Trackside Spares Package

#41

I have actually cut the belt and re-dynoed the car…and you have? Chuck

#42

cwbaader wrote:

Annoyed a couple engineers, evidently.:laugh:

OK. 7 horsepower from disabling power steering. With the pump not under load. Stationary on a dyno. Sure. Let’s just go with that.

The best part of this thread is now Chuck Taylor will go faster when he takes out his p/s pump. For that I am truly happy.

#43

Steve D wrote:

I can’t corroberate the hp#'s from any personal testing, but the pump would be under about the same load no matter what you are doing with the steering wheel. That’s just the nature of pumps.

#44

Ranger wrote:

[quote]Steve D wrote:

I can’t corroberate the hp#'s from any personal testing, but the pump would be under about the same load no matter what you are doing with the steering wheel. That’s just the nature of pumps.[/quote]Steve, appreciate the positive thoughts, thanks.

Ranger, really? Then why would a typical under-maintained vehicle driven by the typical American, back in the day before serpentine belts, generally only make the tortured PS belt squeal with the car stationary when turning the wheel vigorously but not when the steering is at rest? Isn’t it because when the wheels are turned the pump starts working harder, i.e. hard enough to make the belt slip?

#45

ctbimmer wrote:

[quote]
Ranger, really? Then why would a typical under-maintained vehicle driven by the typical American, back in the day before serpentine belts, generally only make the tortured PS belt squeal with the car stationary when turning the wheel vigorously but not when the steering is at rest? Isn’t it because when the wheels are turned the pump starts working harder, i.e. hard enough to make the belt slip?[/quote]
I think that a power steering box box senses “torque” on the steering column, not “position”. When the steering wheel is turned to right or left lock, the box still senses torque but can’t move anymore. That causes pressure to peak and put’s strain on the pump.

#46

Ranger wrote:

[quote]
That causes pressure to peak and put’s strain on the pump.[/quote]

hence increasing the load on the pump i would think… have we really started this discussion now? lol… from whatever reading i’ve done on the topic, 2-3hp seems more realistic but chuck does have the raw dyno data showing 7hp… whatever, 3 or 7, i’ll be happy with it.

#47

Ranger wrote:

[quote]ctbimmer wrote:

[quote]
Ranger, really? Then why would a typical under-maintained vehicle driven by the typical American, back in the day before serpentine belts, generally only make the tortured PS belt squeal with the car stationary when turning the wheel vigorously but not when the steering is at rest? Isn’t it because when the wheels are turned the pump starts working harder, i.e. hard enough to make the belt slip?[/quote]
I think that a power steering box box senses “torque” on the steering column, not “position”. When the steering wheel is turned to right or left lock, the box still senses torque but can’t move anymore. That causes pressure to peak and put’s strain on the pump.[/quote]

think conservation of energy: energy in = energy out. if the pump is continuously consuming 7hp (or whatever figure you choose to assign) then where does that work go when it isn’t busy helping you turning the wheels? btw 7hp is over 5000 watts, meaning that according to these figures the power steering pump is consuming enough energy to run three of my wife’s hair dryers. color me skeptical.

#48

Does not work that way. What we have is a constant pressure pump (I assume:cheer: ) so no matter what the load, the pressure/hp requirement stays the same, and in the same vein, the effort to turn the wheel stays the same. CB

#49

cwbaader wrote:

+1.
Think of your water pump. All it does is move fluid, as opposed to moving fluid and hydraulic cylinders, yet the water enters the block at ~30psi and comes back to the pump at ~4psi. Where does the energy associated with the missing 27psi go? Friction.

I’m not getting involved in the issue of just how much hp does it take. Chuck’s data, some reading around the Internet, and even Steve’s government chart, all seem to agree around 5-7hp tho.

#50

cwbaader wrote:

gotcha, i’ll just forget all that silly talk about conservation of energy that i learned while studying mechanical engineering.

#51

http://auto.howstuffworks.com/steering4.htm

#52

jtower wrote:

[quote]cwbaader wrote:

gotcha, i’ll just forget all that silly talk about conservation of energy that i learned while studying mechanical engineering.[/quote]
Dude, both Chuck and I are also ME’s. Don’t be a hardhead. Chuck’s right.

Looking at power steering from the standpoint of thermo is a bad approach because the system is not designed to transfer energy. It’s designed to amplify force and it works. If you want to understand power steering from an energy frame of reference you’re going to have to track down all the losses in the system. And in a complicated fluid system that’s all done empirically anyhow.

#53

i’m not trying to “track down” the losses, i’m merely saying that if the ps system is “consuming” 7hp then it has go somewhere. and when the system isn’t working to turn the front wheels then it’s gotta be dissipated as heat. and 5kw is a lot of heat.

i also don’t believe that the ps system “consumes” the same amount of energy when it’s actually helping to turn the front wheels as it does when the rack is stationary. obviously the pump is spinning (therefore SOME energy is required) but as there’s no external mechanical work being done it’s not much.

#54

i think we need to install many sensors on rangers car to figure this out :slight_smile: oh wait…

#55

jtower wrote:

I know a few guys running new cars and they run power steering fluid coolers. I can only assume the PS system creates a lot of heat in some systems or racers would not add extra weight to their cars for no good reason.

I am just bummed I had my PS belt off and my dyno numbers are still not that great. Wish I could find an extra 2 - 7 HP by just removing a belt. Thats a lot easier then a rebuild.

#56

i miss my ac alot more than my ps. maybe i can install a switch that disengages the ac clutch at full throttle. extra engine braking FTW.