Urba Centurion Update - (Kubota diesel, 100+ MPG in mixed driving - Fall 2012 on)

[changzuki]

Originally Posted by UltArc

Losing weight in rotational force is a huge gain uphill, I have found.

UltArc,
This was my experience also and the lighter wheels I ended up with confirmed my suspicions. In addition to uphills, it included every acceleration and had a profound impact as sprung weight. I always question blanket statements but this held true for cycling as well as the Centurion.

~CrazyJerry

[changzuki]

Originally Posted by sendler

You are thinking racing, not fuel economy. Generally in real world driving, lighter can be better because you do have to use the brakes occasionally and no one is going to religiously PnG. But with PnG adding mass to a grotesquely over powered vehicle such as most motorcycles will improve FE. Your comparison with human power is forgetting one thing. The brake specific fuel consumption of a combustion engine is terribly inefficient over all but a small spot on the map. The difference between the optimum operating range at 35% efficiency and the average of 15% is huge. Soaking up the energy that is delivered at the optimum range is difficult. Even the meakly powered CBR250R will absolutely average better FE on a real world cross country trip with 250 pounds on the bike instead of 150 if Pulse and Glide is used. Stressing out over reducing total mass in a hypermiler is a big misconception. Performance suffers with added weight, but FE not so much if you don't touch the brakes.

Back to the bikes. A human powered vehicle weighs 5 times more than a road bike but goes 3 times as fast due to the better aerodynamics.

Sorry, rant over. Replacing the lead battery in your pick up truck with lithium in order to improve the fuel economy is a huge waste of money.

sendler,
After reading your postings, I believe You are the perfect candidate to put your theory to its next test!
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As an example, what would stop you from doubling your total external added weight to the same bike and then revisiting the Green Grand Prix? Since you have a baseline to work with (past results from the Green Grand Prix - same course - same bike - same driver), and already know the course (should be an advantage), you could do all of what you're saying and then publish the results. This is a golden opportunity where you may even be able to greatly exceed your current Green Grand Prix numbers.
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There is likely a limit as to how heavy you could make the bike but with different sets of real world numbers maybe we could see what the cut-off point is and possibly come up with a forumla where "X" added weight can yield "Y" gain in mpg. Also, if the extra weight is general in nature then this may be the easiest and most cost effective way to raise mpg. Would you do this in the name of science and ecomodder camaraderie'? What say you?
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~CrazyJerry

[changzuki]

Originally Posted by BobS

CrazyJerry,
Wow, what a great part-by-part system analysis. Are you retired or just don't bother with sleep, anymore? If you don't mind, a couple of questions:
1. With an alternator cutoff switch, the alternator rotor is still engine-driven. Could a switch-driven clutch like the AC compressor clutch reduce the load on the belt even further (and the relays then could be replaced by a diode bank)? Would this be of advantage?
2. Have you seen Lasersaber on Youtube? He has replaced his car battery with 6 supercapacitors and a very small battery. With your minimal draw, you may be able to
get by with an even lighter setup than his, maybe 1/2 lb. If you haven't seen his video, Youtube the words "boost pack".
Looking forward to much more of your analysis.
BobS

@ BobS,
From the lengthy reply to your earlier question about the above, I wanted to add another thought.
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Lithium (lifepo4 such as what I have) would lend itself better to your suggestion of the AC clutch/alternator on/off setup than lead-acid chemistry. Reason being is lead acid prefers a bulk charge to a point, then a float charge to fully charge. Failure to do this over time can result in shorter battery life.. Lithium has greater charge efficiency and lends itself well to accepting a steady charge - or pulse for x-minutes charge cycles - until full, then the charge unit can and should be shut off.
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Also, the Lithium discharge voltage is more stable over time than lead acid. So generally speaking there's less fluctuation between the highs voltages and the low voltages. Some of the more sensitive electronics that are less tolerant to voltage swings will fare better over the long haul from the steadier flat discharge voltage of the lithiums...
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Ok, that's a bit off course but is relevant to supporting the idea of an on-off type system where an AC compressor clutch might be used to engage an alternator to charge a battery, then disconnect it in light of fuel savings while at the same time, preserving the lifespan of a battery,. System will be disappointing if it means replacing a lead acid battery prematurely due to sulfation; inadequate charging of a lead acid battery...
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~CrazyJerry

[changzuki]

Details - Exhibit #4: Fuel Tank
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Barring any unforseen circumstances, I knew Centurion was going to have to run of its life and I wanted the tank fill to be as accurate as possible... A small amount either way would change the results drastically.
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Typical refueling before and after Stage I at the Green Grand Prix is done at the local Valero station. A Green Grand Prix official fills your tank and another writes down the amount on your tech sheet. The typical way the tanks are filled is to insert the nozzle into your filler tube and let'er rip. At some point the fuel will cause the pump handle to click off, and that essentially is the end of your full up.
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Filling the tank in this way is a problem for Centurion and a possibly a problem for the pump official. Read on...
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Per the original plans, Centurion uses the original Spitfire 10 gallon fuel tank. It's just a steel tank; no internal bladder, just a rectangular 10 gallon can. Refueling the original Centurion was done from inside the car - there was no external filler.
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CrazyJerry's Centurion has the optional external fill tube located on the drivers sail panel.
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The sail panel fill tube will accept the large nozzle at the diesel pump. From experience, I know that fully squeezing the pump wide-open until the first "click off" will result in anyone within a foot or so to be wearing at least some of the diesel-deluge that's going to come out! Depending on how much "minimum cetane 40" projectiled out, would certainly skew the fuel fill results.
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What to do? Well ask for a solution and ye shall receive! Actually it was the Centurion's creator RQ Riley who provided a solution in his inaugural post on page 6 of this thread / post #60.
Fuel Economy, Hypermiling, EcoModding News and Forum - Ecomodder.com Fuel Economy Forum
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6.html#post416423
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"We disconnected the fuel line from the tank and ran a hose to the fuel pump from a beaker inside the cabin."(RQ Riley post #60)
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I learned a lot from that entire post and thought what a great idea - run an external tank! How fitting that this Centurion would use a graduated cylinder of sorts for its MPG test just as the original had done back in the early 80's!
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And while I was at it, may as well save some weight and take out the stock tank that was not going to be used.
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To pull the fuel tank is not exactly easy.. In fact, of all the things one could do with a Centurion, this would be right near the top for difficulty. You might think you could just "drop the tank" but directly underneath the tank is the Spitfire X-frame, differential and rear of the driveshaft.


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And with the rear floor storage area removed, the buggy spring and differential frame support also are in the way..
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How about removing the rear wheel and sliding it sidways to freedom? Another detour - Ummm, fraid not...
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The body needs to be unbolted and then raise the rear off the frame until the tank is free. The tank can then come right out through the removed rear floor storage area. It may be able to come out through the wheel well too with a little finaggling. (So make sure your tank is excellent if you plan on building a Centurion)..
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Knowing the procedure makes things a bit easier and replacing the tank wasn't as much of a big-deal but I'd rather not ever have to do it again.
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It would've been really cool to leave to 2 gallon tank in...


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But it's waayyyyy cooler to be able to tell folks that I could go through all of June, July, and August before a fill-up was needed if using Centurion just for the work commute (30 miles round trip daily)...
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Another piece covered, and more to be uncovered....
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~CrazyJerry

[sendler]

Originally Posted by changzuki

[B]Details - Exhibit #4: Fuel Tank

Barring any unforseen circumstances, I knew Centurion was going to have to run of its life and I wanted the tank fill to be as accurate as possible

This was my only concern with your official results when you stated that you didn't pull up to the same pump on the same side each time for the competition. With your sight glass on the side of the tank, any tilt, one way and then the other, could make a huge error.

[nemo]

Originally Posted by sendler

This was my only concern with your official results when you stated that you didn't pull up to the same pump on the same side each time for the competition.With your sight glass on the side of the tank, any tilt, one way and then the other, could make a huge error.

Even filling from the same side unless you literally marked the stop points the error could be significant with that small tank. Some of the pads at stations are not very level in any direction. And the accuracy of the pumps is another question. By leveling the tank some error could be reduced. Mount a level on the tank then hinge the tank on one side and an adjusting screw on the other to level the tank. A two axis system would be even better.

[changzuki]

Originally Posted by sendler
This was my only concern with your official results when you stated that you didn't pull up to the same pump on the same side each time for the competition.With your sight glass on the side of the tank, any tilt, one way and then the other, could make a huge error.

Originally Posted by nemo

Even filling from the same side unless you literally marked the stop points the error could be significant with that small tank. Some of the pads at stations are not very level in any direction. And the accuracy of the pumps is another question. By leveling the tank some error could be reduced. Mount a level on the tank then hinge the tank on one side and an adjusting screw on the other to level the tank. A two axis system would be even better.

Well, it seems like luck was with me yet again and there was almost zero chance of a screw-up at the pump. The local Valero we were directed to, only has one diesel pump so I had to go to that one. And the flow of traffic at the pump only allowed one direction so my only option was to stay left to be on the correct side of the car for fuel filling.
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The external tank was mounted right behind where Sheepdog 44 was sitting - where the headrest would be if there was one. The clearance between the two gallon tank/the roofline/and the length of the hose would only allow it to be removed from the passenger side of the car and set on the ground with no extra hose to spare - so again there was zero chance for a screw up. Even the fill hole for the tiny tank is dead centered, sooooo....
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On both fill-ups, I did ask the same official to fill to the top line on the sight tube which he did with no problem. This would be more accurate than the full-bore handle squeeze until the mystery pump click-off, and allow for a small amount of leeway in the event things got sloshing around. When I returned to the car after paying for post Stage I "fill-up", Pete had already taken the liberty of checking the level of the pump pad with his Iphone.. The phone level does seem to be extremely sensitive, impressive if it's correct, and it did show the pad to be level no matter which way it was placed. If anyone is in the area they could check this and post their findings here.
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For the next couple of hours, it was a challenge to create some of the most incredible alternate scenarios explaining how such a pitiful amount of fuel was used to cover over 100 miles. And in the end after scrutiny, all of the stories simply fell apart. Centurion just broke all of its own records! And like that amazing run set by the original on an old stretch of Arizona asphalt back in 1982, this one had a fantastic journey all the way down to the Green Grand Prix!
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From its maiden voyage on the road I made the statement that it seemed like the fuel gauge was broken. It never really was about the gauge though....
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~CrazyJerry

[nemo]

Originally Posted by changzuki

The clearance between the two gallon tank/the roofline/and the length of the hose would only allow it to be removed from the passenger side of the car and set on the ground with no extra hose to spare - so again there was zero chance for a screw up. Even the fill hole for the tiny tank is dead centered, sooooo....

On both fill-ups, I did ask the same official to fill to the top line on the sight tube which he did with no problem. This would be more accurate than the full-bore handle squeeze until the mystery pump click-off, and allow for a small amount of leeway in the event things got sloshing around. When I returned to the car after paying for post Stage I "fill-up", Pete had already taken the liberty of checking the level of the pump pad with his Iphone.. The phone level does seem to be extremely sensitive, impressive if it's correct, and it did show the pad to be level no matter which way it was placed.

~CrazyJerry

Removing the tank eliminates any possibility of the car leaning.

Great thread.

[sendler]

An interesting comment about increased economy despite adding 1,300 pounds in an aero trailer.
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"The highest mpg I've recorded with my truck was when pulling my gap-filled, full-boat-tail trailer.I was 1,300 lbs heavier than stock and recorded 22% better mpg than the best ever recorded without it.(47.9 vs 39 mpg)"
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http://ecomodder.com/forum/323828-post14.html
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[changzuki]

Originally Posted by sendler

An interesting comment about increased economy despite adding 1,300 pounds in an aero trailer.
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"The highest mpg I've recorded with my truck was when pulling my gap-filled, full-boat-tail trailer.I was 1,300 lbs heavier than stock and recorded 22% better mpg than the best ever recorded without it.(47.9 vs 39 mpg)"
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http://ecomodder.com/forum/323828-post14.html
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sendler,
Yes, let's continue the volley since you revived it!
Looking at the "keywords" in the passage - here is what I see:
"gap-filled, full-boat-tail trailer".:
The phrase never says, same trailer with 1300 extra pounds thrown on for good measure, it suggests a more aero trailer that weighs more, but more importantly, supporting the notion that aero is where it's at, and if the aero happens to add some extra weight than so be it.

You may have missed my earlier post:
http://ecomodder.com/forum/432009-post141.html

basically asking if you might wish to back your theory at next year's Green Grand Prix by simply adding (possibly even doubling) more weight to your bike and then publishing the numbers. If you are correct and blow away your previous mpg at that venue, then we might be able to come up with a formula where adding X-pounds = added mpg. This may be a really cost effective way for folks to gain mpg's on the cheap. So, what say you? Will you put your theory to the test as suggested?
~CrazyJerry