1G Electric power steering pump options

[marcmsj]

I did a search on this and only came up with a dead thread a couple of years old. I've come across a few different electric power steering pumps off different vehicles and was wondering if anyone had successfully converted to electric.

I think the biggest issue or concern was the draw on the alternator and if it would be able to handle it. I have a Bosch high output alternator (200+ amps) so this wouldn't be an issue.

I believe the pump of choice would be of a Toyota MR-2. At least that's what seems to be used the most.

 

[DGajre777]

"There are 3 different types of power steering.
1) Hydraulic (HPS)
2) Electric (EPS) and
3) Electro-Hydraulic (EHPS)

The Electric power steering (EPS) uses 100% electric power for steering and does not use any hydraulic fluid or hydraulic pumps. These are used on cars like the Acura NSX and Honda S2000.

In an EHPS system, the the engine drive pump is replaced by an electric pump while still using hydraulic fluid for power steering. The pump on the Gen II MR2 is an EHPS. The last thread states '92 - '93 pump.

Benefits:
- Allows removal of the engine driven power steering pump
- Less power steering lines

Drawbacks:
- Power sucker (80-100 amps)"

More info in the post below:
http://www.dsmtuners.com/forums/151499076-post10.html

 

[marcmsj]

Thanks for the info

 

[Defiant]

What's your reason for wanting to do this? You'll only be moving where the load is. The load will remain the same for the amount of work done.

 

[marcmsj]

It was just something I was thinking about the other day. I've never seen it done on a dsm so I was just doing some research on it. I would think that the load on the engine would be less though, could anyone confirm or deny this? I would think the electric pumps would be more efficient than a mechanical one.

 

[Defiant]

Okay.... and where are you getting the electricity from? You're falling into the "electric cars pollute less" tiger trap.

 

[DGajre777]

It depends on what kind of driving you plan to do. Power steering is helpful most of the time at idle RPM, and at idle RPM the alternator is barely pushing out any amps compared to 3000 RPMs. You might be able to get away with it if your 200+ amp alternator pushes more than stock at idle and I doubt that it does.

 

[underradar92]

The pump would likely be wired to the battery since it can easily supply that sort of power for short bursts. The alternator doesn't need to constantly supply the peak load or else an MR2 would have a 200 amp alternator. They only have a 100 amp piece when equipped with (electric) power steering.

See where I'm going here yet?

 

[Defiant]

Yes, down a dead end.
The battery can turn the motor, but the alternator has to put that energy back into the battery, and it comes at the cost of load on the engine.
Seeya at the free lunch counter.

 

[GDNF2ET]

It would be one less pulley thats robbing power verses an alternator working harder when your turning...In a straight line you should get back some horsepower and it would free up some space on the engine..

 

[marcmsj]

Yes, down a dead end.
The battery can turn the motor, but the alternator has to put that energy back into the battery, and it comes at the cost of load on the engine.
Seeya at the free lunch counter.

I totally understand this.. but it would just be another option for guys out there depending on what they have in mind and relocating their p/s pumps to locations where otherwise would be impossible for a mechanical one.

 

[Defiant]

It would be one less pulley thats robbing power verses an alternator working harder when your turning...In a straight line you should get back some horsepower and it would free up some space on the engine..

The "gain" from not spinning that belt and its sheave friction would be trivial, less than a horsepower.

I totally understand this.. but it would just be another option for guys out there depending on what they have in mind and relocating their p/s pumps to locations where otherwise would be impossible for a mechanical one.

Yes. That's why my first post in this thread was to ask why you would want to do it.

 

[underradar92]

That's why my first post in this thread was to ask why you would want to do it.

I can not speak for the OP but I can give a few good reasons why I'm doing it.

1. Move that weight away from the exhaust and away from the overburdened drivers side front of the car. Balance is everything.

2. Free up some space in front of the water pump so as to plumb the coolant directly into a side tank style radiator.

 

[Stapl3]

They way I view it, the PS pump is working its hardest when the vehicle is at very low speed or not moving at all. The alternator on the other hand is working all the time, so the battery power made for the electric pump could be produced while the vehicle is driving, which is most of the time anyways. This is more efficient to do the same job.

In my mind, it's not a free lunch, but a cheaper lunch.

 

[GDNF2ET]

Here's an interesting read on underdrive pulleys, pulley removal, and horsepower gains on the dyno..
Underdrive Pulleys ... Our Testing

 

[jrohner]

It may be more efficient, because you could turn the ps pump at almost the same speed all the time. Instead of the pump running 600 rpms to 7500 rpms, it could run a constant 1000 rpms or whatever.

The coolest thing is you could shut it off when drag racing or when on the highway. I don't use the power steering on my 2G, and the ONLY time I miss it is in a parking lot. If you're going more than like 5 miles an hour you don't really need it. Plus, I like heavy steering anyways.

I can't believe it takes 100+ amps to turn a ps pump, unless you're sitting with the steering cranked hard to one side which is not good and is pointless. I can see it taking quite a bit of power for a very short amount of time when you're cranking on the steering, but if you aren't it shouldn't be taking much at all. Even if it COULD draw 100 amps, you'd probably never get it do actually draw that much.

Something like this would be pretty sweet, but it's 6 GRAND!: Electric Power Steering

 

[marcmsj]

I've also thought about the whole situation about shutting it off whenever you don't need it or just turning it on for parking situations or what not. That would be a nice little feature about it as well.

 

[gixxerdrew]

My car is getting this right now. I chose to do it because of maintenance issues with crowded space in the engine bay as a major factor. Ability to turn power steering off and on under different circmstances. For example, on a dry lake it is not needed there isnt enough grip on the surface to make it take effort to turn the wheel. On the freeway it is also not needed which is a huge waste of power. I believe power steering and other accessories turning off on low throttle cruise is important for gas mileage (which is one my goals for this car). I am not sure whether I'll use AEM to turn it off and on at speed or some kind of PWM controller varying with speed. I might have to play with it. When your only using 50hp to maintain speed of your car, 6hp loss is substantial.

Also helps cold starting to remove load from the engine. I see several advantages. I severely dislike our factory power steering bracket. It likes to flex a lot and stands in the way of critical components. Several maintenance tasks like water pump removal, turbo charger removal and others are made easier by relocating the system. My pump will be in the driver fender well as well as its cooler. Pump is from a peugot and has an integrated reservoir.

 

[DGajre777]

^^^ A writeup and review of your setup after you up and running will be appreciated.

 

[jrohner]

When your only using 50hp to maintain speed of your car, 6hp loss is substantial.

It doesn't take 6hp to turn a mechanical ps pump, especially cruising on the highway. I bet it doesn't take 1 hp on the highway. I wonder how much power it takes to move a big ricer bumper and spoiler down the highway, with the extra aero drag.

 

[marcmsj]

^^^ A writeup and review of your setup after you up and running will be appreciated.

Agreed. This is exactly the type of feedback I was looking for and knew at least one person out there would be interested in doing.

Looking forward to your progress, please keep us updated on what's going on.

 

[wishihadatalon]

This thread had me start to do a little research as this is something I am considering. I should be able to control this via a speed sensor and my stand alone ecu. I want ps because I will likely drive my car often, but I will also have some sticky wide tires on it and would like to not fight the car all the time.

Here is a link to honda tech with some dyno numbers and other information.
Honda-Tech.com: Road Racing/Autocross: Special Projects - Electro Power Steer

 

[marcmsj]

Here is a link to honda tech with some dyno numbers and other information.
Honda-Tech.com: Road Racing/Autocross: Special Projects - Electro Power Steer

That's a lot of useful info and the dyno numbers are pretty much what I expected. I know the Honda guys have been playing around with these pumps for a while now and have had great results with them.

I haven't been able to find any used pumps yet but a new MR2 pump is going for around 300, so it's not that bad. Has anybody found any used ones? I might play around with it as well before I put my new motor in.

 

[gixxerdrew]

It doesn't take 6hp to turn a mechanical ps pump, especially cruising on the highway. I bet it doesn't take 1 hp on the highway. I wonder how much power it takes to move a big ricer bumper and spoiler down the highway, with the extra aero drag.

My number for that isnt an estimate, its a dyno tested and conservative number. A wing depending on its design can be anything from horrible and substantial to null to actually helping drag.

 

[underradar92]

Here is a link to honda tech with some dyno numbers and other information.
Honda-Tech.com: Road Racing/Autocross: Special Projects - Electro Power Steer

Awesome. I just committed to memory all the relevant points in that writeup.