Electric steering???

[hoveringuy]

From personal dyno test, it frees up about 8hp.

that probably came from this article

https://www.motortrend.com/how-to/ccrp-1304-gm-power-steering-secrets/#:~:text=For%20example%2C%20Roethlisberger%20tells %20us,heat%20at%20the%20same%20time.

I've heard of 6hp on the dyno but I think 2hp, maybe 3hp at higher rpm's when it's churning more fluid is correct for BMW.

According to this calculator: http://www.metaris.com/hp-calculator.php , 1200psi at 4 gallons per minute would be about 3hp. Since they're positive displacement pumps they internally bypass most of the fluid while some is always flowing through the rack. More rpm means more flow, and more hp...

[cwbaader]

What’s wrong with manual rack ?

Research for an E36 E Production race car. Tried no rack but with 245 racing slicks the steering was way too hard. Was not a problem on my E30 ITA car with Dot radials.

"The 8hp going to be when the wheel is turned a bunch where maximising power is not needed anyway. There is no way the pump consumes 8hp when going straight/ish unless it's shot."

The test I ran was with a stock E30 in ITA trim. Ran several dyno tests and then cut the PS belt and ran another test. Results were the PS pump took just under 8hp to run. Did the same with back to back runs. Remember, this is a pump the operates at around 1600PSI and must power the steering at idle. Yes, it does require 8hp.

"that probably came from this article"

Nope...came from me standing in the dyno room and watching results. BTW, since this was an ITA car and an "E" motor, max revs were 5500. AND, it is a rotary sliding vane pump so positive displacement?

[hoveringuy]

The test I ran was with a stock E30 in ITA trim. Ran several dyno tests and then cut the PS belt and ran another test. Results were the PS pump took just under 8hp to run. Did the same with back to back runs. Remember, this is a pump the operates at around 1600PSI and must power the steering at idle. Yes, it does require 8hp.

"that probably came from this article"

Nope...came from me standing in the dyno room and watching results. BTW, since this was an ITA car and an "E" motor, max revs were 5500. AND, it is a rotary sliding vane pump so positive displacement?

That's good data and interesting that your direct observation agrees exactly with the article.

Rotary vane pumps are positive displacement same as a piston pump, whereas an impeller (like a water pump) is not.

My N52 goes to 7500 easy and it's pressurizing and moving a LOT of fluid at those speeds which is sucking lots of power.

I've had the PS off and the few times I drove it was a complete PITA, but I also have a 2.5 rack and wouldn't want to flail with a 4:1 rack, either

[Chuck Baader]

We are turning our EP motor 8300RPM during the races. Can't imagine the drag from the PS pump at that speed. Hard to dyno because of the serpentine belt!

[TobyB]

when the car is going straight, the shuttle valve in the rack lets the fluid bypass
any restriction, and pressure is marginal. Flow is significant.
Once there is load on the shuttle valve, it displaces slightly, turning a little bit of that flow
into pressure. As steering effort rises, there's more valve displacement, and more and more
fluid's diverted into the rack. volume continues to go down, and pressure continues to rise.
Eventually, you hit the pressure relief valve, and pressure tops out. There's still some flow,
but now the system's at 'relief pressure' of 1600 or whatever.

So it's only high pressure when you're cornering hard. The rest of the time, it's high flow.

t

[hoveringuy]

when the car is going straight, the shuttle valve in the rack lets the fluid bypass
any restriction, and pressure is marginal. Flow is significant.
Once there is load on the shuttle valve, it displaces slightly, turning a little bit of that flow
into pressure. As steering effort rises, there's more valve displacement, and more and more
fluid's diverted into the rack. volume continues to go down, and pressure continues to rise.
Eventually, you hit the pressure relief valve, and pressure tops out. There's still some flow,
but now the system's at 'relief pressure' of 1600 or whatever.

So it's only high pressure when you're cornering hard. The rest of the time, it's high flow.

t

That's true, but I think at some flow the capacity of the shuttle valve is overwhelmed, the pressure builds and the flow starts to bypass in the pump itself. There is some magic in the regulator poppit-thing in the pump and miniscule variations in the shape of the metering valve determine the bar rating of the pump.

I had a Luk-20 pump in the N52 and so does the Porsche Cayman. The Porsche, being a mid-engine car, has much lower pressure requirements compared to the E90 so I bought a Cayman pump and swapped the regulator. It did wonders!!

I found another car like a Seat that had the same pump with an even lower pressure but didn't bother.

[digger]

https://www.r3vlimited.com/board/forum/e30-technical-forums/general-technical/220260-does-anyone-have-before-after-dynos-for-the-power-steering-delete#post4687787

[MrBurgundy]

I've heard numbers from 4-6hp, but what I saw on a dyno was more like 1-2hp. Which is on the order of the repeatability/uncertainty in dyno runs. So I'd have say the power advantage is pretty much nothing.

I deleted the power steering on my race car and have run it like that for a long time. But I've recently learned that really isn't a great idea. The lack of power steering increases driver fatigue and means having to move your hands around on the steering wheel for leverage, though deleting PS does increase steering feel. AFAIK, all pro road race cars have some form of power steering. I've put the system back on, but one of the small rack lines is leaking and will have to be changed.

What I'd really like is "dial back" the pump for less assist.

quote from the GOAT

[ghostbear777]

so ive done a good bit of research on this. im highly angst the prius column as it basically turns you into a 700lb gorilla, your able to put huge amounts of force on the input of the rack that a human would never be able to generate, my biggest fear is overcoming adverse steering forces and cracking the rack housing on the input side or slipping splines or aluminum couplers.. but i havent seen any info to support this fear. however that data pool is very limited, and its questionable if those affected would tell others in racing, if they where even able to determine the point of failure.

this is ignoring the mounting options of the prius pump on the sheet metal firewall of the e30 or other bmw's.......

the volvo pump seems the way to go, there are a few other makes that make a similar pump but in my research, it seemed volvo was the the way to go in USA. there was a guy on the ford mustang forums that was selling a kit to use gps to add a speed sensor to the pump for variable adjustment. apparently if you just wire this in, it runs in its failure/failsafe mode that isnt the most desirable. also it apparently pulls 40ish amps. and 80amp bmw alternator might not be able to do it. the big boy bmw altranator conversion might be inorder.

i recently found out the e46 m3 powersteering pump can be limited in pressure the add"weight" to the steering. i know e30s arnt to bad to drive with a powersteering delete with the stock rack but my e36 m3 with a z3 rack is ridiculous, to the point of dangerous.

[hoveringuy]

the volvo pump seems the way to go, there are a few other makes that make a similar pump but in my research, it seemed volvo was the the way to go in USA. there was a guy on the ford mustang forums that was selling a kit to use gps to add a speed sensor to the pump for variable adjustment. apparently if you just wire this in, it runs in its failure/failsafe mode that isnt the most desirable. also it apparently pulls 40ish amps. and 80amp bmw alternator might not be able to do it. the big boy bmw altranator conversion might be inorder.
.

I have Bruno Steering's rotary knob that adjusts the speed manually. I don't plan on "full-on" installing the pump until I've had a chance to drive it in a jury-rigged configuration, meaning it will be mounted on some plywood in the trunk until I'm satisfied that it "works".

Bruno also has the GPS version you mentioned, I've asked him why he just doesn't tie it to Vss and he said it wouldn't be very easy for him to make it compatible with all of the possible configurations across the brands. He says the GPS one works perfectly, but I'm not jazzed by the idea.

If I'm satisfied with how it works I'll make a speed controller that reads Vss. My version of that will have the speed go to the lowest setting when Vss=zero, otherwise it would be grinding away at stop lights.

I'd love to tie steering angle in. Maybe some, day...

[Chuck Baader]

Originally posted by jlevie View Post
I've heard numbers from 4-6hp, but what I saw on a dyno was more like 1-2hp. Which is on the order of the repeatability/uncertainty in dyno runs. So I'd have say the power advantage is pretty much nothing.

I deleted the power steering on my race car and have run it like that for a long time. But I've recently learned that really isn't a great idea. The lack of power steering increases driver fatigue and means having to move your hands around on the steering wheel for leverage, though deleting PS does increase steering feel. AFAIK, all pro road race cars have some form of power steering. I've put the system back on, but one of the small rack lines is leaking and will have to be changed.

What I'd really like is "dial back" the pump for less assist.

AND GUESS WHO TAUGHT JIM LEVIE THIS!!!