3SGTE Twin Charged

[CHB]

air filter -> turbo -> throttle body -> supercharger -> intercooler -> engine

if doing this way, will the turbo air flow choke down at supercharger during high boost(14 till 30psi)? this make sense but i am consider about the life span of the supercharger too as it will receive hot air from turbo. did you disable the supercharger at high boost when going this route? i think we can't right as once SC stop spinning the charged air from turbo hardly can pass thru the supercharger right?

[fixeruperer]

yep the sc will become the ristriction, the hks setup had a valve than when it reached a certain pressure would open up and let the turbo air go directly into the engine bypassing the intercooler (using top mount i/c), now if you had a intercooler after the turbo and a intercooler after the s/c it would cool the air down but but that valve is too small to make any real power.
Its all in the valve, you need a Y shape valve that has atleast a 2 1/2" ID thats stong and air tight up to a decent psi rating, controls quikley and is not to bulky wich it will be for a controlled 2 1/2" ID.

ive been thinking about twincharging for years but im not starting this project till i finish the ae86, but i think im close to a good setup.

[oldcorollas]

??
the SC is supposed to be a restriction. otherwise it will not have higher pressure going into it.
the SC will move it's volume of air, regardless of the pressure..
turbo will move air at a given pressure, but that volume is very variable.

ie, if the SC has 15psi air going into it, then it will move twice the MASS of air as normal.

ie, if SC is spinning to make 1 bar air, then it is moving twice the engines VOLUME.
if the turbo is pushing 1bar PRESSURE, then the MASS of air going into the SC is doubled.
since the SC moves twice as much VOLUME as the engine needs, then the result is, 4 times the MASS of air.

is it actually possible, for the SC to have higher pressure on the intake side than it's outlet? how can that situation occur? (unless it has MASSIVE internal leak back)


edit: there have already been a couple of decent threads on serial and parallel twincharging on toymods....

[fixeruperer]

wouldnt a turbo on full noise be better off going straight into the engine instead of going threw the s/c even tho the s/c is pumping the air thru, the turbo will be able to do it more efficiently especially if you got a big sized turbo.
superchargers generate extra heat you dont have to have also.

[oldcorollas]

a turbo at full noise making 1 bar, won7t be able to make 2bar and get the same flow... and will have a lot more exhaust restriction to do so

big size turbo needs big exahust flow to spin it up, and then you get laaaaag

here you have big turbo, powered by the flow from SC, and not pushing against a large resistance = win?

[fixeruperer]

win


910

[Norbie]

It's important to remember that roots type superchargers are a positive displacement pump, and a piston engine is also a positive displacement pump. So when considering a twincharged engine in a compund boost configuration (ie turbo feed SC with no bypass) it's useful to think of the engine + SC combo as just a bigger engine, so for example a 4A-GZE with the supercharger delivering 1 bar of boost is very similar to a 3.0 litre NA engine from the turbo's perspective. The fact that the air leaving the turbo gets compressed further by the supercharger makes NO difference to the turbo. Talk of the supercharger causing a "restriction" is missing the point somewhat.

[CHB]

thanks for the tips. but i have more question about the SC. once SC is switch off, does that means the supercharger act like a dead valve(block all the air from the SC inlet thru the SC outlet)?

[Norbie]

The SC will "freewheel" when switched off but it will definitely restrict airflow.

[Bazooka]

This pretty much says it all. This picture is of the Lancia Delta S4 Twincharged setup and what I believe to be the best explanation of this sort of system.



If you get onto the Skylines Australia form there is a guy on there that goes by the name Warpspeed. He seem to know everything there is to know about Twincharging and has done quite a few setups in his time. He is a wealth of information and a very helpful guy.

[e30-323ti]

c/o the old forum:

In a KE70 from NZ IIRC

Link

[brett_celicacoupe]

if you are only going to have 1 intercooler then its much more critical to cool the air entering the supercharger (PD type).

the supercharger will displace a fixed volume of air rather then pressurize the air to a fixed value like the turbocharger.

your aim is to force the most air mass into the engine. so for the supercharger to displace the largest amount of mass there is 2 things you can do. best way to look at this problem is with the ideal gas law. if you arent familiar with it, have a look here

we want the maximum air mass or maximum moles of air to enter the engine. so rearrange the equation to get n as the subject.

n=PV/RT

there are 3 ways you can increase n from that equation since R is a constant so it cant be changed.

-decrease T. T is the temperature so lowering it makes sense. for a supercharger-only application this is one of the 2 variables you can change . from this equation you can also say the mass of air pumped by the supercharger does not change with the introduction of a intercooler. the only benefit of a intercooler on a supercharger is to reduce engine combustion temperatures and to allow more timing advance. boost will typically drop with the introduction of an IC (can be proved by ideal gas law). this variable T, is limited to the ambient air temperature for all practical applications.

-increase V. In the real world, this corresponds to spinning the supercharger faster. ie more volumetric displacement per revolution. its pretty self explanatory. this variable is limited to either the max RPM of the supercharger or the inefficiency of the blower at high rpm

-increase P. This is the interesting one that is applicable to the twincharge discussion. increasing P corresponds to increasing the pressure at the supercharger inlet. so how would you do this? ..... with a turbocharger . if all other variables remain the same, then increasing the pressure at the SC inlet will result in no supercharger efficiency decrease.

is it actually possible, for the SC to have higher pressure on the intake side than it's outlet? how can that situation occur? (unless it has MASSIVE internal leak back)

this can occur if the displacement of the supercharger is less than the displacement of the engine (/rev (also disregarding VE of both)).

[oldcorollas]

i was assuming if the SC was set up correctly initially, to have more displacement than the engine...

[brett_celicacoupe]

its important to clearly state assumptions

[CHB]

i wonder how this GZTE runs
2 inlet, one on turbo, another from SC, only 1 intercooler. it seems like this is a parallel setup?