super/turbo combination

[spitfireguy]

I'll admit in advance that I'm still relatively new to engines, and am not sure if everything I'm saying is right, but I just thought I'd throw it out here anyways.

I have been trying to think of ways to make an engine that made good performance throughtout the entire RPM range. I then saw a post about a clutched supercharger, and thought up this setup: having a clutched roots-type supercharger feed air into a modified engine at low rpms to (hopefully) give strong low end torque, then, at a certain rpm range, have some kind of electronic/mechanical relay disconnect the supercharger from the system, giving the now higher revving engine freedom from the parisitic power loss caused by the supercharger. At the same time, set one large or preferably two small turbos to kick in and feed the engine at higher rpms.

I'm thinking that by doing this, you would get the best of both worlds: the engine would have strong, immediate lowdown torque without the problems of turbo lag, and then in the higher rpms still recieve plenty of boost, without the powerloss associated with supercharging. And (possibly?) because the supercharger is flowing more air at the lower rpms, a more radical head could be used without compromising lower end torque? So that's my stupid idea, I'm not even sure where you would get a clutched supercharger, so I think I'll just wait for your guys opinions/laughter before I do any more research....

[spitfireguy]

Man isn't someone even going to flame me? I would like someones input on this idea...

[benchtest]

Okay...It's not a stupid idea. In theory you could make it work. Aside from the control aspects of the turbo(s), it's pretty simple and doesn't require a clutch on the supercharger. If the supercharger is not making boost (i.e. the air isn't flowing into the engine), it requres very little power to turn it. OEM systems often bypass the blower. Spooling up the turbos and engaging them and dis-engaging the blower smoothly, without spikes, is the real challenge. Good luck.

[KevinE326]

Originally Posted by spitfireguy

Man isn't someone even going to flame me? I would like someones input on this idea...

evolutionm.net in forums under turbo/drivetrain

we have a guy making a 2.3l with a supercharger to spool up the turbo and he is almost done with it!

[Oscuro]

Not a new concept, it has been down before by Lancia for their Rally car....I believe the one that used the turbo/supercharger system was the Stratos, and did precisely what you are looking at.

On a side note, You would use a single, large turbo after the supercharger. A larger turbo pushes more air and higher boost (usually) than a smaller turbo. The problem with the larger turbo, is that because of the increased mass of the impeller, it takes more gas pressure to spin it, which is where the turbo lag comes from. If you use two smaller turbos, then there is not point to the supercharger in the first place.
The second alternative which has been in use in many twin turbocharger systems, is a sequential turbo system where you have a smaller turbo that spools up first, followed by the larger turbo which kicks in at higher RPM's, minimising turbolag.
As well, apparently a properly set up twin-scroll turbocharger can minimise turbolag as well.

Just filling in the blanks and other options.