Electric power steering advantageous in motorsports?

So yesterday I was doing an autocross...actually more like a gymkhana, the guy who set up the course this time was an old-schooler doing his first AutoX course. It had some stopping and reversing. Mostly good but there was an ultra-tight slalom section where it felt like the AE92 was just barely capable of making it if I set up each corner perfectly and came almost to a stop. This resulted in ultra-E36 M3ty times. Ideally a course should not be set up like this but I want to improve this capability anyways. I've finally got an engine lined up for the swap so now would be a good time to consider electric power steering.

Traditionally my car is one of the fastest through a slalom, even the tighter ones, even though I'm not the best driver and my suspension is relatively soft (ordering coilovers tonight though!), but beyond a point it's like a square peg in a round hole.

I can't do anything about the chassis length and lock angle, but if I could point the wheels where I want faster that could help. I was really struggling to haul the AE92 through that slalom section. I had the engine at almost idle revs so that doesn't help boost the power steering.

So from what I understand the usual conversion is to just swap the pulley-powered pump for an electric-powered one that activates based on load somehow - I'd want to be able to adjust this ideally - and this should give me loads of power steering assistance even at low revs. Of course I do some googling before asking questions:

This guy makes it sound like exactly what I need:

http://www.honda-tech.com/showthread.php?t=1556487

(would an SW20 pump be a good candidate? The car it's built for is heavier overall but it's RWD and mid-engined - the front wheels surely require less force to turn)

Some issues with speed-sensitive EPS, but I would want it to be only force-sensitive:

http://www.team-bhp.com/forum/technical-stuff/5062-how-good-electronic-power-steering.html

So right off the bat I know:

Disadvantages:

Weight (probably not much)

Advantages:

Power, efficiency, simplicity (one less pulley-powered device).

Sounds like a good idea. Could pump heat be a bigger issue? Any other comments? Any recommendations for conversion kits? The SW20 system has the pump separate from the reservoir, a simpler combined system would be preferable.

edit: The SW20 has some separate electronic doodad (called the "power steering control module") that measures the steering assistance required and adjusts the voltage to the pump. I'd definitely want this. Anyone know about this system?

How would it affect your overall steering feel and feedback?

On an unrelated note, what sort of engine are you getting? 4AGE of some description, I presume?

Luke wrote: How would it affect your overall steering feel and feedback? On an unrelated note, what sort of engine are you getting? 4AGE of some description, I presume?

It should, in theory, feel like how your power steering feels at the redline (or more powerful), all the time. The guy with the Civic I linked to has his running at max power all the time, which is kind of a hackish solution and obviously not good for longevity or street use. Factory systems are idle when driving in a straight line, and they somehow (still researching) detect the force being applied at the wheel and increase the power at the pump to make steering easy. They may also reduce or kill power at speed, but I would want it to be purely force-sensitive (although a "max power switch" could be handy for AutoX).

I'm switching to a 4AGE blacktop, freshly rebuilt with Technotoy pulleys and velocity stacks (although I think I'm gonna switch to a filter, at least on the street). That'll be hooked up to a C160 6-speed box. It has an open diff right now but I'm thinking of installing some kind of LSD.

I would just do normal power steering or start working out. Power steering racks are faster, which is definitely a good thing.

The complexity of EHPS system is unncessary IMHO. The MR2 only uses one for packaging reasons. That said, the MR2 PS is good. It had plenty of feedback and a pretty quick ratio.

A lot of traditional factory power steering pumps and systems can't keep up with the quick inputs needed for autocrossing, especially the courses you mentioned so that's why the electric power steering system Tyler.

Tyler H wrote: I would just do normal power steering or start working out. Power steering racks are faster, which is definitely a good thing. The complexity of EHPS system is unncessary IMHO. The MR2 only uses one for packaging reasons. That said, the MR2 PS is good. It had plenty of feedback and a pretty quick ratio.

Already have normal power steering. Carguy123 covered the issue here.

So I guess the SW20 pump looks like a good bet.

For future reference, from what I've read the MR-S pump and old Subaru pumps are problematic.

FWIW, my wifes saturn Ion (not a sports car by any stretch) has electric power assisted steering, and its the numbest, must unresponsive, non feeding back experience Ive had since I went to the dentist and got novocaine. I HATE driving that car, especially in anger.

Perhaps a larger pulley by a few percent will add the extra oomph you need. Try to find a lightweight aluminum aftermarket pulley for another vehicle that matches the dims you need for your current PS pulley, but that will be slightly larger diameter than stock.

4cylndrfury wrote: FWIW, my wifes saturn Ion (not a sports car by any stretch) has electric power assisted steering, and its the numbest, must unresponsive, non feeding back experience Ive had since I went to the dentist and got novocaine. I HATE driving that car, especially in anger.

I've read about this car, it doesn't have the same kind of system, it has an electric motor that acts directly on the steering shaft, not what's basically a regular hydraulic PS system powered by an electric motor.

A larger pulley on an engine-driven system still might not give enough power at low revs...and with the new engine having a nearly 9krpm redline, I don't know how it would handle the greatly increased power at high revs (which would also be a problem with the current setup) - swapping to an electric pump would take care of all these problems.

The S2000 has an electric power steering pump and it's steering feels very good.

With my old A4 when I first got, it killed me in the slaloms as it seemed like it was fighting me. Either it lightened up over time, or I got better at turning in quicker. Honestly, I'd wait until you change your suspension setup before you mess with the steering setup. Shouldn't be a ton of steering input on a slalom unless you are late. That being said, are you sure everything is currently in good health?

...as does the 1st Gen MINI. The R56 MINI use a direct motor on the rack set-up.

I've had similar thoughts for fitting power steering to an 1800, since provisions to fit an engine driven pump are limited. I was considering relocated hte battery to the trunk and putting the pump near it and running hard lines to the engine compartment. For one, the additional 14' of steel tubing would act as a passive cooler.

Having some knowledge of the p/s pump in a MINI, I can offer a couple of observations. First, the electrical lead for these is pretty substantial. I think it's about a #2 wire. Second, on the MINI, they had to add a cooling fan to it due to overheating issues. So we have this little electric fan down in the nether-bowels of the car... constantly getting battered by road debris and grime... needless to say, fan failures are somewhat common... and since it runs on the same fused circuit as the radiator fan... well, let's just say there are times when you just know a MINI is British...

Just get a ZX2 and you will have no problem with power steering.

I'm sure the suspension and steering are in good health, other stuff not so much I might get a chance to test the new coilovers with the current power steering, depending on a lot of things...I might be forced to go with EPS anyways if I want to free up space on the pulley system for the AC compressor. Not having AC down here is like not having heat in Alaska.

The EPS on the S2000 is probably the best EPS I have ever felt, and would also be pretty easy to retrofit. It is speed based, so the slower you go the more assist it provides, and the wiring is relatively isolated from other vehicle systems minus power, ground, and speed input which makes it an easier retrofit.

There are three different versions of the EPS controller in that car. The AP1 and AP2 CR rack is a 13.8:1 ratio while the AP2 rack is a 14.9:1 ratio. What you most likely would want is an AP1 rack with the non-CR AP2 control box. The program in the AP2 controller has the best assist profile and feedback of the three (AP1, AP2, and CR). My car had that setup on it, but was switched back to my AP2 rack so I could still run A-stock.

If you're interested, I could scan the wiring diagram from the service manual for you as well.

That sound pretty cool. Is the S2000 front steer or rear?

Front

Couldn't you use what I think is called a steering quickener? I've seen planetary gear setups that do this. Lots of different ratios are possible. But, if the power steering pump is maxed, I think this would make it worse. Something like this:

Yeah a steering quickener would just make the wheel even harder to turn when the stock PS is overloaded...I don't have any complaints about the stock steering ratio.

The S2000 system might be an option - it probably feels so nice because it's only speed-sensitive, so it's always providing more than enough power, I'd just have to retrofit a reed switch to the speedo cable. S2000 parts would literally be impossible to get locally though - I might have a chance to smuggle some stuff back later in the year. SW20 parts would be close to impossible to find anyways so I guess rarity is a problem with both options...

I haven't found any more info on the SW20's power steering control module, but RX8s have some kind of torque sensor as part of the steering shaft.

I've never taken apart a Toyota pump so I don't know if this will help.

On most Saginaw (GM) pumps the outlet fitting also holds the relief valve. You can unscrew the relief valve and adjust it to give yourself higher pressures.

There are also different pumps built with different flow ratings and pressures. The largest being from trucks and vans with hydroboost brakes.

Perhaps the Toyota pump is adjustable, if not, make some brackets and swap in a dirt-cheap junkyard GM pump from a 1-ton with hydroboost.

Circle-jerk shops like Speedway Motors have just about every kind of fitting and adapter you might need to make this work as well. Plus, later (after 1980) GM pumps have metric fittings.

Failing all that, can you dial in more caster in the suspension?

Shawn

seems this is adding complexity... you say you already have power steering Why not just swap to a tighter ratio rack like from a Mitsu Evo or a Z3?

It's not the speed of the rack, it's that the power steering won't keep up with the quickness of the inputs.

When you give it the quick inputs his power steering bacially cycles off and on.

I had 2 '07 350 Zs like that. You simply couldn't do a slaloom in them. You would make it thru the first cone, but by the second cone when you turned back the car fought you. All of a sudden the power steering disappeared and you had to manhandle the car around the cone. You might make it around the 3rd cone but it was next to impossible to complete a 4th cone.

A quicker rack would just aggravate the situation and make the muscle power needed to turn the wheel greater. The really big issue is that it doesn't telegraph when the steering's going to go out so it is very hard to prepare for it.

Nobody's mentioned the NSX? That had electronic steering if I remember correctly

JeepinMatt wrote: Nobody's mentioned the NSX? That had electronic steering if I remember correctly

...and I'm sitting here wondering where I could find S2000 parts...

Ian F wrote:

JeepinMatt wrote: Nobody's mentioned the NSX? That had electronic steering if I remember correctly

...and I'm sitting here wondering where I could find S2000 parts...

I didn't say my information was particularly useful, I just put that out there

Still, half of the world's NSXs went to the US, so that gives you 9000 potential cars, not that it would be my first choice (or second)

Gameboy, I don't mean to hijack your thread, so I apologize going off-topic here, but could someone give a general pro/con of running velocity stacks without filters (what are the real risks?)? I agree, they look great, but I'm not sure I'd like to run my motor without a filter, even though I realize you will lose some power/tq. I guess I get a little queasy when I'm reading BringATrailer.com and see fully restored 911's with full $15K+ engine rebuilds running stacks with no filters...