12V Electric Clutch for Paxton Supercharger

[mfg]

I've been thinking about trying to adapt a dual groove clutch assembly from a '70's style Chrysler air conditioning compressor to a spare Paxton Supercharger I have. The idea would be to have the option of shutting down the supercharger 'over the road' (say, driving to a distant auto show) The base of the electric clutch assembly woud have to bolt up to the front of the supercharger, and the shaft size would need to be the same. I looked at one of these twin cylinder a/c compressors recently, and it appeared that the clutch just may fit a Paxton Supercharger. Has anybody tried this? The savings in Supercharger wear and tear, and the reduced drag on the engine would be benificial I think. And the supercharger could be engaged via a toggle switch 'on demand'. Does this idea have any merit?

[PackardV8]

Some of the direct-drive superchargers have been able to use an electric clutch.

The problem with the Paxton is the electric clutch would be engaging a 5:1 ball drive. Say your engine is turning 3,000 RPMs on the highway and the switch is flipped. The ball drive has to instantly spin the impeller up to 15,000 RPMs. That may not be good science.

jack vines

[mfg]

Yes, that makes good sense. Personally, I'd probably bring the engine down to idle speed before engaging the electro-magnetic clutch. I don't think there would be an additional torque issue for the clutch spinning a Paxton supercharger as compared to a double piston, older style, A/C pump....Do You?

[mfg]

This idea still intrigues me, however no, I haven't tried it!

I think it would be best to have the engine shut off completely before energizing "supercharger clutch"........but it could be de-energized at any engine speed. (I would think)

[Kodjo]

Why do you want a clutch? The supercahrger should spin all the time not?

[Leo B]

Air-Fuel Ratio? Would that be a problem? Is the adjusting same with Supercharger and without? I think not.
I'm quite sure that AFR is adjusted high (rich but correct to charger) when you use Charger and shutting down the charger you will have too rich adjusting. If you adjust AFR optimal without charger and using charger again you will have dangerous lean mixture.

Edited November 17, 2021 by Leo B

[mfg]

On 11/16/2021 at 6:27 AM, Kodjo said:

Why do you want a clutch? The supercahrger should spin all the time not?

The idea would be to extend the life of the Paxton supercharger drive element.....Unfortunately, these superchargers were not known for their longevity!

Also, they produce a parasitic drag on the engine when not producing 'boost'.....Ed

[mfg]

15 hours ago, Leo B said:

Air-Fuel Ratio? Would that be a problem? Is the adjusting same with Supercharger and without? I think not.
I'm quite sure that AFR is adjusted high (rich but correct to charger) when you use Charger and shutting down the charger you will have too rich adjusting. If you adjust AFR optimal without charger and using charger again you will have dangerous lean mixture.

Leo, I agree with you that the carburetor on R2 Avanti engines is calibrated to work with the supercharger...basically producing a richer fuel/air mixture at all times....so to run the car with the supercharger disconnected would definitely give less fuel mileage than, say, an unsupercharged R1 Avanti Carb would give.

In my opinion though, it would not be detrimental to the engine to occasionally operate the car with this (hypothetical) 12V electric clutch 'free wheeling', the supercharger not spinning, and the carb 'richer' than necessary....Ed

PS....Many R2 Avanti owners have driven their cars with the supercharger removed for various reasons, and have had no issues other than a 'thirsty' vehicle.....On a collector car which is not in everyday service, I don't believe 'thirst' is such a big deal!

[Leo B]

OK. If you want to save Paxton, then I suggest to keep it just a decoration. Adjust AFR to work correctly without charger. This way you will have clean engine (combustion chamber, pistons, valves, block etc) and better mileage and save engine and Paxton to future. In the photo you see how piston and valves looks when used without charger. One valve was leaking just because it was so dirty. (photos are from Golden Hawk piston and valve used with disconnected, broken supercharger).

My opinion is that if you drive with supercharger carburetor adjustment w/o charger the mixture is too rich and result is not acceptable. So... with or without Paxton. I recommend to speak with professional mechanic and ask about this idea.

Edited November 18, 2021 by Leo B

[mfg]

The issue of driving with an over-rich carb is a bit vexing, however, I believe pre WW2 Mercedes & Bentley supercharged automobiles had a 'mechanical' way of disconnecting the supercharger, controlled by a dashboard lever at the driver's discretion...........I wonder if at the same time the blower disconnect also somehow leaned out the carb??

By the way, great borescope photos!......Ed