Opening chase scene...

[Rootsblower]

New here, but have been a MM fan for decades. Anyone ever realize the a blower or supercharger can not be turned off? It's a direct drive to the crankshaft with a gilmer belt....no blower ....no air...no move. I would even give it the benefit of a doubt for having a clutch of some sort, but the belt even stops moving when Max turns it off....gotta LOVE this movie though!!

[Foxtrot X-Ray]

(In Theory) There's a clutch setup at the Harmonic Balancer and an air-gate and secondary intake manifold and fuel injection system all hidden under the hood.

Another thing that tends to get skipped past is the "Sucks Nitro" comment from Barry in the MFP Garage.
Does the BoB run Nitromethane in MM1 and is converted to run Guzzolene in MM2RW?

[DetritusMaximus]

It was a fictional motor, you know. I don't recall Ford having a twin overhead cam V8 at that time. At least, not outside Indy.....
Besides, I think Toyota later developed an electronically controlled supercharger for the MR2.

[roadwarriormfp]

Not only was it fake (ie you couldn't turn it on/off) it was just an empty blower casing... we are talking about the movies

[LTDHO]

Welcome rootsblower

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Well, so much for naturally aspirated HP anyway.

[[email protected]]

It was a fictional motor, you know. I don't recall Ford having a twin overhead cam V8 at that time. At least, not outside Indy.....
Besides, I think Toyota later developed an electronically controlled supercharger for the MR2.

I believe the MR2 was turbo charged not super charged.

[DetritusMaximus]

Second gen MR2s were turbo.
From the wiki page on the MR2:

"In 1987 (1988 for the US market), Toyota introduced a supercharged engine for the MR2. Based on the same block and head, the 4A-GZE was equipped with a small Roots-type supercharger and a Denso intercooler. T-VIS was eliminated and the compression ratio was lowered to 8:1. It produced 145 horsepower (108 kW) and 140 pound-feet (190 N·m) and accelerated the small car from 0 to 100 km/h (0 to 62 mph) in 6.5 to 7.0s.[13][14] The supercharger was belt-driven but actuated by an electromagnetic clutch, so that it would not be driven except when needed, increasing fuel economy. Curb weight increased to as much as 2,494 pounds (1,131 kg) for supercharged models, due to the weight of the supercharger equipment and a new, stronger transmission.[3] A fuel selector switch was also added in some markets, to allow the car to run on regular unleaded if required to. In addition to the new engine, the MR2 SC was also equipped with stiffer springs, and received special "tear-drop" aluminium wheels. The engine cover had two raised vents (only one of which was functional) that visually distinguished it from the naturally aspirated models. It was also labeled "Supercharged" on the rear trunk and body mouldings behind both doors. This model was never offered in European or Australian markets, although some cars were privately imported."

I think it's pretty obvious that on a small displacement motor, using something akin to an a/c compressor clutch is feasible. I would expect it to be problematic (at the least) on large displacement motors, especially if you are trying to get significant boost levels. Plus, in the MR2 it is controlled by the ecu, not switch on the shift lever.

[MWFV8]

About the supercharger: I've often wondered...suddenly forcing that much boost at a high rpm...? Your motor would blow.

If the engine can handle the compression pressure during normal operation then switching the blower off and on shouldn't make any odds. It wouldn't be that much different to a turbo spooling as you come off and on the throttle.

Besides what purpose would it serve to not just have it running all the time like all blowers are set up? Engines do run more efficiently with forced induction which would be more helpful in a place where gas is scarce.

While power is a factor of efficiency, that doesn't mean the engine is necessarily more efficient throughout it's entire tractable range. With forced induction there's always a trade off somewhere, in the case of a blower it's the parasitic loss of turning a compressor when it's not generating pressure above atmospheric pressure. Besides, the critical thing here is the fuel setup, Max's BoB may simply have run very rich under boost, perhaps part of the intended setup or simply very out of tune in the wasteland.

[[email protected]]

You're probably right...I never thought of it that way...interesting. I guess he would be using that weinand supercharger as a turbo. Of course it'll run more rich...it's adding maybe 8 to 10 psi of boost...? That motor at say 10 to 20 psi compression is going to require such a hot spark that extremely hi octane fuel maybe even nitro as suggested in MM is what it would need to run efficiently.