Tuesday, June 16, 2009

Twin-cas 4AG...~

In my opinion the beauty of a twincharger.. is having a small capacity engine that has effortless acceleration and feels like a larger engine due to the supercharger, yet has the ability to ram copious amounts of air into the engine for awesomeness and top end power. YET be able to turn the s/c off for fuel efficient naturally aspirated motoring at cruise and idle biggrin.gif I see this as a performance ideal we will see more of in the future as engine emissions and also engine capacities will be getting more and more restricted.

i've been doing a bit of research into this as I'm seriously keen to build a 20v twincharger in particular myself.

I would like anyone that has any decent links or info to add to this thread

Fensport have bought an hks twincharged front cut and installed it in their project ae92 and are now modifying it
they have a diagram of it too (below). (unfortunately their site has not been updated in a while???)

has anyone done their homework on s/c controlling and controlling the bypass valve?
a simple solution (as 'twincharger' has done on his ae86) is use a one way valve as a bypass so that when the turbo out flows the s/c, the one way automatically opens to bypass the s/c

I'm wanting to go a step further and use a diaphragm operated butterfly.. (have found a perfect source for one too! the 2L-T diesel has one). this runs off vacuum so will likely require a vacuum reservior (brake booster). bonus of this is have stepper motors and vsv's to keep it open all the time or closed all the time, all controlled from switches on your dash.. problem is how to operate it for a smooth transition to turbo. i was thinking to have it operate similar to the one-way, ie have it open once the pressure before it raises above the pressure behind it. is a bit more complicated than that so I'm very interested in more ideas on this.

as to s/c control.. i have limited experience of the 4agze system apart from a fang in a mates aw11 s/c.
control of the electromagnetic clutch engagement/release is going to be the dancing.gif or wallbash.gif in a twincharger project. simple but not the most efficient is have both running together. turbo blowing into the charger.. air from the turbo will need to be intercooled if you want the charger teflon coating to stay in one piece. the idea of this is that the s/c is sucking in 10psi or so and then compressing it further by 10psi.. does it actually work like this? maybe i dunno. if you have the turbo sucking from the s/c (look at vw system) without a bypass valve, it will be restricted by how much air the s/c can move.

ultimate would be to have a dedicated s/c controller that did everything.. someone please tell me how to build it haha hmmmm.gif .

another idea would be to make use of the std gze ecu controlling the s/c clutch on/off events yet intercept it at higher rpm and/or once turbo is boosting to switch it off, yet cut back in when intake plenum has vacuum and rev's dropped below the turbo's operating range... wouldn't want the sc clutch to engage as you back off the gas at 7000rpm every time.. this is another hurdle to overcome. was the HKS system somehow similar to this?

VW have recently put into production their 1400tsi twincharger engines which won awards. 125kw and 32.5mpg

1 comment:

Twincharger@hotmail.com said...

Hey, those diagrams look familiar.. :)

The one-way valve is just a copper plumbing check valve, no fancy controls on it at all.

The 4age ECU and injectors only handles about 16 psi of boost, so you will need an aftermarket ECU.

My supercharger clutch is activated with 75% throttle opening. Megasquirt takes care of that. I leave the supercharger on while the throttle is > 75%. That way, with small throttle opening you can run the turbo, and full throttle gives you both.

I haven't updated my website, but my twincharged 20v just put down 240 hp at 20 psi on pump gas on the dyno. Next time I should hit 275 with a better tune.