Any guess on what MPG gains I'd get if I removed power steering and air conditioning?

[cheapybob]

I think on my 97 Saturn SC1 I can use a different belt and bypass either or both of these without needing any other changes.

Anyone know how much MPG gains I might get by bypassing either or both of these?

[Compaq888]

expect 3-5mpg

[Matt Timion]

I'm guessing 1-2mpg, but I'm VERY interested in knowing either way. Are you going to run a controlled experiment in order to determine the exact results?

[cheapybob]

Originally Posted by Matt Timion

I'm guessing 1-2mpg, but I'm VERY interested in knowing either way. Are you going to run a controlled experiment in order to determine the exact results?

If I do it I will. I have a scangage and a 25 mi test trip that I run at a steady 60 mph to compare with. 1997 Saturn SC1, EPA rating 28 city, 39 highway, 33 overall. Baseline with no mods, fresh tuneup, 45 psi tires and all synthetic fluids was 40.4 mpg. Adding hot air intake got it to 43.6 (max temp 119f). Insulating it and putting in a 2c higher thermostat got me to 46.8 (max temp 179f). Adding a resistor to fake IAT temp of 242f and a manifold to get the intake temp higher (up to 230's) got me to 51.4. Aero mods to smooth front end and cover almost all holes got me nothing. Spark plug gap reduction to .035 got me nothing. Using my foot instead of cruise control got me to 53.3. If I run it at 65 mph the mpg drops by 3 or 4. MPG's are higher is I was to go slower, but that's too dangerous here in Chicago. 60 in a 55 is about as slow as you want to go if you value your life.

[MetroMPG]

can you give a bit more info about your testing?

- were these tests conducted at the same ambient temperature?

- round trip, or one way? (grade & wind issues)

- in a traffic flow, or on your own (aero differences from corridor effect)?

- cruise control for testing purposes or manual control?

[cheapybob]

The baseline and mods up to 46.8 mpg were in cold conditions, ie around 30f. The more recent ones were at about 65f. Interestingly enough, all the Saturn gurus were saying my MPG improvements would dissapear with warmer weather and summer gas, but it hasn't happened that I've seen.

All are round trip with same 5 mi warmup trip to starting point back to the same end point with RPM +/- 100 max, and there was no drafting of traffic, ie nothing closer than 50 yards in front of me. Cruise was used for initial tests just to eliminate variability, but I don't plan to use it because I found that I can do much better with a steady foot. Cruise control costs 3 mpg from what I've found as compared to keeping one eye on a TPS and RPM reading. I don't do any of the coasting, shutting off the engine, or driving at 45, or porposing type stuff like I've read here. My point was/is to see what I can get normally driving on the highway at reasonable speeds. Around town I'm getting just under 40 mpg in suburban stop and go driving at an avg of 27 mph. I only mention that for comparison purposes since I consider that kind of driving impossible to use for any kind of test because there are way too many extraneous variables involved.

[cheapybob]

Originally Posted by Matt Timion

I'm guessing 1-2mpg, but I'm VERY interested in knowing either way. Are you going to run a controlled experiment in order to determine the exact results?

BTW, I found someone that added PS and an idling AC compressor to their Saturn, and they said there was no noticeable change in gas mileage. Admittedly this person wasn't testing for gas mileage, either, but I'd guess that means if I get 1-2 mpg out of it, I'd be doing well, and 3 to 5 mpg is an unreasonable expectation. If it were AC that was running vs no AC, it might be a reasonable difference.

[kickflipjr]

Hey, cheapybob i guess you found the site from my link on saturnfans. I was hoping we could get some more saturns on this honda dominated site :P




http://www.gassavers.org/forum_topic/ac_and_power_steering_on_fe.html

this thread shows some improvement by removing ac/ps.

[Matt Timion]

Originally Posted by kickflipjr

I was hoping we could get some more saturns on this honda dominated site :P

As do I. I didn't realize until recently that Saturns were build for fuel economy. Just check out the EPA ratings for Saturns and you'll see that high MPG was always a goal.

[diamondlarry]

MPG's are higher is I was to go slower, but that's too dangerous here in Chicago. 60 in a 55 is about as slow as you want to go if you value your life.

I have driven in Chicago numerous times at the posted speed limits(45 & 55) and have never have never had any problems nor have I even had any close calls. I stirred up quite a bit of trouble on another forum by sharing my views on going the speed limit so I won't go into that much here but I never worry about going the posted speed limit wherever I am; it's not my problem.

[cheapybob]

Its Ok, Larry. I won't get mad at you. I just get nervous when everyone is whipping around me doing 75 in the 55 zones. I keep my speeds reasonable, but I can tell people are getting aggravated when they stack up behind me and give me looks when they finally get a slot in the fast lane to get around.

[SVOboy]

I'm glad that people drive reasonably around me, I haven't gotten honked or yelled at or anything except for my friends giving me the finger,

Blessed are those from new jersey.

[diamondlarry]

Originally Posted by cheapybob

Its Ok, Larry. I won't get mad at you. I just get nervous when everyone is whipping around me doing 75 in the 55 zones. I keep my speeds reasonable, but I can tell people are getting aggravated when they stack up behind me and give me looks when they finally get a slot in the fast lane to get around.

Thanks Bob. You are much nicer than those guys on the other site. Must be a Saturn thing.:-) I generally try to stay in the right lane but every once in awhile I'm in the center because someone merges in and I can't get back over right away.

[cheapybob]

Originally Posted by kickflipjr

Hey, cheapybob i guess you found the site from my link on saturnfans. I was hoping we could get some more saturns on this honda dominated site :P

http://www.gassavers.org/forum_topic/ac_and_power_steering_on_fe.html

this thread shows some improvement by removing ac/ps.

Could be, I don't remember where I found it... Thanks...

Also thanks for the link to the thread. Its sort of odd that removing both PS and AC got him 3.2 mpg, but removing PS alone only got him .3 mpg. I find it hard to believe that just having the AC on the pulley and not running would sap 2.9 mpg from it.

If I get some time I'll see if I can find a used idler and belt at a yard and try it both ways under the same weather and traffic conditions.

He seems to have a similar test routine to mine, but I noticed his mph was very low 34-36 mph, and different by 2 on the one run as compared to the other, so it can't be open expressway driving, which I like better for a test because it keeps the number of variables to a reduced level.

[Matt Timion]

Originally Posted by diamondlarry

I have driven in Chicago numerous times at the posted speed limits(45 & 55) and have never have never had any problems nor have I even had any close calls. I stirred up quite a bit of trouble on another forum by sharing my views on going the speed limit so I won't go into that much here but I never worry about going the posted speed limit wherever I am; it's not my problem.

Whenever we go on road trips I make a point to go 65mph the entire way. Every so often I'll go up to 70, but it's rather rare.

I mean, I wouldn't want my gaslog to drop, right? Screw safety... my gaslog is more important :P

[cheapybob]

Originally Posted by diamondlarry

Thanks Bob. You are much nicer than those guys on the other site. Must be a Saturn thing.:-) I generally try to stay in the right lane but every once in awhile I'm in the center because someone merges in and I can't get back over right away.

Larry, I see you have an SL. Do you have AC or PS on it? My SC1 has both.

The wild one on my test loop is when they merge in 2 lanes from the right and they thin out to becomes the slow lane, but the cars are coming in at 75 and I'm only doing 60. I try to get over, but its tricky with them passing me on both sides.

[cheapybob]

Originally Posted by Matt Timion

I didn't realize until recently that Saturns were build for fuel economy. Just check out the EPA ratings for Saturns and you'll see that high MPG was always a goal.

Actually, its only really true for the S series Saturns with the 1.9L. The newer Ion's with the 2.2L Ecotech motor which puts out lots of hp but only get 35 on the highway vs 40 for the old SOHC 1.9L. GM seems to be creating whatever car you wanted 5 yrs ago, today all the time, it seems. Actually, all they'd need to do is give it a 6 spd double od trans to get the mpg and performance at the same time.

So I see you drive 65 on road trips. What do you get for mpg when out on the road doing a steady 65 like that? I get about 50 or 51 out of the Saturn at that speed. Still trying to improve it.

[JanGeo]

Well it looks like PS in my xB is a function of engine RPM because with a fast idle cold on a warm day I get a lot less assist than when it is turning 650rpm. Also turns out my AC compressor is always turning no clutch just a variable compressor spiral. I don't see a big difference in MPG but I have not used it a lot yet. PS drain may be first to change the fluid to Synlube tomorrow.

[Matt Timion]

Originally Posted by cheapybob

So I see you drive 65 on road trips. What do you get for mpg when out on the road doing a steady 65 like that? I get about 50 or 51 out of the Saturn at that speed. Still trying to improve it.

I have some engine damage (burning oil, a few blown seals *ba-da-bing!*, etc) so I'm getting about 41mpg on road trips going 65.

Last summer I got 46mpg going 70-75 with four people in the car and AC blazing.

[diamondlarry]

Originally Posted by cheapybob

Larry, I see you have an SL. Do you have AC or PS on it? My SC1 has both.

The wild one on my test loop is when they merge in 2 lanes from the right and they thin out to becomes the slow lane, but the cars are coming in at 75 and I'm only doing 60. I try to get over, but its tricky with them passing me on both sides.

I have A/C but no PS. It's not too bad even in parking lots.

[DaX]

Originally Posted by diamondlarry

I have A/C but no PS. It's not too bad even in parking lots.

I know, same here. I've only owned one car with PS, and it was more of a luxury than a necessity. It really isn't that bad.

[thisisntjared]

not having ps is no big deal at all until you put drag radials on.

[DaX]

Originally Posted by thisisntjared

not having ps is no big deal at all until you put drag radials on.

Haha, it's funny you mention that. I remember the time I put my old set of 24.5 x 8 slicks on my VX...THAT sucks without powersteering!

[Silveredwings]

I always wondered why the P/S pump has never been made with a cutout clutch the way the A/C compressors are. Above about 25 mph, I doubt any car needs P/S. I once had a car that lost a P/S pressure hose. It was pretty kantankerous below 10 mph w/o P/S, but above that I didn't miss it at all.

If the v-belt itself saps that much engine power, why haven't more cars been made with other types of P/S as the VUE and NSX have? Just curious.

[JanGeo]

My Scion has a variable assist PS - only works at low engine rpm and then they took the clutch off the AC compressor so you can't win.