Can someone tell me the pros and cons of the two

That could fill a pretty fat book.

I can give you my own, personal "Cliff's Notes" version, but it will just skim the surface, I'm afraid. I know a LITTLE about both, because I currently own one of each, but to learn anything that will really help you understand the vagaries of both systems, you really need to read a book or two, on the subject. Several books, if you are going to base a personal decision on the information at hand.

To start with, both systems accomplish the exact same thing; they enhance the amount of air going into the engine's cylinders by forcing it in under pressure.

Air contains oxygen, which is what the engine uses to mix with fuel to ignite, and uses the resulting pressure to drive the pistons down, and the resulting torque that comes from this action is what moves the vehicle.

It follows that, the more air (oxygen-laden atmosphere,) you can get into a cylinder, the more fuel you can burn to make more power, because gasoline and air (oxygen) will only work together in certain ratios to make effective power. Generally, somewhere between 11:1 and 15:1 is deemed usable, but that figure changes as increases in cylinder pressure, boost, or anything over natural-atmospheric pressure, (14.7:1) requires an increase in the ratio of gasoline to air in order to forestall a phenomenon called "detonation." Detonation is an explosion instead of a coherent burning of the fuel, and can cause catastrophic damage to an engine in the twinkling of an eye and is to be avoided at all costs.

Both supercharging and turbocharging systems can fall victim to this unfortunate happening if the wrong conditions are present; too much ignition timing, too much compression of the charge, too much heat, too lean a mixture, not enough octane, a hot spot creating an opportunity for pre-ignition, and probably five or six more situations I left out.

The pertinent fact is, any increase in cylinder pressure that takes the mixture beyond what the octane can effectively handle, will make this devastating scenario possible, and it can happen before you realize your engine is in jeopardy.

BOTH turbos and all kinds of superchargers share this possibility, so just be aware that neither is immune...

The turbo gets its motivation from the exhaust your engine produces, and nowhere else.

That "captured" heat and pressure coming out of the cylinders, is directed to a scroll containing an impeller wheel of an appropriate size, which is on a shaft, the other end of which is situated a similar scroll and impeller "wheel." The exhaust is many times the volume of the needed intake charge, so it is possible to pressurize the intake charge by turning the compressor wheel a lot faster than it needs to turn just to "keep up" with the intake charge's speed. That is how a turbocharger creates boost... and its degree of pressure over atmospheric is controlled by a control device called a "waste gate," usually. That device "leaks" exhaust (or, re-routes it around the compressor wheel,) to the extent that the smaller amount of exhaust slows the compressor wheel to the extent that it won't spin any faster than is needed to make whatever amount of boost has been mandated.

Turbos are not "free horsepower." They create a lot of back pressure that hurts engine performance. I have read that these exhaust-driven superchargers utilize power that is otherwise wasted. No, they don't. They are able to overcome the detrimental aspects of the effects they have on engine performance by cramming enough extra intake charge in to make more extra power than they use... sometimes a LOT more. But, in no way is it "free."

Belt, or otherwise, mechanically-driven superchargers have several advantages over turbos, such as instant boost , if they are the positive-displacement variety, and, additionally. most are draw-through configuration, (as opposed to most turbo's which are blow-thru systems.) The advantage here is, a draw through fuel system is generally a lot easier to set up (and, tune,) than a blow thru system, because in a blow-thru system, the carb is asked to meter fuel under some conditions (pressurized,) that are totally foreign to its original design parameters. Fuel injection is a welcome addition to most blow thru systems, while a carb is usually a lot less problematic on a draw-thru setup.

NOT A:WAYS, but usually, I think.

Turbos heat up the intake charge to a lesser degree than positive displacement superchargers, I have heard on pretty good authority.

That's an advantage both in power-production, and dealing with the mixture control (not as demanding because it's cooler air.)

Now, the centrifugal superchargers are more like a turbo that just happens to be driven by a belt instead of exhaust heat/pressure.

Turbos generally spin faster; my Vortech S-1, T-trim, belt-driven supercharger has a manufacturer-mandated rpm limit of 50.000. while my Turbonetics exhaust-driven (and somewhat smaller,) unit routinely goes over 100,000 rpm.

Most OEM mauufacturers have been putting positive-displacement, belt-driven superchargers on their large, high-performance engines recently (such as the Hellcat, ZR-1 Corvette and similiarly powered Cadillacs, and the Shelby 700+ HP engines, and I fail to understand any of that... I'd think turbos would be the way to go, but, what do I know??? Not much, apparently.

That having been said, it is this writer's opinion that turbocharging is VERY MARGINALLY, the more powerful of the two... but that opinion, and $1.25 MIGHT get you a cup of coffee... probably not...

Bill in Conway, Arkansas

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1964 Valiant 4-door sedan, 225 turbo/904

Porque los dos?


There's someone on these forums building a turbo/supercharged slant under slixer's gallery. It looks like a fun build.

Are you talking about the one going into a pickup?

Bill in central Arkansas

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1964 Valiant 4-door sedan, 225 turbo/904

This one:

O wow..........

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~Nic

Have a link for that

It's in the "boost" thread line, it's a few threads below this one, "my slow as molasses..." you'll see it.