Thread: Remote Turbo's?

a couple of years ago (or more) I read and article in a "fast 4's & rotaries" type mag and someone remoted a turbo right down the back of a japanese van (Hiace or similar). not a huge amount of boost as I recall, but no need for intercooler, oil cooler and got rid of the heat from the cramped area between the seats where the motor sits. I thought it was a great idea at the time as was a very easy retro fit

Originally Posted by clean32

Um yes but there tubos feed into a centrafugal super charger that was on the back of the motor. and was only any use at altatude.

That was the whole point of supercharging aircraft piston engines, to maintain performance at altitude.The Allisons on P38's were fed through intercoolers between the turbos and the centrifugal blower.

HIJACK!

Hey Brian,,, any chance of a FLOW chart of your previous post?

On topic

any of the turbo gurus have a Air Mass temp chart thay could post ?

7 psi cold is a lot more than 14 hot ( or could be) a good possable selling point for remote turbos?

Originally Posted by clean32

Bang on,

Only thing is as the Gas cools its Volume decreases. But mass will not. As it is it quite difficult to convert velocity into pressure, and centrifugal turbines are far from the best at doing this ( as are tunnel rams etc) maybe remote turbo will lead to coaxcel units. Boosted at 30+ bar anyone?

possibly a free flowing manifold may negate some of the lag issues, the long return pipe work I would imagine could remove the need for a intercooler.

As an idea may be mounting a turbo in\on the winch bar? Or may be the roof? or maybe not. At least I could keep my Air con

While you still do have the same mass flow rate, the cooling of the exhaust gas means that you have lost both kinetic energy and internal energy.

The energy of a flow consists of kinetic energy, internal and potential energy. Obviously the kinetic energy comes from the velocity of the flow, the internal energy from the temperature and pressure of the gas and the potential energy from altitude that it is at.

The pressure of a gas is proportional to its temperature, so having a gas cool means you are loosing internal energy, also the density of a gas is inversely proportional to its temperature so again, as it cools its volume reduces and the velocity of the flow reduces so a loss of kinetic energy also results.

The amount of energy you can get out of a turbo really depends on how much energy is being delivered to it in the exhaust gas, so really you want the turbo as close to the engine as possible to reduce the amount of heat that is lost through the pipes.

If you were ever to measure the temperature and pressure of a flow going in and out of the turbine side of the turbo you will find that the gas going in is at a much higher temperature and pressure than the gas going out. The difference in these values can be used to know how much shaft power is being delivered to to the compressor.

Sooo... just to sum up, if you fit a turbo a long way from the engine, insulate the pipes... or don't do it.

Sorry for the spiel on thermal dynamics there, I just figured I better elaborate on it a little more for those interested.

[QUOTE=stirlsilver;848795]

The pressure of a gas is proportional to its temperature, so having a gas cool means you are loosing potential energy, also the density of a gas is inversely proportional to its temperature so again, as it cools its volume reduces and the velocity of the flow reduces so a loss of kinetic energy also results.
QUOTE]

ok but as the Gas cools it slows down, but the total mass passing any given point is still the same.


[QUOTE=stirlsilver;848795]

The amount of energy you can get out of a turbo really depends on how much energy is being delivered to it in the exhaust gas, so really you want the turbo as close to the engine as possible to reduce the amount of heat that is lost through the pipes.

QUOTE]

closer to the outlet just meens there is less pipe or volume to get up to pressur before the turbo begins to spin.

we realy need to get a chart up, it sort of exsplanes where the energy is.

but as i posted before, 7 psi could = 14psi cold, thats why we have intercoolers.

I suspect the reason the hair dryers are rear mounted is that there is insufficient room under the bonnet. Most of these modern jiggers have barely enough space left under the bonnet to get a feeler gauge in.

Originally Posted by clean32

ok but as the Gas cools it slows down, but the total mass passing any given point is still the same.

At the end of the day, there is more energy going in the exhaust system at one end (from the engine) than what is going out (into the turbo) because there is energy losses in the pipe. Without going through the thermal dynamic equations to show this, the energy content in the exhaust gas reduces as it goes along a pipe because you have heat being radiated/convected out into the atmosphere. This energy that is lost is now no longer in the gas and as a result, less energy is being delivered to the turbo for it to produce shaft power for the compressor.

Originally Posted by clean32

closer to the outlet just meens there is less pipe or volume to get up to pressur before the turbo begins to spin.

we realy need to get a chart up, it sort of exsplanes where the energy is.

but as i posted before, 7 psi could = 14psi cold, thats why we have intercoolers.

Perhaps having some length between the engine and the turbo is beneficial, since the exhaust gas is delivered in pulses rather than a continuous flow, but i'm really not sure here. But from a thermal dynamics stand point, less pipe the better.

I would be interested to see this chart actually. And you are probably right, depending on what temperatures hot or cold are, the cold gas at 7psi could be denser than the hot gas at 14psi.


By the way, I'm not intending to take stabs at you here or anything, I just enjoy these sorts of discussions