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Discussion Starter #1
Hey all,

This link is to Holley's discussion of their centrifugal superchargers, which operate very similar to a turbo, with the exception of being belt-driven. Otherwise, the mechanical makeup is very similar. Anyway, there is a great discussion of boost, compression ratios, and how effectively forced induction engines operate.

One minor point mentioned that I noted is how superchargers give improved startup time b/c they immediately are able to deliver air into the intake, rather than waiting on engine vacuum. Could that possibly mean that the reason our turbo cars take a tad time to crank is b/c they have to wait for the shaft to be spun sufficiently by way of exhaust or whatever? Just a question I had reading this.

Anyway, enjoy.

http://www.holley.com/HiOctn/TechServ/TechInfo/SCTech.html
 

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That table of compression ratios on the Holley site is incorrect. I had a discussion about this some time ago. The problem is that "compression ratio" is not the same as "pressure ratio". The piston in the cyllinder acts as the former, and the supercharger the latter.

A quick example to show you what I mean: If I take the gasses in the cyllinder and move the piston so that they have half the space, the pressure doesn't double. Actually, it MORE than doubles, because it's an adiabatic process. Whereas, if I take a supercharger and put it at a 2:1 pressure ratio, it operates at exactly that pressure ratio, no more.

Twice the manifold pressure is not equal to twice the compression ratio. When intercooling is brought into that, it becomes an even more pronounced difference.

Adrian~
 

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I should have known...:cheesy: I have more links, I just saw this one as a good overview. The real one was good, I thought, b/c of multiple links.
 

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Wow, I really like the stealth link! My new "performance" mechanic despises those V-6's though. He said they were hands down the most complicated engines to rebuild. He was trying to pawn one off on someone while I was in his shop! I still love the looks of the 3000 GT VR4, though. I drove my wife's old eclipse for a while, so I have a place for DSM cars.
 

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bkrell said:
I should have known...:cheesy: I have more links, I just saw this one as a good overview. The real one was good, I thought, b/c of multiple links.
Heh, the Stealth link was one of my faves as well. I have a few more. But that link has a LOT of information across a broad range of turbo-related topics all in one place. Whereas the rest of the sites just each contain one facet.

This isn't exactly a turbo-research link ... but it's Saab related and uber coolies: http://project911.luminasweden.com/

You might have seen it already. But just in case. ;) heh

Adrian~
 

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these are good resources. maybe should be included in clevesaabs faq over in the workshop?
 
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