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Discussion Starter #1
Anybody thought about this, negates need for intercooler or even lowering compression of engine.
 

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Supercharger Noiseaholic
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I'm guessing you've seen this in PPC? It does work well, provided you don't care if you total your engine, as you would be in fairly unchartered waters.

As for leaving the compression, that's only possible if you're going to use silly low boost, otherwise you're going to have issues. The chap who did it in his 205 (IIRC) was doing it on an old engine so he doesn't have to worry about the ECU throwing a shitfit and packing it in.
 

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MINI Obsessed...
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Think this was discussed to death on NAM and deemed as not worthwhile when its easier to just add one to the manifold. Still requires all the same considerations such as fuelling and cooling(although very much less important at very low boost). :) And just think of the lag to pressurise 2 metres of air in the pipes....
 

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Discussion Starter #4
yeah did, Think he's using an emerald ECu anyway, But its not the first time i have seen that. Saw it first time on a Golf Mk2 a fair few years. they soudn absoloutly mental.

Just thought some plucky individual might want to try it on their cooper
 

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Discussion Starter #5
Think this was discussed to death on NAM and deemed as not worthwhile when its easier to just add one to the manifold. Still requires all the same considerations such as fuelling and cooling(although very much less important at very low boost). :) And just think of the lag to pressurise 2 metres of air in the pipes....

See if you read the article thats where your wrong. Cooling is'nt needed as the charge air is cooled by the pipework back to the engine, it also allows the air intake to be taken at the back of the car miles form any engine components. Lag is also not present due to the compression aspect and the way the turbo is set up. They used the anlogy of a hose pipe, which would allow water to come out first a full hose at 1m long or a full hose at 20m long. Neither, they'd both be the same.

I'll try and scan the article and post it up. a very interesting read, also why ilove that mag as they don;t just speak about things in their, they do it. some great features, esepcially the current builds involving the first ever Vag TDi Westfield and a mk2 escort with SAAB Turbo power
 

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MINI Obsessed...
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See if you read the article thats where your wrong. Cooling is'nt needed as the charge air is cooled by the pipework back to the engine, it also allows the air intake to be taken at the back of the car miles form any engine components. Lag is also not present due to the compression aspect and the way the turbo is set up. They used the anlogy of a hose pipe, which would allow water to come out first a full hose at 1m long or a full hose at 20m long. Neither, they'd both be the same.

I'll try and scan the article and post it up. a very interesting read, also why ilove that mag as they don;t just speak about things in their, they do it. some great features, esepcially the current builds involving the first ever Vag TDi Westfield and a mk2 escort with SAAB Turbo power
Errr ok....the analogy of water just makes it sound like unbelievable. We're talking about compressing a gas to 8+psi where volume and density makes a huge difference. Whats easiest and quickest to pump up, a bike tyre or a car tyre?? That's a closer analogy as both require a volume of air to be compressed and one requires a far greater volume of air to be compressed to get the same pressure. Unless you mean they reduce the diameter of the pipe massively?

Post it up if you can :) Always worth a good read :)
 

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PowerSteeringPumpActivist
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Lag is also not present due to the compression aspect and the way the turbo is set up. They used the anlogy of a hose pipe, which would allow water to come out first a full hose at 1m long or a full hose at 20m long. Neither, they'd both be the same.
Assuming both hoses are already completely full with water, when you turn the tap at one end, water will come out the other instantaneously. If both pipes are empty, when you turn the taps on each pipe, it would obviously emerge from the end of the 1m pipe first.

Another factor to consider is that water is not really compressible, unlike air. With the engine trying to suck air out, and acheive sub-atmospheric pressures in the intake pipes, the turbo has to replace this and then re-build the boost.

I'm afraid I need to agree with Morgan on this one - bike vs. car tyres is a much more apt analogy. And if keeping the same volume for the intakes, the pipe would need to have its diameter reduced to maintain the same volume.

But then you have the question of how difficult it might be to force air into the engine through a long thin tube vs. a short thick one... :confused:

Also, wasn't it agreed that higher pressures in the R50 engine wasn't a good idea and that it's far more sane to simply upgrade to the S? :confused: I know there's a good novelty value from discussing superchargers and turbos on the R50 engine, but practically, it's not really viable, is it?

All the best,
Andrew.
 

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This is interesting , the turbine section of a turbo works by heat ,it extracts the heat energy and transforms it to rotation , by having the turbine the farthest away from the source of heat -in the tail exhaust -the turbine would be immensely inefficient as the heat is so much lower back there ,looks like the idea redefines the turbine rules?
 

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PowerSteeringPumpActivist
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This is interesting , the turbine section of a turbo works by heat ,it extracts the heat energy and transforms it to rotation , by having the turbine the farthest away from the source of heat -in the tail exhaust -the turbine would be immensely inefficient as the heat is so much lower back there ,looks like the idea redefines the turbine rules?
So... rather than forced induction, it'll be more like wafted induction? :confused: :p
 

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a.k.a. BrainRush
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Squiers turbo system has been at it for years, I once saw an episode on two guys garage where they installed one onto a corvette and tested it out, here's the link on the sts website: Squires Turbo Systems - TV Episodes
 

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They have taken the fact that a turbine needs the maximum heat to extract power ,and turned it around saying that the denser (cold) air drives the turbine better that hot air !!!!
Any benefits of fiiting to a large engine car (corvette) to pass greater quantity of air through the turbines is lost as the compressor has to also feed greater quantity to the induction side .
Given the "wrong " position of the turbo they could have improved it slightly using a multi stage turbine, 2 or more turbines on the same shaft ,this would prove expensive and still not produce any real boost ,
Why dont they simply put up a compressor map in the tech section and all would be answered for visitors to the site -rather than point out supercharger belts can snap?
 

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PowerSteeringPumpActivist
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Squiers turbo system has been at it for years, I once saw an episode on two guys garage where they installed one onto a corvette and tested it out, here's the link on the sts website: Squires Turbo Systems - TV Episodes
Do the on set mannerisms of those two remind you of Tim Taylor and Al Borland on Tool Time (from the sitcom Home Improvement)? :p

Still, pretty neat-looking system they've got there.
 

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Supercharger Noiseaholic
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This is interesting , the turbine section of a turbo works by heat ,it extracts the heat energy and transforms it to rotation , by having the turbine the farthest away from the source of heat -in the tail exhaust -the turbine would be immensely inefficient as the heat is so much lower back there ,looks like the idea redefines the turbine rules?
What are you talking about? Since when did heat provide thrust? It's the simple action of air being forced over the wheel that spins the turbine, not the heat turning it! It's a known fact that the lower the exhaust gas, the more efficient you can spin the turbo, because you've got denser air and also you're not heating the charge either.
 

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Discussion Starter #16
guys guys guys stop arguing in the same issue of the amazing practcal perfomance car mag there is a beginners guide to supercharging. Remember these guys are also the mad bunch who bought a 1970's Rolls royce stripped it track prepped it and banged a turbo on it then took it to the ring. When in work tomorrow i'll scan up the article. as i said its an interesting article and like they say themselves in theorey it goes against everything we all know of turbocharging, but for some reason it works, and this is on a series winning track car.
 

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The application of a compressor to increase pressure at the point of cylinder air intake is often referred to as forced induction. Centrifugal superchargers operate in the same fashion as a turbo; however, the energy to spin the compressor is taken from the rotating output energy of the engine's crankshaft as opposed to exhaust gas. For this reason turbochargers are ideally more efficient, since their turbines are actually heat engines, converting some of the thermal energy from the exhaust gas that would otherwise be wasted, into useful work. Contrary to popular belief, this is not totally "free energy," as it always creates some amount of exhaust backpressure which the engine must overcome

"What are you talking about? Since when did heat provide thrust? " - A mr frank whittle would be dissapointed :D
"It's the simple action of air being forced over the wheel that spins the turbine, not the heat turning it! I" --- that would be a totally different type of turbine -this process is actually very complex -
"It's a known fact that the lower the exhaust gas, the more efficient you can spin the turbo, because you've got denser air and also you're not heating the charge either"
The complete opposite is true - the hotter the better as far as the turbine is concerned it can extract more energy

Please take this post in the in the informative way ,it is not intended as a "look im right" type way
your comments are a very common thinking and the physics behind turbos/and chargers seldom mentioned in articles (it is boring ) which leads to misconceptions.
 

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Supercharger Noiseaholic
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After quite some reading it appears we're both correct,

But i must address one thing, a turbine is not the same as a turbo, that draws in cold air, mixes it with fuel and ignites it, this then uses the expansion of the gas to turn the turbine, so that's not directly extracting heat, it's using the principle of gases expanding when hot to turn it.

Whereas in a turbo, according to Garrett the heat is only used in the fact that the turbo must cool it down to cause a relative suction in the exhaust, otherwise the turbo would produce boost, but then instantly produce no more power due to the engine experiencing denser air at both intake and exhaust
 

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The turbo has a turbine and compressor on a common shaft -the turbine extracts energy and provides the motive force to rotate the compressor ,which in turn provides the air compression

hot air enters the turbine and exits cooler , cold air enters the compressor and comes out hot

the hotter the turbine entry air the better hence having the hot turbine entry air -cooler at the exhaust tip end it provides less motive force to spin the compressor -
the compressor having less motive force -torque -spins slower and does not compress as well -far less output boost pressure and volume of air produced -less CFM -hence less power

For this reason Turbos are fitted as close to the hottest gas as possible ,even though having a hot turbine connected to the compressor and transmitting heat to the compressor is not helpful it produces more boost as the heat extraction from the turbine is more efficient than the loss of boost due heat in the compressor
 

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there is no reason this couldn't work on the Mini. lag is down to the specing of the turbo to the engine. if you kept the SC (i would) then boost would be instant anway. lol it has been provne to work, and worek ALMOST as effective as as a front mount turbo , on verious US V8 cars. no before everyone says "they have massive V8, lags not and issue" that just shows you know nothing about the cars! people are allways tryuing to minimise lag no matter what platform you are dealing with.

the other thing a rear mounted turbo would help with is twincharged cars. the big problem with TC car with front mounted turbos is you have to run massive boost to make the same power as the turbo only gusy are making! this is partly due to the superchargers (SC) inefficency and the fact you are feeding the SC with HOT gasses form the compresor. this can get so bad it can damage the SC! with the turbo out the back the chage air will have time to cool before it get to the SC. this will help with performance and redcue the stress on the SC. the chage could then follow the normal path through a intercooler or chargecooler and then intothe engine.

tuning would be no more difficult as it would be with a conventional twin charged engine.

also the enguine by would be MUCH less crampt. also as the HOT turbo will be at the rear there will be lower under bonnet temperatures.

Lag. big problem with any turbocharged engine. as said befroe if you retain the SC you will have instant boost responce anyway. but you still want the turbo to spool as fast as you can. so what can we do?? well normal practice is to use stock manifolds. this is to keep the speed of the gasses up and also to retain heat. also most people now wrap the exhaust pipework back to the turbo to help keep the heat in. this has been proven to help with spool. as for the exhaust piping, leave it small and you may as well use stock. its there and it works. as said before, wrap it to help with the heat. the cold piping only needs to be 2inch tops! as long as gas speeds are below 250ft per second you are not over sterssing the turbo. 1000++BHP evos are only running 3inch cold piping so 2inch will be fine.

i can see why people dont like the idea, its totaly against what has been told to people for years, but it dose work! yes it wont be quite as effective as a fornt mount, but then it will be alot easier to fit! ;)

cheers

Chris.
 
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