[andre]

What are they. For one, I know that its less maintainance than turbo, but doesn't give as much power....please elaborate on the pros and cons.

 

[morepower2]

What are they. For one, I know that its less maintainance than turbo, but doesn't give as much power....please elaborate on the pros and cons.

They have much less efficent compressors, plus they have parasitic losses to turn the compressor by the crank.

The thing about them needing less maintanace than a turbo is not true either.

 

[andre]

OK...I heard that as long as you give the engine good maintainance i.e. oil changes, that you shouldn't have trouble with the superchargers.....
And I heard that they're more efficient...meaning it doesn't take time spool like the turbo does.... Dont be afraid to elaborate.....I just want to educate myself a little on the subject.

 

[morepower2]

OK...I heard that as long as you give the engine good maintainance i.e. oil changes, that you shouldn't have trouble with the superchargers.....
And I heard that they're more efficient...meaning it doesn't take time spool like the turbo does.... Dont be afraid to elaborate.....I just want to educate myself a little on the subject.

The adiabatic effieciency is worse meaning that if you figure out what the heating should be from just compressing the air via the ideal gas law, pv=nrt and what it acutaly is from the compressor, the turbo is more efficient and heats the air less while compressing it.

A roots supercharger is about 50-60% efficient and a centrifugal is around 60-70%.

A good turbo is from around 75-80%.

It equates to less charge heating, less work needed to compress the air with a turbo.

Mike

 

[ClassicSE-R]

The advantage of a supercharger is that it is directly coupled to the engine, so that boost is coupled directly to your foot. In a turbo, there is a delay between cracking the throttle and getting boost.

A well matched turbo, however, will have very little lag, and for equivalent peak horsepower output, a turbocharged engine will make more power over the engine's entire operating range (if the turbo is matched properly).

Rob

 

[andre]

OHhh..thanks...someone else had told me that it causes more heat in the engine...and you say that a good turbo is more efficient...but I dont want to get rid of my header, and change my exhaust again (got 2" piping...damn expensive strumong). Oh well, as long as I get the facts straight. Thanks.

 

[ClassicSE-R]

OHhh..thanks...someone else had told me that it causes more heat in the engine...and you say that a good turbo is more efficient...but I dont want to get rid of my header, and change my exhaust again (got 2" piping...damn expensive strumong). Oh well, as long as I get the facts straight. Thanks.

Turbochargers can increase exhaust gas temperatures more than superchargers do. They can also increase underhood tempeartures.

However, most supercharger systems aren't intercooled, and IMO that offsets any thermal advantages that a supercharger supposedly has. Consider that a roots-type supercharger running 10 psi of boost will have a 160 to 180 degree delta T. This means that your intake manifold temperature on an 85 degree day will be about 245-265 degrees F! A well matched turbocharger will only have about a 115-120 degree delta T, and then a decent intercooler will drop intake manifold temperatures down to the 115-130 degree F range.

Which engine do you think will have bigger thermal problems? The one with the 250 degree F intake manifold temperature (hotter than boiling water!), or the one with a 120 degree F intake manifold temperature? Which motor will be more likely to detonate? Which one will have to run more retarded ignition timing (further driving up EGT's)?

It is true that turbos introduce thermal issues, but a well designed turbo kit (like the F-Max kit for Sentras) and some decent thermal barrier coatings (like Swain's White Lightning or HPC) will keep temperatures down to a reasonable level.

Keep in mind that nobody makes a supercharger kit for your car, but there are turbo kits available. The pain of removing your header and exhaust won't be nearly as great as the pain of developing your own supercharger kit.

 

[andre]

The pain of removing your header and exhaust won't be nearly as great as the pain of developing your own supercharger kit.

I hear ya....just exploring options. I guess I'll just continue with bolt'ons then go Nitrous.