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Engine Specific Info and Questions => IDI Engine => Topic started by: hamradio on May 04, 2008, 04:32:57 pm

Title: Some thoughts/questions on controlling a vnt
Post by: hamradio on May 04, 2008, 04:32:57 pm: So,
I've been thinking about how I'm going to set up the linkage on my vnt for my na diesel.

I'm going to simply control the vanes with a cable linked to the throttle cable bracket on the IP. Then use a external wastegate set at probably 12 psi.

When would I want the vanes fully closed at? 1/4 throttle? 1/2? 3/4? WOT? I would think one would want the vanes open as soon as possible, to quickly build boost.

Would it be worth it to rig up another cable to a manual control, so I could open or close the vanes as I please, from inside the car? I was thinking just a snowmobile/jet ski style choke switch under the dash. The kind with the little lever that pulls on a cable when you flip the lever up.
Title: Re: Some thoughts/questions on controlling a vnt
Post by: jimfoo on May 04, 2008, 06:23:46 pm: Quote from: "hamradio"

When would I want the vanes fully closed at? 1/4 throttle? 1/2? 3/4? WOT? I would think one would want the vanes open as soon as possible, to quickly build boost.

You want the vanes closed to build boost. I'd say have them opening between 1/4 and 1/2 for better economy. When manually controlled, they are easy to adjust.
Title: Some thoughts/questions on controlling a vnt
Post by: hamradio on May 05, 2008, 01:11:08 pm: Ugh, that's what I meant. :oops: It somehow seems backwards that closing vanes=spooling up. :D

Anyway, I'll set it up so that the vanes are fully open by around 1/4 or 1/2, like you said. How 'bout closed? By 3/4 throttle?

Another aspect-
I'm going to be running an external wastegate. Should I even bother with making some sort of boost control to open the vanes? Or would I be fine with closed vanes and an open wastegate? (don't they flutter or something at some point?)
Title: Some thoughts/questions on controlling a vnt
Post by: jimfoo on May 05, 2008, 05:12:42 pm: The only problem with not having an actuator to apply pressure is the vanes can start to stick after a while if carbon builds up. The actuator applies more force to them then just spring tension would. 3/4 for fully closed would probably be good.
Title: Some thoughts/questions on controlling a vnt
Post by: hamradio on May 06, 2008, 06:55:13 am: I won't be driving this more than a few thousand miles per year (and the vanes will get a good workout with autox), so I think I'll be fine. I designed my whole linkage last night; it'll work out pretty nice, I feel, when I'm done. I mocked up some parts, and will tig weld them later this week. :twisted: So, open by 1/2 and closed by 3/4?
Title: Some thoughts/questions on controlling a vnt
Post by: jimfoo on May 06, 2008, 07:34:38 am: I'd say open by 1/4, closed 3/4.
Title: Some thoughts/questions on controlling a vnt
Post by: numbnuts on May 06, 2008, 07:45:22 am: when u do this can u take a load of pics as i am sure there are quite a few of us that would like to see this done :wink: