Flow rate of PS Fluid and how much power is the pump robbing

[Infinitiguy19]

The recent topic posted here about Power Steering (PS) fluid has sparked my attention. If one decides to add a cooler to the PS system how does one decide the size to prevent over/under cooling?

Would a electric PS pump increase engine power or would it be just like adding a electric fan, and shift the load elsewhere (Alternator)? Of course viscosity matters so when the fluid is cold the pump works harder (more engine power is robbed) VS when the fluid is warm. How might the Engine Control Unit (ECU) react during the warm up process though? Or would the car warm up faster because less power is robbed and because the Fast Idle Cam is responsible for warming up the engine to 150* F then the Idle Air Control Valve/Idle Air Control Valve (AAC/IACV) takes over? (I think 150*F is a little off as I have been out of the Q game a little while.)

This topic shows some figures based on a Audi PS pump: transmission-cooler-btu-question-t233104.html

This topic also helped a great amount: transmission-cooler-btu-question-t233104.html

With a dealer/specialty shop power steering pressure gauge we can measure PS Pump PSI VS Engine RPM and with a few other figures create a graph to find out how much fluid is flowing through at a given time. Of course ambient temperature would be another variable.

But the Active Suspension (Act Sus) pump is run off the power steering pump*! The Act Sus system uses 6 Quarts and the cooler has a BTU per hour rating of 8,730. Of course the Act Sus system uses a different type of oil which makes the math slightly harder.

*Active Suspension Q45's only.

I wish Q45Tech was here.

[RustyBucket]

Doesn't the Q have speed sensitive power steering?

If so, then the amount of power lost to the P/S system will vary depending on speed, as it will be working less higher speeds.

An electric P/S unit will likely require at least as much power as the belt driven one. The load will merely be transferred to the alternator. Ever notice how the engine works harder after a car has been started by jumper cables due to a dead battery? The alternator is working harder to recharge the battery. You would get a similar effect by putting an electric P/S unit in, although less pronounced. The only way you could potentially reduce power loss through the P/S pump by using an electric one is if the electric unit is much more efficient than the stock one.

Honestly, in my opinion, the minimal power gain you might see would not be worth the effort.

That being said, it could be worth the effort because it would free up a pulley on the engine... a pulley that could be used to drive a supercharger!

[Infinitiguy19]

And we all know especially Owner CS fun replacing a Alternator is! I didn't focus as much on the electric PS pump when I posted this. But I did a quick Google search and saw its a little more involved than I thought.

[maxnix]

Pump consumes more power at full lock than straight ahead.

[Lokim]

Paul, leave it to you to ask something like this. You have one of the most curious minds I've ever encountered!

I know from experience that removing a belt driven fan is good for anywhere between 5-20 HP depending on whether it is a clutch fan, blade pitch, etc. Our Q's do have variable-orifice (a.k.a. speed-sensitive) power steering, so power gain would vary with vehicle speed and steering input.

I think that the actual increase in engine load due to added electrical load by an electric P/S pump would be negligible. I suspect the alternator heat load would substantially increase, though.

If I were to do a conversion like that, I'd take the alternator to a reputable starter/alternator shop (NOT Start-Mart!) and have them customize the alternator for increased output (more windings, bigger commutators, etc.) Then I would delete the fan and P/S pump and replace with electric units. I'd be willing to bet that you'd gain a minimum average HP increase of 20 HP, likely closer to 35 HP under load when hot.

Whether this is cost-effective depends on your thirst for HP and the depth of your pockets.

On a different note, does anybody know the CFM rating of the Q's factory fan? I was actually considering an electric fan swap, but I'd like to know what CFM fan would be necessary. I asked Joe at IOS and he said he wasn't privy to that sort of spec...

[qship96]

Not so sure I agree with the above, as the clutch based stock fan is free-wheeling most of the time the Q is actually moving down the road, using minimum HP. As far as the steering,pump is sapping minimal HP under real world actual driving {unlike when you are turning the wheel at great angles while trying to park,etc.} Not to mention you would lose the speed sensative steering by removing the existing pump.


The increased load of adding the electric motors for the ps and cooling system would make the alternator draw more hp to power them

[Lokim]

Not so sure I agree with the above, as the clutch based stock fan is free-wheeling most of the time the Q is actually moving down the road, using minimum HP. As far as the steering,pump is sapping minimal HP under real world actual driving {unlike when you are turning the wheel at great angles while trying to park,etc.} Not to mention you would lose the speed sensative steering by removing the existing pump.


The increased load of adding the electric motors for the ps and cooling system would make the alternator draw more hp to power them

The alternator load would increase a bit, but likely only a couple HP and every so often. The primary load would be absorbed by the battery, as the P/S pump and electric fan would only be active intermittently (i.e. when turning or at certain temperatures.)

The speed-sensitive steering is not controlled by the pump, but by a variable-orifice valve attached to the rack (see your FSM.)

You're right, the fan does freewheel when the airflow temp is low and at high engine speed, but the rotational weight of the fan clutch assy. would be gone, resulting in better throttle response (less inertia to overcome by not having to turn the weight of the fan clutch and P/S pulley) and more available power.

[qship96]

Meh...waste of time and money in my book. The Q is just not a "fast" car in todays world, swallow that pill and move on. spending time and $$ trying to shave a few tenths here and there is fruitless when to be competitive, you would need over 400 hp and torque, along with the 6-7 speed transmission to make the best use of it. Enjoy it for what it is.

[Infinitiguy19]

A good way to get some numbers with and without power steering would be on a dyno. One could detach the belt then re attach it and get the numbers. But then you would have to figure out how much power the electric pump requires under full load and factor that into the math....

But lets forget about this for a moment and focus on the Power Steering (PS) cooler, Please.

Anyone feel free to put the most cryptic, scientific answer possible as long as its an answer!

[qship96]

plenty of options for low cost ps coolers exist,just look at any speed shop{jegs,etc} online. The stock ps cooler is just a bent metal line in front of condenser-simple to cut and add a plate and fin inline heat exchanger.....real question is if it is even needed, as plenty of Q have made it to 3-400 thousand miles with no issues, maybe if you were going to autocross the old beast, it would be a necessity?