Most efficient speed for best MPG?

[Jerry W]

<div class='quotetop'>QUOTE(bwilson4web @ Mar 22 2007, 09:48 PM) [snapback]410449[/snapback]</div>

This is magical-mystery technology compared to any ordinary car:


Questions?

Bob Wilson
[/b]

Bob, having seen your last post I would like to nominate you for the Oscar for "Best Supporting Graphical Representations Submitted as Attachments"

Only a Prius can generate this sort of data; I just love the car to death

regards

Jerry

[Fibb222]

Can somebody explain what the consensus is to us laymen?

[usbseawolf2000]

<div class='quotetop'>QUOTE(mwbueno @ Mar 22 2007, 03:35 PM) [snapback]410344[/snapback]</div>

Load: 450 lbs. above OEM vehicle weight
[/b]

Do you still have the extra battery pack? I assume the tests were done with just the NiMH HV pack.

[windstrings]

410344[/snapback]</div><div class='quotemain'>

Hi Bob & All,

I have done 5, 10, 15, 20 & 25 benchmarks under 30 MPH... I will add 30, 35 & 40 MPH since I have them also. I will be glad to share the results but, because they were done over a period of several months (I had to wait for windless days; each test takes over 4 hours) so, one will need to note the temperature differences. I will post the actual data along with the Temperature for that day & then another column with the temperature corrected to a 77 °F baseline which the initial 5 MPH test was done at.

I also corrected for humidity & barometric pressures on each test to match test one]

Bob, having seen your last post I would like to nominate you for the Oscar for "Best Supporting Graphical Representations Submitted as Attachments"

Only a Prius can generate this sort of data; I just love the car to death

regards

Jerry

[/b]

LOL!..I can't decide if that looks like a Pancreas or a string of eggs from a Perch!

[bwilson4web]

<div class='quotetop'>QUOTE(Fibb222 @ Mar 22 2007, 07:30 PM) [snapback]410543[/snapback]</div>

Can somebody explain what the consensus is to us laymen?
[/b]

To get 100 MPG or better:

15-25 mph - current model Prius, NHW20
15-20 mph - previous model Prius, NHW11

All it takes is a warmed up Prius, tires inflated to the maximum rated pressure, a flat driving area, no wind, temperatures at least in the mid 70s and the patience to hold the car within the steady-state speed range. Anyone can do it.

It also validates an energy model of the Prius based upon drag measurements.

Knowing the maximum MPG performance allows us to look at lower performance driving and analyze what is going on. This may lead to insights, the 'eureka' moment, when a new technique or technology improves ordinary performance. For example, it may be possible to map out more efficient highway driving profiles and develop a custom cruise control that follows such profiles.

This also lays the foundation for investigating what is going on in pulse and glide driving. The theory of pulse and glide is the pulse puts the ICE in a more efficient energy conversion range. So instead of getting the ~31% conversion of gasoline to mechanical energy, the engine is getting 35% or higher. How to achieve such efficiencies has not been explained in terms of ICE rpm and or ICE torque. However, some specific fuel consumption data indicates an rpm range from 1,600-2,600 is a good start and avoid going over 3,100 rpm.

One of the things Wayne's data shows is the importance of tire pressure for low rolling resistance. During the Prius marathon, I understand the team used nearly bald tires inflated to 65 psi. This would have given them unusually low rolling resistance. On dry pavement without other traffic, this would be OK but it is not a good idea for normal driving and in slippery conditions. However, even more radical, low-rolling resistance tires are possible.

A suitably modified Prius should achieve 125+ MPG in a marathon. All it would take would be: (1) computer controlled accelerator, (2) custom tires, (3) seriously baffled ICE compartment, (4) European or Japanese tank, (5) aerodynamic clean-up, (6) weight reduction, (7) high energy content gasoline, (8) ICE and transaxle tuning and (9) high efficiency lights.

Since it would be drop-dead boring, I would want an automatic pilot to handle steering around a limited access flat track, say an empty shopping center, large parking lot or unused airport. Ideally the track would be above 5,000 ft., say Wyoming or the upper plains. Also, a pre-heating cycle should be used before topping off for the endurance run. It would be important to have a telemetry link, WiFi, to a data analysis system to track progress and tune the accelerator profile. With this approach, a small team, say three light weight drivers and one engineer, could set a new Prius marathon record using either model Prius, NHW20 or NHW11.

It might would make sense to have two or three teams and cars to minimize the risk of mechanical failure and show this is not vehicle unique. The only problem with multiple cars, like bicycle racers, they might be tempted to draft each other and set a record that would be exceptionally difficult to beat.

Bob Wilson

[mwbueno]

<div class='quotetop'>QUOTE(usbseawolf2000 @ Mar 22 2007, 09:50 PM) [snapback]410615[/snapback]</div>

Do you still have the extra battery pack? I assume the tests were done with just the NiMH HV pack.
[/b]

Hi usbseawolf2000,

Yes, the tests were performed with the OEM HV only. The 450 lbs you reference is the cumulative weight of me, the extra HV array, test gear & etc. Part of the reason it takes me 4 hours per test is that I have to 'condition' the OEM HV for a while after I unhook my extra 18Ah NiMH array. If I don't 'recondition' the OEM HV Battery before testing, it goes through a similar 'reconditioning' during testing which throws the data way out of whack (usually on the low side). The Toyota BMS (Battery Management System), like the rest of the car, is quite a marvelous piece of engineering.

Best Regards,
Wayne

[bwilson4web]

Hi,

Thanks to a recent posting, I found the log from the Prius marathon. I've add each leg to the chart:

MPH MPG
30.72 104.68
31.69 100.59
32.57 102.95
30.16 106.66
29.30 111.88
29.69 114.84
28.60 115.04
30.52 107.03
28.82 108.41
24.32 120.56
28.91 116.35
30.69 110.59

Notice that the leg with the lowest speed, 24 mph, had the best MPG, 120.56. Also the data is within spitting distance of the MPG vs MPH charts.

Bob Wilson

[ken1784]

<div class='quotetop'>QUOTE(bwilson4web @ Mar 24 2007, 10:29 AM) [snapback]411242[/snapback]</div>

Notice that the leg with the lowest speed, 24 mph, had the best MPG, 120.56. Also the data is within spitting distance of the MPG vs MPH charts.
[/b]

I believe the marathon was done using Pulse&Glide, a lot of speed changes, and we can't compare the data with Wayne's constant speed graph.

Ken@Japan

[John in LB]

ZERO... that's the best speed. Just park it - and take a walk.

You NEVER have to fill your tank again. It won't matter if it's nitrogen or plain air that's in your tires... and you definitely don't need the touring model or the NAV system. Just make sure you get the DICE IPod Integration Unit - because you still need to sit in your car and listen to your IPod.


:P

[Vincent]

Ha!

I'm doing better than that right now where my Prius is at its best (in my garage).

0 MPH = 0 MPG
0 MPH = 0 MPG
0 MPH = 0 MPG