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Old 04-12-2004, 06:09 PM   #1
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Default turbo plus supercharger

i hope someone can answer my question. now this isnt just concerning subarus. alright let me see if i have this right. the main plus side to a supercharger (roots type) is that it produces power from idle and doesnt get as hot as a turbo. the negative is that it tapors off at the top end unless you install a bigger pulley but then you need more initial horsepower. the pluses of a turbo is that you can control how much boost you make easier but it only works from the mid to high range and can get extremly hot. now here is my question. can you install a high boost turbo plum it through a intercooler and then to the intake of a roots supercharger. in my thinking the suction of the air through the supercharger should make the vanes of the turbo start moving faster while at the same time creating its own boost and by the time the supercharger is tapporing off the turbo should be spooling really good and creating its own boost. i have never seen this done so im assuming there is a reason why and i just want to know what it is and nobody i know can give me a good answer. lets just say the engine we are doing this bullet proof and there is no money or space restraints why cant this be done. thanks
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Old 04-12-2004, 06:44 PM   #2
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Its called twincharging... its been done before on some cars. Try searching the web.

Your theories on how it works is a bit off, but the reasons you want to do it (low end torque and high end power) are why its been tried in the past.

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Old 04-12-2004, 07:06 PM   #3
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this is also similiar as to why they use sequential turbo setups on some cars.

Try doing a search for the Meguire's Integra Type R. It uses a Supercharger and a turbo charger.

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Old 04-12-2004, 09:19 PM   #4
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This might be a little off topic, but the two diesel engines that ran the backup power generators at the Nuclear Power Plant I worked on as an intern this fall had a supercharger running on the intake and a turbo on the exhaust. The supercharger got the (16 pistons, 6000HP) diesels started and then at something like 3 - 5PSI a wastegate opened and they switched over to a massive turbo. The idea there was to have the engines up and running at 100% power within 30 seconds from a cold start. Doubt the SC/Turbo combo would be very practical on a car though; if nothing else, it would take up tons of space and cost a LOT...
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Old 04-13-2004, 06:23 PM   #5
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Originally posted by Unsung Boxer
this is also similiar as to why they use sequential turbo setups on some cars.
This is probably the most realistic way to get low and high end. you put both a tiny and a big turbo on the same exhaust line so that the tiny one spools fast to add boost quickly at low rpm and then the large turbo catches up later on to give the boost at higher rpm.

As for the supercharger/turbo combo it seems like it would be a bit tough to do. having already compressed air go into the superchargers intake seems like it would cause problems.

what POWERLABS is talking about sounds like the supercharger is effectivly disconnected when the turbo charger kicks in. as he said, i think this would be a bit impractical on a car
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Old 04-13-2004, 10:25 PM   #6
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cant say I havnt thought about it It sounds like a good idea...but there are always ins and outs to everything. and it seems like it would be more work than it would be worth....for the added money of the supercharger, you could effectivly tune nitrous into the mixute, helping spool the turbo much faster.

I know someone posted a while ago about tractor racing and nitrous. These guys inject nitrous directly into the exhaust housing of the turbo, in turn creating a SHIATLOAD of INSTANT boost and a torque curve flatter then the state of kansas!
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Old 04-13-2004, 10:31 PM   #7
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ehh... its not cost effective. You can have a twin scroll give you the low, full spool by 2.5-3k, and high end. If you just want low you have have a high C/R with a small turbo and have huge low end tq with a little power up top. All for a lot cheeper....
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Old 04-14-2004, 10:20 AM   #8
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I read in SCC where there was a twin charger MR2 (AW11). they have also used this on diesel inboard motors. They actually had the supercharger controlled by a AC clutch
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Old 04-14-2004, 12:17 PM   #9
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Old 04-14-2004, 04:07 PM   #10
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Detroit Diesels are made that way, turbo blowing boost into a supercharger. Easy way to get higher pressure ratios without expensive single components. I.e. it's cheaper to have two compounded turbos making 50 psi than it is to get one turbo to make 50psi boost. -Chuck
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Old 04-15-2004, 10:32 PM   #11
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If you want the best of both worlds and are adventerous enough (which it sounds like you are) fit a lysholm blower to your car, higher efficiency than a turbo even at very high flow rates with better response characteristics and low end than a roots blower. Audi used to run these things back in the 40's and 50's on their le-mans cars around 40-50lbs of boost and set a few oval track records that weren't broken until the 80's, very cool stuff, I would scrap my turbo hardware in a heartbeat if someone could come up with a better way to fit one than the old rimmer kits. You don't see them too much because they are banned in just about every form of motorsports out there... including top fuel.

sells standalone blowers and various pulleys.... there are a few other companies out there that sell the blowers but whipple makes the most bulletproof.
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Old 04-18-2004, 12:50 AM   #12
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Powerlabs, if you're talking about KAPL's Kesselring site you're almost correct about the way the turbo is a supercharger. It's gear driven and the only thing that adjusts whether or not it's a turbo or super is exhaust pressure. The gear driven feature helps to scavenge the cylinders on the exhaust stroke when it's starting and pressurize the cylinders on the intake stroke.

oh, and it's 10 seconds to full output.

and they are 2400HP.

This works great on an engine that only goes from 0 to 900 rpm. However, trying to get a system like this to work on a high reving engine is almost impossible.
Notice I said almost. I've been working on this for about a year now.
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Old 04-28-2004, 11:30 AM   #13
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ImprezaRSX: I'm not familiar with the site you mentioned. My description was regarding the two backup diesel generators located inside the turbine building of Vermont Yankee Nuclear Power Plant (now Entergy Nuclear Vermont Yankee (ENVY)), where I worked last fall as a co-op. There are two actual separate boost systems on those diesels; a turbo on the back and a supercharger up front. The supercharger spins at all times but a blow off valve bleeds it after a certain RPM is reached.
The start up time to full output power is specified as 30s max (any more and the generator is deemed faulty and in need of repairs). You could be right about the HP figure though, I remember it being HUGE but there were several numbers (max, mean, median, max for 1 hour, 3 hours, 24 hours, etc) on the thing. I think 6000 was the absolute tops, and it might have been Kilowatts, not HP..
Now for a REALLY powerful motor, the 3 stage steam turbine that ran the main generator had a (1ft dia almost) shaft that was transmitting about 780thousand HP Not much torque though, I remember those turbines had to be brought up to speed at only a couple rpm/sec.
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