4AGZTE winter project

[JasonFriday13]

Good point. I wonder if the ecu turns the supercharger clutch off once the turbo spools up, therefore never operating in compound mode?

[Ash Kelly Barr]

Cant find the article but there was a guy in tasmania that twin charged his 70's alfa 2L GTV

From memory he ran the charger feeding the turbo with no bypass. Charger ran 7psi and gate had a 12psi spring. But ran compound boost of 22psi

And I have read of a guy that had a different method
He had the super feeding the turbo. Both chargers had their own intakes and filters
How ever the turbo had a flap and would switch between super and atmos intake
The super mag clutch would switch with this

The flap wwas controled by a solinoid much the same as most high end cars exhausts have muffler bypass' between town and sport mode

[Ash Kelly Barr]

Both set ups had IC before intake manifold and where based on turbo spool from feeding it air and exht gas rather then just a higher rate of exht gas

[Mike n Rochelle]

Mine is going to feed the turbo from the supercharger and i will run a bypass from there to a single filter. As for the throttle body I was going to put it just after the filter but is it the wrong place to put it?

[Ash Kelly Barr]

Dont see why not but id think it would lack throttle response?
Edit: throttle being so far away might make it hard to tune and get running well. From memory the alfa guy said tuning it was the hardest part and he had books of math calc's he had done

I know your've come this far but why not an NA intake and throttle?
Ive got a couple sitting here free to a good home if you want to try

[Mike n Rochelle]

That is a point it would need to be modded to mount the supercharger to the bottom of it but it might buy me some space too. I know of one down here I should be able to get my hands on so i will chase it up. Thanks for the offer

Just out having a bit of a play and am going to go throttle at the intake manifold and i also had a play with the electronic throttle body i have here to see if i could get it to work as my bypass valve. It has a small amount of leakage that i would need to sort if i dont want it to loose some of the pressure from the supercharger but it looks like its going to work. the idea was stolen from a Corolla that had used the same idea only difference being that he used a Nissan v6 throttle body instead of the Holden one i am using. He seems to have had success with his so i thought what the hell lets give it a shot.

I also now have a cas from a 101 gze to go on and possibly some other bits so that will help a bit later with the whole wiring situation.

[JasonFriday13]

Have you thought of using some sort of one way valve (with a return spring)? Just another idea I'm throwing out there.

[Malcolm]

IMO there are only two options for plumbing arrangements:
1. Parallel intake tracts - one is air filter > supercharger to Y pipe, other is air filter > turbo to Y pipe; from the Y pipe you then go intercooler > throttle body > intake manifold > engine

With this layout you NEED a bypass valve to recirculate air from the supercharger when the throttle is closed or partially open (the stock 4agze ABV would be fine)
You also NEED a flapper valve (i.e. a one-way valve) on the outlet of the turbo so the supercharger doesn't blow backwards through the turbo before it spools up
If the flapper valve is designed correctly it wouldn't need any external control to balance the flow between the two, so it should be an entirely passive device. This layout should give you the best of both worlds - normal supercharged performance at low RPM with the overall power output of an engine with a large turbo.

2. Series inlet tract - air filter > turbo > throttle body > supercharger > intercooler > inlet manifold > engine

With this layout everything after the throttle body is the same as the stock 4agze layout, you simply have a turbo installed before the throttle body. This is much simpler to control but you would be limited in potential power output by the supercharger. It's important to remember the supercharger is a constant-displacement pump, meaning for a fixed rotational speed it will flow the same volume of air (within certain limits). By putting the turbo before it, you can compress the air before it reaches the supercharger, so you have denser air entering it (i.e. higher PSI) and therefore a higher mass flow rate of air into the engine for the same volumetric flow. Unfortunately with this layout, once the turbo is spooled the supercharger starts to become an inline heater for the air and doesn't contribute to increasing the mass flow through the engine at all. You could try utilising a large diameter bypass valve to divert air around the supercharger once the turbo is spooled (I'm guessing this is how the HKS system works), but I would imagine it could be very difficult to properly configure the switching of this to give any useful driveability/throttle control - perhaps OK for a drag car but probably not for circuit racing/street use. Of course the only way to find out is to try it.

Personally, I'd pick the first option.

[Mike n Rochelle]

Twincharger setup.png (9.71 KiB) Viewed 2348 times

This is a crude pic of what I was planning

Filter to a y pipe
one branch to the supercharger inlet and one to the branch between the supercharger outlet and the turbo inlet that will open with the electronic throttle body when the turbo has reached boost and the supercharger will switch out at the same time.
I wont need to worry about the supercharger holding pressure when the bypass valve opens as the valve will not close the outlet off from the supercharger so the excess pressure will just get sucked into the turbo. there will be a blow off valve between the ic and the intake manifold for when the throttle closes. I might need to put in a second bov in between the supercharger and the turbo to stop any pressure spikes.

[JasonFriday13]

So it sounds like the VW 1.4 TSI engine:

[Mike n Rochelle]

That was the pic i was looking for
That was what i was working towards

[Ash Kelly Barr]

Would make sense youred need to bypass the charger actually. Think the alfa guy had trouble tuning because his flow and pressure rates where all over show
Would think somethink bigger then the ZE abv would be ideal though as it would be restrictive of flow unless you left the charger on full time?
Even then?

[Mike n Rochelle]

I have a electronic throttle body ex a horden crewman for the job that is from memory 80mm so i wont have any issues with flow via that

[Mike n Rochelle]

My gates cambelt has arrived just got to pick it up

[Mike n Rochelle]

Not alot of progress of late as motor is almost done. Got a pair of cannon mufflers today for it, 2' in and through to the 3' outlet. should look good and with the rest of the exhaust set up right should sound good too.
Car going into the garage tomorrow so i can start on the body finally as Rochelle's car is running (starts by bridging the starter).
Looking to do the bonnet vent mod along with the front wall cut. Also have to make holes in the rear wall in the engine bay for the intake pipes.
I am also looking to do a one part boot\ engine bay lid with the bigger vents from a sw over the engine bay end. Might never happen but i will see how it works out when i do the mock up.