Clutched Supercharger?

broncr

broncr

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Brain fart?

I know that one of the major "complaints" about SC is that you are ALWAYS running on boost & see poorer gas mileage ( also caused by the crank-drive nature of SC's). I was just wondering if an AC style clutch would allow you to have "flip switch" boost...?

I know it would also take a bit of bonnet modification - allowing for filtered/unboosted airflow... doesn't seem too difficult.

Switch off - econodrive.

Switch on - Yeehaw!

Brain Fart?
 
Mercedes Eaton superchargers use an electromagnetic clutch. It's a typically German idea, always finding complicated electric solutions to simple vacuum problems. A standard vacuum bypass valve is MUCH better though.
With a low tech, vacuum controled bypass valve, the SC rotors are always spinning at operating speed, but in freewheel mode, with practically zero parasitic drag. When engine vacuum closes the bypass valve, you get instant boost.
A clutched system doesn't spin the rotors until a MAP sensor (vacuum, hmmm...) tells the ECU to tell the clutch to engage. BAM! instant boost, and a big instant shock load as well. That's a good chunk of mass to start turning instantly, if you ask me.
I can really feel my A/C compressor kick on, and it's only 8 cid per rev (sanden 508). The Eaton that Mercedes uses, displaces 62 cid per rev. Most of the cheap superchargers around are M90s, which displace, you guessed it, 90 cid per rev.
The only reason I could see to use an electric clutch SC is with a draw through system, you can't run a bypass valve with a draw through system. My opinion on draw through systems with a roots type blower for everyday driving is... not positive. Draw through with a roots type blower is for full throttle blasts that last for 12 seconds or less.
So, to recap:
1 cheap Supercoupe Eaton M90, a vacuum bypass valve (GM M90s have the bypass cast into the SC body), a blow through carb, .040 head gasket on undecked block, headers, and you're in business.
Low tech all the way.
Rick(wrench)
 
Toyota 1GGZE blowers have a clutch and are very cheap to buy
You could rig it up to come on at any RPM or you could go MAD MAX style and have a switch on your steering wheel :D
 
broncr":261zzsxl said:
Brain fart?

I know that one of the major "complaints" about SC is that you are ALWAYS running on boost & see poorer gas mileage ( also caused by the crank-drive nature of SC's). I was just wondering if an AC style clutch would allow you to have "flip switch" boost...?

I know it would also take a bit of bonnet modification - allowing for filtered/unboosted airflow... doesn't seem too difficult.

Switch off - econodrive.

Switch on - Yeehaw!

Brain Fart?
Click to expand...


Already done on production Toyota Sprinters, Coronas, Levins, and aftermarket Holden Commodore CRS coversions.They runoff a a/c fan clutch, and boost hp by 25 to 35% depending on how much revs. Boost is low, but they work okay if mild hp is your goal. They are noisey as an aftermarket conversion, but a 35% boost is a 35% boost. Turn it off, and its back to normal.

All use either the SC12 orSC14 Ogura supercharger, a thing no bigger than the stock York air con unit found in older 200/250 Mustangs and Falcons. Up to 280 hp from the SC14, 250 hp tops with the SC12.

They are cheap, strong, and plenty of expertise exists for them.

Regards,

xtaxi
 
I'd like to go turbo, but the cost and complexity are a bit much for my needs. I drive the Bronco every day, and only need/want "boost" on the somewhat rare occaisions that I'm pulling a load. I'd be satisfied with ( & even prefer) keeping the boost in the low range.

Of course I'd have to play with it regularly, to ensure that everything remains in working order :roll: .

I've got a strong rebuild with (stock = low) compression. A CSC sounds like a decent, low cost, low tech solution (for me). Being a greenhorn at the boost table, I have to ask- would any of the above mentioned SC's be MORE appropriate for a 300 spinning 500 - 3500 RPM ?

StrangeRanger - as I said, I'd like to go turbo but, from what I've read, the cost & complexity sounds prohibitive for me. You might recall my self -inflicted limitations... I'm not looking for high RPM, high boost output. I USUALLY drive my "mule" like the middle aged conservative that I am. :lol:
 
To me a turbo seems LESS complex than a belt-driven SC w/clutch, etc. There's way more mounting hardware to design for the SC and way more things to relocate under the hood. All the fuel system, ignition and internal engine mods are identical whichever way you choose to add boost.

As for turbos being high-rev/high HP devices, it just isn't so. Turbos come in all sizes, and one size does not fit all applications. If you want to run at 6-7 PSI and mostly keep it under 4000 RPM, take a look at the turbo map for a T03 with Super 60 trim. It's almost perfect for a 300 used as a workhorse (and almost totally useless on a 300 built to boogie - for that you need a T04.)
 
Boost, with either a turbo or a supercharger, is more a function of throttle position and load than rpm. You aren't "on the boost" all the time or at all rpms. At light throttle openings, at any rpm, they will only make limited boost. It's not until you open the throttle and allow air into the supercharger or increase the amount of exhaust pressure that they begin to make boost.

For example, turbo or supercharger, at 60mph cruise, light throttle, will show very little on the pressure gauge. Tip into the gas, and both will start to build boost.

The biggest difference is that the supercharger will always put a mechanical load on the engine. That's the reason that Mercedes clutches the SC; not to disengage boost, but to remove the mechanical drag to increase mpg at light cruise.
 
If you're going with the roots-type, the GM/Eaton supers on the 3800 is probably the best option with the bypass valve built in, but this was covered above. no load on the engine during low-power cruise, the rotors are always spinning, and your boost time is limited only by how quickly the bypass valve can close. sounds like the best choice in a positive-displacement flavor.

of course, a properly sized turbo is something to behold...
ern
 
Thanks guys,

As ususal, a great response with some valuable info. Now I've got to do some legwork on a cost/"do-ability" comparison.

I'll do some checking on the above mentioned SC's, AND have a look at the T03/S60.

That picture of the Paxton SC - over on the Big Six forum, is what got me started. ... and I was doing so well at knocking off the honey-do projects :lol: .

Thanks for the input. I know most of you are more interested in REAL power.
 
FWIW for your application, you want to avoid Paxton, Vortec and any other belt-driven centrifugal. They make boost proportional to RPM. They will give you little or nothing at low revs which is where you want the help
 
StrangeRanger is correct. Stick to a roots type blower (with a bypass valve). With the right pulley ratio on an m90, you can have full boost from just a little off idle to danger. Don't be mislead by the relatively low pressure numbers advertised for these types of SCs. The 6-8 or so psi of boost is available throughout the entire rpm range, that's a 40-50% increase in airflow. A centrifugal like a paxton is useless at lower rpm, great for freeway on-ramps, but that's about it in the real world. For an offroad vehicle (i.e., a Bronco), crawling around at 1800 rpm in granny low, there is no better power adder than a roots type blower.
Rick(wrench)
 
http://www.superchargersonline.com/faq.asp

Question: Will a supercharger affect my fuel economy?

Answer: Fuel economy depends entirely on your driving habits and in some cases you may experience an increase in gas mileage. Under normal freeway driving, for example, the supercharger is not under boost but is increasing the efficiency of the engine by forcing air through restrictions like the air filter. But let's face it, you are not interested in a supercharger to enjoy "normal driving conditions." When you are demanding additional performance from your vehicle it will require additional fuel. If you are a "lead foot" your fuel economy will decline because your car is working harder. If you are simply using the supercharger for occasional acceleration and passing performance, then your fuel economy should remain about the same. Remember that the only way to make more horsepower is to burn more fuel per unit of time, and that's exactly what a supercharger is designed to do.

(EDIT: This quote is no endorsement of the site listed above.. or even the information provided there. Just something I happened upon in my various searches over the past month or so)
 
exactly what kind of carb would ou needfor this 300? I have been reading up on this forum and have started to gather many ideas. Im still not sure the type of carb for a offenhauser intake manifold. What plumbing would need to be done, like what to what and where to where?
 
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