I want to know all the N/a turbo guys' take on keeping the auxilary ports functional after converting the N/a block to a forced induction system like a stock TII turbo. I am talking about fully electronic(not electro-pneumatic) using a pair of servos or actuators. I would also use the same thing for the VDI if it was on my S5. Would you all want to keep the system or would you remove it? I was talking about it with a friend and he said he thought it may be dangerous because of the presssurized intake charge but I didn't really see a problem with it. Both of us aren't that experienced with this situation but would like some imput on what would be optimal. This is a street car application as always. To me it always seemed that the aux port system's removal resulted from clearance problems with the turbo. What if there is enough clearance for the actuators?


Santiago

 

I removed my actuators for two reasons:

1. No space
2. After I pulled the upper intake, I had noticed that some "helpful" mechanic had removed the sleeves while the car was still owned by a DPO (Dumb Previous Owner). I didn't feel like removing the lower intake to reinstall.

Really, the system is not needed with forced induction. The turbo more then makes up for any lack of torque created by the removal of the 5th and 6th port sleeves...

However, if you want to keep them, I would suggest using bicycle cable to actuate them, since there is no room for the actuators, and electronic actuators that can stand up in the environment would be very expensive. Just bring the two bicycle cables to the inner fender, then attach to the actuator plunger. Connect actuator directly to manifold pressure.

But a lot of work for probably no gain. Might have slightly better off boost torque, but then if you need that torque, you'll be under boost anyway, so...

 

I plan on removing my for simplicity. I don't know how well electronic survos would hold up under the heat of being aroudn the turbo for very long.

I suppose, that it might increase low end torque like it does on the NA, but i'm not certain. This is something you'd have to experiment with.

 

Thanks for the input guys, the answer Aaron Cake gave me really isn't that clear on what your take is on it. Parasite is on the right track I think. I would probably have to drive around with and without them to see if there is any benefit to either setup. Now that we have found a nice dyno with affordable rates in town I will probably be able to do dyno's before and after.

 

Get back to us with the info, if there benefits to do so (and it's not too complicated to do) I'll put it on my car in the spring.

 

I would leave the Aux ports open from what I have read.

The NA's Dynamic Effect Intake is tuned to make nearly 2psi of positive pressure on the NAs at 6,500rpm in order to overcome the extra duration of the aux ports. Impressive for an NA.

Though, on a turbo 2psi should be available ~1,000rpm or so...

 

pmed u 87

 

Blue TII thats true so the VDI should stay closed? The aux open?(maybe removed sleeves)

 

zp1979

got your pm thanks for the heads up. At that cost I will definately try it.

 

The S4 intake doesn't have a VDI, so it might be different.

 

I have an 89 GTU sorry

 

Get a S4 NA intake then! LoL

 

lol I have one actually. I'll have to see which one is better for the forced induction.

 

We can guess and theorize, but no one will know without dyno results...do a baseline with them closed, one with them open, and then experiment with various opening points for both systems.

 

If things turn up for me after I get through paying some of my parts off I will be doing a dyno set with the primary baseline being fully N/a. Then I want to go full electro actuation for the VDI and aux system. This will probably take me a while because I will need to buy two RPM switches for the two setups. Then going back under 8psi of boost on the N/a block with fuel curve adjustments Then do the different rpm timings.


Santiago

 

I've searched before but never did find out EXACTLY how the VDI works. I know its an S5 feature only, but what the **** does it do? open up a bigger passage in the UIM or something? thats all I can guess.

 

Something to do with pressure and air flow. Oh well, i alraedy removed and blocked off my aux ports, and am gonna leave my VDI shut for turbo. my car felt faster with it being non-functional anyways. maybe my new setup didnt create enough pressure for it to work properly or something...i dont know, but as of now, my actuators/sleeves are gone, and my VDI is shut, turbo rebuild (self rebuild ) is in order.

 

Although you're right, you know people on here like to "theorize" stuff and never actually do it .

 

your welcome i think it might work pretty well. My only concern is the life expectancy of them? But at that price oh friggin well...

 

We can guess and theorize, but no one will know without dyno results...do a baseline with them closed, one with them open, and then experiment with various opening points for both systems.

Good point. I am hoping to do this w/ throttle plate opening. Right now I have all plates open at once , but I was going to dyno the low end w/ just the primary plates opening VS all opening at once. I suspect boost will not build as fast w/ just primary opening because of the pressure drop, but this may be offset by the higher runner velocity.

 

I would actually be more inclined to find a way to keep the 6 port system functional. This off boost torque is a good thing when it comes to fuel economy or just cruising. I'd just hook up the pressure lines to the intake manifold. Once boost kicks in, they open. Simple enough. I would also find a way to keep the VDI working. Again I would just hook it up to a vacuum (or in this case pressure) source from the intake manifold. Use an rpm switch to trigger a valve at the stock rpm opening point. Basically the same thing as the air pump actuated 6 port system. My logic is that if the effect is beneficial, it will be beneficial regardless of intake pressure. A turbo does make up for alot of things though. That's just how I'd do it.

 

The problem would be space. A Turbo manifold would not fit with the stock 6port actuators still installed.

The VDI, on the other hand, coud be connected directly to the manifold should work.

 

Yeah I know there isn't much space there. I would probably just build a new manifold to relocate the turbo elsewherre. Of course at this point you may as well just use a different turbo since it isn't an easy (so to speak) bolt on anymore.

 

I think rotarygod has it right. Keeping the aux port actuation should help mileage and off-boost throttle response as well as idle quality.
The VDI system changes effective manifold runner length based on RPM. It looks like it should work very well for a near-stock NA, but after playing with my S4 manifold and FC-Chan's S5 manifold I'm sure the S4 will flow more air. It's also possible to port the S4 without extrude-hone equipment. (If anyone knows an easier way to get into that damned S5 manifold, I'd love to hear it!)

 

I have.

Alright, here's what I did. (Each run had the MBC at 12psi)


I used two servos, with with obvious custom brackets/etc to mount them back and away from the turbo and obviously space. I then did basically 3 gtech runs in with each config (yes, not quite dyno, but it's 4 hours away and I'm broke, so, STFU, don't want to hear it). Anyway, the net result was basically this, with them servo actuated the turbo began spooling about 200rpm earlier (this was just noticed) As for time comparison? The difference of both averages was less than .02, so I really don't think performance wise there's much else to say. Sorry, no VDI experience.

Overall result? I wasted my time. With the stock turbo and n/a rotors, you really won't have much to worry about, except keeping the tires planted.

Oh, previos poster was right, the S4 manifold flows better than the S5's.