EcoModder.com

EcoModder.com (https://ecomodder.com/forum/)
-   Hypermiling / EcoDriver's Ed (https://ecomodder.com/forum/hypermiling-ecodrivers-ed.html)
-   -   Case Study: 45% above EPA? (https://ecomodder.com/forum/showthread.php/case-study-45-above-epa-25307.html)

wobombat 03-20-2013 09:46 PM

Case Study: 45% above EPA?
 
A friend of mine is skeptical of the influence my hypermiling techniques have on my gas mileage, and stated that he wouldn't believe it worked unless I could achieve 26 MPG (45% above EPA) on a tank. I thought, challenge accepted! My problem? So far I can't get better than 22.5 MPG on any one tank (25% above EPA), and I'm out of ideas on how to improve. Here's the situation:

My car is a 2000 Lincoln LS 3.0L V6 Auto Transmission, 213k on the odometer.
EPA: 16 city, 18 combined, 23 Highway.

What I've done:
Tires to 50 PSI
Folded in passenger-side mirror
I don't want to do any extensive ecomods because I plan to sell the car in a few months (when I finish rebuilding my mustang). Any other cheap, easy, reversible ecomods I can do?
50-55 highway speeds, steady speed
minimize brake use in city, timing lights, engine braking when appropriate (e.g. when engine is cold)
Goal to stay in bottom of top gear as much as possible.
coast in neutral whenever I can do so for more than 15 seconds ( my tranny does high rev's when re-engaging to drive mode, and when in neutral, rpm gauge often shows higher rpms than when in drive at the same speed. I think it's to keep the tranny pump at the right speed. Anyway, point is I don't often go into neutral).
Neutral at lights. (I used to turn off the engine, but then once when I did so the electrical system failed and I couldn't restart the engine. After bugging a few dozen cars, I got mine to the side of the road and fiddled with it until it started working. I'm not turning my car off at lights after that)
Low RPM's, try to stay below 2500 at all times.

On a side note, I tested P&G with 75% throttle with 1500-2000 RPM from 50 to 60, then coast to 50, on several tanks, then steady speed on the same routes on several tanks, and I always got 20.5-21 MPG with P&G, and 21.5-22 with steady speed. Perhaps the car is old enough that compression losses at high throttle decrease efficiency. And I can't EOC because of the Auto Tranny.

Do you think it's possible for me to get 26 in combined driving with this car? Is there anything I'm missing that I could do?

HydroJim 03-20-2013 09:48 PM

tell your friend that 25% is a highly significant difference and is quite impressive for an automatic.

101Volts 03-21-2013 12:05 AM

I suggest you accelerate slower and keep the load on the engine low; If you have a ScanGauge II or other on-board gauge this is easier/quicker to learn. Try to keep the load under 20, 15-20 at the highest (Though YMMV depending on the vehicle, I'm basing this on the Caravan I drive.) You may also attach pizza pans to the hubcaps though they might start rusting quickly if not painted. Also, 50 PSI may or may not be the most fuel-efficient tire PSI for your car; It may be best to test the FC for various tire pressures.

Edit/Update: Find what works for you and your car and locality while staying safe.

Piwoslaw 03-21-2013 01:32 AM

Quote:

Originally Posted by 101Volts (Post 362489)
I suggest you accelerate slower and keep the load on the engine low; If you have a ScanGauge II or other on-board gauge this is easier/quicker to learn. Try to keep the load under 20, 15-20 at the highest (Though YMMV depending on the vehicle, I'm basing this on the Caravan I drive.)

Actually, most BSFC maps suggest that IC engines are most efficient around 80% load, with rpms around max torque.
The BSFC chart thread

HypermilerAX 03-21-2013 05:49 AM

Quote:

Originally Posted by Piwoslaw (Post 362502)
Actually, most BSFC maps suggest that IC engines are most efficient around 80% load, with rpms around max torque.
The BSFC chart thread

I've been able to test that. My average consumption on the flat at 75 km/h is 3,05 l/100. On a 2,5% average slope, at the same speed, the consumption didn't exceed 3,50 l/100 (5th gear, 1900 rpm, throttle pressed at about 75%). After calculating the power needed in both cases, the engine efficiency is 21% on the flat and 35% on that slope.

razor02097 03-21-2013 07:49 AM

This might be cheating but... maybe see if you can find a more efficient route. Without a manual and DFCO going up and down hills in an auto wastes a lot of fuel....

101Volts 03-21-2013 08:37 AM

Quote:

Originally Posted by Piwoslaw (Post 362502)
Actually, most BSFC maps suggest that IC engines are most efficient around 80% load, with rpms around max torque.
The BSFC chart thread

I was speaking from my experience, I did manage some decent FE by keeping low but perhaps it can be improved yet. I haven't tried using the engine at its most efficient load (Though I exceeded it,) Thanks.

Austin

razor02097 03-21-2013 09:18 AM

Quote:

Originally Posted by 101Volts (Post 362525)
I was speaking from my experience, I did manage some decent FE by keeping low but perhaps it can be improved yet. I haven't tried using the engine at its most efficient load (Though I exceeded it,) Thanks.

Austin

In my experience older autos seems to do better if you apply enough throttle for brisk acceleration then let off at the appropriate speed to lock up the converter then keeping a steady throttle to keep the converter locked. So what you say is correct. :thumbup:

101Volts 03-21-2013 04:46 PM

Quote:

Originally Posted by razor02097 (Post 362533)
In my experience older autos seems to do better if you apply enough throttle for brisk acceleration then let off at the appropriate speed to lock up the converter then keeping a steady throttle to keep the converter locked. So what you say is correct. :thumbup:

I need to be more specific, I meant that I've tried accelerating very slowly to the speed limit or just under it (Which worked pretty well in some cases, IMO but perhaps that's due to not P&Ging most efficiently yet) and that I've also tried mashing the pedal to the floor to try P&Ging. But, I don't always do the latter one and I certainly exceeded the best operating engine load when mashing the pedal; I haven't yet learned a more fuel-effieient P&G method. Thanks for mentioning that about the converters in older cars, Though.

Was I straying off-topic?

EDIT:

When I was accelerating I was scarcely holding the pedal down. The HPR gauge would read at 6-7ish or so when I wasn't holding the pedal down and I only pressed it down enough to go to about 8 HPR and that would not exceed 20 on the TPS (Throttle Position Sensor). When the throttle isn't held down at all it's at 16.

- Austin

wmjinman 03-21-2013 05:45 PM

If your route has areas where you'll be driving at 50 mph or so, grille blocking would probably help. Every time I've tried it, there's been a significant improvement (like 2 mpg). Definitely get a ScanGauge, or something that shows you what kind of results your getting from your different ideas you try.

When I tried to P&G or hold a good BSFC load going up a hill in my Jimmy with auto trans, I couldn't do it - mashing the throttle enough to get the engine load up there would always cause it to downshift & also shoot up right past my best fuel economy speed. So I found that just trying to hold it at best fuel economy speed did the best.

And 50 mph might be too high for your car. I was assuming it would be around 50 mph for my Jimmy - that lower speeds might be "lugging" it. But nope, turns out 40 mph was actually the best speed. (and I checked it a couple times to make sure). Too slow for the freeway (I tried it & got honked at a lot :eek:), so then I found NON-freeway routes where the speed limit was closer to 40. With the ScanGauge, I found that coasting up to stops from half a block away in neutral really boosted the average mpg, too. It was weird getting used to acceleraing off a green light & then throwing it into neutral and coasting before even getting up to the speed limit, but if you see the light 3/4 of a block ahead turn yellow, that's what you do - and it works!!!

But do a grille block - that should help a lot.

vacationtime247 03-21-2013 08:14 PM

How good is your fabrication skills? Duct tape and coroplast. Build a Kammback onto the trunk.
VT247

olds455 03-21-2013 09:46 PM

I found gains at highway speeds using the Ultragauge. I could see how much I could feather off the throttle and still maintain speed or just let it SLOWLY creep down. In the Buick, I thought I was doing a good job feathering to just sustain cuise speed at around 36mpg instant, then watching the UG and the speedo, I could feather down to around 43mpg instant. Once up to 55 to 58 mph, I can average 43mpg in the winter and 46.5 in the summer on a 10 mile stretch of small rolling hills at highway speed. The Buick is not happy cruising at less than 55 mph, the convertor locks around there, so above that by three to four seems to make it happy and allow me to feather to a good number. I'm currently at 61% above EPA average. I commute 55 miles in about 70 minutes with a fair number of stops and lights in the 12 miles closest to home. The auto makes it more challenging, but you can probably get there. An air dam helped me quite a bit. Made getting big number averages easier. Not a whole lot of fuel log for the Century without an airdam or other mods. Before adjusting my driving, I could sneak a 30.5mpg tank in the summer and 28.5 in the winter. Now I can get 34.5 on my morning commute when the ambient temps are 40 deg. (higher on the commute home.)

SpeedyCorky 03-21-2013 10:02 PM

between the fact the car has +200k, and is an automatic - i'd say 25% over EPA is EXCELLENT

wmjinman 03-21-2013 11:41 PM

Quote:

Originally Posted by SpeedyCorky (Post 362652)
between the fact the car has +200k, and is an automatic - i'd say 25% over EPA is EXCELLENT

No doubt. But he wants to try to get 45% over. ;)

While doing coroplast (or cardboard if willing to be a "redneck" like me), rear fender skirts may or may not help some, too. They didn't seem to work on my Jimmy (oh, how I wish they would have), but others are reporting good gains from them. :thumbup:

Fat Charlie 03-22-2013 12:07 PM

I'm busting my butt out there and I'm 46% over- with a manual and a route made for hypermiling. Winter's a killer for good numbers.

wmjinman 03-22-2013 12:52 PM

Good point!! But winter will be over soon, so all this "practice" might pay off once the temps warm up & the car starts rolling freer...

bestclimb 03-22-2013 01:02 PM

I find that as long as I am not crawling up to speed or keeping the pedal on/near the floor. it makes little difference how I accelerate. I find that I end up accelerating faster than much of the traffic.

Re your tire pressures You may see very little difference fuel mileage wise between 40psi and 50psi. At that pressure you may begin to see center wear. You should monitor it checking tread depth at 3 points across the tire, recording then checking again in a few thousand miles.

cfg83 03-22-2013 02:16 PM

Fat Charlie -

Quote:

Originally Posted by Fat Charlie (Post 362733)
I'm busting my butt out there and I'm 46% over- with a manual and a route made for hypermiling. Winter's a killer for good numbers.

Oakland is admittedly milder than other parts of the country, but I still think this is an excellent point. I looked at wobombat's fuel log and I see a good start that needs more data.

CarloSW2

RedDevil 03-22-2013 05:25 PM

Modder Nature will help a hand when the weather gets hotter making the air less dense and shortening the heatup time for the engine.
So even if you cannot get to 45% above EPA now, you might when the weather gets above 25C (and use the A/C with moderation).

wobombat 03-22-2013 11:20 PM

Amazing Responses!
 
Wow that's a lot of advice! I love it.

Quote:

Originally Posted by 101Volts (Post 362489)
I suggest you accelerate slower and keep the load on the engine low; If you have a ScanGauge II or other on-board gauge this is easier/quicker to learn. Try to keep the load under 20, 15-20 at the highest (Though YMMV depending on the vehicle, I'm basing this on the Caravan I drive.) You may also attach pizza pans to the hubcaps though they might start rusting quickly if not painted. Also, 50 PSI may or may not be the most fuel-efficient tire PSI for your car; It may be best to test the FC for various tire pressures.

I have to say that keeping the load extremely low is one thing I haven't tried. Maybe my engine is so old that compression losses make low acceleration more efficient. I'll have to test that. I'm considering the pizza pans. How do you attach them though? and as for the PSI, I noticed an approximately 5% increase in efficiency at 50 PSI rather than 40 PSI. I may be wearing the tires down unevenly though that way. I have suspension problems so I think they're doing that anyway.

I do not have a scanguage yet, but I plan to get one in the very near future. I noticed that the scanguageE is significantly cheaper than the scanguageII. Any opinions on why the scanguageII is better? Any other gauges I should consider? I got a little obdII reader a while back really cheap that would communicate with an app on a smartphone and read out all the info. If it worked, I think it'd be better than the scanguage because you can customize the environment and save graphs to analyze later, but the thing was a piece of junk and didn't work with my setup. Worked with my brother's setup though.

Quote:

Originally Posted by wmjinman (Post 362610)
If your route has areas where you'll be driving at 50 mph or so, grille blocking would probably help. Every time I've tried it, there's been a significant improvement (like 2 mpg).

At your advice, I made a very rudimentary partial grill block, and put it behind the grille. I know it isn't as effective as in front, but I don't want the car to look ridiculous. I'm considering it though. After one day of driving I saw no difference in warm-up time or coasting ability, so any improvement I'm getting from it is probably minimal. And is there a better way to attach it than duct tape? :)

Quote:

Originally Posted by wmjinman (Post 362610)
And 50 mph might be too high for your car. I was assuming it would be around 50 mph for my Jimmy - that lower speeds might be "lugging" it. But nope, turns out 40 mph was actually the best speed. (and I checked it a couple times to make sure). Too slow for the freeway (I tried it & got honked at a lot :eek:), so then I found NON-freeway routes where the speed limit was closer to 40.

I've found that my tranny shifts into top gear between 45-50 at low loads and I can maintain top gear as low as 42, but you have a point. I could go slower on the freeway. Just today I found a RV thing going 45-50. That was a real gem. But a civic hx got the drafting spot right behind it. I just followed so people wouldn't blame me for the slow speed. I can get closer to 45 without causing a real disturbance though. And I haven't found any good non-highway routes that don't contain a plethora of stops, which I think would decrease my fuel economy, unless if I coasted to a stop which then would take forever.

Olds455 your MPG numbers are impressive! Especially since our cars are very similar. I don't think I have what it takes to do an air dam, but I'll consider it. And a kammback is way over my head. I'm also considering rear fender skirts. I'm not entirely sure how to attach these sorts of things to the car though.


Quote:

Originally Posted by cfg83 (Post 362753)
Oakland is admittedly milder than other parts of the country, but I still think this is an excellent point. I looked at wobombat's fuel log and I see a good start that needs more data.
CarloSW2

My car has some vacuum problems with the fuel system, where the gas pump will cut off at random points for no apparent reason. It makes it really hard to accurately measure MPG, so a lot of fill-ups have gone unrecorded. Winter here probably has only decreased my fuel economy by about 5%. I've been averaging 20-21 through the winter, but I certainly could do better.

Sven7 03-22-2013 11:48 PM

All you need to do for 45% over EPA is aeromod the living sh*t out of it and take a nice long road trip at 55mph. See if you can get some high-adhesion painter's tape to hold wheel skirts, grille blocks and a kammback on. Pull the mirrors off- they should be bolted on, making re-installation easy. Make coroplast wheel covers and zip tie them to the spokes. Make a lawn edging air dam. You're going to need to pull out all the stops.

To put it in perspective, this got 46% over EPA Hwy (41 actual, 28 epa) on a sunny 50 degree day, going about 62mph over 400 miles. No P&G... only coasted on a few long hills. Little drafting since I was passing most people.

http://farm9.staticflickr.com/8044/8...8079b181_z.jpg
New Air Dam by Tyler Linner, on Flickr

wmjinman 03-23-2013 03:25 AM

You need a ScanGauge - or something that'll do essentially the same thing. I can't remember the difference between the SG-II and the "E" off the top of my head, but the feature of the "II" that makes it worth it's weight in gold is the "trip" feature. Read MetroMPG's article on A-B-A testing. (I think it's a "sticky" at the top of the EcoModding Central catagory). The ScanGauge with "trip/reset" is what makes that possible. Do you have cruise control? With a Lincoln, I'd assume that's a "yes". By using the ScanGauge, cruise control, and MetroMPG's A-B-A testing method, you can get a lot of ACCURATE data really fast (well, it might take you over an hour, but not a whole tankfull with many days of variables screwing up your accuracy).

To really know your grille block's effectiveness, you'll probably need something better than warmup times and coasting ability (depending on how rigorously you're testing your coasting ability). The main benefit is in preventing excess air from getting into the under-hood area, where it causes tremendous drag getting out again. Much better to force the air around the front of the car - regardless it's shape - than let it go into the under-hood torture chamber.

For Grille Blocks: Yes, in front tends to be a bit more effective than behind the grille. One thing I tried on my Jimmy was using pieces of plexiglass (or lexan) in front of my headlights. If you got something like that (clear plastic) and put that in front of your grille, it wouldn't stand out too much, and maybe not look too ridiculous for you. ? An "el-cheapo" alternative could be to get some of that 2" wide clear packing tape (like ultra-wide "scotch tape"), and create your block from that. Since it's clear, your grille would show through it, and it wouldn't be too visible unless the light was reflecting off it just right.

Better mounting that duct tape? Sure. Let's see - glue it on with silicone, tie it to the grille around the perimeter with "zip-ties", maybe use a few well-placed sheet metal screws - - - I think one guy made a "panel" that actually replaced the grille - - -

Sounds like 45 might be a good speed for you. Seems I remember there's a rule of thumb that goes something like "go as slow as you can & still keep 'er in top gear". Again, once you get the ScanGauge, testing to find your maximum MPG speed should be fairly simple. - that's assuming you can find a fairly lightly travelled, fairly flat, straight section of road you can do your two-way testing on. Around Oakland, I dunno - that's a pretty big city!!! But even if you have to take a trip 1/2 hour to 45 minutes - even an hour - away to find your "testing road", the information you'd get would be super-valuable.

PressEnter[] 03-23-2013 07:46 AM

Good luck. I can relate to your skeptical friend. I thought hypermiling might gain me a few mpg, so I am thrilled to get 30% over EPA. 45% is a pretty arbitrary number, but I guess it might be fun shooting for it.

As for instrumentation, I shelled out for the SGII, but I think anything with instant and average mpg would be a big help. Even if it's not 100% accurate, making the numbers go up is the name of the game :)

wobombat 03-23-2013 08:08 PM

Quote:

Originally Posted by wmjinman (Post 362812)
An "el-cheapo" alternative could be to get some of that 2" wide clear packing tape (like ultra-wide "scotch tape"), and create your block from that. Since it's clear, your grille would show through it, and it wouldn't be too visible unless the light was reflecting off it just right.

Better mounting that duct tape? Sure. Let's see - glue it on with silicone, tie it to the grille around the perimeter with "zip-ties", maybe use a few well-placed sheet metal screws - - - I think one guy made a "panel" that actually replaced the grille - - -

The packing tape idea is genius! I used it to make a lower grille block so that except for a 2" X 12" spot under the license plate, I have a full grille block, and it really isn't that noticeable. I'm considering using the packing tape to make rear wheel skirts too. I also like the silicone idea. I have some extra silicone sealer around with nothing to do, but I'm assuming that's the wrong type of silicone to use. Isn't silicone also really hard to remove? and I don't understand how sheet metal screws would work without putting holes in the car's body.
Anyway, in driving the car today with the grille, it really seemed to warm up fast and coast well. I can't wait to get my scanguage and see how much better it's doing. And in normal driving, I hit 3/4 tank at 100 miles. Right now I'm at 130 and I haven't hit the 3/4 mark yet.

101Volts 03-23-2013 11:22 PM

Also know that not all gas gauges installed in cars are quite accurate for monitoring the exact amount of fuel in the tank. The tank in the van I drive can hold 20 gallons of fuel and although it's currently running below E, According to the ScanGauge II over seven gallons are left. (You can use a Scangauge II to monitor how many gallons are in your gas tank; If you buy one, Read the manual fully so you may use it to its largest potential.)

(The ScanGauge was not calibrated when I posted the above text on 2013 March 23, Take the above statement with a grain of salt.)

wmjinman 03-23-2013 11:39 PM

Outstanding!!! Great to hear the packing tape is working for you. Just be sure to keep one eye glued to the temperature gauge so you don't get it too hot! Before you're done, you'll probably have to adjust the size of your opening so it's as small as possible, but still cools sufficiently

To me, the silicone seems to be a nice, flexible, waterproof "glue" that can be relatively easily peeled off if ever needed. Of course, there are different types, and I'm not an expert on them or anything. But the clear stuff (GE, I think) seems pretty easy to peel off. It may leave a residue though, so caution is probably in order. The Permatex "ultra black" is incredible, BUT - - - if you ever manage to accidentally get it on anything, it makes it really nasty & black. I wouldn't suggest using it on anything you wanted to be able to return to "nice & shiny condition"!! HAH!!!

Well yeah - the sheet metal screw idea would require holes somewhere. Depends on how your car's made. I was thinking that if you wanted to stay with the BEHIND THE GRILLE block, maybe you could screw it into the frame around the radiator, or ? ? ? Just a wild idea - no guarrantee it was a good one! :D

Great to hear about your extra 30 miles before the 3/4 tank mark. ... of course, the position of the fuel needle is probably one of the least accurate ways to figure your mileage. Nevertheless, if you know from experience that you're usually down to the 3/4 mark at 100 miles and you're at 130 & still not to it yet, that's a pretty good indication you're having a "good tank". Can't wait until your next fill-up to see how it comes out. Hope it's a new "personal best" for that car!! :thumbup:

101Volts 03-23-2013 11:46 PM

Here's another reply, I hadn't read Page 2 at the time of the last one.

Quote:

Originally Posted by wobombat (Post 362796)
I'm considering the pizza pans. How do you attach them though? and as for the PSI, I noticed an approximately 5% increase in efficiency at 50 PSI rather than 40 PSI. I may be wearing the tires down unevenly though that way. I have suspension problems so I think they're doing that anyway.

Here's a link.

http://ecomodder.com/forum/showthrea...-6-a-4368.html

***

That's not quite how the pans are attached to Moony (The van I drive,) Though; We didn't modify the hubcaps beyond marking them with numbers in a sharpie marker, 1-4, To ID where each pan goes. Instead, We took some plastic with holes in it (Six pieces per hubcap; Three pieces on each side, One for each screw) and attached screws through those. However, When/if the bolts that hold the plastic pieces loosen the screws and plastic lose their places on the hubcap so it may take more time to re-attach them if one becomes loosened. It might be better to just drill through the hubcap if that's not a problem or maybe I'm missing something here.

***

Quote:

Originally Posted by wobombat (Post 362796)
I do not have a scanguage yet, but I plan to get one in the very near future. I noticed that the scanguageE is significantly cheaper than the scanguageII. Any opinions on why the scanguageII is better? Any other gauges I should consider? I got a little obdII reader a while back really cheap that would communicate with an app on a smartphone and read out all the info. If it worked, I think it'd be better than the scanguage because you can customize the environment and save graphs to analyze later, but the thing was a piece of junk and didn't work with my setup. Worked with my brother's setup though.

I'm not familiar with other gauges. I know that with a ScanGauge II, You can monitor how much fuel is in the gas tank and monitor the battery voltage, The engine coolant temperature, Your overall MPG average and more. Here's a link to the Scangauge II manuals.

ScanGaugeII User Manual : Linear Logic

Edit, 2013-September-18: The section between the asterisks isn't quite right now. The pans were attached to the hubcaps but two fell off, One while I was driving downhill. Did the brake heat effect them?

Also, I need to think before I post.

End of edited in section.

Austin

vacationtime247 03-24-2013 01:18 AM

In case no one has mentioned it or you haven't done it yet. Do the basics of car maintenance. Spark plugs, plug wires, fuel injector cleaner, 02 sensor(s), fuel filter, alignment. Any other known running issues will decrease MPG substantially. Clean out the EGR passages too. Doing those fixes will bring up your MPG.
VT247

wmjinman 03-24-2013 02:20 AM

Yes, basic maintenance, for sure. Make sure it's running right. - and an alignment. Definitely make sure the wheels are aligned.

Pizza pan wheel covers - never tried them myself. Seems like I read on here somewhere that someone drilled holes in them & used zip ties in like 3 locations to tie them to the wheel's spokes (assuming the wheels have some sort of spokes). If I was doing it, I might put several spots of - silicone - under the edges in a few places - to help them stay put.

And for aerodynamics, make sure there isn't any big weight in the trunk or back seat you don't need. .... if the back end is "squatting" down, more air will get jammed underneath the car where it will cause high drag. You're better off with the car level. You don't want the rear end up - higher than stock height - but just level. DEFINITELY not down, though. Dunno how you could do it on the cheap, but lowering the nose could help. . . . . maybe smaller front tires if you need new tires. . . . may need to get an alignment if you do that, though.

wobombat 03-24-2013 03:39 AM

I just bought the scanguageII! Can't wait for it to arrive.

I don't have hubcaps, and it'd probably be a terrible idea to drill into the wheel itself. The ziptie idea might work, but I have nice shiny chrome wheels and I'd prefer not to cover them up. I'll see what my fuel economy is like after my other mods and then decide. Concerning rear wheel skirts, I discovered that the wheels stick out enough that I can't simply stretch packing tape across the wheel well. I might be able to attach coroplast or something jutting out of the wheel well than stretch tape across that. And I'd have to double side it too. If the sticky side decides to attach to the wheel while driving, that might not be good. I also plan to try out a lawn-edging air dam.

This is responding to a reply a while back. I do have cruise control, but it doesn't work. Neither does the horn, which luckily hasn't been a big problem, yet. I still should be able to do fairly accurate testing with the scangauge though.

I was considering ditching the spare tire. It probably adds 30 pounds or so, and the car is AAA protected, so It's probably unnecessary, and it'd lighten up the back.

I feel stupid saying this, but I didn't even think about maintenance. I'll start work on that though.

IamIan 03-24-2013 06:21 AM

Quote:

Originally Posted by Piwoslaw (Post 362502)
Actually, most BSFC maps suggest that IC engines are most efficient around 80% load, with rpms around max torque.
The BSFC chart thread

Just two things to keep in mind about peak efficiency point on a BSFC.

#1> It is just about engine efficiency on a stand , does not take into account a moving vehicle with factors like wind resistance that increase exponentially with higher speeds ... ie , if you have to increase your speed by 20% to get the ICE RPMs up to see a 1% increase in ICE efficiency ... it might be a net loss of MPG even with the 1% increase in ICE efficiency due to the higher losses from the faster vehicle speed.

#2> The BSFC assumes you need and / or want exactly 100% of all the power generated at any point on the BSFC ... no more , no less ... If at that peak efficiency point the ICE would be producing more power than you wanted or needed ... it might just be wasted ... more power than you wanted / needed would give you acceleration you didn't want ( and wastes fuel energy to give it to you ) ... even if the ICE was more efficient in the conversion of fuel chemical energy to shaft mechanical energy.

ie ... peak ICE efficiency does not necessarily = peak vehicle efficiency.

RedDevil 03-24-2013 08:39 AM

...but it does make clear why pulse and glide works.
Short bursts of power using the engine efficiently combined with long coasts with the engine off instead of running the engine all the time, wasting fuel on pumping losses from having the throttle all but closed.

The alternative is having a final drive ratio that allows for low RPM as highway speed and an engine that runs efficiently at those low revs. The lower the revs, the higher the load on the engine and the efficiency.

IamIan 03-24-2013 09:45 AM

Quote:

Originally Posted by RedDevil (Post 362944)
...but it does make clear why pulse and glide works.
Short bursts of power using the engine efficiently combined with long coasts with the engine off instead of running the engine all the time, wasting fuel on pumping losses from having the throttle all but closed.

The alternative is having a final drive ratio that allows for low RPM as highway speed and an engine that runs efficiently at those low revs. The lower the revs, the higher the load on the engine and the efficiency.

Pulse and glide on the ICE ... to avoid running at low efficiency conditions ... yes.

Not so about the vehicle speed itself changing.

The two are in competition ... changing vehicle speed will always need more joules of energy than a steady state vehicle traveling at the same average speed , for the same distance , and same conditions... that is always a negative of Vehicle P&G.

Sometimes the additional joules of P&G vehicle are countered by enough increase in ICE P&G efficiency ... sometimes not ... like many things it depends on the specifics.

Another alternative ... instead of an ICE that can work as you describe ... would be an efficient transmission that compensates for the difference between Tire RPM and Load vs ideal ICE RPM and load.

RedDevil 03-24-2013 11:00 AM

Quote:

Originally Posted by IamIan (Post 362952)
Pulse and glide on the ICE ... to avoid running at low efficiency conditions ... yes.

Not so about the vehicle speed itself changing.

The two are in competition ... changing vehicle speed will always need more joules of energy than a steady state vehicle traveling at the same average speed , for the same distance , and same conditions... that is always a negative of Vehicle P&G.

Sometimes the additional joules of P&G vehicle are countered by enough increase in ICE P&G efficiency ... sometimes not ... like many things it depends on the specifics.

Another alternative ... instead of an ICE that can work as you describe ... would be an efficient transmission that compensates for the difference between Tire RPM and Load vs ideal ICE RPM and load.

Wow. First, joule is a measure of energy in itself. A certain mass moving at a certain speed has energy in the form of momentum that can be expressed in joules.
Raising the speed means increasing the momentum and needs additional energy.
Lowering the speed releases energy. The friction with the air, tires and mechanical parts generates heat. That friction is always there when moving, but when coasting there are no other forces involved.
The energy you have to invest to accelerate is gained back when coasting as the engine would have to run when maintaining speed.
Changing speed does not change the total amount of energy, just the state of that energy.

Tire RPM is just a function of speed and tire size, should not matter much and there is not much you can change about the size anyway unless you adapt the speedo.
The relation between RPM on the engine and the speed is what matters. Changing the final drive is way easier than changing the gearbox in most cases

wobombat 03-24-2013 02:32 PM

Iamian you pose a good point. In order to maintain the same average speed with p&g as in steady state driving, you need more energy. This is because air resistance increases exponentially with speed.
Another detraction from p&g, older engines suffer from compression loss. I haven't confirmed this and I haven't seen this on this site, but when you p&g you are trying to hold larger pressures in leaky cylinders, so more pressure is lost, therefore more gas used

RedDevil 03-24-2013 03:11 PM

When you P&G the difference between highest and lowest speed does not need to be so big that air resistance plays a mayor role. The speed would be low anyway. It pretty much evens out.
Below 55 mph the air resistance is way less than the other factors combined.
It is not my invention. P&G is a well-known and proven way to save gas. Check the hypermiling tips.

P&G with an automatic can be quite hard, if you cannot get the tranny in neutral during coasting (may damage the tranny so check the manual). Also you don't want the kickdown on the pulse.
Maybe you can mod the tranny to shift up at lower revs, allowing for slower cruising in top gear and better acceleration without downshift.

IamIan 03-24-2013 04:37 PM

Quote:

Originally Posted by RedDevil (Post 362957)
Wow. First, joule is a measure of energy in itself. A certain mass moving at a certain speed has energy in the form of momentum that can be expressed in joules.

Joules are a measure of energy yes.

Momentum however is not the same thing as Kinetic Energy ... Momentum is not measured in joules ... Kinetic Energy is... although both relate to a moving body , they are not the same thing.

Quote:

Originally Posted by RedDevil (Post 362957)
The energy you have to invest to accelerate is gained back when coasting as the engine would have to run when maintaining speed.

Nope.

It is not a 100% efficient system.

Weather you input joules of energy to maintain a given average speed constantly or you input joules of energy in pulses it net the same average speed ... either way you must input energy... but the varying speed always costs more energy to the same average speed and otherwise same conditions.

Quote:

Originally Posted by RedDevil (Post 362957)
Changing speed does not change the total amount of energy, just the state of that energy.

nope.

Going faster takes more energy to cover the same distance.
A fluctuating speed takes more energy to cover the same distance at the same average speed and conditions.

Quote:

Originally Posted by RedDevil (Post 362978)
When you P&G the difference between highest and lowest speed does not need to be so big that air resistance plays a mayor role. The speed would be low anyway. It pretty much evens out.

Any variation in speed results in more joules of energy being used.... even 0.000001% variation.

Quote:

Originally Posted by RedDevil (Post 362978)
It is not my invention. P&G is a well-known and proven way to save gas. Check the hypermiling tips.

As I said above ... I'll repeat again here:
Quote:

Originally Posted by IamIan (Post 362952)
Sometimes the additional joules of P&G vehicle are countered by enough increase in ICE P&G efficiency ... sometimes not ... like many things it depends on the specifics.

I think it is more useful to understand how it works ... both the good and the bad ... then one is more able to maximize the good aspects , and minimize the bad ... pretending the bad doesn't exist is not useful.

wobombat 03-24-2013 06:18 PM

Lets say you've taken steady speed to its limit and are traveling at the bottom of top gear, let's say at 40 MPH. Two questions.

1.How do you DWL when you reach a hill? If you decrease speed you'll be forced to downshift, which I think is obvious would waste more gas.

2. How do you get better Fuel economy from P&G? The only way you can extend the bracket is to faster speeds. I'd say 10 MPH is the minimum speed change to realistically take when doing a P&G, so in this case you'd pulse to 50, then back down to 40, then back up to 50. Given that the average speed in this case is 45, that increases air resistance by 26% over the steady speed. That, along with all the reasons listed above, to me would mean that P&G would not actually be a bigger gas saver. It would require much more effort and clutch wear, though.

Oh and by the way, concerning the compression losses, a while back I tested my car's 0-60, and found approximately a 20% loss of power over it's original rating, at full throttle. True there's a lot of factors, but I would say we could roughly estimate that that is approximately the loss of power encountered by having really high loads using that engine. That to me is a really significant factor too when considering P&G.

jeff88 03-24-2013 08:09 PM

Why 45%? Or are you trying to increase your FE by 10mpg and the percent is not your concern?

In terms of maintenance, definitely check your battery. If you have even a less then perfect battery, your alternator will be working harder, negatively effecting your FE. Make sure your oil and transmission fluid are not only "fresh", but not too full, it will make the bottom end of your engine and transmission work harder.

Do you have LEDs?

In terms of aero, I would do a rear diffuser. It is relatively simple, easy to take off, depending on how you design it and can be fairly well hidden if you want it to be.

What part of Oakland? I assume you are staying well clear of the "Maze".

101Volts 03-24-2013 08:16 PM

Here's a link to a page about Pulse and Gliding.

Driving technique: exploring 'Pulse and Glide' - MetroMPG.com

I believe I was becoming confused earlier when speaking of P&Ging on page 1. I've done it but to a lesser extent, And to some decent effect; On highways, I accelerated to 65 on down slopes and slowly went down to 55 on up slopes and then held 55ish.

Also, I must again mention proper tire pressure; If you exceed the most fuel-efficient pressure (Which may be lower than you think,) Your FE is going to go down a lot more than you may think.


All times are GMT -4. The time now is 06:47 PM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com