time the smaller one is running out of steam and runs to redline+

lee101315

The mercedes C class charger looks like its shorter than the Jag

86 951 Driver

Twin turbos would be the way to go most likely. It seems that everyone gets rid of that kind of setup when they want to make big power on RX's and supras though.

gt37vgt

nah i dont think a twin charged thing would be more usable than a 16v 3.0 BB i think a medium sized BB Turbo but on a un opened 3.0 and running e85 or simlar high octane fuel may end up being a relitivly cheap thing ..
Obsene check the maps strait roots yes %50 or some crap twin screw around%73 very close to Max efficiency of most turbos and the map's are much better so your genraly able to plot a demand curve with a higher average efficiency using a twin screw.

DDP

Install an LS1 and save yourself a lot of headache and money. I'm all about new ideas and design, however, some ideas just get silly.