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Old 12-15-2001, 09:23 PM   #1
bln scub
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2001 Legacy L Wagon
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Question SUPERCHARGED LEGACY'S

am in process of getting a supercharger installed in my my01 wagon. BUT the builder is interested in doing a kit or a production run.
the simplest version would use a vortech centrifical s/c. so could use a wrx intercooler, and installation would be less intrusive.
the other choice is a magnuson roots type with a custom intake manifold, but would have a lot more bottom end.
both apps have carb E.O. for those of us in the golden state.

boost would be in 4.5 to 5 psi range

surf2di4@yahoo.com if interested
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Old 12-16-2001, 12:02 AM   #2
GTBGUY
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bln scub - I hope your project goes well. I don't want to p*ss on anyone's parade, but there haven't been many good reviews in terms of engine longevity and overall reliability with S/C's for the Subarus in general. There's only one I can think of that's actually 1/2 decent (one that will be coming out by Suby Sports IIRC, which uses an autorotor S/C)

Please remember not to skimp out on fuel and electronics! Those will be crucial for your project.

The new manifold etc (a la CAPA S/C kit from Australia) would be an interesting idea to test, but a major hinderance in performance would become the restriction of the S/C's internals.

If you have a 5spd in your Legacy w/ the S/C, be forewarned, your tranny won't be liking that much torque on idle. Start saving up for a new tranny.
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Old 12-16-2001, 11:26 AM   #3
bln scub
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Default GTBGUY

TY
have talked to cobb enginneering they are also doing a s/c but they have no time table on completion. the company i am dealing with does custom apps for nissan mazda lexus and a few others. true this will be there first subaru.

as for the the things you mentioned
i have an auto which is a better choice for drag racing.
and i was looking at the liberty on capa's web page for idea's.
that is on reason am looking at the C/F hood with scoop.

personlly i want to go with forged pistons and new rods ( have talk to cobb about these pieces) so i can run nitros. but the builder want to run a completely stock app to get the CARB e. o.

have been reading about everyones tricks with t/c so am taking precautions with fule supply and electronics

also i have a backround in building high horse-power street bikes and super-bikes

but will listen to anyone with experience with subarus

ty gtb
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Old 12-16-2001, 02:46 PM   #4
GTBGUY
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bln scub - yup I know about Cobb trying to develop a S/C kit b/c iON and Cobb are working together on that project. It's purely a design study at this point in time.

I'm just wondering if the builder is "Swift Racing"? I think they're one of the few Co's that have a IS300 S/C or the GS300 S/C available.

In anycase, add a tranny oil cooler with the addition of the S/C, and DON'T cheap out on engine fluids (ie: synthetic oils, ATF etc)

On thing with the Vortech or Paxton S/C (Centrifugal S/C) you may have to either 1) relocate the battery, or 2)relocate your ABS pump to be able to mount the S/C properly in the plane of the engine pulleys.

One big reason why I'd choose to stay away from S/C's is if in the event a belt goes, you're screwed not just being w/o boost, but possibly your whole engine.
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Old 12-16-2001, 02:53 PM   #5
bln scub
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Default gtbguy

well its not swift who ever that is!
well actually we are looking at the passanger side down by the timing belt
area the vortech s/c is compact enough.
yes we are going with alllllll the normal hot rodding tricks!!!

but do you know what they do different to the auto in the turbo that is different than the N/A trans?????
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Old 12-17-2001, 11:33 AM   #6
omahasubaru
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Why re-invent the wheel






Existing kit from the UK can easily be modified to fit with an Intercooler. Already is designed for the Legacy. I'd love to put one intercooled or not on the Fiancee's car... would be quite the sleeper.

Quote:
If you have a SUBARU whether it be an IMPREZA, WRX, LEGACY, or FORESTER then say hello to Force One Superchargers Ltd, based here in Bridgwater. Force One Superchargers Ltd, in addition to Supercharging as their title suggests also specialise in the servicing, tuning and super-tuning all variants of the marque. As the leading Independent Subaru Specialist in the South West, having a history of forced induction behind them, an enthusiasm for the marque and 15 years experience developing Subaru's, you get a lot of knowledge behind your servicing. Nick, Graham and Alan have dedicated themselves to giving the Subaru boxer engine much more go with complete safety in mind. Normal servicing is undertaken, as well as engine, brake, or suspension upgrades.. These upgrades can be graded dependant upon the customer's needs. These upgrades are not just for owners requiring more speed, but also packages which will benefit the touring / caravan owner offering almost effortless towing while still retaining fuel economy.

Exhaust systems under development, please contact us for further details.
Thanks - Jon
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Old 12-17-2001, 01:36 PM   #7
monovich
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ANY reliable forced induction system with a CARB EO# will be a godsend.

So, because I am a layman, could someone explain in a NUTSHELL the main differences between Turbocharging and Supercharging? I have a basic knowledge of them, but is it true that a Supercharger makes more torque? How does a supercharger make boost?

How much is this proposed SC going to cost?

-S
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Old 12-17-2001, 02:37 PM   #8
gavin
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Quote:
Originally posted by monovich
So, because I am a layman, could someone explain in a NUTSHELL the main differences between Turbocharging and Supercharging? I have a basic knowledge of them, but is it true that a Supercharger makes more torque? How does a supercharger make boost?
The basic difference is that a turbo impeller is spun by a turbine that is driven by the engine exhaust. A S/C impeller is driven by a belt.

The two different designs have pro's and con's.

A turbo is generally a better option, for a smaller engine, because it doesn't have a the parasitic power loss that comes with a S/C. You have a power loss/gain equation, with either system, nothing is free, but the loss is smaller, with a turbo. You'll generally run a larger boost, with a turbo, as well.

S/C's are usually a bit more reliable, over all, since they have fewer moving parts, and don't generate the heat of a turbo. And, the power is immediate - no 'turbo lag' - since boost isn't dependent on the turbine spinning up.
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Old 12-17-2001, 02:59 PM   #9
Patrick Olsen
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First, take a look here: http://www.howstuffworks.com/question122.htm

There are two basic types of superchargers, centrifugal and positive displacement/screw type. Popular centrifugal blowers include Procharger, Vortech, and Paxton (if, by chance, you pick up a Mustang magazine of any sort you'll see those names all over the place). Roots, Eaton, and Lysholm are different types of positive displacement blowers (the Ford F-150 Lightning uses an Eaton I believe, the Mazda Millenia S uses a Lysholm blower, I think Mercedes uses either Roots or Eaton blowers on the various AMG products).

As they said on Howstuffworks.com, the big difference between a supercharger and a turbocharger is how they're driven. A turbo uses exhaust gases to drive a turbine which is on a common shaft with a compressor which compresses the air. A supercharger uses (usually) a belt drive to spin the compressor. Centrifugal superchargers look very much like the compressor side of a turbo, because it's essentially the same thing. Here's a view of the blower I had on my Mustang:

You can see the air intake comes in through the black hose at the back of the blower. The big, round section of the blower is where the compressor is - this picture doesn't show it very well, but the shape is just like a turbo, only bigger. Between the compressor and the drive pulley is the gear train, which steps up the speed about 3.5:1 (combined with the pulley ratios on the belt, the total step up is about 10:1 I think).

A centrifugal supercharger builds up boost relative to RPM. So, my Mustang kit was a 9# kit, which meant it was rated at 9# @ 6000rpm. It didn't actually show positive boost pressure until around 3000rpm I guess (never really paid much attention to that), but it is always working because it's always being driven by the belt. If I ran the car without the belt there was a noticeable loss of torque and power, even just off idle.

A positive displacement supercharger uses intermeshing lobes or screws to compress the air. Full boost comes on pretty much instantly, under 2000rpm in Mustang applications, and as long as the blower is sized correctly you hold full boost to redline. So there's no gradually increasing boost pressure as you would see with a centrifugal blower. Great for low end torque, but often they peter out on the top end.

The big "disadvantage" of superchargers that turbo proponents like to point out is that a supercharger places a drag on the engine because it steals power from the crank to drive the blower. Obviously that is true, but based on my personal experience the adverse effect of that drag is grossly exaggerated by the turbo crowd. Even at low RPMs, the benefit of the forced induction out-weighed any drag that the blower may have been placing on the engine.

Quote:
but there haven't been many good reviews in terms of engine longevity and overall reliability with S/C's for the Subarus in general.
This is another type of comment I often see from turbo proponents. Another one is that "Subarus work better with turbos, they aren't designed for superchargers," or words to that effect. Boost is boost, it doesn't matter how it's made, the engine doesn't give a damn! The engine sees more air, that's all it cares about. The exact same tuning tools you use to tune an aftermarket turbo kit would be used to tune an aftermarket supercharger kit. Depending on the type of supercharger used your timing and fuel maps/corrections will look different than those of a turbo'd car, but the ideas are all exactly the same.

Quote:
If you have a 5spd in your Legacy w/ the S/C, be forewarned, your tranny won't be liking that much torque on idle. Start saving up for a new tranny.
This will depend entirely on the type of blower used. A positive displacement blower will definitely put out some serious torque at the low end, and would not be very tranny friendly. A centrifugal blower would nicely complement a Subaru engine - the already-good low range would get a modest boost, gradually increasing towards the top end. The top end surge of the centrifugal blower would help overcome the lack of power the stock 2.5L has at high RPM.

Edit: Gavin added his post while I was typing...
Quote:
and don't generate the heat of a turbo.
Incorrect. Compressing air makes it hotter, regardless of whether you use a turbo or a supercharger. The late 80s/early 90s Thunderbird SC, which uses an Eaton blower, had a air-to-water intercooler sandwiched between the blower and the lower intake manifold. I think the Lightning has a similar setup. One of the limitations of the aftermarket positive displacement kits for 5.0L Mustangs is that there's no provisions for any sort of intercooling, so they have to be very well tuned to prevent detonation.

Quote:
And, the power is immediate - no 'turbo lag' - since boost isn't dependent on the turbine spinning up.
Again, this depends entirely on the type of supercharger used.

Pat Olsen
'97 Legacy 2.5GT sedan
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Old 12-17-2001, 03:58 PM   #10
gavin
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I didn't say it wasn't hot, just not as hot as a standard turbo. Everything that I said was intended as a generalization, the details of any system are going to be dependent on the system used.
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Old 12-17-2001, 07:59 PM   #11
bln scub
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Default thanks pat

the eaton s/c used in the cadillac escalade is an eaton design
they have a bypass valve that is patented that under part throttle operation reroutes the air coming out of the compresser section of the blower back to the inlet side of the blower so highway milage is the same as a non-s/c motor(ie no parisitic loss from the drive because no back pressure)
as confirmed by the EPA. and they have a factory warranty to boot.

so eaton s/c ARE reliable.

its a good thing i live close to VENTURA, CA since all 3 companies that make these are right here magnuson, vortech and paxton ( which is now part of vortech)

and GTBguy when is hoods going to be done
karl waiting to bln scub

and am not trying to reinvet the wheel am just trying to invent a CARB e.o. wheel

Last edited by bln scub; 12-23-2001 at 05:55 PM.
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