Author Topic: aftermarket controller to control a VNT? (Read 26149 times)

xud9te · « **Reply #30 on:** February 08, 2007, 12:52:57 pm »

Have you used a bleed valve on the actuator to test? This gives the effect of a stronger spring, but also shortens the full travel in some cases (raising max boost).

Tintin · « **Reply #31 on:** February 08, 2007, 03:09:54 pm »

yes, but that creates boost spike.

jimfoo · « **Reply #32 on:** February 08, 2007, 03:34:40 pm »

I know some of you wish you had an engine speed dependant vacuum source. How about a vacuum source based on boost? I was thinking that a tube stuck in the airstream at the intake of the turbo would create a vacuum that varied with the ammount of air being sucked in, and boost being produced. This could be used for whatever control purposes one wished, and could also be used to protect against loosing a hose post turbo. I have no idea how much vacuum could be produced as my engine is currently in many, many pieces, but I bet it would be a fair ammount. Just something to think about....

xud9te · « **Reply #33 on:** February 08, 2007, 04:01:40 pm »

Tintin, not a ball-spring valve, but a simple screw bleed valve? Did you find a spike with this one??

Tintin · « **Reply #34 on:** February 08, 2007, 04:05:16 pm »

No, I have a filter minder between my turbo and my airbox and when I put 30psi of boost in my turbo, the minder indicate aprox. ½-¾ psi of vacuum, at 15-20 psi, 0 indication.

Tintin · « **Reply #35 on:** February 08, 2007, 04:09:31 pm »

Quote from: "xud9te"

Tintin, not a ball-spring valve, but a simple screw bleed valve? Did you find a spike with this one??

Yes, it's a bleed valve, So that a bleed valve run correctly, a restriction should be made, and that causes spikes, dont forget, a vnt reacted very quickly.

jimfoo · « **Reply #36 on:** February 08, 2007, 04:19:06 pm »

Quote from: Named Tintin

No, I have a filter minder between my turbo and my airbox and when I put 30psi of boost in my turbo, the minder indicate aprox. ½-¾ psi of vacuum, at 15-20 psi, 0 indication.

I don't mean just a hole to the intake, but a tube that will have a venturi
effect, kind of like how a carb sucks gas out of the fuel bowl.

____________| |_________
........................| |_
........................|___ to turbo ->

________________________
Ignore the dots. I had to put them there to make everything line up.
Something like this. I had a Jeep truck that used a similar effect from the
air going to the EGR to create vacuum for the heater controls, so I know
it can work.

xud9te · « **Reply #37 on:** February 09, 2007, 02:31:50 am »

Yes, but I have a bleed valve on my VNT and there is only 2psi spike at 25psi, less than it shows on your video no?

xud9te · « **Reply #38 on:** February 09, 2007, 01:19:55 pm »

A boost spike is just an overshoot of the desired boost point (where it settles)

Tintin · « **Reply #39 on:** February 09, 2007, 02:55:46 pm »

If it is of my video that you speak about the spikes, it is normal, I do not have a bleed valve and I do not have a ball valve, I tested a bleed valve only one time during 15 minute and I removed it :wink: