Herman and Operation 30MPG

[Teddy1975]

I'm still following this topic as fuel economy is always interesting.
However, my guess is you'll lose the money you save here and now by over-inflating your tires to the additional wear on them.
Short term saving might lead to a long term loss. Just saying

[Rattnalle]

40 isn't too high though. It's sensibly high with regard to economy without ruining stuff. What does the sticker say? I usually always go with the "high speed high load" pressure indicated there and that should be pretty close to 40.

[abscate]

Quick math for US only costs of course.

4 tires at 40,0000 miles and $400 - so about 1 cpm cost

Gas costs about 10 cents per mile at 30 mpg, 15 cpm at 20 mpg

so if you get a 10% increase in mpg, and half your tire life, you probably break even.

Extra credit for working out the green footprint of tires vs fuel

(back under my troll bridge)

[callahanoffroad]

Quick math for US only costs of course.

4 tires at 40,0000 miles and $400 - so about 1 cpm cost

Gas costs about 10 cents per mile at 30 mpg, 15 cpm at 20 mpg

so if you get a 10% increase in mpg, and half your tire life, you probably break even.

Extra credit for working out the green footprint of tires vs fuel

(back under my troll bridge)

Yeah that's very similar to what I worked out. But like I said I need to run a few control tanks to see what's up yo.

Also, a small delivery driver secret. Never buy new tires for your delivery cars. I can get used tires with 90% tread on them for $180 out the door. That's about 45% the cost of new tires. Considering that I drive about 30,000 miles a year, I basically need a new set annually. Too bad no one sells tires with a lifetime warranty like they do with brake pads! (At least not that I know of)

Glad to know that people are appreciating all my silly antics!

Made a MAJOR upgrade to my car last week. Improved the stereo system to a touchscreen with GPS, Pandora music streaming, and Bluetooth phone calls. Ie I got a tape adapter for my phone. Hahaha. Pic below.

Still need to replace the speakers in the rear deck. Dead as door nails.

[callahanoffroad]

Okay update time.

Three tanks of results with the over pressurized tires.

1: 21.5 mpg (rained for 300 miles)
2: 23.5 mpg (dry and cool)
3: 22.5 mpg (rain for 150 miles)

Tanks 1 & 3 had the ac on most of the time. My car fogs up pretty bad when it rains. Tried rainx anti fog and that somehow made it worse. Must have applied it wrong!

So I am pretty convinced that over inflating your tires does nothing for city mpg. It does though, make your ride terrible.

I installed some new back speakers last week. I'm going to do a detailed write up on how to repurpose your sedan deck speaker cases for aftermarket speakers and will post it in a separate thread. What I will say is that it is nice to have a bass range in my car again!

I wanted to also take the time to make a quick note about my car and the differences b/t my '95 and my old '96.

The fuel system in my '95 is the old jetronic fuel system. Whereas my '96 had the newer motronic.

On the mpg and octane debate, I was actually surprised that my 95 didn't lose 2 mpg and a noticeable amount of power. My '96 actually went from 26mpg to 24 mpg during my daily 100 mile commute when I tried 87 octane a few years back. It also lost power. My '95 doesn't act like there is any difference at all between the two grades of gas. I'm going to attribute that difference between them to the difference between the ECU systems.

What that means is that the things that work for me, may not get identical results in a '96 + system.

Moving on from the octane topic:

It looks like the biggest increases and decreases in mpg come from drag and load on the engine. So looks like the place to find any remaining mpg will be in any place that causes resistance on the engine.

So the easiest place to reduce resistance is by switching from conventional to synthetic. And following that flushing the transmission fluid with some fresh synthetic fluids. Next would be to inventory the engine and find anything that may be causing too much load and see if it needs to be replaced. Maybe a lightweight flywheel?

I'll start with synthetic oil on Friday and go from there.

What do you guys think? Will synthetic fluids make an effeciency difference?

[WhatAmIDoing]

1) So I am pretty convinced that over inflating your tires does nothing for city mpg. It does though, make your ride terrible.

2) On the mpg and octane debate, I was actually surprised that my 95 didn't lose 2 mpg and a noticeable amount of power. My '96 actually went from 26mpg to 24 mpg during my daily 100 mile commute when I tried 87 octane a few years back. It also lost power. My '95 doesn't act like there is any difference at all between the two grades of gas. I'm going to attribute that difference between them to the difference between the ECU systems.

3) It looks like the biggest increases and decreases in mpg come from drag and load on the engine. So looks like the place to find any remaining mpg will be in any place that causes resistance on the engine.

4) Maybe a lightweight flywheel?

5) What do you guys think? Will synthetic fluids make an effeciency difference?

1) Good to know. Was actually expecting to see some improvement from this. Roads are so rough where I'm at right now, I wouldn't want to go above 35psi.

2) This is an interesting observation. Would be interesting to dyno test an 850 with the different ECUs and all other variables constant to see if there is a performance difference. Can you swap a jetronic for a montronic ECU in a '95 850 without tuning/doing anything?

3) The biggest is driving style. Always use highest gear possible, try to use engine breaking over friction breaks, avoid stopping, predictive driving, etc. For city driving, decreasing rolling resistance should do more than improving aerodynamics. Make sure all the wheels move freely, wheel bearings are good, no brake drag, alignment is good, fuel economy rated tires.

4) NO, just no.

5) In the long term, yes. Short term no, 30 weight oil is 30 weight.

[callahanoffroad]

1) So I am pretty convinced that over inflating your tires does nothing for city mpg. It does though, make your ride terrible.

2) On the mpg and octane debate, I was actually surprised that my 95 didn't lose 2 mpg and a noticeable amount of power. My '96 actually went from 26mpg to 24 mpg during my daily 100 mile commute when I tried 87 octane a few years back. It also lost power. My '95 doesn't act like there is any difference at all between the two grades of gas. I'm going to attribute that difference between them to the difference between the ECU systems.

3) It looks like the biggest increases and decreases in mpg come from drag and load on the engine. So looks like the place to find any remaining mpg will be in any place that causes resistance on the engine.

4) Maybe a lightweight flywheel?

5) What do you guys think? Will synthetic fluids make an effeciency difference?

1) Good to know. Was actually expecting to see some improvement from this. Roads are so rough where I'm at right now, I wouldn't want to go above 35psi.

2) This is an interesting observation. Would be interesting to dyno test an 850 with the different ECUs and all other variables constant to see if there is a performance difference. Can you swap a jetronic for a montronic ECU in a '95 850 without tuning/doing anything?

3) The biggest is driving style. Always use highest gear possible, try to use engine breaking over friction breaks, avoid stopping, predictive driving, etc. For city driving, decreasing rolling resistance should do more than improving aerodynamics. Make sure all the wheels move freely, wheel bearings are good, no brake drag, alignment is good, fuel economy rated tires.

4) NO, just no.

5) In the long term, yes. Short term no, 30 weight oil is 30 weight.

Honestly if we could find someone with a Dyno we could use I'd be more than happy to drive to it and do the runs. It would be really interesting to see the effect of vvis, different ecu's and different octanes of gas.

I think the wiring harnesses are different between the jetronic and motronic. Jetronic uses two ecu's, one for spark, the other for fuel.

There is probably a way to swap but I'd need to do some digging hahaha

[callahanoffroad]

Alright, two week update.

I think I'm finally up-to-date on all of my repairs and I think we're settling into a nice constant. I started noticing an interesting mpg pattern that my 96 did as well. When it's time to change to oil I lose 1 mpg. Went down to 22.5 mpg avg (it was doing 23.5 the two tanks previous). Hahaha.

So I changed the oil, 10w-30 again, and it shot back up for the last two tanks. 24.6 mpg

It's also getting warmer here and with that the car warms up within about a mile of driving. So I'm confident that is helping immensely.

I have a big road trip on Tuesday, so we will get a nice solid highway reading and see if these repairs have made an effect on highway fuel consumption. Last time I did this trip I got 22 mpg. I'll be driving from St Louis Missouri USA to Evansville Indiana USA.

I'm also pretty confident that I'm rinsing gunk out of the oil with every oil change. I inspect the heads through the oil filler port and there is less burned black gunk on the metal after every change. So that's a good thing I'm thinking. Maybe I should put in an engine flush before the next oil change.

Looks like the next time I'll have access to a garage to do repairs will be over the summer. So I've begun to compile a to-do list for myself. I'll probably pull and rebuild the head, timing belt, water pump, fuel filter, re clear coat the passenger side fender, r&r the VVIS manifold actuator (pretty sure it is seized on high rev mode), repaint the side skirts, replace the HVAC blower motor, and some other odds and ends.

New rear deck speakers work great. I went with some sosche 5"x8" speakers from Walmart. Removed the old speakers from the boxes and they mounted directly into the old speaker boxes. Screwed them down with some 1/2" sheet metal screws and now when I listen to music I can actually hear some bass. I was going to do a write up but it was so simple it would be unnecessary.

I think my posts should should including a summary hahaha. But I like to write, and I think car forums are better with personal stories. I used to own an old land cruiser and the best threads had personal stories attached to them. The best was this guy's epic journey from Austin Texas to Hawaii in an old FJ40.

I think Volvo's attract a very reliable and serious sort of people, but I think everyone has a sense of humor. I mean we debate oil viscosity, octane and oem parts. So, let's share our favorite Volvo stories. You guys go first. Post it in this thread!!!!

[callahanoffroad]

Okay! Back from my all day roadtrip and I am very happy to report that my average highway mpg has officially gone up!

I did this exact drive last August and got 22 mpg. Yesterday I got 27 mpg!

Summary:
So it looks like the doing stage 0 tune-up really does work. But the systems that specifically affected mpg the most were the pcv system, and viscosity of oil. Which makes sense, excess crankcase pressure causes higher resistance in the engine as does a thicker viscosity oil.

I'll keep updating this thread as it is my build thread.

[callahanoffroad]

2) This is an interesting observation. Would be interesting to dyno test an 850 with the different ECUs and all other variables constant to see if there is a performance difference. Can you swap a jetronic for a montronic ECU in a '95 850 without tuning/doing anything?

So I have been looking into this and it is possible to swap the jetronic 3.2 for the newer motronic 4.3 fuel system. But. and its a big but, you basically have to swap the entire engine wiring loom. Also since I have VVIS the 4.3 Motronic wouldn't be able the activate it at all. Although I don't think it actually works presently either way. So, If I could get ahold of a 4.3 or 4.4 non turbo ecu and engine wiring harness I could spend an afternoon swapping it out and see what happens. I found out you can do this from a guy over on volvospeed who did a NA+T by adding the turbo bits and ECU to a 94 non turbo. He managed the tune by just adding a stock turbo 4.3 ecu and wiring loom. Apparently because the 94-early 95's use the same fuel return system as the turbos you can use the Turbo Fuel Pressure Regulator and fuel injectors. Anyways that was a fun little bit of info I learned. Seems like an interesting way to get a 5 speed turbo in the US! hahaha