Power Steering delete for fuel economy gain - anyone done it?

[orange4boy]

Sorry to be a killjoy but...

I've read some physics threads on the subject of rotating mass and those factors you guys are quoting are really high. They calculated more like between 1.5:1 to 4:1 but so much depends on how far from the axis the weight is. ie. One lb of tire weight has more effect than 1lb of rim weight etc. It also depends how fast you are accelerating. If you are drag racing then it makes a big difference.

Physics thread:

Rotating Mass when keeping a minimum weight Text - Physics Forums Library

Tuner thread:

Reducing Rotating Mass: Ditching Dead Weight [Archive] - Bimmerforums - The Ultimate BMW Forum

I ran similar numbers for the M3 flywheel just to see how they'd come out. I'm calculating a 1% acceleration difference in 1st gear going from a 26lb fly to a 12 lb fly, ignoring all other rotational mass (gearbox, wheels, driveshaft, accessories, etc). In this case that's like dropping 31.5lbs off the car's weight, or 2.24lbs for each pound of rotational mass drop. This doesn't seem like the dramatic difference that people seem to feel.

[Christ]

Yeah, see, I knew even I was wrong...

[SVOboy]

Originally Posted by Christ

Yeah, see, I knew even I was wrong...

Everyone knew you were wrong from the start!

Just kidding.

I wonder if there's a good web calculator out there for calculating inertia etc?

[Christ]

Eh, It happens!

I'm not the infallible one, ya know...

[Peter7307]

Originally Posted by bennelson

A bypass for power steering? Sounds like a cool idea!

A few weeks ago, I fixed my gas laundry dryer. The problem was the coil that electronically opens and closes the gas valve.

Couldn't a similar electronic valve be used to open and close a bypass for power-steering?

Bennelson,
Electric / hydraulic p/s units use exactly this method to achieve the result and a small processor attached to the steering column works out when the power is needed and how much.

As an aside the numbers from component supplier ZF (a main player in this area) suggest the fuel used just for conventional hydraulic p/s from a belt driven pump is around 0.5 litre/100 klms. The range varies depending on the application from about 0.2 to about 0.7.

Car makers would rather give up their first born than part with this sort of info in most cases.

Full electric systems draw about 35 amps at 12 Volts at full demand as a comparison.

Pete.

[orange4boy]

420 watts. That's half a HP. The engine has to supply double that to the alternator so the engine will have to supply 1 hp at full load.

A 200-W electrical load accounts for about 0.4 km/L (.94mpg) in the FTP 75 cycle test.

[meanjoe75fan]

I've spent a fair amount of time now in my Contour in EOC, and I find that the steering effort is quite acceptable. Also, I think that--for safety reasons--it'd probably be best if steering effort were constant (so that an emergency situation can be dealt with w/o having to think "wait: am I in EOC or not?")

The PS pump is right out where I can touch it in my car, and the inlet and outlet lines are, too. Thus, it'd be a 10-minute job just to bypass the pump and allow it to freewheel.

What I need to know is if this would eventually cause the pump to sieze. Is the pump mechanism lubricated by the PS fluid? I don't want to do anything that would take out the serpentine and (egad!) timing belts when the PS pump siezes. I could just loop the pump to the resevoir to "get a feel" for power-free steering, but that wouldn't do much to reduce pumping losses.

Another possibility woudl be to grid off the fins/lobes/whatever that actually pump the fluid, so that what's left could spin, but not actually do anything, or create (virtually) any resistance.

[Frank Lee]

What? If you aren't taking the belt off the pump, there's no point in it.

[meanjoe75fan]

Yeah, I know there's no FE gain, but I thought I'd route pump output back to the resevoir for a tank or so, just to see how I tolerate the PS delete before I do anything irreversible.

If I do delete the pump, I'll have to either put an additional idle pulley in place of the PS pulley, or try to find a shorter serpentine belt w/ the same width.

[4ringcircus]

I removed my belt for about a week. I could instantly feel the power improvement, but on a heavy 4x4 it was just too dangerous in tight situations.