VDI on my turbocharged N/A? I can finally use it again!!
06-18-02, 07:46 PM
#1
I came, I saw, I boosted.
Thread Starter
Join Date: Apr 2001
Location: Windsor, Ontario, Canada
Posts: 1,921
Likes: 0
Received 0 Likes
on
0 Posts
VDI on my turbocharged N/A? I can finally use it again!!
Well, I just thought of something- I will now be able to actuate my VDI (which is currently locked in high) since I will be putting the turbo on!
I am guessing it won't have dramatic effects, since the system was tuned for non-pressurized N/A, but I still think I may get some low-midrange gains by having it switchable again.
Since the VDI uses the airpump pressure, sent to the VDI by a solenoid that opens at 5200 rpm. With the turbo I can just use manifold pressure! By 5200 rpm, the turbo will (I hope
) there will be substantially more than the 2 psi required to open it.
One thing I am wondering though.... should I run the actuator directy to manifold pressure, and removing the solenoid completely. This will cause the VDI to open as soon as the 2 psi is reached.... but this may be way too soon, when is this pressure normaly reached?? 2500 rpm?
I may just use the solenoid, to open it at 5200... even that may be a little late considering the extra airflow the engine is getting...
Maybe I'll use the disconnected 3800 rpm aux port solenoid...
This just occured to me today as I was replacing and securing all my vacuum lines.... I've never heard of anyone using it, but then again, I've never seen anyone turbo an S5 N/A!
I am guessing it won't have dramatic effects, since the system was tuned for non-pressurized N/A, but I still think I may get some low-midrange gains by having it switchable again.
Since the VDI uses the airpump pressure, sent to the VDI by a solenoid that opens at 5200 rpm. With the turbo I can just use manifold pressure! By 5200 rpm, the turbo will (I hope
) there will be substantially more than the 2 psi required to open it.One thing I am wondering though.... should I run the actuator directy to manifold pressure, and removing the solenoid completely. This will cause the VDI to open as soon as the 2 psi is reached.... but this may be way too soon, when is this pressure normaly reached?? 2500 rpm?
I may just use the solenoid, to open it at 5200... even that may be a little late considering the extra airflow the engine is getting...
Maybe I'll use the disconnected 3800 rpm aux port solenoid...
This just occured to me today as I was replacing and securing all my vacuum lines.... I've never heard of anyone using it, but then again, I've never seen anyone turbo an S5 N/A!
06-18-02, 08:08 PM
#2
Rotary Enthusiast
Join Date: Aug 2001
Location: Tallahassee, FL
Posts: 1,402
Likes: 0
Received 0 Likes
on
0 Posts
The VDI will probably net you no gain. If anything it'll just delay turbo spooling, since being closed, it will act as an intake restriction. It's designed to work under a vacuum, and make use of port reversion. Once the VE goes above a certain point, it really won't do anything. You also won't realize any low- or mid-RPM gains, since the system's not designed to work there - only at 5500 RPM and up.
I'd just leave it wired open. (Sorry if I've rained on your parade)
Brandon
I'd just leave it wired open. (Sorry if I've rained on your parade)
Brandon
06-18-02, 08:14 PM
#3
Rotary Enthusiast
Join Date: Aug 2001
Location: Tallahassee, FL
Posts: 1,402
Likes: 0
Received 0 Likes
on
0 Posts
Revision:
After reading an article by Paul Yaw, I think that you may in fact find some top-end gains from the system vs. not having it at all. Turns out that in the third gens, Mazda designed a similar system to the VDI. While it's sort of a moot point, since my recommendation to simply leave it open still stands, I'd be interested in seeing some open vs closed comparisons.
Brandon
After reading an article by Paul Yaw, I think that you may in fact find some top-end gains from the system vs. not having it at all. Turns out that in the third gens, Mazda designed a similar system to the VDI. While it's sort of a moot point, since my recommendation to simply leave it open still stands, I'd be interested in seeing some open vs closed comparisons.
Brandon
06-18-02, 11:15 PM
#5
I came, I saw, I boosted.
Thread Starter
Join Date: Apr 2001
Location: Windsor, Ontario, Canada
Posts: 1,921
Likes: 0
Received 0 Likes
on
0 Posts
I was assuming that the tuning of the reversion waves would require different timing to work under pressure...
But I have to dissagree that it was designed to work under vaccum... It was designed as a full throttle power adder- therefore under 0 manifold pressure.
I may have to brush up in it's operation- but I don't think it actualy restricts the intake at all when in the lo rpm setting- I'll check the diagrams, and when I get the turbo in, I will definately do some tests.
But I have to dissagree that it was designed to work under vaccum... It was designed as a full throttle power adder- therefore under 0 manifold pressure.
I may have to brush up in it's operation- but I don't think it actualy restricts the intake at all when in the lo rpm setting- I'll check the diagrams, and when I get the turbo in, I will definately do some tests.
Thread
Thread Starter
Forum
Replies
Last Post
mulcryant
2nd Generation Specific (1986-1992)
10
09-09-15 05:24 PM