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| How's a turbo and a super charger work? https://www.slantsix.org/forum/viewtopic.php?t=9047 |
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| Author: | ShivaDart [ Thu Apr 15, 2004 4:54 pm ] |
| Post subject: | How's a turbo and a super charger work? |
I was curious, just as a FYI, what the differen't types of chargers are and do. I'm talking about the turbo-charger and the super-charger. I'm not sure how they work, and I am just wondering if a super-chargers just a pumped up turbo. Also, is their any other sort of charger? ( |
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| Author: | 73dart_swinger [ Thu Apr 15, 2004 4:58 pm ] |
| Post subject: | |
a turbo is exhaust driven while a supercharger is driven by the engine. |
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| Author: | bmimken [ Thu Apr 15, 2004 6:14 pm ] |
| Post subject: | My 2 Cents |
Quote: I'm not sure how they work, and I am just wondering if a super-chargers just a pumped up turbo.
73dart_swinger has it right.Each one has its pros and cons but they end up with a similar result, creating a denser incoming air charge for the engine. Because air heats up as it is compressed, it is desirable to use an intercooler to cool the compressed air down. This is a disclaimer, the following will be referring to basic, in general theory. There are exceptions to every rule, I will not be covering those exceptions. Turbo pros: doesn't rob engine power to work, easy to use with intercooler, can use multiple turbos on same engine. Turbo cons: turbo lag (exhaust pressure has to build a bit before turbo's effective), requires some clearance in engine bay (or very creative routing) for V-engine designs. Super pros: works with the engine (instant results, except at low rpms), easy to use with all engine designs, doesn't use a lot of space. Super cons: can't use an intercooler unless using a centrifugal type, robs engine of horsepower. I'm sure there are others that can tell you more about them than I can. And there are ways to combat each one's cons, but I won't get into that. If I have omitted anything, I apologize in advance. This is just a well-meaning attempt at describing them. Brian |
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| Author: | slantvaliant [ Thu Apr 15, 2004 8:24 pm ] |
| Post subject: | |
To make things even more confusing, both are actually superchargers. A supercharger forces a higher pressure "charge" of air into the system than a "naturally aspirated" system would get. There are, or were, belt drive and crank driven superchargers. Then someone used exhaust to drive a turbine compressor. The original term for that was turbosupercharger, later shortened to turbocharger. Fun? Wait until we get into why the cooling radiator in some turbo systems should actually be called an after cooler, rather than an intercooler ... lol |
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| Author: | Matadem [ Thu Apr 15, 2004 10:00 pm ] |
| Post subject: | |
go to www.howstuffworks.com |
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| Author: | Al T [ Sat Apr 17, 2004 8:37 am ] |
| Post subject: | Non-Centrifugal Supercharger can be used with intercooler |
I use the positive displacement blower with intercooler - no reason why you cann't. http://www.projectplato.com/cars/supercharger.html |
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| Author: | mnecaise [ Mon Apr 19, 2004 9:34 am ] |
| Post subject: | |
A turbo does "rob" (i.e. draw) power from the engine -- in the form of exhaust back pressure. |
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| Author: | Tom Drake [ Mon Apr 19, 2004 11:07 am ] |
| Post subject: | |
What about when the backpressure is lower than the boost? ie - 13# of boost and 11# of back pressure. |
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| Author: | mnecaise [ Tue Apr 20, 2004 5:54 am ] |
| Post subject: | |
It's still producing back pressure to generate the boost (even though the boost is higher). There is a net gain of power; but, some power is used by the turbo. |
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| Author: | Tom Drake [ Tue Apr 20, 2004 6:17 am ] |
| Post subject: | |
I think what you are refering to is how efficent each system is. A roots type blower is only 50% efficent at best. A centrifugal supercharger can run as high as 65% with a really well thought out system and maybe even higher. A well thought out turbo system can run as high as 75% and up. In each case a poorly designed system could be considerably lower. Using the term "rob" is kind of misleading when describing a turbo. It does not take anything away from the motor like a belt driven supercharger. In a roots type system if you want to make 500hp you have to build a 600hp motor to make up for what the supercharger "robs" from the motor. Yes the back pressure in a turbo system is something to consider. Design a bad set-up and you can see pressures 3X the boost pressure. Design a good exhaust, size the turbo correctly and the effect becomes very, very minimal. Tom |
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| Author: | mnecaise [ Tue Apr 20, 2004 11:17 am ] |
| Post subject: | |
efficiency... yes. That's the applied physicist in me showing... I see what you mean by "robbing" power from the engine; but, I see it as overall output of the "system". Sure, you do have to have a crank that can handle the extra force required to turn the supercharger. You also have to consider that Roots blowers are notoriously inefficient at high rotor rpm and that most people set them up to produce boost at low crank rpm. It's a design issue... (and out comes the engineer in me...) As you said Tom, a poorly designed turbo system can kill efficiency and result in really bad performance. |
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| Author: | panic [ Tue Apr 20, 2004 2:16 pm ] |
| Post subject: | |
"Using the term "rob" is kind of misleading when describing a turbo. It does not take anything away from the motor" It's called pumping loss In order not to have pumping loss, the exhaust pressure in the cylinder must be atmospheric @ BDC at all engine speeds. A well-designed NA system will have negative pumping (extraction) at certain tuned RPM, and positive above and below. |
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| Author: | mnecaise [ Wed Apr 21, 2004 8:08 am ] |
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Right, I agree. I was originally responding to bmimkin's comment "Turbo pros: doesn't rob engine power to work" The term "rob" is misused... I wanted to make it clear that you're not getting something from nothing. Your extracting energy from somewhere; and, there will be <i>some</i> penalty (in terms of system energy loss) to pay for it. I was trying to keep it K.I.S.S and avoid the discussion of Otto cycle efficency, pumping loss, the psuedo Rankine cycle efficiency of the compressor, adiabatic vs non adiabatic systems, etc, etc, etc. |
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| Author: | kesteb [ Wed Apr 21, 2004 12:50 pm ] |
| Post subject: | |
NACA tests with piston driven aircraft engines during the '30s seems to indicate no differances in power loses between exhaust driven and crank driven superchargers. The NACA was the predecessor to NASA, the research is available on the web. |
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| Author: | Tom Drake [ Wed Apr 21, 2004 1:39 pm ] |
| Post subject: | |
I think the key there is when the test were done. Turbocharger and Supercharger technology has come a long way in just the last 10 years. EFI is one of the main reasons as well as the internal design. The next wave will be VNT turbos. Chrysler fooled around with them in the 80's but all the info I have read says the new generation will be the ticket! Tom |
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