Supercharging?

[Clifford Heath]

Anyone know of any available kits for supercharging
(belt driven or otherwise, but not exhaust-driven)
a Suby motor?

 

[Ian Brown]

Anyone know of any available kits for supercharging
(belt driven or otherwise, but not exhaust-driven)
a Suby motor?

Someone mentioned this a while ago...

http://www.forcedairtech.com/turbokits_wrx_stage5.html

Ian.

 

[chip]

Anyone know of any available kits for supercharging
(belt driven or otherwise, but not exhaust-driven)
a Suby motor?

I'm just curious; Why supercharge instead of the turbocharger? I mean I
could see it for a dragster. And the Subie has been reliably turbocharged
for years with predictable results.
Chip
'05 FXT

 

[Clifford Heath]

I'm just curious; Why supercharge instead of the turbocharger?

In a word: lag. Still get the intercooler lag of course,
but even that can be less than with turbo due to shorter
ducting. I don't know why real superchargers don't get
more play...

 

[Michael Pardee]

In a word: lag. Still get the intercooler lag of course,
but even that can be less than with turbo due to shorter
ducting. I don't know why real superchargers don't get
more play...

Efficiency. They are a constant drain on the engine, like an enormous A/C
compressor. Large ones can consume up to 100 hp, according to an article I
read about them back in the muscle car days. Turbochargers don't load the
engine (they use the velocity of the exhaust gases to operate, rather than
the pressure) so they don't increase the fuel consumption when not being
used the way a supercharger does. In addition, they can't boost at low rpms
the way a supercharger can so the engine suffers a lot less under a turbo.
Superchargers have a nasty reputation for putting holes in pistons if not
carefully set up.

Mike

 

[Clifford Heath]

Efficiency.... Turbochargers don't load the
engine (they use the velocity of the exhaust gases to operate, rather than
the pressure)

Exhaust back-pressure reduces engine efficiency too.
Turbochargers don't load the engine *as much* at low
RPMs, which is why they suffer lag.

There's no such thing as a free lunch. I'd rather have
the torque on tap whan I ask for it.

 

[Michael Pardee]

Exhaust back-pressure reduces engine efficiency too.
Turbochargers don't load the engine *as much* at low
RPMs, which is why they suffer lag.

There's no such thing as a free lunch. I'd rather have
the torque on tap whan I ask for it.

The choice is yours. Most people don't want the serious hit on the fuel
economy when not using the supercharger, and that is probably the main
reason they are more popular at drag strips than on city streets. I know I'd
never want that. Add in the high potential for engine destruction and it
just isn't foremost in everybody's wish list.

Turbos don't raise back pressure enough to worry about so few people worry
about it. The back pressure increase really only occurs while the turbo is
spooling up - a second or two with every use.

Have you looked into nitrous? It is an "all or nothing" increase, unlike the
continuum of power with a blower, and can't be used too long at a time, but
it has a number of other advantages (like inherent detonation resistance)
that make it attractive if you want a large, lagless power increase.

Mike

 

[Theodrake]

The choice is yours. Most people don't want the serious hit on the fuel
economy when not using the supercharger, and that is probably the main
reason they are more popular at drag strips than on city streets. I know I'd
never want that. Add in the high potential for engine destruction and it
just isn't foremost in everybody's wish list.

I must admit I'm not a auto techie, but I do remember from the Mad Max
movie that the character had a switch that would disconnect the
supercharger to save fuel. Is there such a thing? Or was this just done
for the movie?

 

[Ragnar]

I must admit I'm not a auto techie, but I do remember from the Mad Max
movie that the character had a switch that would disconnect the
supercharger to save fuel.

It wasn't to save fuel. It was there to add dramatic amounts of power.

Is there such a thing? Or was this just done
for the movie?

No, just for the movie. Although it would be cool if you could do it.

 

[Michael Pardee]

It wasn't to save fuel. It was there to add dramatic amounts of power.


No, just for the movie. Although it would be cool if you could do it.

I imagine the barrier is that the intake on a supercharged engine always
goes through the supercharger. Since all the automotive superchargers I've
heard about are positive displacement, shutting one down would block the
intake. Maybe if there were a bypass with damper doors....

Mike

 

[Tom Reingold]

I can attest to efficiency of a turbo. I had a 1986 Saab 900 turbo. My
mileage varied very widely, depending on how hard I drove. Using a light
right foot increased my efficiency greatly. When I wanted power, I just
pressed down and paid the price for the fuel.

 

[Michael Pardee]

I can attest to efficiency of a turbo. I had a 1986 Saab 900 turbo. My
mileage varied very widely, depending on how hard I drove. Using a light
right foot increased my efficiency greatly. When I wanted power, I just
pressed down and paid the price for the fuel.

Yes - I drive a 1985 Volvo turbo wagon. I can appreciate Clifford's concern
about lag - coming off the line here at 7000 ft I wish I could do the Fred
Flintstone thing, but once the turbo gets its mojo working it has plenty of
power. Around town it gets about 20 mpg, same as the non-turbo version
usually does.

Mike

 

[y_p_w]

I must admit I'm not a auto techie, but I do remember from the Mad Max
movie that the character had a switch that would disconnect the
supercharger to save fuel. Is there such a thing? Or was this just done
for the movie?

Aren't most modern superchargers controlled (electronically or
from intake vacuum) by a clutch? Which presents its own set of
potential problems of course.

 

[chip]

Yes - I drive a 1985 Volvo turbo wagon. I can appreciate Clifford's
concern about lag - coming off the line here at 7000 ft I wish I could do
the Fred Flintstone thing, but once the turbo gets its mojo working it has
plenty of power. Around town it gets about 20 mpg, same as the non-turbo
version usually does.

Mike

My '04 STi had very little to no turbo lag. So the issue is pretty much
moot with the newer Subaru's. I notice very little turbo lag with my FXT.
But, my older '96 Eagle Talon Turbo was wait, wait, wait,then wheee! The
boost would come on like a freight train.

 

[Ian Brown]

My '04 STi had very little to no turbo lag. So the issue is pretty much
moot with the newer Subaru's. I notice very little turbo lag with my FXT.
But, my older '96 Eagle Talon Turbo was wait, wait, wait,then wheee! The
boost would come on like a freight train.

My '04 FXT AT has a lot of turbo lag, the one I test drove was
exactly the same, but then at that point the UK was only getting
the 2 litre turbo, and I couldn't wait for a new car. now you can
get the 2.5 turbo here. Mine is very much a case of
"wait, wait, wait, then wheee! The boost comes on like a freight train."

Ian.

 

[nothermark]

It wasn't to save fuel. It was there to add dramatic amounts of power.


No, just for the movie. Although it would be cool if you could do it.

Nope, it is there for some superchargers. Basiclly the same type of
electric clutch as is used for air conditioning. There is more than
one way to supercharge and engine. The roots type used on dragsters
is taken from heavy diesel engines that are always on. There were
other versions that worked through the carb or has bypass gates. I
don't know what is available now but Google does. ;-)

 

[chip]

My '04 FXT AT has a lot of turbo lag, the one I test drove was
exactly the same, but then at that point the UK was only getting
the 2 litre turbo, and I couldn't wait for a new car. now you can
get the 2.5 turbo here. Mine is very much a case of
"wait, wait, wait, then wheee! The boost comes on like a freight train."

Ian.

We get the 2.5L here. And there is no turbo lag issue. You would be hard
pressed to even know it was turbocharged. Other than it has lots of power
to spare. Great sleeper. No one expects that kind of speed out of the
Forrester.

 

[Michael Pardee]

We get the 2.5L here. And there is no turbo lag issue. You would be hard
pressed to even know it was turbocharged. Other than it has lots of power
to spare. Great sleeper. No one expects that kind of speed out of the
Forrester.

Is that a two stage turbo or a light pressure type? I hear either of those
have a lot less lag than the older single stage full pressure type (mine).

Mike

 

[k. ote]

My '04 STi had very little to no turbo lag. So the issue is pretty much
moot with the newer Subaru's. I notice very little turbo lag with my FXT.
But, my older '96 Eagle Talon Turbo was wait, wait, wait,then wheee! The
boost would come on like a freight train.

My '04 STi (Canadian Ed.) also has no turbo lag, but the turbo itself has a
much broader, more gradual power delivery band; i.e. it's capable of
supplying boost at much lower RPMs than the normal WRX. At what cost?
Endless supplies of gas and large volumes of air. You know our STis get
worse gas mileage than a 2001 Corvette, right? =]

 

[gpatmac]

Anyone know of any available kits for supercharging
(belt driven or otherwise, but not exhaust-driven)
a Suby motor?

There is a guy on the N. Amer. Subaru Impreza Owners' Club with the screenname of reddevil who has supercharged his legacy. Maybe you could shoot him a message with your questions.