Supercharger For Extracting Exhaust Gas.

[r33_racer]

I dont think it would handle the heat. Unless it was purpose made to suit with bigger rotor clearances and whatnot. Other then that I cant see why it wouldnt work, so long as you can overcome the engineering difficulties in fitting it and setting up the drive for it.

But anything is possible with enough time and money!

[Marlin]

Good chat though!

[N1GTR]

Seriously though, if your exhaust is flowing enough, it should have no issues getting rid of the gasses.

10 points for thinking outside the box though

[Rolls]

Not quite sure how to word it, but...

Rolls, people are negative, such is life. I honestly though I came up with the idea for sequential turbo's, posted, and of course it'd already been done. You can only learn from asking, and some are better less negative/harsh teachers than others. I've asked much stupider things and learnt from my mistakes, but am better off/smarter from doing so.

Yeah I wasn't actually proposing anyone build this, was more just interested in what effect creating negative backpressure would have on an engine and how much energy would be required to do so.

It is always interesting to discuss things like this as they enhance your understanding of how it all works and keep you thinking.

Negative posts that don't even raise any points about the idea serve to just discourage people from thinking about new ideas, in reality the more people you think actively thinking about things like this higher the chance someone will come up with an actual working idea that can benefit people.

Mafia seems to really like posts like this, hell even when people are asking genuine questions (like differences between neo and s1/2 rb25) he posts bullshit like that.

I thought up an idea a while ago of a large tank (say 5 litres) hidden somewhere that stores vacuum under idle/cruise etc, then switches a solenoid at WOT to lower the dump/front pipe pressures for a split second to try help spool a turbo quicker. Don't know if it'd work, but thought it was interesting..

I like the idea of energy storage, much like the KERS system they are using in F1 and other hybrid energy drives. Would definitely be interested in how effective something like this would be as well. Another option would be to use compressed air stored up from braking etc and then using this to pre-spool the turbo when getting on the throttle.

Seriously though, if your exhaust is flowing enough, it should have no issues getting rid of the gasses.

Of course it should have no issues getting rid of it, but it would help get rid of them better. If you reduce backpressure you help exhaust flow, more exhaust flow increases scavenging and helps get more air into cylinders. You can see this effect when going to a bigger hot side, you make far more power for the same boost as you have just opened up the exhaust side of the car much more. If you were to attempt to achieve the same thing via sucking the exhaust out, you could have the gains of going to a larger hot side but whilst retaining the response of a smaller hot side.

It all just comes down to how much energy is required to do so, eg if it is more or less than you would gain by reducing the back pressure. if it is less then you have a net gain, eg you make more power, if it is more then you will loose power.

Get what I mean?

I dont think it would handle the heat. Unless it was purpose made to suit with bigger rotor clearances and whatnot. Other then that I cant see why it wouldnt work, so long as you can overcome the engineering difficulties in fitting it and setting up the drive for it.

But anything is possible with enough time and money!

I agree that heat would certainly be an issue, but what if you use a centrifugal design, eg like the compressor on a turbo, there is only one moving part so tolerances are not as big an issue (just look at the rear end of a turbo, they work fine).

Edited September 6, 2011 by Rolls

[Nee-san]

[urtwhistle]

I love outside the box thinking. if no 1 ever had crazy idea's we would still be on horseback.

But from what I can think of it would be just too big and over complicated unless it was on some form of stationary motor like a big genset. I think you would be better off running a bigger dump and modding the turbine housing with a CO2 jet plumbed up to it so that it pre spools the turbo. Sort of like how RIP'S has his drag car.

[Rolls]

We should kiss now.

[Room42]

On the subject of new ideas... We all love the toyota prius now don't we blokes?! We all love formula one too. Both the prius and f1 cars use braking energy and convert it into acceleration energy. Here is my idea. If we swapped our braking system with "air compressor brakes" then we could pump up an air tank and use the gas to spool the turbo quicker. I'm sure there would be easier ways to pump up a tank to help spool the turbo but why not use braking energy. It gets wasted anyway...

[Rolls]

There are actually companies researching using compressed air as a way of storing energy in a hybrid system.

[Nee-san]

We should kiss now.

It wouldn't even be gay !

[SargeRX8]

On the subject of new ideas... We all love the toyota prius now don't we blokes?! We all love formula one too. Both the prius and f1 cars use braking energy and convert it into acceleration energy. Here is my idea. If we swapped our braking system with "air compressor brakes" then we could pump up an air tank and use the gas to spool the turbo quicker. I'm sure there would be easier ways to pump up a tank to help spool the turbo but why not use braking energy. It gets wasted anyway...

Have the car fitted with an air tank for storing 100 litres of air at 300psi, then have nozzles in the intake and at the lights with closed throttle unleash 100litres of air into the intake on take off. Instant boost! Then pull up in your nearest petrol station and fill it up again! FREE!

[Nee-san]

Have the car fitted with an air tank for storing 100 litres of air at 300psi, then have nozzles in the intake and at the lights with closed throttle unleash 100litres of air into the intake on take off. Instant boost! Then pull up in your nearest petrol station and fill it up again! FREE!

MONORAIL....MONORAIL....MONORAIL, What's that word ? MONORAIL !

[Rolls]

Have the car fitted with an air tank for storing 100 litres of air at 300psi, then have nozzles in the intake and at the lights with closed throttle unleash 100litres of air into the intake on take off. Instant boost! Then pull up in your nearest petrol station and fill it up again! FREE!

Assuming the BOV opens up when you do this would probably be a very effective pre spool!

[GTSBoy]

I just wanted to come in here and say that the idea isn't worth pursuing. It's not quite up there with tailpipes with louvres in to cause the outside air to flow through and "suck" the exhaust gas out, but it's still attacking the problem from the wrong end.

Here's why. The turbo is a bloody great obstruction in the exhaust. Quite deliberately so. Sure, reducing the downstream pressure will enhance the spool behaviour and all the other little aspects of turbo performance that we'd like to enhance, but really, when you get right down to it, a decently free flowing exhaust, sized to suit the power level and hence total gas flow rate of the engine, does not put up much back pressure on a turbine. A couple of psi** at the max. Now, if you could drive a pump of some sort to pull that small backpressure down to say zero, then it will help, sure. But, I'm pretty sure that if you spent the same amount of power (be it electrical via the alternator or be it mechanical via a supercharger or be it just by running the turbo harder and putting a bit more backpressure on the exhaust ports, so as to create some more compressed air that you can burn fuel with, then you will make more power.

As has been written by others above, twin charging will give you exactly what you are after - reduced exhaust manifold pressure though being able to use a larger turbine housing as well as more low rpm boost and total power. This all achieved with a blower that is easier to package than whatever you would have to do to put it in the exhaust stream, and just handling clean cold air instead of nasty, hot exhaust gases. Alternatively, as some OEMs are working on, you can use an electric motor on the same shaft as the turbo to spin it up to speed prior to the exhaust flow becoming large enough to do it. Gets you some of the same benefits - if you upsize the turbine housing and rely on the electric motor to get it spooling then you get more power and better cylinder fill, etc etc.

In vehicle compressors for hybrid drive systems are in use in bigger vehicles. Trucks and buses. Not really feasible in cars, especially performance cars because of the mass of the receiver. You have to remember that in our cars and and trucks and buses, we're talking about the same sorts of power levels - 350 to 500HP engines. But in trucks and buses we've got multi tonne masses being pulled around, so adding a few extra hundred kilos for the compressor and storage is not as big a penalty as in a 1500kg car.

** I don't want to hear about cars with 4 and 5 psi of measured backpressure. I don't care if your exhaust is not big enough. The fact remains that it is quite possible to put a big enough exhaust on to bring the backpressure down to something reasonable.

[Rolls]

I just wanted to come in here and say that the idea isn't worth pursuing. It's not quite up there with tailpipes with louvres in to cause the outside air to flow through and "suck" the exhaust gas out, but it's still attacking the problem from the wrong end.

No doubt, I just want to know what will happen.

Now, if you could drive a pump of some sort to pull that small backpressure down to say zero, then it will help, sure.

I'm not talking about taking it down to zero, I'm talking about taking it down to say -20mmhg or greater, eg creating a vacuum and literally sucking the exhaust out, not making it zero restriction, creating the opposite of a restriction.

[GTSBoy]

I'm not talking about taking it down to zero, I'm talking about taking it down to say -20mmhg or greater, eg creating a vacuum and literally sucking the exhaust out, not making it zero restriction, creating the opposite of a restriction.

Doesn't matter. You'd still spend your energy doing that when it would be better spent at the other end. You can get much more from compressing some air and intercooling it than you can from stretching it out into a vacuum. Also, going to negative pressure, even a little bit, makes the gas volume larger, velocity in the pipe larger and so you need an even bigger exhaust system in order to stop pressure drop from clawing back some of your gains.

[89CAL]

Have the car fitted with an air tank for storing 100 litres of air at 300psi, then have nozzles in the intake and at the lights with closed throttle unleash 100litres of air into the intake on take off. Instant boost! Then pull up in your nearest petrol station and fill it up again! FREE!

Injecting that much air would send your AFR's a bit mental, plus you have to match that with fuel and it won't actually spool the turbo instantly

EDIT: actually thinking about this. If you inject air after the turbo it may want to turn the turbo backwards (maybe), and if it is injected before turbo, your gonna lose most of it out of the filter

Holset (from memory) were researching and developing an "E-Boost" that used a small electric motor to help the turbo accelerate from low RPM or something like that. Saw this a while ago so don't remember much but this is a much better idea. Still I can't really justify it on an RB. As had been said. You would lose alot of the energy ou are "gaining" with powering whatever you end up using

A KERS type system is what I'd have to say would be the closest to using an energy sorce to help acceleration, but the weight/complexity of such a unit on an older car would make it kinda useless, especially when you have to recharge it. On new cars where it can be built in, yeah but I sorta don't see the point unless it's used for taking off/getting up to speed rather then an actual speed boost

Edited September 7, 2011 by 89CAL

[blk94r33]

Has anyone else here heard about (I think it's VW)'s regenerative braking experiments using a flywheel that spins up on braking, then returns the power to the wheels under acceleration?

[Rolls]

Has anyone else here heard about (I think it's VW)'s regenerative braking experiments using a flywheel that spins up on braking, then returns the power to the wheels under acceleration?

Porsche have done it and so have many other companies, it can be quite effective.

[Legionnaire]

Yes, someone have heard about it: Kers