I agree that the location of the turbo's will have a big impact on their performance and result, but I believe the above requires some additional information.
A low-presure (small turbine) turbo gives you a fast response at low rpm's starting around 2000rpm, this gives you a quick pickup of boost but its overall HP+ is lower than for a high-presure (bigger turbine) turbo that takes longer to spin up 3000rpm but creates a bigger boost and thus more HP+.
I admit I have never seen a setup like the one on the video ever in Europe and at the moment I am wondering what kind of results you would get from such a setup if any.
Thank you for the further explanation.
Think of a smaller A/R ratio as putting your thumb on a garden hose to increase the speed of the water coming out of it. Pressure goes up, flow goes down.
Turbos are meant to be mounted close to the engine where the exhaust gasses are hot. The exhaust gasses have a much higher volume when hot. The difference in temp between the exhaust manifold where a turbo should be and where a remote mountedturbo sits is probably 600-800 degrees if not more. With a remote mountedturbo the engine must pressurize the complete exhaust system before the turbo starts making good boost. Likewise the turbo must pressurize the complete intake size before the boost becomes effective.
There will be huge frictional losses in flow on both the exhaust and intake side.
Turbo's like to be HOT when working, a hot turbo will make the oil thinner reducing drag on the shaft making the turbo "spool" quicker.
The turbo will take a lot longer to spool, rearmounted turbos generally start created boost around 3500rpm. A conventional turbo will make boost at 2000rpm. To counteract this remote mount companies will decrease the A/R Ratio on the turbine housing. This will create a huge flow restriction and power is lost.
Overall its a bad idea, take the money you would spend on one of these abominations and put it toward a real turbo.
Love this post and everything sounds correct to me. It is really not an 'efficient' system when compared to conventionally mountedturbo set-ups. The exhaust gases contain much less energy (as you explained) that far down an exhaust system. I have no doubt that this set-up will produce more power, but it is a poor design at the end of the day.
When will a street legal supercharger by Paxton or Vortex come out? I have a gaping hole where my airbox used to be just salivating for a supercharger!
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Top Banana Daytona #2700/4000
When will a street legal supercharger by Paxton or Vortex come out? I have a gaping hole where my airbox used to be just salivating for a supercharger!
It appears that we are trying to discuss a little heat transfer, gas, and fluid flow fundamental theory.
First, “heat” is not what makes a turbo work. Heat is nothing but radiant energy. Radiant energy will never do anything other than heat something up. The cylinder burn that releases the energy from the air/fuel creates the heat in the cylinder, but what moves everything (pistons, and turbine wheels) is first the pressure created from the expanding gasses in the cylinder that force the piston down to turn the crank. The expanding gasses eventually get driven out of the cylinder on the exhaust stroke and head down the exhaust system.
The exhaust gasses consist of two primary components, heat energy left over from the combustion process, and gas molecules (“the exhaust gas”) that are traveling at a very high rate of speed. It is the molecules in the exhaust gases striking the turbine wheel that actually makes it turn.
The exhaust gasses whether they are at the exhaust valve or the exhaust pipe tip, have the exact same number of molecules in either location. They are captured in the pipe, so it can’t change. What does change is the temperature of the gas. It does cool as it travels along the exhaust piping, so heat energy is lost. But heat is not what drives the turbine wheel, so something else must be going on. As the exhaust gasses cool, their density increases. The molecules in the gas become closer together so the gas takes up less space. As this occurs, you do get some velocity change, the gas slows down some.
Now, if you simply put a turbo sized for installation on an engine at the rear of a vehicle, then it is going to be sluggish. Since the gasses have cooled, and no longer occupy (or need) as much physical space, one reduces the AR on the turbine side housing. This increases the velocity of the exhaust gas prior to reaching the turbine blading. Since the gas density has increased, there are more molecules per sq mm striking the blading area than a turbo using hotter exhaust gasses to spin it. This also helps to bring the turbo’s performance level to what the designer is seeking.
To simply say a rear mount, remote mount, whatever mount is “wrong”, is showing bias. Everyone has an opinion, and the engine mountedturbo is the one most are familiar with. As I mentioned early, what is right for some may not be right for others, but that does not make it wrong, just different.
One last thing to consider, boost is boost, the only bad boost is a boost level too high for an engine to tolerate leading to failure. However, all boost is not created equal. 10 lbs of boost pressure at an intake temperature of 150 degrees is not going to produce the same performance level as 10 lbs of boost at say 80 degrees intake temperature. Why? The hotter intake charge has a lower molecular density than the cooler intake charge at the same pressure. Meaning you can get more power from the cooler 10 lbs of boost since there are more oxygen molecules in the same space that can be utilized to run more fuel and still maintain the same air/fuel ratio.
In regards to discussion on the time it takes to pressurize the exhaust piping, the exhaust tubing is always pressurized to an extent when the engine is running, what one is desiring is to increase the exhaust flow velocity to spin up the turbine blading. Due to the speed of the exhaust gasses, a properly designed and sized system is going to react within milliseconds as compared to the response of an engine mounted unit. Properly balanced, they can be just as responsive.
This concept has been used successfully for well over 60 years.. It is a common mounting method for use in high performance piston driven aircraft. It is not a new concept at all.
Again, everyone has their opinion, and there are always going to be individuals with opposing opinions. That’s good; otherwise, it would probably be a very dull world.
I certainly hope no one reads this and thinks I am bashing on their opinion, which is not my intent here. I am simply trying to explain some of the technical aspects as to why this method is not “wrong” from a technical standpoint.
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Can they mount the turbos any farther away from the engine??The next step will be plumbing it from the car behind you!!lol
Don't Hassle the HOFF
and 
Linear Mode
