Stupid Idea (forced Induction)

[Tom]

Im bored at work looking at turbos and stuff, and i had a thought.

Is it possible to build a supercharger/turbocharger hybrid in one unit?

 

[Bryan]

nope

run differently IIRC

 

[MaLicE]

there are cars that run a turbocharger and a supercharger, there is a nissan micra that has it .... 1.3 and some stupid bhp as standard

 

[Tom]

But i mean one unit.

with the benifits of both "megacharger"

 

[BenR]

you could theoretically run a single compressor off a crank drive then swap over to a exhaust gas driven unit once the gas speed exceeds the speed the crank could drive the compressor. But youd need a centrifugal clutch which is REALLY light as you wont be able to spin it very fast otherwise, not to mention harmonic balance, then heat resistance.

More than feasable i guess.

 

[Tom]

Would it actually be worth it? Would there be a use for combining the two systems?

Clutch isnt a problem, borrow porsches PCCC clutch design.

Heat is a huge issue, as for balance im none the wiser

 

[ChavyBoy]

The only benefit I could see is no turbo lag at all and the ability to increase the boost pressure via a regulator, where as if it was just SCd you would have to mess with all the gearing to get a high boost pressure.

 

[morgan349]

BENR, what do you do for a living?

how do you know so much about engines?

 

[Tom]

So in theory its a good idea, in practice its going to catch fire/get stupidly hot.

No lag would be a good thing indeed, plus it wouldnt need to be that much bigger than a supercharger.

 

[BenR]

the ceramic clutch design doesnt solve any problems. What were trying to acheive is an auto switchover controlled by rpm, clamping pressure is not a main prority.

 

[ChavyBoy]

It would be a good idea but take this into account as well.

You can get around lag by having a smaller turbine but then you cant create as much boost pressure, lower boost pressure=lower power output. A bigger turbine would mean high boost pressure but big turbo lag.

 

[Tom]

Ben

Its extremely light (10 times as) compared to a "normal" clutch, thats why i suggested it.

 

[BenR]

yea, but a roots high boost supercharge is almost as big as the engine its slapped onto!

Michael.........erm, i dont know that much.

 

[KDF]

I dunno there would be too many downfalls, what about the fact the power loss by driving the supercharger part when the turbo is trying to do the work ? and vice versa.

I think any gains through no turbo lag would be offset by power drains to the engine.



BenR stop being modest, yes you do.

 

[Tom]

But that would dissapear after switchover to turbo mode.

Ben knows loads.

 

[BenR]

i know the benefits of the Porche ceramic clutch since i work for them. BUT, the design doesnt translate into the solution that we would need, the material might, but then again the material isnt that new, the use on a rd car IS new.

 

[Tom]

so what do you suggest?

(this is quite good i havent seen this sorta thing for a while)

 

[BenR]

Quote: Originally posted by _KDF on 25 November 2003


I dunno there would be too many downfalls, what about the fact the power loss by driving the supercharger part when the turbo is trying to do the work ? and vice versa.

I think any gains through no turbo lag would be offset by power drains to the engine.



BenR stop being modest, yes you do.

Hence the clutch to stop drive to the pully drive, both turbo and charger would use the same compressor wheel so taht would be driven all the time, you simply change the drive source.

Powerdrains are offset, those silly top fuel 6000+bhp dragsters, the blowers they use need rediculous amounts of power to run, and last thing i heard that was in teh region of 400bhp. still, whats that compared to the 6000bhp itll help make.

 

[BenR]

what would i suggest...lol........this is why i dont like forced induction cars, too much messing about hahaha.

Erm, a fecking fancy centrifugal clutch on the transfer shaft.

 

[KDF]

The intersting part would be finding out at which point the clutch would make the changeover.. what revs does a turbo start making more power than a supercharger, ofcourse that depends on the size of the turbine etc.

So, if you used the same compressor then that would solve problems with having to add seperate intercoolers.

 

[KDF]

Could you not use an electronic clutch ? controled by rpm ?

 

[BenR]

well, you would switch it over when your exhaust gas speed becomes high enough to drive the turbine faster than the gearing from the crank drive. Dependant on the engine matching, on a good setup that should be about 2500-3000rpm to run a higher flow compressor.

oh, and bang on with the single compressor solution

 

[Tom]

Its a crazy idea.

the other big problem is the exhaust manifold, it would need to have a bypass thats switchable and the change over wouldnt be very smooth would it?

 

[BenR]

You could run a electromagnetic clutch or similar, but thats just increasing size and complexity.

And you wouldnt HAVE to run a manifold that would divert the exhaust gas, have an electronically controlled wastegate .

 

[KDF]

I guess thats why its not been done, although im sure it could be done.. the more complex the more can go wrong.

 

[Tom]

IMHO it need to be as simple as it can be. What about the heat issue?

 

[BenR]

it gets HOT! lol

 

[KDF]

what about a belt drivin fan to cool it down.. no wait a minute thats what the supercharger is .. a giant fan... hmm



oil and water cooled ?

 

[BenR]

turbos already are.

 

[KDF]

cast the turbo into a heatsink style shape (maximise air surface) and duct the hot air out of the engine bay using a bonet scoop ?



aswell as oil and water cooled.

 

[Tom]

Not bad, who can build this for me?

i want one.

 

[Tim172]

For information from someones earlier post..

The turbo/supercharged micra was known as the March ST, 930cc and 140BHP as standard. They were import only and theres 1/2 examples in the UK. A guy on the Micra Sport Club has one...

http://www.micra.org.uk/features.php?action=1&uid=2http://www.micra.org.uk/features.php?action=1&uid=2

Although its pretty heavily modified by now, but the basic specs arent much different to the standard one.

I used to love my 1.2 Micra, but then I wouldnt go back to it

Tim