super and turbo charging

tipota · 02-07-2005, 08:55 PM

i heard that put a super charger and a turbo in a car would be difficult to do. what is so hard about it? the only thing i cna think of is finding space in the engine bay, and also synchronising them both. would you really need to synchronise if you dont care too much about the lag between the two?

Reed · 02-07-2005, 09:08 PM

im not sure what you mean by synchronising. the main problems are finding space for them both and space for the plumbing. Also when you compress air twice it gets a whole lot hotter and if your supercharger is a roots type that means you can't intercool. if you dont care about lag (man i hate that word) then why would you want to do both, you can only run so much boost and you can get all the boost you want out of a turbo.

Schister66 · 02-07-2005, 10:48 PM

Why the hell would you supercharge and turbo and engine? Why don't you just put a supercharger or a turbo on the engine. Instead of wasting your time, you could do something that isn't pointless and build twin turbo kit...one large turbo w/ a small one to help spool it up. That is called a biturbo and it is a good idea. I don't mean to sound like and asshole, but this is just kind of a stupid question in my opinion.

Reed · 02-08-2005, 06:13 AM

For any kind of racing bi-turbo is a terrible idea. its less efficient, and more complex. single or twin is the way to go.

i think that Turbo magazine about 2 years ago had an issue where they put a turbo and a roots blower on MK-2 MR-2 that had a 5m-fe v6 (i think)swapped into it. they said it performed pretty well but i dont know any specifics.

tipota · 02-08-2005, 11:30 AM

well im really new to all this. the only reason id consider doing it is to have the super charger provide power at lower rpm's until the turbo kicks in, but i guess thats what the smaller turbo in a twin turbo system is for. so, is it much better to use a single turbo over a supercharge? i see a lot of talk about turbos on a lot of forums, but no one really talks about superchargers. the only car i know to use it is the 88 mr2, but then the next gen used a turbo

Schister66 · 02-08-2005, 03:03 PM

the only problem with most superchargers is that they are model (car) specific. You cant exxactly fabricate a bracket for most superchargers. There also is a type of supercharger called a centrifical supercharger that is a belt driven turbo more or less. It is set up the same way as a turbo, just w/o the exhaust housing. I would turbo a car before i would supercharge it....unless it is a V6 like my Bonneville and in that case i would supercharge it because there is a ZZ2 supercharger for the 3800 series engines. If it were a 300ZX, i would turbo because there are kits. I guess if it was a V6, it would depend on what's available for the car. Otherwise i think that a turbo is much easier and there are more choices.

duplox · 02-08-2005, 04:26 PM

A supercharger will always be much easier to install... simply because you don't have to touch the exhaust. Exhaust can be a huge pain in the ass. Turbos are much more complex devices.
Your idea for a turbocharged and supercharged car is a good one. It has been done before. I prefer it to a staged turbo system. Staged turbos are excessively difficult to set up and configure. A turbocharged and P.D. supercharged car has may benefits:
Instant throttle response. The supercharger takes very little time to hit full boost, which then provides the exhaust volume and heat to spool the supercharger.
It provides an easy way to achieve high boost numbers without putting an extreme ammount of stress on either system. If you have both set to create 8psi, this is 150% of air pressure. The turbo will create 8psi, the supercharger will then take 8psi and compress it 150% - resulting in nearly 20psi boost.
Backpressure in a street turbo setup is very close to boost pressure - so you have ~8psi exhaust pressure, and ~20psi boost - providing a very nice scavenging effect.
Parasitic loss because of the supercharger is not very high, certainly nowhere near what would be required to produce 20psi by itself.

Reed · 02-09-2005, 10:25 AM

apperently when turbo magazine had that turbo and supercharged mr2, the turbo (which was a rather large one) actually pushed the supercharger and put some power back into the belt. or so they said. sounds like a good system, though complex. If i had to push a motor and try to run a whole bunch of boost i think i would just run a big turbo and keep my revs up.

(i feel like we're constantly on the verge of another T vs SC argument around here)

duplox · 02-09-2005, 10:34 AM

I'm not sure about the whole 'pushing the supercharger' thing. The supercharger doesn't know the difference between 14.7psi absolute pressure(atmospheric pressure) and 25 psia. All a positive displacement supercharger does is move a set volume of air through it. If there is a restriction on the output side, then it increases the pressure. It doesn't care what the pressure is to begin with.

nissanfanatic · 02-09-2005, 09:29 PM

Years ago, top fuel dragsters would use the instant boost of a roots blower and the high efficiency of turbochargers. That stopped when turbocharged cars had a weight penalty.

The idea is credible, but for any kind of high HP car, you can't expect instant response. Even highly tuned NA cars are tuned to run in a desired rpm range with tuned intakes and exhausts. Also with the turbos avaliable today, most of them can make more boost alone than your engine can handle with somewhat low response time. Some cars even use nitrous with added fuel to help spool large turbos.

SaabJohan · 02-10-2005, 03:51 PM

Lancia Delta S4 used both a blower and turbocharging. The blower was used at low speed and the turbocharger at high engine speed. A system like this does however require some fine tuning.

For most racing cars it's however quite pointless since low engine speeds are rarely used anyway and the turbochargers can be used to build boost before there is any load by the use of anti-lag.

Black Lotus · 02-10-2005, 07:43 PM

Quote:

Originally Posted by SaabJohan

and the turbochargers can be used to build boost before there is any load by the use of anti-lag.

Cool!
ANTI-LAG!
Can I put it on my car...or does it come in a can---or what?

"A huge stress on the exhaust manifold and pipes (mounted on a street car a bang-bang system would destroy the exhaust system within 50-100 km)"
Seriously... sounds like a no-go to me. At least on my car.
Would stop people from tailgating 'tho.

SaabJohan · 02-11-2005, 09:38 AM

Anti-lag can be used on a road car, and it won't destroy anything if the engine is built for it.

beef_bourito · 02-12-2005, 10:31 PM

I have thought about this (I'd never do it to any of the cars I'd ever get, too ecpensive) and I thought of having 2 turbos (If it's a V engine) and a positive displacement blower, have the blower running untill the turbos kick in then have an electronic clutch disengage the blower and the turbos would be producing max boost with little parasitic loss to the supercharger. You would of course need something to stop the supercharger from putting enough pressure on the turbos to make them stop spinning or your engine will stall. The way I'm thinking though isn't the turbos feeding into the blower (which would probably work better) but I wass thinking more like this:

Turbo Super Turbo
\ | /
Engine

nissanfanatic · 02-12-2005, 10:44 PM

Like possibly check valves on the intake charge pipes from the turbo? Sounds feasable. But also sounds expensive.

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