What is the difference between a blower and a supercharger? How do they differ from turbo chargers? What are aftercoolers, intercoolers?

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A blower is a supercharger. I'm not sure if anyone calls turbos blowers or not, but I've never heard the term used to mean turbocharger.

 

Blowers and superchargers are the same thing. They are belt driven to force more air into the engine.

A turbo spins from your exhaust gases, with then forces more air into the engine.

Because you are compressing the air, it heats up, so some people use an aftercooler to cool the air down... like a radiator for air. Intercoolers and aftercoolers are the same thing.

 

actualy jeevs could probably do a better job at explaining this. not that people here are stupid, its just there is ALOT to explain if u want details, and we're lazy.

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series Muffler added to Unkown CatBack, Ported Intake

http://www.geocities.com/david_angel_16

 

I thought that 'intercoolers' ran the air through a cooler/radiator before the air entered the charger (be it turbo or super) and after coolers ran the air through the cooler 'after' the turbo/supercharger, then to the carb/TB? I've seen both set-ups.

If this is not correct, then I guess I thought wrong.

AJ

 

L98,

Actually, a "turbo" is also a supercharger, by definition. A supercharger is any device that forces induction rather than relying on ambient air pressure to charge a cylinder with the fuel/air mixture.

A "blower" is typically a positive displacement supercharger, with intermeshing rotors or gears that actually pump a relatively fixed amount of air per revolution. Thus the term "positive displacement". These have been used since the 1940's, first on GM/Detroit Diesel two-stroke diesel engines. Over the years, many of these have been retrofit to gasoline engines with very positive results. GM/Detroit, Weiand, Roots, and several other manufacturers offer these units, with most designs at least loosely based or sized on the GM standard, like 6-71 or 8-71 blowers. Most of these units operate at relatively low RPMs, not much above engine RPM. These units are generally belt driven and the drive ration determines the amount of boost pressure applied to the engine.

A "turbo" (technically a turbo-supercharger, or more commonly "turbocharger") is a variable displacement device that moves a varying volume of air depending on air temperature and density, static pressures, exhaust gas pressure, and other factors. These are usually driven by a turbine wheel (thus the name "turbo") in the exhaust stream, and the turbine is coupled to and drives a compressor section that pumps air into the intake. These were also originally used on the highways for diesel engines, but four-stroke diesels. Their first uses in gasoline engines were during WWII on American fighter planes. Ironically, the first aircraft to get a turbo-supercharger was the Lockheed P-38, which used two GM/Allison V-12 engines. A guy that used to live up the road a bit (Major Richard Bong) used to fly one of these pretty skillfully. He is personally responsible for putting more than 40 Mitsubishis on the floor of the Pacific (my hero). Turbos typically operate at much higher RPM than the engine, and speeds of 20,000 RPM are common. These require a dedicated oil supply to protect and cool the bearings from high RPM operation and from the extreme exhaust heat. Boost pressure is controlled by a wastegate valve that opens at a given pressure setting to prevent over-charging. Boost pressure usually lags engine RPM due to the time required to spin the turbine up from the exhaust gas pressure. This "turbo lag" is not evident in positive displacement types, but is usually just a momnentary lag.

There is another type of supercharger that is becoming more popular. It is belt driven like the positive blower, but uses a compressor similar to the turbocharger that displaces a variable amount of air. These commonly operate at a lower RPM than turbochargers, but don't always require separate lubrication. They are easier to install due to the lack of exhaust modifications required, but generally don't provide the same potential for boost pressure that one can expect from a turbocharger or positive blower. Boost control is still governed by a wastegate in moderate power applications, like street vehicles. Several companies offer these units, such as Paxton, ATI Procharger, and others. There are even a couple of companies offering electric motor drive blowers. I really have to laugh at that one, though. I just keep remembering the "leaf blower" incident of 1999 - not a pretty situation.

Oddly enough, even though GM implemented both the blower and turbocharger concept well before anyone else, they never offered in in a street vehicle until after other companies had marketed the scheme. They've generally made most of their power more reliably, with cubic inches instead of boost. Maybe that's why there are still so many older Chevys around, and very few turbocharged Mitsubishi engines still running after 200,000 miles. Most smaller turbo engines that are still running have poor reliability records by comparison, since the engines are constantly straining to make the same power as a larger, naturally aspirated engine. They use the same amount of fuel to make the same power output, so I guess I never understood the real advantage. The beautiful part is, if you want to really stomp the crap out of one of those weenie little L-4 of V-6 turbos, all you have to do is add some boost, too - just to level the playing field.

There is a bit more discussion on the topic in the Power Adder forum, too.

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Later,
Vader
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If you want to beat the World, it might reach up and pull you down...
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www.howstuffworks.com

'nuff said!

 

Never mind

[This message has been edited by 8Mike9 (edited December 05, 2001).]

 

Now you see why I didn't ask Jeeves!

Vader's insight is much better... as well as everyone else's.

I asked becuase there is such misconception on what these things are... most people act like they know, but really don't. Now I know...

 

Yeah, I knew someone was going to bring it up. I was told that intercoolers went between a blower/turbo setup, and an aftercooler went after any of the forced induction. But my dad's a boat guy, so what does he know Although his LCVP has a 6-71 in it...

 

we can always count on vader !!

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series Muffler added to Unkown CatBack, Ported Intake

http://www.geocities.com/david_angel_16