The single most important improvement to FE you can ever do. FREE. - Page 2 - Gas Savers

CO ZX2 · 02-17-2007, 11:58 AM

Quote:

Originally Posted by diamondlarry

This is the conclusion I came to soon after I got my first SG. The SG is a great tool but, as great as it is, there are so many variables involved that you can't get an absolutely 100% accurate reading ALL the time. You can get it dialed in pretty close but you'll never always be dead on. I use the SG for measuring improvement over different segments and the hand calcs when topping off the tank as the final word. As for those who were criticising CO XX2 recently, Carlos is right, when you analyze things as carefully as Carlos has, CO ZX2 is doing even better than he was reporting. It's all about the commute conditions.

diamondlarry. Are you still using your injector shutoff? If so, does your ScanGauge go to 9999 MPG in Gauge Mode when you shutoff to coast? If not what do you see? It would also be interesting to know your MPG reading in Current Trip mode during shutoff. Do you show any GPH used during shutoff?

According to Ron DeLong 9999 is the expected preferred reading and they work to achieve that in cases where needed. I appreciate your info, just trying to understand how a few various cars are different than most.

diamondlarry · 02-17-2007, 12:16 PM

I only see 9999 in instant mpg mode for a very brief time right after I bump-start the engine at the end of the glide. While it is gliding, I see what appears to be the speed x* readout. Current trip mode just shows accumulating mileage as usual.

CO ZX2 · 02-17-2007, 02:09 PM

Quote:

Originally Posted by diamondlarry

I only see 9999 in instant mpg mode for a very brief time right after I bump-start the engine at the end of the glide. While it is gliding, I see what appears to be the speed x* readout. Current trip mode just shows accumulating mileage as usual.

diamondlarry. Thanks. What do you see for MPG during your glide before you get 9999? What I meant to ask of in Current Trip mode is the MPG reading during glide. You should be showing a steadily rising MPG number as you glide. Also do you show a reading of GPH in Gauge mode when injectors are shut off.

Have you talked with DeLong about your SG? What does he say?

diamondlarry · 02-17-2007, 03:35 PM

Quote:

Originally Posted by CO ZX2

diamondlarry. Thanks. What do you see for MPG during your glide before you get 9999? What I meant to ask of in Current Trip mode is the MPG reading during glide. You should be showing a steadily rising MPG number as you glide. Also do you show a reading of GPH in Gauge mode when injectors are shut off.

Have you talked with DeLong about your SG? What does he say?

In instant mode I see, for example, 550, 540, 530, etc. as my speed falls. It seems to be .1 gphX speed. In current trip I see a rising mpg number as you mentioned. When I'm gliding with the engine off the GPH shows .1 GPH. I haven't contacted Ron but it sounds like it may be a good idea.

Wazabi Owner · 02-17-2007, 06:49 PM

Now if I just had hills big enough to do this on, our hills are very gradual around here. Enough to suck up gas going up, but barely enough to glide down and see much of a difference...........

I have ONE hill that I can drift down .7 of a mile IF no one is behind me because at the end I am at a crawl - again, very gradual. That being said, I do live in the highest point of Florida - yep, the Florida mountains.

skewbe · 02-17-2007, 09:03 PM

Quote:

Originally Posted by BluEyes

...I think the best way to run this test would be to do the neutral coast first. Mark where the car falls below 30mph and then on the engine-off, in-gear test, restart the engine and continue driving to the point where the neutral coast ended (but at what speed???)...

I think you are homing in on it here, the trip back up shouldn't really factor into it if it was a different trip for each test. Even just in practical terms, the store isn't going to move 3.6 miles farther away just because you are coasting in neutral, and you are not going to just fire up the engine and turn around if your engine in gear coast didn't make the distance.

I retract my suggestion of firing up the engine on test 1, a matched terminal speed if only examining the downhill legs is a sufficient reference point.

The fact that it went 3.6 miles farther is significant.
The fact that the second test averaged 20mph faster is also significant.
The fact that it was on top of a mountain is also significant

I don't know that we learned enough to make a mpg comparison though (didn't actually use any fuel).

CO, I'd love to get your mileage ratings. You have to cover a lot of ground out there so it's especially awesome that you are making those kind of numbers.

The Toecutter · 02-17-2007, 09:30 PM

Quote:

I wonder if a diesel or electric would respond this way?

My hunch is that a diesel would, but an electric wouldn't. The losses for an electric drive tend to increase with load(P=(I^2)*R)

cfg83 · 02-17-2007, 11:40 PM

diamondlarry -

Quote:

Originally Posted by diamondlarry

I only see 9999 in instant mpg mode for a very brief time right after I bump-start the engine at the end of the glide. While it is gliding, I see what appears to be the speed x* readout. Current trip mode just shows accumulating mileage as usual.

That's exactly what I see. I wonder if the instant RPM jump from 0 to 1000+ throws off the implied "0.1 GPH" failsafe in the software.

I think this is a question for the ScanGauge guy. Also, why not go to 0.01 GPH? Is this just a display thing where we ScanGauge only wants to express x.x digits?

Question : Would switching to metric units for ScanGauge usage yield better accuracy in the ScanGauge because the liter as a unit is smaller?

Todo List : 1.00 Gallons equals 3.79 Liters. Therefore, 0.1 Gallons equals 0.379 liters. This would imply that for the "0.1 GPH" scenario, the ScanGauge should display "0.4 LPH" (assuming roundup). However, IF the ScanGauge displays 0.1 LPH (a failsafe value for a different unit), then the "KPG" calculation would be more accurate for engine-off strategy.

This would imply the need, for accuracy, to use the ScanGauge in "liter display" mode and convert as needed,

.

CarloSW2

diamondlarry · 02-18-2007, 05:08 AM

I will give the Metric thing a try today. I'll also see if you can switch back and forth without having to convert back to gallons.

CO ZX2 · 02-18-2007, 09:37 AM

I'm in Daytona. FE is pretty important here sometimes, especially with 1 or 2 laps to go. No coasting here till you're out of gas.

cfg83 · 02-18-2007, 01:50 PM

diamondlarry-

Quote:

Originally Posted by diamondlarry

I will give the Metric thing a try today. I'll also see if you can switch back and forth without having to convert back to gallons.

I just tried it and saw "0.3 LPH". Soooooo, I think there is no round-up. Since it is not "0.1 LPH", I think that the units are English-centric, which would make sense for a product developed in the USA.

I don't think changing units will make any difference in MPG,

.

CarloSW2

diamondlarry · 02-18-2007, 02:31 PM

I had the same thing.

JanGeo · 02-18-2007, 04:37 PM

yeah but that is .75gph maybe you can't burn at any lower a rate - guess I need to try it in my xB and see if it gets lower than the .2 - 1. gph I see all the time when warmed up...

CO ZX2 · 02-19-2007, 11:34 AM

Quote:

Originally Posted by Wazabi Owner

Now if I just had hills big enough to do this on, our hills are very gradual around here. Enough to suck up gas going up, but barely enough to glide down and see much of a difference...........

I have ONE hill that I can drift down .7 of a mile IF no one is behind me because at the end I am at a crawl - again, very gradual. That being said, I do live in the highest point of Florida - yep, the Florida mountains.

Get a little speed up before the downhill. Makes the hill last a little longer and keeps you from getting run over. If you coast for .7 mile, your MPG should be 10% better for the following 7 miles. Add 'em up and they amount to something. Pulse and Glide can be done on level ground. 60 to 40 works pretty well for me but only if I glide in neutral, engine off.

Get in that Toyota and come see us in Colorado. We'll go trout fishing.

Wazabi Owner · 02-19-2007, 01:44 PM

Ahhh, but here's the catch. I do just that BUT the road has a HUGE bump at the bottom PLUS it turns to a rocky dirt road PLUS it switchs to 15mph in the area where I'm capable of still coasting 30mph PLUS the ONE house on the road in the 15mph area has a cop as a best buddy, he's always there in that 15mph zone. He even waits for me sometimes at 0500am - pretty cool guy as I am normally cruising 35-40mph through there at that time of the morning, This is really out in the middle of nowhere with no side roads, kids etc.

I do have an alternate route I do an engine off coast on when I am driving my Metro, HUGE savings and it is about .5 of a mile. Always cars on that road though, I hate traffic.

Toyota still needs work, I need to find the time (and motivation and $$$) to work on it. BTW, if you're still in Daytona and drove out PM me, I'm just a few minutes off I-10 - I'll let you take the Insight out for a spin.

Quote:

Originally Posted by CO ZX2

Get a little speed up before the downhill. Makes the hill last a little longer and keeps you from getting run over. If you coast for .7 mile, your MPG should be 10% better for the following 7 miles. Add 'em up and they amount to something. Pulse and Glide can be done on level ground. 60 to 40 works pretty well for me but only if I glide in neutral, engine off.

Get in that Toyota and come see us in Colorado. We'll go trout fishing.

Brock · 02-19-2007, 02:36 PM

Quote:

Originally Posted by The Toecutter

My hunch is that a diesel would, but an electric wouldn't. The losses for an electric drive tend to increase with load(P=(I^2)*R)

Not sure about all diesel?s, but my TDI uses no fuel coasting in gear down hill. At idle scangauge will show about .2L/hr once warm. If I am going down a hill in 5th with no throttle added it shows 0.0L/hr, if I push the clutch in it goes back up to .2L/hr.

So the big debate on the TDI forums is whether to coast in neutral or coasting in gear. Of course you slow down a lot sooner coasting in gear.

If I have to stop I have figured out how far out I can coast clutch in to make it just right, or if I am in traffic how far out I can coast clutch out, no throttle. From the testing I have done it is better to coast in neutral at .2L/hr then coasting in gear at .0L/hr because you have to stay of the throttle longer leading up to a coast in gear (assuming a flat run out).

Unless you have just the right hill to gain no speed in gear and have to slow down anyway, I use neutral.

omgwtfbyobbq · 02-19-2007, 02:58 PM

Quote:

Originally Posted by Brock

Not sure about all diesel’s, but my TDI uses no fuel coasting in gear down hill. At idle scangauge will show about .2L/hr once warm. If I am going down a hill in 5th with no throttle added it shows 0.0L/hr, if I push the clutch in it goes back up to .2L/hr.

So the big debate on the TDI forums is whether to coast in neutral or coasting in gear. Of course you slow down a lot sooner coasting in gear.

Just compare it on a KE+PE/top to KE+PE/bottom basis (I'm guessing it depends on the hill). You can calculate the difference in energy between the car's initial state, higher up on the hill, and it's final state, lower down on the hill. Compare these initial states to find out which car, in gear/no fuel or out of gear/little fuel, gains more energy from rolling down the hill. Since the car out of gear is idling, calculate the energy used while idling multiplied by the appropriate modifier for diesel engine/transmission efficiency, and account for it including it in the car that's out of gear's delta E. You could test this on a few different hills to get a curve of best fit, and approximate the grade where it becomes better to keep it in gear, or coast in N, barring of course speed limits.

CO ZX2 · 02-20-2007, 04:20 AM

Quote:

Originally Posted by basjoos

Your test results agree with my driving style. I coast the downhills with the engine off and only use engine braking on steep downgrades where my speed would rapidly get too high or where there is no straight runout area at the bottom.

An extension of these tests would be to test the uphills. Do you get better FE if you accelerate on the flat at the bottom of the hill to build your speed up before reaching the bottom of the hill so you can get further up the hill before having to drop into a lower gear, or is it better to maintain the lower aero drag of your normal cruising speed and accept having to drop into a higher fuel consuming lower gear earlier on the uphill?

Sorry, I first thought your reply was directed to someone else.

I have done no official tests on uphills but have been driving in the manner you describe by accelerating before and quite often during uphill climbs. I almost always do this on hills not too long, i.e., that I can see the crest. I am sure I have improved my uphill FE with these methods.

Longer climbs I get questionable payback for increased approaching speed. But during long climbs I will accelerate if my instant MPG drops below 30 MPG. When my SG II drops into the 20-30 MPG range, extra throttle does not lower the MPG reading substantially(when it's that low, how much lower can it get?). Quite often I can level off after acceleration to a higher speed and see much improved MPG readings for a time. I downshift only when absolutely necessary and when I do I will accelerate immediately to gain enough momentum to get back in 5th gear as soon as possible.

If you drive this way, I would like to hear your assessments.

skewbe · 02-20-2007, 05:30 AM

Quote:

Originally Posted by CO ZX2

... I downshift only when absolutely necessary and when I do I will accelerate immediately to gain enough momentum to get back in 5th gear as soon as possible...

Do you drop to the next lowest gear, or an even lower gear so you can accellerate better?

CO ZX2 · 02-20-2007, 08:11 AM

Quote:

Originally Posted by skewbe

Do you drop to the next lowest gear, or an even lower gear so you can accellerate better?

I always drop into the next lowest gear. I don't very often go lower than 4th. In the past, if I let my car pull way down 5th, it was also too slow for 4th to pull strong. Then I would use 3rd to bring it back up. I do not skip shifts often.

Keep in mind that I have a 130 HP 2.0 liter engine. But it may not be as different as it seems. At my 10,000 ft. altitude, I may be losing 35% of HP and torque. Actual barometer readings here are in the 21-23 in. Hg area, vs 29-31 in. Hg at altitudes of 0-2000 ft. What this means is that I have about one third less atmospheric pressure pushing air into the engine. Like a supercharger in reverse.

cfg83 · 02-20-2007, 09:55 AM

CO ZX2 -

Quote:

Originally Posted by CO ZX2

I always drop into the next lowest gear. I don't very often go lower than 4th. In the past, if I let my car pull way down 5th, it was also too slow for 4th to pull strong. Then I would use 3rd to bring it back up. I do not skip shifts often.

Keep in mind that I have a 130 HP 2.0 liter engine. But it may not be as different as it seems. At my 10,000 ft. altitude, I may be losing 35% of HP and torque. Actual barometer readings here are in the 21-23 in. Hg area, vs 29-31 in. Hg at altitudes of 0-2000 ft. What this means is that I have about one third less atmospheric pressure pushing air into the engine. Like a supercharger in reverse.

Is there a way you can measure your "effective HP" at your altitude? I was using a tangential "Colorado Rockies" metaphor where, in Denver, a baseball can travel 10% farther in the thin air of Coors Field, 5280 feet above sea level.

Ok, maybe I can answer my own question. I just googled "engine horsepower elevation" and got these results :

Engine Tuner's Calculator
http://wahiduddin.net/calc/calc_hp_dp.htm

Using this in conjunction with weather.com, I got current "relative horsepower" assumptions for Denver to be 83% of rated HP, a 17% reverse supercharger in Denver.

Density Altitude Calculator - selectable units
http://wahiduddin.net/calc/calc_da_em.htm

CarloSW2

CO ZX2 · 02-20-2007, 12:29 PM

Quote:

Originally Posted by cfg83

CO ZX2 -

Is there a way you can measure your "effective HP" at your altitude? I was using a tangential "Colorado Rockies" metaphor where, in Denver, a baseball can travel 10% farther in the thin air of Coors Field, 5280 feet above sea level.

Ok, maybe I can answer my own question. I just googled "engine horsepower elevation" and got these results :

Engine Tuner's Calculator
http://wahiduddin.net/calc/calc_hp_dp.htm

Using this in conjunction with weather.com, I got current "relative horsepower" assumptions for Denver to be 83% of rated HP, a 17% reverse supercharger in Denver.

Density Altitude Calculator - selectable units
http://wahiduddin.net/calc/calc_da_em.htm

CarloSW2

Carlo, Here I am trying to help anyone who wants help and you seem to have made it your life's work to repeatedly dispute anything I say. Review the responses you have made on my posts since I have been on GasSavers. What is the deal?

You are literally and actually a mile off on this one. Denver(5280) is near half of my altitude. I gave you my altitude (10,000feet). All you would really have to have done was enter my altitude (10,000 feet) into the calculator. For a guy obsessed with figures, how could you not have seen that in my post? Even so 10,000 feet may be a low average figure. I regularly drive over mountain passes 11,000-12,000+ feet elevation. I do drive to Denver occasionally but overall a small percentage of my driving.

Answering your own questions with careless factfinding is not very scientific. I raced in Denver many years and used NHRA altitude correction factors so am very familiar with them. I have spent endless hours running engines on dynamometers using altitude and weather correction factors for HP and torque.

I am not very sure of the validity of the baseball travel statement. I have heard it many times but have no idea where it got started. It stands to reason that thinner air would have some effect but I've never worried about it much. If you can make it into something that will produce more FE for me, I'll take it. CO ZX2

cfg83 · 02-20-2007, 01:27 PM

CO ZX2 -

Quote:

Originally Posted by CO ZX2

Carlo, Here I am trying to help anyone who wants help and you seem to have made it your life's work to repeatedly dispute anything I say. Review the responses you have made on my posts since I have been on GasSavers. What is the deal?

You are literally and actually a mile off on this one. Denver(5280) is near half of my altitude. I gave you my altitude (10,000feet). All you would really have to have done was enter my altitude (10,000 feet) into the calculator. For a guy obsessed with figures, how could you not have seen that in my post? Even so 10,000 feet may be a low average figure. I regularly drive over mountain passes 11,000-12,000+ feet elevation. I do drive to Denver occasionally but overall a small percentage of my driving.

I am not disputing anything you say. I already know that you are at 10,000 feet. You are reacting to this :

... for Denver to be 83% of rated HP, a 17% reverse supercharger in Denver

I am saying it is in Denver. I am not claiming it to be your location. Sorry for not making that clear in my post

.

The reason I did not enter your altitude is that there are 4 inputs to the calculation. I did not want to make the assumption that the weather conditions in Denver are identical to yours, especially with a 1 mile altitude differential. Wouldn't you agree?

If I had plugged in your altitude, your estimate of 35% is inline with a doubling of altitude, aka 17%*2 = 34% reverse supercharger.

Question : Can you go to the website and plug in your zipcode/location and tell me the numbers you get? Also, can you go to the website and interpret the numbers for accuracy for me?

Quote:

Answering your own questions with careless factfinding is not very scientific. I raced in Denver many years and used NHRA altitude correction factors so am very familiar with them. I have spent endless hours running engines on dynamometers using altitude and weather correction factors for HP and torque.

You know this stuff off the top of your head, but other people do not. The level of car smarts in this forum is great. That ain't me. I am just "Joe car owner". I have to do "unscientifical research" to find stuff out. I have to go "somewhere else" to learn and understand information that you know by rote.

I never knew the existance of "NHRA altitude correction factors" until you just posted them.

Quote:

I am not very sure of the validity of the baseball travel statement. I have heard it many times but have no idea where it got started. It stands to reason that thinner air would have some effect but I've never worried about it much. If you can make it into something that will produce more FE for me, I'll take it. CO ZX2

Thinner air implies less oxygen (to me) which implies lean-engine running (to me) "up thar" in the Rockies, but I can't prove it because I haven't done this stuff all my life. You have.

Dammit, Jim, I'm a programmer, not a race engine builder

!!!!!!

CarloSW2

MetroMPG · 02-20-2007, 01:45 PM

Quote:

Originally Posted by cfg83

Thinner air implies less oxygen (to me) which implies lean-engine running (to me) "up thar" in the Rockies, but I can't prove it because I haven't done this stuff all my life. You have.

The a/f mixture will be corrected by the ECU via the O2 sensor - a modern engine won't run leaner in thinner air.

What it IS doing though is running at a wider throttle opening to generate a given amount of power (relative to a car at lower elevation), which reduces throttle/pumping losses.

Add to that the reduction in aero drag in the less dense air...

Add to that the mountainous terrain, likely forcing the engine into an even better BSFC zone under higher loads on the ascents...

And you have the makings for better than average FE, when driven correctly (which CO clearly knows how to do!).

MetroMPG · 02-20-2007, 01:45 PM

Quote:

Originally Posted by cfg83

Dammit, Jim, I'm a programmer, not a race engine builder

!!!!!!

Good one!

CO ZX2 · 02-20-2007, 03:29 PM

Quote:

Originally Posted by MetroMPG

Good one!

More silliness. And mistakes. Do you know Jim? I do not.

diamondlarry · 02-20-2007, 03:37 PM

Quote:

Originally Posted by cfg83

Dammit, Jim, I'm a programmer, not a race engine builder

!!!!!!

CarloSW2

I have a sneaking suspicion that the above was a reference to Captain Kirk.

landspeed · 02-20-2007, 03:48 PM

10,000 ft

. I wish I lived that high up!. I suppose, it shows the value of 3 things for good fuel economy:

(1) Driving style
(2) Aero mods (if you can't thin the air, at least you can reduce the resistance!)
(3) Reducing pumping losses (again if you can't thin the air). Unless you can get new cams made, this will have to be be increasing the throttle load.

By the way, a simple way to think about the engine on + idling or 'coasting in gear' argument would be...

- The engine uses a certain amount of fuel to idle at 750rpm
- If you coast in gear at 1500rpm, the engine will be 'wasting' more energy
in the form of engine braking. This energy originally came from petrol, so, by coasting in gear at 1500rpm, you are wasting more energy than by idling in gear.

The only real reason to coast in gear would be to slow your car down, without using the brakes, because there is a red light / junction etc up ahead. This is more efficient than idling + using brakes.

Something I have noticed with my new lambda sensor - the brakes run on vacuum, so, at idle (with the car not moving), if I press the brakes 3 times in a row, the mixture goes to 20:1 briefly (because the brakes are using the vacuum by letting air flow from the environment into the inlet manifold). When this happens, the engine runs OK, maybe *slightly* unevenly. I know that you do get a lot of NOx emissions with lean running, but would this be the case at idle?. If not, it might be possible to modify the mapping so that, at idle, the car runs lean and uses a lot less petrol (noting that diesel engines run very lean at idle).

cfg83 · 02-20-2007, 04:49 PM

diamondlarry -

Quote:

Originally Posted by diamondlarry

I have a sneaking suspicion that the above was a reference to Captain Kirk.

NO NO NO!!!! My reference is to that guy from priceline that keeps trying to book your vacations for you! He also played the police chief on TJ Hooker back in the 1980's, and was in that Black and White Twilight Zone episode where the gremlin/monster was trying to destroy the engine and crash the passenger plane.

CarloSW2

diamondlarry · 02-20-2007, 05:17 PM

Quote:

Originally Posted by cfg83

diamondlarry -

NO NO NO!!!! My reference is to that guy from priceline that keeps trying to book your vacations for you! He also played the police chief on TJ Hooker back in the 1980's, and was in that Black and White Twilight Zone episode where the gremlin/monster was trying to destroy the engine and crash the passenger plane.

CarloSW2

Oh yeah, now I remember.