Supercharger vs. Turbocharger

[ietech]

I have owned both turbocharged and supercharged engines and I have been impressed with the performance of both.

The initial lag on startup with turbo is the only obvious difference I noticed.

Does the supercahrger. being belt driven, impose a significant extra load on the engine?

What are the advantages / disadvantages of each. I have never come across a detailed comparison in the car mags.

Just Curious -- Thanks,

ietech

 

[evelrod]

Type in "supercharger/turbocharger" in the search function and look for a "search post (Keyword)". You will find a "ton" of stuff. We have done several looooog threads on this subject in the last few years and it is all still available with a simple search.

Rod

 

[mpg99999]

Turbochargers generally provide better efficiency, especially when compared to roots type superchargers. Mike Kojima did a very good comparison article in SCC. If you can stand reading through some stupid post, then I would check out this thread on another forum:

http://www.b15sentra.net/forums/showthread.php?s=&threadid=65964&highlight=turbo

I get into an argument about superchargers and turbochargers, and there is alot of good info in it. If you skip to page five (

http://www.b15sentra.net/forums/sho...65964&perpage=15&highlight=turbo&pagenumber=5

), check out smartbombs post. That is Mike Kojima, the one who wrote that article. He breaks out the math and what he says is pretty much in his article. Very good read.

-Mike

 

[patprimmer]

As Rod said

Lots of info in existing threads.

Just a hint. Look at the size of the supercharger drive belt and ask why so big. How much power does it take to cause one to fail?

While the power consumed to drive a turbocharger is not as obvious, it is NOT free as many imply. It does increase back pressure which works against the piston on the exhaust stroke.

Enough. Read the other threads

Regards
pat

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[ietech]

Hey Thanks,

Lots of good stuff to read. Learned a lot in just a couple of mouse clicks.

Thanks again for your input,

ietech

 

[EfiOz]

Has anyone ever done a compound supercharged engine?

I know Cosworth did one back in the 80's but it never saw a race track.

 

[mackerm]

patprimmer said
While the power consumed to drive a turbocharger is not as obvious, it is NOT free as many imply. It does increase back pressure which works against the piston on the exhaust stroke.

Has anyone attempted to send the high-pressure exhaust through the turbine, and release the remaining exhaust at ambient pressure?

 

[patprimmer]

At least the Rolls Royce Merlin was compound supercharged in WW11. I expect that many other WW11 aircraft motors might also have been

Regards
pat

eng-tips, by professional engineers for professional engineers

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[evelrod]

In addition to the Merlin and Griffon engines (Rolls and Packards) the coumpound supercharging idea goes all the way back to experiments on the turbocharged Liberty V-12 Aero engines of 1918 and earlier. Another WW II example was the Allison V-1710. This is just 'off the top of my head' without doing a lot of research (Y'all do your own), there were several Formula One cars of the 20's and 30's that tried coumpound and duplex supercharging to one degree or another. It is definitely NOT a new idea!

Rod

 

[SBBlue]

MacKern asked:

"Has anyone attempted to send the high-pressure exhaust through the turbine, and release the remaining exhaust at ambient pressure?"

I think what you are referring to is the difference between the "blow-off" pressure in the cylinder when the exhaust valve first opens and the pressure in the cylinder during the exhaust stroke, when the engine has to "push" the exhaust gas out of the cylinder. The "blow-off" pressure is typically around 6-7 atmospheres of pressure.

And yes, people have tried a variety of schemes to separate the "blow-off" exhaust from the exhaust stroke exhaust. See, for instance, US Patent 5775105:

http://164.195.100.11/netacgi/nph-P...5105.WKU.&OS=PN/5775105&RS=PN/5775105

As far as I know none of these have proved to be commercially viable.

 

[76GMC1500]

I know of an application that uses a staged turbocharger/supercharger. The emergency generator on our ship is a 2-stroke Detroit Diesel 8v92. The supercharger is necessary to overcome the scavenging deficiencies of the 2-stroke for fast startups necessary for emergencies. The turbo charger is there to make more power and increase efficiency.

 

[aorangi]

Extremely comprehensive information about every concepts of supercharging, turbocharging and turbocompounding here:

http://www.auto-innovations.com/document2/doc-engine.html

There's a small charge, but it's worth it.

Cheers
Aorangi