Electric PS Pump Conversion

[dukeofchen]

I know there's been some discussion in passing here about electric PS pump conversions, usually shops that have done it or folks doing it in Europe. But has anyone on here successfully done one?

Curious to know if it's primarily a custom / one-off type project people do for track builds, or if there's at least an established method / placement / pump model that people use as it seems like an attractive functional upgrade.

Edit: Also, if we were to figure out a good pump location / parts list it would be awesome to create a CAD design for mounts that we could have made by sendcutsend or other third party, since the placement seems to be a major question mark. Looks like there are even companies that specialize in selling conversion kits / hardware, and pumps are readily available from junkyards.

[karter16]

Interested to follow this discussion. The MomentManager module in the DME OS has specific logic for dealing with the varying torque requirements of the power steering, particularly when it comes to building torque reserve as the steering reaches its limits, haven't thought it through in detail but would presume this logic would need calibrating at the least.


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[bigjae46]

Looks up Alex Miller in the E9X M3 community - he sells an EPS conversion for that platform. I can't imagine the major hardware being drastically different. Maybe just mounting, hoses, and electrical connections.

One piece of the puzzle is the belt with no PS pump. I tried deleting the PS and I think the belt is from a Mazda 3. Look in my build thread, I think a pic of the part number is somewhere in there. The belt will be really close to the belt tensioner pulley. I ran the car on track and didn't run into any rubbing issues.

[Altaran]

I have checked into this as well. Here's the feedback I've heard from a race team that has done the conversion on an E46 M3 for testing purposes.

You can use the electric pump from a Mercedes A Class. They're available here for 200ish. Shipping should not be too bad.
Other than the pump, you just need hoses and the wiring. I don't remember exactly which, but it will need a rather large fuse.
Steering feel is normal, so no drawbacks there.
However, there is not going to be any weight savings from this switch, the electric pump has similar weight compared to the OEM pump. There's only really space to mount it up front unless you want really long hydraulic lines, so no real potential in improving weight distribution.
They have also tried Dyno runs with steering angle and power gains did not change outside the measurement tolerance on the Dyno, so it's also not worth it from that perspective.

Based on that feedback I decided to stick with a mechanical ps pump.

The S65 is a bit different, as the PS pulley is on the aux belt with AC. A change may make sense when deleting AC, as you can delete the entire aux belt.

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[dukeofchen]

They have also tried Dyno runs with steering angle and power gains did not change outside the measurement tolerance on the Dyno, so it's also not worth it from that perspective.

Based on that feedback I decided to stick with a mechanical ps pump.

Interesting. I'm surprised that there weren't any power gains, which I suppose speaks to the efficiency of the mechanical unit. In that case then it doesn't seem worth the squeeze outside of a high performance application.

Looks like the parts I'm sitting on for a full OEM refresh will be going in then!

[sapote]

Does the stock alt have enough current to drive the pump?

[dukeofchen]

Does the stock alt have enough current to drive the pump?

In my limited research I saw people using 80A fuses with peak draw of ~60A, but varies depending on the pump used and some seem to be lower. So that vs. 120A on the stock alternator, or 140-150A on some of the direct fitment alternatives from Z4/X5.

[sapote]

In my limited research I saw people using 80A fuses with peak draw of ~60A, but varies depending on the pump used and some seem to be lower. So that vs. 120A on the stock alternator, or 140-150A on some of the direct fitment alternatives from Z4/X5.

Total current of the car should be less than 120A max spec of alt, but efan is already rated at 50A fuse, plus headlights, DME, power seats, audio, etc. So with additional 60 to 80A for the pump I think 120A alt is marginal.