Twincharged AW11

[ohms]

Hi all,

I've been doing a bit of reading on this subject and have decided that I would rather spend the money on making the supercharger go like hell through turbocharging than feel dissatisfied with the reults of a wrung out SC12 build.
Having just sold my MK1.5 to start a new life here in Sunny south QLD it seems only right to build a car which in many ways will exceed the greatness and hopefully all round performance of the 2 litre 16v turbo...It's a tough act to follow!

So where to start with the twincharge. I've read more or less everything on the net regarding ideas for potential 4AGZTE plumbing and most just seem too complicated for there own good.
So far Cameron_Datto's set up seems to be the simplest and most cost effective way of getting the 2 compressors to work together.
As i understand it camerons car doesn't use any sort of bypass once the turbo comes on boost and it blows straight through the SC. I like the idea of this, but how effective will it be. What happens to the compressed air once it's recompressed, or does it even get recompressed?

If the SC is putting out a thoretical 10psi and then the turbo puts out 10psi as well what pressure will the inlet mani see?? Excluding pressure losses etc????

Thanks chaps

[Negative Boost]

I've never read too much on the subject of twincharge but i've always had the thought of Having the Turbo and SC using their own air supply. e.g one or the other not blowing through each other. So you have 2 inlets on the intercooler, the SC feeds one and the Turbo the other. Most likely you'll need to use a MAP ECU for this and not sure how you would control boost through the wastegate on the turbo and the (whatever is it) on the SC. I've seen this setup on a picture of RB26 and looked pretty good. Nice clean setup. Just controlling boost would be the main issue i would think.

[ohms]

The problem is, without completely reengineering the whole throttle setup/position side of things on the 4AGZE this wouldn't work. As I say like the idea of keeping it really really simple. But how will it work in practice?

[JBs]

So just from someone who has zero experience setting up turbos. Air > Turbo > Supercharger > Engine? Wouldn't it slow down the performance of the turbo once it hits the supercharger because the SC is more linear and is connected to the driveshaft? I know I made no sense there.

[ohms]

That's what I'm getting at mate, what happens when it hits the sc. Was thinking some sort of boost controlled bypass after throttle body around the sc maybe an external wastegate. But still like the idea of keeping it simpler still.

[Hash_ra23]

From my basic knowledge, having the turbo blowing into the supercharger is better because the supercharger creates exhuast pressure at lower revs which spools the turbo quicker. Then when the turbo takes over it creates boost which is further compressed by the supercharger but will reach a point where the supercharger cannot compress anymore. Not sure what happens then. I think you need to do a lot more research before you take on something like this.

Search for brett_celicacoupe's twincharging thread.

[brett_celicacoupe]

a few things to consider;

youll need to vent air between the SC and TB if you have the main TB after the SC

if you put the main TB before the SC then you will have to minise the volume of piping of the effective 'plenum'. this rules out a large IC after the SC.

if you have the TB before the turbo then youll need a special seal to stop oil being sucked through the turbo. the same consequence if you feed pressure into the turbo (i think?).

if youll use the clutch of a SC12/14, then you need some sort of decent bypass to provide the engine with sufficient air flow when the SC is off

[Drew]

mine runs a vg30 t03 on a hks high mount manifold>sc12 >front mount> gze inlet manifold.
bov between turbo & t/body (it used to blow the hose off before the bov was fitted)
with stock crank pulley & wastegate setting it has 18 pound at the manifold,i haven't checked the pressure between the turbo & blower yet .
it also has fullboost at 2500rpm.

bypass systems seemed to compicated,it works how it is ,will play with it more once i get a gearbox back in the car

[jfallen]

I like the idea of this, but how effective will it be. What happens to the compressed air once it's recompressed, or does it even get recompressed?

If the SC is putting out a thoretical 10psi and then the turbo puts out 10psi as well what pressure will the inlet mani see?? Excluding pressure losses etc????

Firstly the SC12 and 14 are positive displacment air pumps (blowers) and don't compress air.

Secondly they are overly complex and thus very few have ever been released from factory, infact only 3 come to mind :

1: Lancia Delta S4 (200 examples)
2: some Nissan thing in Japan
3: The new Golf.

This from wikipeadia:

Announced at the 2005 Frankfurt Auto Show to be used in the Golf GT, The 1.4l Twincharger is a TSI engine with a turbocharger and a supercharger in combination. Its downsizing leads to economy, with 14% more power than the 2.0 FSI but consumming 5% less fuel. The mechanical compressor operates at low engine speeds below 2400 rpm to increase low-end power, the turbocharger engages at middle revs, a clutch disengage the supercharger which will then be bypassed once the turbocharger reaches sufficient speed to provide boost above 3500 rpm.

This system is controled by the ECU but can be done mechanically as was the case on the Dela S4, (with a system of vacuum lines and diaphrams,) which operated in the same way with a bypass circut for the turbo.

If you were to pump the turbo into the supercharger you'd want 2 intercoolers, with this setup, you'd only need 1 on the Turbocharger circuit. + you can run bigger crank pullies without fear of your supercharger overspeeding as it is not in operation at high seeds.

My 2cents

don't bother and spend the money on a better turbo setup.
Jordan

[ohms]

Just the lag issue, it's always going to exist. A couple of years ago I used to run a VNT powered Renault 5 GT Turbo and although this would see full boost by 3000rpm and pull like nothing else higher up the rev range, lag still made itself felt. VNT might be a good idea but I like the low end shove provided by the SC...WOuld be nice to allie this with the top end shove of a fat turbo!!!

[myne]

Cameron Dattos is the simplest.
IIRC he was running the stock 8psi pulley, running the turbo at 10psi with appropriate intercooler into the SC, which then compressed the air to 23psi. Throttle body was in the stock position and the computer can be stock if you use an AFM gze.
All you need is a manifold, turbo, intercooler, a bit of pipe and it's done.

It's the totally simplest method there is and from what he says it pulls smoothly and has power much like a v8.

[ViPeR_NiPPleX]

could just run a twinscrew s/c? or just a well matched turbo, i'm sure something could be rigged up and not be laggy.... even staged turbos is simpler than twin charging, yeah?

[ohms]

Dunno mate, from what Myne has just said, Twincharging sounds easier than standard turbocharging the ZE...No pissing about with inlet manifolds etc. If it is and you get all the benefits of turbo power with none of the drawbacks(lag), then it could be a winner! 250whp is the aim...Should make it as quick as the 1.5!

[oldcorollas]

if you are chasing big power, wouldn't the standard ZE inlet be one of the first things to go?

[Cameron_Datto]

Here is a link to good chat on Twincharging , The Guy " Warpseed" has Been Playing with Twincharging for years , He likes to Run throttle Body on intake manifold and use a small external waste gate to regulate the boost pressure on supercharger outlet side and , this gives a more stable idle , apart from that its much the same Set up as mine , i managed to get stable idle with some fine tuning in the idle load bands , but it was touchy , due to the long distance between the throttle body to the intake manifold ,and the superchager running constantly .

http://www.skylinesaustralia.com/for...hl=twincharged