Supercharger Not Been Driven But Engine Works Fine

The air passages through the supercharger are pretty much wide open, even if it is stalled. Now you have a naturally aspirated engine, but with an extra dab of pressure drop in the inlet air flow, but not enough to make it choke or gasp much.

Is that the same as a turbo?

Of course not!

Supercharger is positively driven by a crankshaft, driven belt pulley arraignment. Pulley shown here on the left.

I've tried to paste a supercharger photo, but no luck. It won't let me.

I'll repost a picture.

A turbo uses exhaust gas to drive a turbine wheel that is directly connected to the driven, compressor wheel. Driven wheel on the left.

Sorry, drive wheel on the left.

The superchargered engines have the ability to draw air around the supercharger at low speeds. This is to aid starting, and low speed engine performance before boost builds.

lynlynch is right of course any restriction of exhaust gases cause a loss of power, but not as much of a loss as the supercharger, But at the moment i have no idea of how much power loss.

Lyn, Thanks, and GA. Stu.

Thanks your self.

Thanks for the sensible answers. The conclusion is that the impellor on this type of supercharger must be quite "loose fitting" - allowing plenty of air leakage past it. That would concur with the fairly mild boost that it gives when in operation. I am getting slightly better fuel consumption now, not because the supercharger isn't functioning (I hardly ever needed to floor the accelerator), but because there is less parasitic power. I think I'll leave the belt off.

The problem with a super charged engine (or turbo-charged) is that to accomodate the extra boost the compression ratio has to be reduced. This means that under non-boosted conditions you are running around with lower compression than you need and the result is an inefficient vehicle (belt connected or not).

With a turbo engine on-boost, due to the extra expansion of the exhaust gases, it is actually more efficient than a non-turbo engine but this is so rare (unless you are a truck) that is really does not happen often. How long can you keep your foot flat to the floor before you exceed the speed limit - a matter of seconds. Just go for a high compression standard engine

the turbo gives boost normally at speeds of just over 2.5000 rpm upwards in fact on some cars the boost is so noticeable when those revs are achieved one must ask the question that if the roads were icy the is a possibility that traction may be lost because of the quite sudden surge

I think if you were to read up on the design of that engine/supercharger, you will find that it was designed to run without the super charger in operation all the time. I beleive that on the end of the snout where the pully is, you will find that there is an electrically actuated clutch pully similar to the type used on air conditioning systems. The only difference is that this pully is actuated by engine demand.

That was how GM controlled parasitic losses and maintained fuel economy and eimissions standards that kept the EPA happy.

Low engine loads mean that the supercharged is not activated. High loads would activate the clutch but without the belt the engine management system will keep fuel, timing and such within proper specs.

The end product to you is an engine that has less than the rated power, which you don't particularly care about and since the super charger isn't operative, you could probably run regular fuel in it as well.

First off, honestly, if you can't tell if anything is amiss, do yourself a favor and buy an economy car. I have one of these regals, and granted it's no sports sedan (they tried) but missing 40 horses is enough to make any but the most frugal drivers want a change. The posts on how superchargers and turbos work is fairly accurate. However the previous about the computer isn't true. The mass airflow sensor measures exactly how much air is entering the system. The air intake temperature corrects for heat and the boost sensor corrects for extra psi. All told then the computer makes a correction and this is how the engine decides how much gas to allow into the cylinders. Additionally with standard tools and 4 hours of time you can have your own upgraded, working eaton m90. There are a lot of aftermarket companies for this car and engine and they provide better superchargers as replacements.