Delphi Electronic Variable Orifice (EVO) - Slicksheet

[1998_K1500_Sub]

I was rummaging through some old computer files and I found this Delphi Electronic Variable Orifice ("EVO") 2-page slicksheet with copyright date 2005.

I thought someone here may find it interesting, since many GMT400s were equipped with EVO.

(edit) I also found an interesting explanation of power steering system function; it was described in a patent for fluid flow control (attached). It's interesting reading.

Judging from the dates, I archived these around 2009.

 

[Supercharged111]

So reduced operating temperature, I wonder if that's why they were so stingy with the coolers in the later trucks?

 

[1998_K1500_Sub]

So reduced operating temperature, I wonder if that's why they were so stingy with the coolers in the later trucks?

That's a good observation. My 1998 Suburban had EVO and *no* cooler, so that jibes.

I've since removed the EVO valve, and installed the tube-and-fin cooler that GM used on other GMT400s.

 

[GoToGuy]

Thanks for the addition to my reference library!

 

[454cid]

So reduced operating temperature, I wonder if that's why they were so stingy with the coolers in the later trucks?

I didn't read the pdfs, as I'm on my phone...
You're saying hydroboost reduces the temps? If so, that's not what I would have thought given the fluid is doing more work.

 

[Supercharged111]

I didn't read the pdfs, as I'm on my phone...
You're saying hydroboost reduces the temps? If so, that's not what I would have thought given the fluid is doing more work.

No, the EVO claims to because it's making less pressure.

 

[454cid]

No, the EVO claims to because it's making less pressure.

I never would have guessed that. I assumed higher pressure.

 

[Supercharged111]

I never would have guessed that. I assumed higher pressure.

Only in a parking lot. Once moving it's less. Less assist anyway. I always thought of it a little differently, like you're backing up the pump and not allowing it to flow. Unless it's cracking open a bypass instead. I also always thought it was on or off, but sounds like the thing has a duty cycle.