Power steering delete in 03 Corolla

[Dr. Dude]

The following will detail my experiment based on a power steering delete for my 2003 Toyota Corolla CE 5spd.

For those who don't want to read the details of my experiment, let me summarize that this modification resulted in a 3.1% improvement in fuel economy (about 1.5mpg for my corolla).

As a car enthusiast turned penny pincher/eco-modder, I have personally benefited from so much of the information provided by the community here. I wanted to give back by sharing one of the relatively successful modifications I have made to my vehicle. I hope this post can help someone else in their quest for saving money/gas/the world!

The modification tested is a power steering delete via re-route of the serpentine belt:

This modification cost me $13.00 in the form of a Goodyear 4060460 belt from Rockauto.com. I have been running this configuration for a little over a year now. I am hesitant to permanently remove any components of the power steering system in the event that I want to sell my car in the future, and a belt re-routing seemed like the simplest way to experiment with this set-up. I love the way the car handles without power steering! The road feel is much more direct and the corolla is a light enough vehicle that low-speed maneuvering in parking lots is very manageable. On a technical note, this re-route pattern results in the grooved side of the belt running on the smooth surface of the tensioner pulley. This has not resulted in any noticeable wear for either the belt or pulley over the last year/ 12k miles.
The experiment was performed over a 7 mile stretch of interstate, data was gathered using an android phone running the “torque pro” app and twelve total runs were recorded with time, outside temp, coolant temp, engine speed in 5th gear and MPG. The initial “A” set was performed without power steering, the “B” set was performed with the stock serpentine belt, power steering enabled. Again for the second “A” set, the belt was changed to disable power steering. I attempted to control as many variables as possible, however, these results of an on-road test are obviously up to interpretation as to their validity. Some of the possible confounders include outside temperatures dropping during the course of the experiment, slight variations in vehicle speed, changes in wind speed, having to use headlights during the last “A” set, etc. The torque pro app gives a more accurate reading for RPM than for speed, therefore RPM in 5th gear was the recorded measurement in place of speed in MPH. The vehicle speed was 60mph +/- .25mph on the dashboard

Avg A runs (no power steering): 48.76mpg
Avg B runs (power steering): 47.30mpg

The average across all runs without power steering shows a 3% increase from stock configuration. I should have started the experiment a little bit earlier to avoid the confounding factors of dropping temperatures and headlight use during the last phase of this experiment, however, I am reasonably confident that these confounders would simply result in a more conservative estimate of any possible gains to be had. The last south run (A South 4) was probably the least reliable run as I had initially set the cruise about 1mph too slow and tried to compensate with the cruise accelerate feature, which resulted in an over-compensation of about 1mph for about a minute of this run.

Although clearly not a scientific measurement, my overall average economy has improved by about 4% over the last year and 12k miles with this modification and relatively consistent driving habits/ environment. While not a good indication on its own, I think it does lend some credibility to my experiment and the idea of better efficiency without power steering losses. My personal feeling is that a 3% gain is a reasonable expectation for modification of a similar vehicle and could especially be applied to other vehicles with the 1zzfe Toyota motor and hydraulic power steering. Based on a 3% improvement and my own personal driving habits of about 12k/yr, I will save about 10 gallons per year with this modification. Every little bit helps!
I hope this experiment is helpful to other eco-modders; of course, please interpret my results with all due skepticism and take any possible safety concerns into consideration before modifying your own vehicle.

[serialk11r]

I've been reading a lot about hydraulic power steering in the past 2 weeks, yes 3mpg is an improvement you can expect.

The thing with hydraulic PS is that it can actually rob more power when doing nothing than when turning the wheel (if you turn the wheel really fast and the pump can't keep up, the pressure will drop, but while the pump is doing nothing all the flow is bypassed through the maximum pressure drop). Depending on the size of the pump, it's a constant 5-8 Nm drag on your engine, which eats a gigantic amount of power as it's several percent of the engine's output that's always being consumed.

Electric PS conversion or delete should be the first mod on any older car.

[seifrob]

Nice writeup. Instructive drawings. Carefully (or at least it looks like to me) measured performance. Pros and possible dangers adressed. Great post! Thank you very much.

Oh, and welcome to Ecomodder forum.

[jcp123]

Wow, very cool. I might do this in my Echo. It has a dedicated PS belt, so things would be easy. I learned to drive on a '66 Mustang with manual steering/drum brakes/trans, had a few others with manual steering (I am only 31 lol) so no big deal for me. Should I be hesitant for any of the PS componentry by doing this? Maybe let it run once a year or something? I am a truck driver and am out on the road four weeks at a time, drive 90 miles home, then 90 miles back to work a week later. It doesn't get much runtime.

[serialk11r]

Originally Posted by jcp123

Wow, very cool. I might do this in my Echo. It has a dedicated PS belt, so things would be easy. I learned to drive on a '66 Mustang with manual steering/drum brakes/trans, had a few others with manual steering (I am only 31 lol) so no big deal for me. Should I be hesitant for any of the PS componentry by doing this? Maybe let it run once a year or something? I am a truck driver and am out on the road four weeks at a time, drive 90 miles home, then 90 miles back to work a week later. It doesn't get much runtime.

If you remove it, loop the lines on the rack, and the rack will be fine, since there's still fluid going around in it keeping it lubricated, and it's sealed shut.

The PS pump might not be good, but why would you run that thing when you can get an EHPS replacement off Ebay for 60 bucks?

[jcp123]

Originally Posted by serialk11r

If you remove it, loop the lines on the rack, and the rack will be fine, since there's still fluid going around in it keeping it lubricated, and it's sealed shut.

The PS pump might not be good, but why would you run that thing when you can get an EHPS replacement off Ebay for 60 bucks?

Ah so loop the pressure and return ports on the rack together? Not too bad I guess.

$60 is a lot of money to put into this car. I'd guesstimate its value at ~$800.

3% is still impressing the heck out of me. I would never have thought it could be that much of an improvement!

[serialk11r]

Originally Posted by jcp123

Ah so loop the pressure and return ports on the rack together? Not too bad I guess.

$60 is a lot of money to put into this car. I'd guesstimate its value at ~$800.

3% is still impressing the heck out of me. I would never have thought it could be that much of an improvement!

The way I would look at it is, the pump still has resale value if the car goes, and it saves enough gas to pay for itself relatively quickly, unlike a lot of modifications. You can also drop it into another car. However your car is pretty light, no PS is probably just fine. My old MR2 with 900lbs over the front wheels was borderline okay to steer with the power steering turned off (aka, extra hard to turn compared to looped rack), but definitely unpleasant. My FR-S with 1450 lbs over the front wheels and electric steering is perhaps a little more difficult with the car powered off, enough to make me grateful for power steering.

Only 1 week ago did I discover how much power belt-driven hydraulic PS robbed! Aside from the water pump (which is always needed anyways, making it a more acceptable loss), the power steering pump is the least efficient thing on the belt, running at full power and 0% efficiency a majority of the time.

Even on a big V8 powered car which usually runs at super low load, dropping a few Nm of load from the belt should be a noticeable fuel economy increase.

[Dr. Dude]

I had the same question as you jcp123 about the ps components. I didn't really want to make any mods such as looping the lines in case I wanted to sell it down the road. I ran my car for a year without turning the ps pump and hooked it back up only briefly to run this test. I didn't notice any ill effects over this past year; power steering worked as well as the day I bought the car. The way I figure it if you leave the system untouched aside from removing the belt there's still the same amount of lubricating property from the ps fluid, just a lower pressure system. This is all providing the car is light enough to manage slow speed steering without looping the lines.

[jcp123]

Originally Posted by Dr. Dude

I had the same question as you jcp123 about the ps components. I didn't really want to make any mods such as looping the lines in case I wanted to sell it down the road. I ran my car for a year without turning the ps pump and hooked it back up only briefly to run this test. I didn't notice any ill effects over this past year; power steering worked as well as the day I bought the car. The way I figure it if you leave the system untouched aside from removing the belt there's still the same amount of lubricating property from the ps fluid, just a lower pressure system. This is all providing the car is light enough to manage slow speed steering without looping the lines.

Great feedback, thanks. I ran my Mustang sans PS for a few weeks a while back and there were no ill effects from doing it. But had never done it really long-term before. Weight shouldn't be a problem, curb weight for the Echo is only 2065lbs and I'd say about 1200lbs over the front wheels. Between that and the skinny wheels, I'd guess it's still pretty low-effort without PS.

Does looping the lines protect componentry, or does it primarily lower effort by giving the fluid a path to travel? I'm trying to gauge how important it is to do it.

[jcp123]

Originally Posted by serialk11r

The way I would look at it is, the pump still has resale value if the car goes, and it saves enough gas to pay for itself relatively quickly, unlike a lot of modifications. You can also drop it into another car. However your car is pretty light, no PS is probably just fine. My old MR2 with 900lbs over the front wheels was borderline okay to steer with the power steering turned off (aka, extra hard to turn compared to looped rack), but definitely unpleasant. My FR-S with 1450 lbs over the front wheels and electric steering is perhaps a little more difficult with the car powered off, enough to make me grateful for power steering.

Only 1 week ago did I discover how much power belt-driven hydraulic PS robbed! Aside from the water pump (which is always needed anyways, making it a more acceptable loss), the power steering pump is the least efficient thing on the belt, running at full power and 0% efficiency a majority of the time.

Even on a big V8 powered car which usually runs at super low load, dropping a few Nm of load from the belt should be a noticeable fuel economy increase.

Probably true on the salability of the pump. This car's next stop is getting run over the scales LOL. It's ugly but it keeps on running. I'll do basic maintenance and such but if anything even halfway major goes, I don't think the car will be worth it.

As to effort, like I said, I have had wheel time behind plenty of manual steering cars. I learned stick in a '66 Mustang with a 289, 4-speed, and manual drums. I liked the experience enough that my next project will have a three on the tree with overdrive (old Borg Warner unit), and again manual steering and brakes. The Echo will be a breeze.