What is an EVO valve?

[denpo]

A couple days ago a thread initiated by 1Michel got sidetracked on the subject of EVO valve.
The subject being of potential interesting to the modding crowd, I'm putting it in a decicaded post.


So people at some point were talking about hydroboost(as usual) and how it was way too powerfull for a Corvette, then I posted this :

What about an EVO valve?



Make it work past 25mph and you got best of both world. no?
Well, weight saving put aside, of course.

Someone needs to make a controller for the EVO valve. Certainly would cure a lot of steering problems. This is a Delphi document that explains pretty well how it works.

CRS sets in, I seen/heard of these controllers, but what sort of problems it cures?? my serp conversion, I fit the stock '72 brass valves into the back of the '88 vette pump, just to hook up the line, then when doing the rack some ten years ago, I cut the ends and spliced them, right off the pump, same valving setup......same trick for adding the HB setup, not a issue in the world with any of it.......what can that valve do for me???

:crutches:

The EVO valve is is a solenoid that pulses at higher speeds to reduce steering assist at speed. So your steering goes from full hydraulic assist at low speeds like parking to little or no assist when you reach a certain speed.

There is a Ford system that is essentially the same that uses a stand alone controller but I think it might be easier to make a controller that uses an accelerometer for speed sensing.

Cool, the PDF explain between which speeds to interpolate.
From what I could read here and there, EVO take a PWN signal to modulate and I know at some point I'll have a dedicated microcontroller to deal with those kind of things.
Anyone know from which car I you could pick a EVO valve that would fit the Corvette ps pump?

Below is a picture of the EVO valve (w/ Standard valve on top).

What car are they from? I see them on pumps from mid 90's GM products like Olds Acheva, Grand AM etc. Some Saturns.

Also, as far as hydroboost, the EVO valve wouldn't have any effect on that.

Here is the catch with the EVO controller. You don't want to reduce pump pressure, at speed, while turning the steering wheel quickly. You will get what is called pump "catch up" where the wheel feels like it hits a stop. All of these systems use a steering wheel rotation sensor to detect that. Thats why I thought a 2-axis acelerometer would be the best choice for the controller.

I have a ton of information on this if you would like to pursue this. I talked to a retired Ford engineer about this and a Delphi steering engineer. They gave me lots of info.

Also, as far as hydroboost, the EVO valve wouldn't have any effect on that.

I was about to ask why, but I rather did my homework.
http://forums.corvetteforum.com/c3-...wer-steering-flow-control-jim-shea-alert.html
http://forums.corvetteforum.com/c3-...e-know-how-a-hydroboost-works-internally.html
Looks like you had the same questioning 6 years ago and looks like you didn't pursue the idea, should I understand it's a dead end?

According to Jim the great, EVO valve modulate the flow and not the pressure to achieve its role.
Now I bought this things in the hope I would get better feeling in my steering and braking :
http://www.borgeson.com/xcart/catal...re_Reducing_Shim_Kit-orderby_0-p-1-c-133.html
Is this kit mis-labelled and should be called "flow reducing kit" or is it acting on the system in another way.
May reducing steering and braking assist level like pulling the rope from both ends?
Frankly I'm lost here.

Here are, may the discussion continue.

 

[Twin_Turbo]

electronic variable orifice

 

[BBShark]

Yes, it was a dead end. The rotation sensor for the steering wheel was a show stopper (although it's not that difficult).

The Ford steering engineer gave me a lot of info about the steering wheel speeds and EVO valve output. So basically you have two sensors (vehicle speed and steering wheel rotation speed) that control the valve. The two signals to the valve would have to be prioritized.

The Ford guy was really interesting. He was the steering engineer for the Panther platform. He actually autocrossed a mid 90's Crown Vic and sent me some video. That has to be the best handling cop car ever.

 

[mrvette]

Yes, it was a dead end. The rotation sensor for the steering wheel was a show stopper (although it's not that difficult).

The Ford steering engineer gave me a lot of info about the steering wheel speeds and EVO valve output. So basically you have two sensors (vehicle speed and steering wheel rotation speed) that control the valve. The two signals to the valve would have to be prioritized.

The Ford guy was really interesting. He was the steering engineer for the Panther platform. He actually autocrossed a mid 90's Crown Vic and sent me some video. That has to be the best handling cop car ever.

Interesting, I know a Clay Co. Florida cop here from maybe 12 years ago now, and he still drives his mid 90"s Crown Vic..wonder if that's why, never discussed it with him.....:beer: