So far, the only change in my driving habits has been to start FAS'ing on even the slightest downhills, whereas before I would only FAS on downhills with enough grade to maintain my speed (it doesn't take much of a downhill for that). In the NC mountains where I do most of my driving there aren't a lot of options as to alternate routes.
The second thing I have been trying is experimenting with acetone (3oz per 10gal). Its too early to tell about any mileage gains, but the first thing I noticed a couple of miles after adding it is that the engine runs a lot smoother at the lower rpm's. I can go a lot deeper into the "lugging zone" without lugging than before. Before my lowest non-lugging speed in 5th was 30mph, but now I can get down to 25mph without excessive lugging. This effect goes away within a few miles if I gas up without adding more acetone. I use industrial grade acetone. The acetone sold at drug stores for cosmetics use usually has other chemicals added to it to reduce its "stinkiness", which negates the high volutility of pure acetone.
Oh! I also broke down and finally ordered a SuperMID.
Peakster wrote: '(wouldn't you think that the MPG loss going up hills be compensated by the large MPG increase doing down slopes)?'
The mpg gain going downhills is never quite good enough to make up for the mpg loss going up.
I did a mini experiment one day. I simply read the mpg meter while reving the engine in neutral. At a steady 2000rpm my motor uses about .84gph. There's no way for me to drive at 2k rpm and use less than .84gph without slowing my car. If I was going downhill using light throttle I typically use about 1.2gph, but only .36 of that is pushing the car (1/4th). When going uphill I might use 3 gph, so 2.16gph is used to propel the car. The percent loss to internal drag is much less.
I was P&G yesterday at 40-35mph and realized that accelerating at good throttle in 5th gets about 20mpg but gliding was about 190mpg so IF is pulsed 50% of the time the MPG average would be (190+20)/2 = 105mpg and it looks like I could pulse less than 50% of the time - just need a long enough road to try it for a while without traffic. Stopping to chat for a few minutes with engine running at .1gph lowered my 50.9mpg trip of 19 miles down to 49.7mpg but still a good trip MPG with an average of 44 for the round trip carrying a load of a couple hundred pounds and headwinds going.
DRW: I did a mini experiment one day. I simply read the mpg meter while reving the engine in neutral. At a steady 2000rpm my motor uses about .84gph. There's no way for me to drive at 2k rpm and use less than .84gph without slowing my car. If I was going downhill using light throttle I typically use about 1.2gph, but only .36 of that is pushing the car (1/4th). When going uphill I might use 3 gph, so 2.16gph is used to propel the car. The percent loss to internal drag is much less.
CO ZX2: I just ran these tests as a comparison to your .84 gph at 2000 rpm in neutral. Hard for me to believe the differences between mine and yours.
I was very careful when reading the rpm and converting from liters to gallons. I used the liter setting for better resolution, SG gph only reads in .1 gal increments. So eveything between .1 gal to .2 gal reads .2 gal etc.
Can my car possibly take that much less fuel to run at comparable RPMs? Would be interested in others' results if they care to test. You can do it sitting still. Warm your engine first.
Turbo? But I would be inclined to think the turbo would reduce pumping loss on intake. Compression stroke would create extra resistance but the power stroke should more than make up for that. Exhaust pumping loss should not be a problem unless your exhaust valve opens extremely late.
How much boost do you see at 2000, 4000 and max boost? I have given some thought to a turbo for Old Reliable. Trying to get some ideas.
Question: CO - was this with your alternator & power steering connected or disconnected? I believe that would make a significant difference.
People doing this should also record what loads were on (or removed from) their engines at the time of the readings. IE - DRLs? Alternator-less? Etc.
Air conditioner compressor, power steering, water pump and alternator were all back on the car and running. I thought my battery was fairly well-charged but was still showing around 14.5 volts when running this test.
I had just driven 20 miles so engine was warmed and stable. Patience is a virtue in this to assure accurate readings. I spent about 15 minutes checking and rechecking for repeatability.