SuperCharged... And Turbocharged?

KnightWalace · Post by **KnightWalace** » Tue Aug 10, 2004 4:49 am

Is it physically possible to throw both on a car's engine. My friend and I were pitching this theory around. Just wanted to know lol.

Stefan · Post by **Stefan** » Tue Aug 10, 2004 6:03 am

Yes, Lancia did it in their group B rally cars in the 80's. I think Hot Rodders have tried it before then in the 60's/70's on slat flat racers....

Stef

KnightWalace · Post by **KnightWalace** » Tue Aug 10, 2004 6:36 am

why/how is this done. What are the benefits and the cons?

Post by **PrecisionBoost** » Tue Aug 10, 2004 11:15 pm

A turbocharger will not produce a resonable amount of boost until the turbo spools up (usually 2500rpm to 4000rpm) where as a supercharger will give you boost right from idle (since it's driven directly off the engine pulley system)

Turbochargers are more efficent because they use the "wasted" exhaust energy where as superchargers will pull 5-10 horsepower off your engine at all times. ( plus the turbochargers compressors are usually more efficent as well )

Some guys will use a supercharger and a big ass turbo that has lots of lag but makes a pile of boost at the top end.

The supercharger will put out a modest 8-10psi and cuts out just as the turbo spools up and starts producing boost.

So for example...

Supercharger

ON

800rpm to 3700 rpm

10psi
Supercharger

OFF

3700rpm to redline (electric clutch disengages)

Turbocharger

does not start producing boost until 3500rpm
Turbocharger

at 3700 rpm it's producing 10psi
Turbocharger

at 4000 rpm and above it's producing 20psi

This is just an example of how one might set up a supercharger/turbo hybrid engine.

Post by **PrecisionBoost** » Tue Aug 10, 2004 11:31 pm

Some hot rods will inject fuel into the exhaust header before the turbo to get rid of the lag problem.

The fuel hits the hot header and ignites.... which creates a pile more exhaust pressure and forces the turbine to spool up very quickly.

So even when your car is sitting at 800rpm your turbo will be running like your car is doing 4000rpm

This is only really used in dragracing because it's illegal on the street due to the emissions.

For the street you want to pre-spool the turbo by reving the engine at high RPM with the clutch in.... this gets the turbo running and producing boost before you launch.

So you might run the car at 5000RPM and just before you dump the clutch you let the engine drop to your target launch RPM ( 2700rpm for example).

If you dump the clutch at 5000RPM you will probably sit there spinning your tires.... so you need to find the ideal comprimise between launch power (high rpm) and traction (low rpm )

If you ask me the added boost at low RPM is not really an advantage considering the added weight of a supercharging system.

I guess it all depends on what your doing with your car.... for me I would allways try to keep the RPM above the "turbo lag" point to ensure that I'm allways making power.

If however you find some application where your driving in RPM levels well bellow say 4000RPM then a hybrid supercharger/turbocharger might pay off ( such as in a rally car where you are all over the place with RPM levels depending on terrain and course condition )

daewooluvr · Post by **daewooluvr** » Wed Aug 11, 2004 7:23 pm

just a slight correction... a supercharger system weighs nearly the same as a turbocharger system.

Post by **PrecisionBoost** » Wed Aug 11, 2004 11:16 pm

What I meant was that it's probably not much of an advantage if you consider the extra weight of adding a supercharger to an engine that allready has a turbocharger.

Say both your turbocharger and supercharger (and all the extra parts that come with them) both weigh 40lbs each (not sure of actual weight)

A turbo only system will weigh 40lbs where as a system with both a supercharger and a turbocharger will weigh 80 lbs

KnightWalace · Post by **KnightWalace** » Fri Aug 20, 2004 4:29 am

good point, my friend wants to do this to his Cavalier and i was like.... no.

genie47 · Post by **genie47** » Sat Aug 21, 2004 3:35 pm

There is a proper term for supercharging and turbocharging setups together on an engine. It is called Twincharging.

Yes Lancia has a twin charged car for the Group B rally. The legendary Delta S4. This beast can chew up modern Rexes with impunity. FYI, Group B was disbanded due to this monster as well. It killed 4 drivers/co-drivers one of them a champion rally driver.

Do a search on it. Italians sure know how to make a car.