Need input for gas mileage experiment. Please Help!!

You might want to start with http://priuschat.com/forums/other-c...uth-about-epa-city-highway-mpg-estimates.html and http://www.consumersunion.org/Oct_CR_Fuel_Economy.pdf.

Clearly you don't have a dyno, don't have access to the EPA's special blend of gas nor their machinery. If you had fuel flow meter that tapped into the fuel line, that'd better, but I doubt you'll go that far. You also only have limited control over environmental conditions.

Maybe look at Bob Wilson's older posts like http://priuschat.com/forums/gen-iii-2010-prius-fuel-economy/64296-updated-mpg-vs-mph-chart.html. When I spoke to at the Gen 3 introduction, we did speak of using cruise control to accelerate so that you always had a reproducible, consistent method of accelerating. Unfortunately, you can't do that until you're at 25 mph.

http://www.npr.org/2011/04/02/135064825/the-gas-gauge-says-full-but-thats-not-quite-true might be insightful. Your mission is made a bit tougher due to the darn bladder.

Also, Bob intentionally ran his NHW11 (1st gen Prius) out of gas over three dozen times (http://priuschat.com/forums/generat...79878-fuel-pump-hack-useless.html#post1116366) and at least 3x in his ZVW30 (http://priuschat.com/forums/gen-iii...ng-running-out-gas-gen-iii-23.html#post997053). The purpose was at http://priuschat.com/forums/gen-iii...ng-running-out-gas-gen-iii-22.html#post966747.

I'll reply w/more when I have some more time.

 

My concern is that 'Brand' does not relate to 'Refinery', if you could separate gas by refinery I think you might find correlation that brand just won't offer.

My 'Brand' story. Growing up I worked in a cranberry plant run by a popular cranberry company in Markham WA. When demand warranted they made their 'brand' products, when they had excess berries, they made 'house brand' product, with the same care as the 'brand name' product. But by amazing co-incidence, monday morning and friday afternoon were always 'house brand' runs, not their own 'brand'. Employees not focus on cranberries were not making product with the company's name on it.

Anyway, brand does not equal production facility.

 

Ok, I though about this a bit more. You're going to face a bunch of challenges and you're going to need to try to keep variables as consistent as possible such as outside air temp, whether it's raining, etc.

You've probably noticed that with a cold ICE (internal combustion engine), your gas mileage for the first 5 minutes is usually terrible compared to the rest, esp. if it's city. The car has much worse mileage when the ICE is cold. The car has numerous stages that it can go through that I believe are triggered thru temperature (can be seen via coolant temperature). See the 1st PDF at http://priuschat.com/forums/gen-ii-...angauge-best-threads-mileage-improvement.html.

Unfortunately, I doubt you have a ScanGauge - Trip Computer + Digitial Gauges + ScanTools (I have a SG II) and the Prius has no temp gauge, so there's no way to monitor the coolant temp or see what stage it's in w/o something like it. The negative IGN is VERY obvious and when the ICE is warm after a shutdown, upon restart, I believe it exits stage 1a pretty quickly (no longer has negative IGN) vs. a cold engine. The negative IGN also coincides w/the engine seeming to run at high and varying RPMs and rather roughly.

To save time, you'll probably want to just deal w/small quantities rather than a whole tank. Since it sounds like you want to base the results on the MFD's MPG calculation, I'm thinking you should run the car out of gas to purge it of the old fuel, fill it with emough gas so that it starts (I believe 3 gallons, maybe carry 4, just in case), then, go, once the ICE is up to temperature (you're going to need to guess w/o instrumentation), reset the MFD and then do whatever run you're going to do. You want to be consistent about how you drive, accelerate, brake, etc. and maintain the same speed, preferably w/cruise control each time. You want to run the same course for every batch of gas and you might even want to run it in both directions to help cancel out effects of wind and elevation change. Then, repeat this for all batches.

Try to make sure the weather conditions are are close as possible for all runs. If it rains, the mileage will likely be lower due to energy being wasted by drag due to wet pavement.

Do Google searches for siteriuschat.com out of gas gallons register start to confirm the amount you need to add. Page 122 of my manual under Fuel Gauage says that if you refuel w/less than 3.0 gallons, the fuel indicator may not change.

Unfortunately, due to the FE of the Prius, it's going to take awhile to use up 3 gallons of gas each time. If you put in too little, the car may not start.

If you don't get the ICE up to temp for all the runs and do them all back to back, the first run will have worse mileage than the rest. If the cool down time between runs is too low and you start measuring, it'll likely have worse results. Also, the tires cooling down if left for too long means their pressure will be lower vs. warm/hot tires. Lower pressures == more rolling friction.

Some warnings, someone did post his opinion about running out of gas and someone else called baloney. See http://priuschat.com/forums/gen-iii...g-running-out-gas-gen-iii-23.html#post1000325. You might want to browse the rest of bwilson4web's posts in that thread or do Google searches for siteriuschat.com bwilson4web [and whatever you're looking for] to find his other nuggets of wisdom. I just located some graphs from his gasoline study at http://priuschat.com/forums/gen-iii...g-running-out-gas-gen-iii-26.html#post1031609. I don't know if he has more info or the raw data elsewhere.

Unfortunately, he no longer participates on Priuschat (another story). So, if you PM him, he may not respond. He can possibly be found on Yahoo Prius groups like one of the technical groups.

Other big warnings: I have never run out of gas on my Prius. I don't know what happens at the end and whether it'll throw codes and a check engine light. I also don't know if it'll clear by itself after a a few restarts or you whether need to disconnect the 12 volt. One problem of disconnecting the 12 volt is that whatever the engine ECUs has learned will be lost and thus the first run (w/o disconnect) might yield different results than the rest, if you choose to go this route.

Bob posted a warning at http://priuschat.com/forums/gen-ii-prius-fuel-economy/30863-gas-experiment.html about the behavior on a NHW11. His reference to the traction battery I believe is (from what I hear), the NHW11's HV battery can be depleted to point where it is unable to start the ICE (it's what starts the ICE, not the 12 volt) and thus needs to be charged at a dealer w/a special HV battery charger (that might need to be sent/brought to the dealer), see http://priuschat.com/forums/gen-ii-prius-main-forum/6589-hv-battery-charger.html#post68086. I've never seen it myself but I believe it's shown on pages 5-6 and beyond of http://www.autoshop101.com/forms/Hybrid15.pdf.

From what I hear, the NHW20 cannot (as easily?) get into this state unless you repeatedly keep trying to start w/insufficient gas.

Might be good to buy a scan tool (Scanguage II can do it) to view and more easily clear the codes. Maybe someone else can chime in. Bob's experiments were on the NHW11 and ZVW30. He never had a NHW20 which is what the 04-09 models are.

Toyota has a warning that someone located at http://priuschat.com/forums/generat...lanning-gas-out-experiment-2.html#post1090128. Take it for what it's worth. Toyota marketing folks did chime into the earlier thread w/a not surprising answer:
http://priuschat.com/forums/gen-iii...ng-running-out-gas-gen-iii-20.html#post896802 (FWIW, I've met Erica and her former boss, Doug, who also posts under Prius Team.)

(I remembered my conversation w/Bob about cruise control to accelerate. I think the conversation had more to do w/pulse and glide (Pulse and Glide plus Warp Stealth in the Prius II for maximum FE … - CleanMPG Forums) and getting a consistent, reproducible pulse via the CC. Example: Accelerate up to 42 mph, set CC, cancel CC, dead band glide down to whatever speed but not below 25 mph, resume CC so that car accelerates to 42 mph in consistent manner. Don't worry about this pulse and glide business. It's not relevant to your experiment.)

Good luck!

 

Following Wayne Brown's test protocol and calibration method (posted here and here) is the only way to get any meaningful result for the real world. On the other hand it may be too much work for a 7th grader project. Maybe the goal was just too ambitious to start with. Instead of comparing brands of gas, how about just compare two speeds like 30 vs. 35 MPH?

 

Isn't that your son's responsibility?

 

As a preliminary experiment you can see if you can tell the MPG difference between straight gasoline and E10.

Cheat [don't look if you are going to be doing the experiment]: (highlight below)
There should be about a 3.3% difference in favor of the pure stuff.

 

Yeah, glad the info was of some use. It's just complicated on the Prius.

On Mythbusters, in many cases, when they've done gas usage comparisons, they used really old cars w/o a lot of modern emission controls and have rigged up some separate clear container w/a known amount of gas. There's likely no way to do that on a Prius or most current cars w/all sorts of emission checks they do. Cars will throw check engine lights now w/loose gas caps. In some cases, some cars have a separate light for checking the cap.

 

Instead of gas brands it could be a good Science Fair project to show how efficent electric is compared to gas.
A regular gas car is 20% or less efficent.
A mild hybrid like Honda is 30% efficent
A FULL hybrid like the Prius is 40% eff
An electric like the Nissan LEAF is over 90% efficent.
Electric can also regenerate instead of braking, use USA power, even direct Renewable Power like Solar PV and Wind power.
No other vehicle is so efficeint, has so much potential as the EV ! , V2G, and V2Home are a few more things an EV can do that no other vehicle can match.

 

Honda's IMA isn't a mild hybrid system. A mild hybrid system provides stop/start and a little assist using energy recovered by regenerative braking. IMA is much more than that.

Also, the efficiency percentages seems like they're plucked out of thin air. To give you an idea, driven to its strengths, on the highway the Honda hybrids can outperform the Prius. IMA has a number of weaknesses, but it's not a bad system.

As has been explained here numerous time, PEVs mostly trade internal combustion for external combustion (and yes I know it depends on where you live). But, if you're comparing vehicle efficiency you can't use 90%.

Flywheel, first seen in performance cars, is now coming to Volvos. Hopefully that's the start of something beautiful and we'll see flywheel regeneration plus start/stop in more cars. Flywheel regeneration isn't as efficient as electric (certainly not lithium) but will hopefully be cheaper.

Success with flywheel regeneration paired with basic start/stop systems would mean global improvements in fuel economy and avoid mild electric hybrids, which would mean resources saved for use in full HEVs and PEVs.

Now, that's the nub to me: fuel supply. Eventually the planet will be reliant on renewable energy, nuclear fission and, hopefully, nuclear fusion. EVs are good for that.

Well bicycles are more efficient than electric cars. But it's true that e-bikes can be even more efficient than human-powered bicycles.

Well, I'm very skeptical about V2G both because it increases battery use, it's not reliable and people don't either pay or get paid the market rates for peak electricity so the incentive isn't as large as it should be.