Can a supercharged intake system be reordered?

[Kender]

I was sitting with the wife watching Love Actually last night when I started thinking about possible modifications to my car (as you do )
The intake system on my 4agze currently goes:
air filter - throttlebody - supercharger - intercooler - intake manifold.

Now, I have an SC14 sitting in the garage, and fitting this requires changing the intake manifold. I've seen people use the intake manifold from a 4age, and at first glance it would seem to make the installation easier if the throttlebody could be left on the intake manifold. ie reorder the intake arrangement so it's
air filter - supercharger - intercooler - throttlebody - intake manifold

I've been pondering this all night and I'd like to get some opinions on my thoughts.

By placing the supercharger next to the airfilter (ie same arrangement as in a turbo car), the supercharger will believe it's permanently operating at full throttle. ie will try to process maximum amount of air. However if the throttlebody is between the s/c and the intake manifold, that air shouldn't reach the engine and the revs shouldn't skyrocket uncontrollably (I love that word "should" ). Now I think we need to introduce a wastegate before the throttlebody to bleed of the surplus boost.

Lets consider 3 situations, idle, wide open throttle (WOT) and 6000rpm throttle closed.
At idle, we need the least air pumping thru the engine, so it would seem that virtually all the air passing thru the s/c needs to be dumped. But my 4agze idles at 1500 rpm, and the s/c speed is controlled by the engine. We'll assume the s/c spins once for every crankshaft revolution (because I don't know what the real relationship is). So while the s/c thinks it's operating at WOT, it's only spinning at 1500rpm, so can't be pumping that much air thru. The throttlebody will meter out the correct amount of air required by the engine, and the surplus will be bled off by the wastgate. I imagine this will make a constant, hissing sound at idle.

As we snap the throttle open, the throttle butterfly opens, the wastegate closes, the hissing stops, and the engine receives full air flow from the s/c, the revs rise, s/c spins faster which in turn feeds more air in etc etc.

This leads us to 6000 rpm and now we want to change gear. We lift off the gas, the throttle butterfly closes, surplus pressure builds up between the s/c operating at full noise and the throttlebody so the wastegate opens. (Insert lots of venting noises here) I imagine the venting noises would quieten as the revs drop, and then stop when the next gear is selected and the throttle nailed again.

Does anyone know how to calculate the air requirements at each of these 3 stages to know if this setup would be possible? Any thoughts on driveability/desireability or my logic?

Cheers
kender

[ants_ae92]

New intake manifold is not necessary, bazda has done this conversion on freds car, just brackets and piping was needed.

There is a rwd celica in australia that used the sc14 like you are proposing. Think its number plate is bluewire, or nicknamed sumthing like that.

[Rick]

introduce a wastegate before the throttlebody to bleed of the surplus boost.

You wont be needing a wastgate as such but more of a BOV.

One item you have missed is the ABV or (Air Bypass Valve) which bypasses the supercharger when its not being used, and if you are using the SC-14 running more than factory boost you will need to disable the boost cut on the ABV. Sure you can have the supercharger running all the time and you wont need the ABV but I woundn't recommend that as the idle would most likely be ruff, unreliable setup etc...

Iam not using a SC-14 on my car but I am using a SC-12 with a N/A intake manifold with the throttlebody after the supercharger. Unfortuantely I haven't finished the car yet so I can tell you how it goes, but if you speak to Tim "gdsup" he has a similar setup in his car which seems to go quite well.

Not the best pic but thats how it looks in RWD format.

[Bazda]

Fred never had the time to get this finished! there was a damn air leak somewhere that we couldnt find so boost would go up to 14psi then drop back down, but when it came on felt pretty good .

he has now taken the kit off and put it back to standard cos he is selling the car.

he has bought a new gtz trueno lol the nice one down in christchurch and will be putting the kit onto that very soon .

[gdsup]

yo, I have this sort of setup on my car, air filter - sc12 - intercooler - blow off valve - throttle body - inlet manifold

ok, this set up seems to work out good, no apparent cons, there are however some slight diferences it the way it drives, before throttle used to feel like it would hang on a litttle on lift off, now it is very very responsive, almost a bit to responsive(could be related to my smaller plenium size and short runners)

you will need very good intercooler piping, with good quality joiners and clamps, when you lift of at 7500rpm the charger is still on and pumping air for around 4.5 seconds, needless to say a piece of junk blow of valve off trade me will not cut the mustard,

I made the change for a reason and that was purely sharp throttle response, not sure if the other side effect would warrent the changes on a dailey/front wheel driver.

Here endeth today's lesson.

[wde_bdy]

Have seen it done with synchronised throttle butterflies, one before supercharger and one after. May be worth looking into.

Callum

[crshbndct]

i am very close to buying a 4agze powered car, and i am interested in this as well, i like throttle response and i am not keen to have a car which leaves the throttle open when i close it.

although a turbo seems like an easier option.

[Kender]

now it is very very responsive, almost a bit to responsive

Interesting, I hadn't thought about that.

when you lift of at 7500rpm the charger is still on and pumping air for around 4.5 seconds

where does this figure come from? Is this the time it takes for your revs to drop to the point where the ecu switches off the s/c? My car has a manually controlled s/c, so it runs all the time - even at idle. Do you think this would pose a problem?

not sure if the other side effect would warrent the changes on a dailey/front wheel driver.

I'm looking at this for an AW11 race car. I started thinking about this configuration as an intermediate step to installing a turbo. This would allow me to setup the intake side side (and use the sc14 I have), and later swap the s/c for a turbo (with the appropriate exh manifold of course)

[gdsup]

when the ecu map sensor or tps on afm versions senses the throttle close and engine come on vacum the s/c clutch remains engaged for around 4.5 seconds as to not wear out the magnectic clutch during mid corner/gear change lift offs, If it did switch off instantly on lift off the clutch would wear out quickly.
also interesting to note that when i take off out of pit lane etc on 1/2 - 3/4 throttle and the revs hit around 5000rpm the pedal feels lighter like it is being pushed open by the s/c, standard 4age throttle return spring seems to control it fine tho

[TygerTung]

How about fitting a plum back BOV that might work?

[Bazda]

how about plumbing it correctly but using the n/a inlet manifold sort all ur problems

[3T-Rona]

There is a rwd celica in australia that used the sc14 like you are proposing. Think its number plate is bluewire, or nicknamed sumthing like that.

yeh its an 18rgeu in a ta28 i think (dnt quote me on that)

this sounds like quite a gd idea, reordering the setup that is, as im running a rwd 4agze in a ke25, so i need n/a intake, bov, intercooler and piping..... how would quad throttle bodies go? who makes adapters for these any way as i have the throttle bodies.
i real thinker any ways...... have a link computer too maybe ill swap the sc12 for a 14..................