alexands

For the first time in several years I read a Hot Rod magazine the other day. I always thought of a supercharger as the big rectangle thing that sits on top of a dragster engine. Now, many of the supercharged hot rods use what looks like a belt-driven turbo charger like this one.

http://www.superchargersonline.com/p...r=RK-010910284

To a non-engineer like myself this looks like a far better turbo strategy as opposed to an exhaust driven turbo like ours. The reason I think this is because of less plumbing, lower under-hood temps, fewer parts to break, same pressure generation strategy (a standard turbo compressor wheel), and I would think the spool up time would be quicker.

Is my logic right? If so, has anyone thought of going this route on a 951?

Jfrahm

The downside is that you are not recovering any waste heat (energy) from the exhaust. Also the centrifugal superchargers (turbo style) are not as efficient at the low RPMs that belt driving them gets you. The

Here is a quick article you might find interesting:
http://www.superchargersonline.com/content.asp?ID=19

-Joel.

Charlotte944

By defination a turbocharger uses exhaust gas to turn the compressor, while a supercharger uses a mechaincal power take off, ie a belt and pulley.

With that said, there are two types of superchargers, namely Roots type blowers like those on a blown Hemi in a top fuel dragster, and centrifigual (sp?) blowers like the one in your link.

As for which is better, that argument has raged, and will rage on for years. However, you are correct about spool up or turbo lag simply because a supercharger is mechanically coupled to the engine, while a turbocharter is fluid coupled.

Under hood temps may be a different matter. Two similar engines, one supercharted and one turbo charged, should (One would think) generate the same amount of thermal energy (heat) for a given horsepower output. The only thing I can see that might make a turbo hotter would be radiation from the crossover plumbing.

As for converting a 951 over to a supercharger, I'm sure it could be done, but would the conversion be worth the cost? I'd wager you could rebuild a 951 power plant (rings, bearings, seals, etc), and upgrade the turbo, exhaust, fuel delivery, and engine management systems for a lot less and come away with a more powerful and more reliable car in the process.

J Chen

Not if it's the Rotrex centrifugal supercharger.
Very compact in dimension. About the size of
an alternator & very efficient.

Ski

Superchargers even though they gain you hp you're still pulling hp off of it to run it. Turbocharging is free in the view of what's running it.

RogueM3

Except they cant be upgraded...and run very little boost. They are small though...

IN terms of FI I think almost everyone realizes the Turbo is the father of them all....just overall the best.

The best type of supercharger is a positive displacement because of its power right at idle...no lag as found in a centrifugal (run off of the crank...so the crank needs to spin into higher rpms in order to spool up the supercharger)

hosrom_951

Bingo.......

sweanders

This has been covered many times and the conclusion is that you need to run higher boost on a supercharged engine to achieve the power of a turbocharged engine.

RogueM3

Yes..due to losses. Also, the power made by a Centri Supercharger is made at high rpms....its not really noticeable near redline.

944J

J chen, where is that 450 whp whipple charged 944?

J Chen

It's a 400 hp 944s2 . Opcon Autorotor installed one with
Laminova air to water intercooler. Search their website.
You may be able to find it.

J Chen

Ski,
I don't totally agree with you. Theres no such thing
as free lunch. Turbos consume power too in the form
of back pressure.

hosrom_951

Back-pressure is one of the many say...."disadvantages" of turbochargers so to speak

In terms of source or energy, the turbocharger is free (exhaust as we all know) but the super charger is belt drivenm thus needs energy (hp) to produce hp.

Which we know of this

Generally speaking!!!!!

J Chen

But still theres hp being loss Hosrum

J Chen

RougeM3,
I would advice you to research more about the Rotrex
supercharger. It's unlike any other centri-chargers
out there & it does not only run at low boost as you
suggested & they can be upgraded as well.