Someone today mentioned to me they came across this system that they were looking into for their camaro. Apparently is becoming popular for the hot-rodder, do-it-yourselfers out there.

Looks very interesting. Seems perfect for a MINI application!

Here is the link:

http://www.ststurbo.com/home

 

Cool idea. Yes, it's been discussed, but I don't believe I've seen anything here on NAM about this...

Less underhood temps, better weight-distribution... but, longer plumbing runs, and complicated ones at that. I would also guess more lag as well, given the same unit being up front...

I still feel like a more efficient SC is the way to go...

 

We did look in to it, but there's some problem areas to consider.
First one, is the very limited space in the rear where the turbo would
rescide.

Secondly, where would you pickup good clean air in the rear/isolate it from
road debri and water.

Third, would be the oiling system, again no space.

Forth the pressurized air has to be forced thru an oval or very thin
tube paralleling the exhaust system.

Fifth, would be the size of the turbo, it has to be quiet large to be able
flow enough cfm's.

Sixth, the system is patented by a company, so copying the idea would
only draw the wrath of their lawyers.

With that said I spoke to the guys at this company and they where
very nice.

peter

 

I'm curious, what caused someone to think of this application? This is an honest question, not a sarchastic one. I'm trying to figure out what problems confronted those folks to cause them to think of a remote turbo, given all the problems you guys pointed out. Or, perhaps some slick marketing to raise a little more revenue...

 

I have looked into this system as well, but I looked into it for turbo charging the VW Toureg... for a side project. Though about it for the mini, but as stated above, the mini has too many clearence issues. it could be done, but would not be a marketable system, and may require the use of interior space.

 

The idea of the remote turbo is actually a good idea, as it solves some issues with turbo charging just by the location diffrence (heat being one main one). It made about 75HP on an LS1 that I saw it get installed on. It can give cooler air, and operate the turbo at a cooler temperature. some benefits. The drawbacks are the oiling system, and the ammount of tubing needed. but overall a good idea.

 

As we heard it , it was originally used in a mini truck application so space was not an issue.

Randy
Team M7
www.m7tuning.com

 

Turbos use hot exhaust gas to spin them. Mounting at the rear of the car will allow the exhaust gas to cool some and available energy would be reduced. This energy is used to provide boost. Too close to head may be too hot and cause damage to turbo unit. My take is that this is interesting marketing, I would like to see the engineering.

 

Dan, regarding some of your comments there is a FAQ page on the site which seems to address some of these issues. Specifically it mentions an install on a lowered truck as Randy mentioned as well as others like water isolation.

 

I have a buddy that has one on a TA with the LS1 engine and another friend that has the LT1 in his with a 150hp Shot of NOS and right now they are neck and neck and believe me that Turbo screams!

 

A turbo uses exhaust gas, that is correct, whether the gas is hot or not does not matter. It is the volume and the rate of flow that is what causes the turbo to spin, not the heat. The heat is only a byproduct of combustion, and there for is not needed to create boost. If all things the same with flow and volume, the turbo with the cooler exhaust gasses can make a cooler charge and therefor make more HP.

 

That's classic!

 

Someone asked why I though Pilo's latest mis-statement was classic. According to Corky Bell, temperature is about 4 times as important as airflow when it comes to turning a turbine wheel. This should be required reading to anyone messing with turbos, or spouting off "knowledge" on a forum:

http://www.bentleypublishers.com/product.htm?code=gtur

:smile:

 

Doesn't heat create the velocity in the exhaust gasses to spool the turbo?
No, heat doesn't create velocity. Heat creates volume. If you look at any of the physics laws for gasses, you will find that pressure and volume and heat are related. PV=NRT is a popular one, The V isn't for velocity, it is for Volume.


The turbine housing is what creates the velocity. The scrolling design that reduces the volume of the exhaust chamber as it scrolls around causes the gasses to have to increase in velocity and pressure to maintain the same flow rate.

Hotter gasses have more volume, thus requiring a higher A/R which in effect means that it starts at say 3" and scrolls down to approximately 1". Lower temperature gasses are denser and have less volume, so they require a lower A/R housing which would start at the same 3" volume, as the turbine housings use standard flanges, and scroll down to say 3/4". Now if you were to reverse the housings in application, the conventional turbo would spool up extremely quick, at say around 1500 rpm but would cause too much backpressure at higher rpms because the higher volume of gas couldn't squeeze through the 3/4" hole without requiring a lot of pressure to force it through. On the reverse side, the remote mounted turbo with its cooler denser gasses, wouldn't spool up till say around 4000 rpms but once spooled up would make efficient power because it doesn't require hardly any backpressure to push the lower volume of gas through the larger 1" hole.

 

So, how many turbocharged cars have you owned?

 

No offence, are trying diffute my statment above by asking how many turbo car's I've owned? Did you read the information I provided?

 

You copied and pasted the above text from the rear-mounted turbo site. I'm not trying to refute a statement that is not yours. I am just curious to know where you have gained your wealth of information about turbocharging?

 

Its really simple. Temperature is a measure of kinetic energy. Kinetic energy is good for moving things.

 

I'm a bit over my head because I've never owned a turbo charged car. This said, I do have some understanding for some of the above - again, I'm trying to help others and me by chatting up and contributing.

The Ideal Gas Law is central to this debate, yes?

Okay, if so, when a gas is heated its psi is increased - assuming the volume remains the same. Now very generally, when this heated high pressure gas enters the actual turbo area - and I mean right there at the turbo, I believe that this area is by design somewhat larger than the passage all this stuff just passed thru. Stuff is a very technical term. So then, if this is so, then we also gain additional energy as the previously heated high pressure air enters this larger space because the air now cools and expands. So, the energy spinning the turbo is from velocity - kinetic energy, and pressure deviation, created by the cooling and EXPANDING air. Pop a balloon in a room; the ballon is under very high pressure. But when it is popped, the air expands (and cools) shooting the balloon off in some odd direction - made possible by the difference in pressure/heat. I beleive these two factors are very much a part of what makes a turbo spin. Heat is good because it is a function of increasing pressure so that, that very pressure can be released thru expansion - in addition to kinetic energy.

I'm actually sweating. Any of this make sense?

I'm thinking of a way to use the balloon analogy for sizing a turbo; The room is the turbo and the balloon is the orafice the heated air is passing thru...I'll need a while.

 

I'd go with Boyle's law. Temperature is the only factor that determines a molecule's velocity.

 

this statement is bozo: "Hotter gasses have more volume" as is it's corollary: "Lower temperature gasses...have less volume"


volume is a function of the boundary containing the gas, not the temp or the pressure.

cheese: one might argue that a molecule's velocity is what determines its temperature, eh?

in this context, the higher the temp means the higher is the molecualr momentum (mV) so that every collison of a molecule with an impeller will transfer more momentum and more energy. More molecules per cc (higher density due to cooler gas) may contribute to more frequent collisons, but each collision will have less momentum transfer. So you have to figure out what the rate of collison as a function of temp and what the molecular velocity is as a function of temp to see which is the dominant effect. I forget the statistical stuff too easily...
"diffute" that!

 

I have had many discussions regarding this exact topic with squires, as well as with Dan over at DPR, as we were working on a side project away from Mini's.

The above statement when taken as a whole, though I may have not expressed this correctly above, is that a turbo system can produce power, when tuned for it's application, whether the exhaust is really hot, or cooled a bit does not matter, because they turbo sytem can be tuned to accomidate that, hence the reason for my quote above from squires site. Power can be made from this system, and I've seen it make power, so I do not think that is at debate. There are some benefits of the cooler exhaust gas for turbo's because the turbine is cooler and the compressor housing can run at a lower temperature and will create lower intake temps, which helps with the fact that as stated, you have less energy in the exhaust gasses. I see how my comment above could have been misinterpreted, but also the text around it was removed from your quote, and was needed to explain what was said as a whole.

That is what I meant by the statement exhaust gas temps do not matter.

 

Yes, you could definately argue that a molecule's velocity determines its temp. Temperature is just a measure of kinetic energy. The more it has, the higher its temp.

For a given number of molecules, higher temps means more kinetic energy. The higher density holds more molecules for a given volume, therefore resulting in the likelyhood of more hits on the impeller for a given time period. I can't argue that.

My "diffute" of that would be:

With volume held constant, you cant increase density without increase mass so where are the extra molecules coming from?

 

So you're saying that if all you want is a 7 PSI foo foo turbo system, you dont have to follow all of Andy's "Corky Bell Maximum Boost" rules? I'll agree with that.

 

Okay, lets not forget that this is a dynamically perpetual process once the key is turned. Those are my words and they may seem, uhm well dumb.

I like the question, "where does the extra mass come from?" I cannot answer that question readily. However, correct me if I'm wrong, but an intercooler increases density by cooling the air charge. And though the process is under pressure, the inlet side of an IC is still hotter than the outlet side. So, how do we get air that is more dense? And it must be, other wise an IC would not work. If the psi in the SC were higher relative to that in the IC, that would explain part of it; the air cools thru expansion via a pressure drop - relatively. I'm probably not helping here because I'm taking my input slightly off topic. ButI'll continue hoping there is something here.

So, we have really reduced this conversation down to the relationship between cold and hot air. Everything in this world flows from high to low pressure. Hot air cannot fall into cold air because it is more dense. So, cold air naturally falls down into warm air, that is the direction. As cold air warms, the molecules become more excited and velocity is increased. But as hot air expands via increasing volume, it cools and the expansion process also has energy. So which is at work here? My intuition tells me that this is a perpetual forward and back process so long as the fuel supply remains constant.

I cannot tell jlm, are you saying the hot gas/cold gas volume thing is bozo? Volume is defined by four walls if you will. Pressure, and therfore temperature cannot change this unless the four wall explode or implode. I think you are saying this. However, a given gas of either different temp or pressure will not equal the same volume. Else why do tires lose pressure when it gets cold and gain pressure when hot. Although this may only be true for a closed system with a given amount of - mass of air.

Minipilo, I would argue the point about hot or cold air not being important for reasons stated in my post above. As a hot gas cools thru expansion, energy is given off and can be put to good use. A turbo my be glowing hot, but if the air entering the turbo impeller area is allowed to expand, it will in fact act with some force in addition to all the others acting on the turbine. This will only occur in an environment rich in heat. Velocity is part of the process, but so is heat.