2010 fuel economy equation

[Pennyman]

Thought I'd post this to get some feedback.

There's a change between the 2009 and 2010 fuel economy equations for positive points.

2009:

Score = 100*[((Vmax/Vyour)-1)/((Vmax/Vmin)-1)]

2010:

Score = 100*[(Vmax/Vyour)/(Vmax/Vmin)]

That being said, plotting the scores from the CA event last year using both equations, I get this:

http://img340.imageshack.us/img340/485/grapha.png

Is this a typo or does it blatantly favor 4 cylinder cars this year?

[Pennyman]

Thought I'd post this to get some feedback.

There's a change between the 2009 and 2010 fuel economy equations for positive points.

2009:

Score = 100*[((Vmax/Vyour)-1)/((Vmax/Vmin)-1)]

2010:

Score = 100*[(Vmax/Vyour)/(Vmax/Vmin)]

That being said, plotting the scores from the CA event last year using both equations, I get this:

http://img340.imageshack.us/img340/485/grapha.png

Is this a typo or does it blatantly favor 4 cylinder cars this year?

[TorqueWrench]

Wow, can't believe I missed that when going through the rules. I really hope that is a typo though. Our decision to stay with our current engine package included the fact its good fuel economy was worth 85-90 points if you could finish endurance. That advantage seems to be greatly reduced now...

[flavorPacket]

I hope this is not a typo. These changes were hinted at by an SAE official at FSG 2009. I am glad to see these rumors confirmed. It's about time they realized how biased the rules are to the top 1-2% of cars. Now the most economical cars still get 100 points, but a car with maybe 15% worse economy receives much closer to 15% fewer points.

[mech5496]

Such a change would be a great surprise, as FSAE series tends to be more and more enviromentally friendly, especially the last few years (100 points on fuel economy, formula student electric, etc.)

[mech5496]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TorqueWrench:
Wow, can't believe I missed that when going through the rules. I really hope that is a typo though. Our decision to stay with our current engine package included the fact its good fuel economy was worth 85-90 points if you could finish endurance. That advantage seems to be greatly reduced now... </div></BLOCKQUOTE>

http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif http://fsae.com/groupee_common/emoticons/icon_confused.gif

[Pennyman]

It's been brought to my attention by Mrs. Zundel
that the equation in the current 2010 rules is incorrect and will be revised shortly.

[Mike Macie]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by mech5496:
http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif http://fsae.com/groupee_common/emoticons/icon_confused.gif </div></BLOCKQUOTE>
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Pennyman:
It's been brought to my attention by Mrs. Zundel
that the equation in the current 2010 rules is incorrect and will be revised shortly. </div></BLOCKQUOTE>

Good to know. Usually only a couple of teams go over Vmax and I don't think any team really worries about it. The 2010 plot is deceiving since 95% of teams would be in the positive point range. This equation would've given a lot more points to teams that should be considered to have poor fuel economy. Looking at the 09 MIS results, these teams would have been given an additional 30-40 points and might be able to make up more with a better endurance score. Making economy ignorable to a majority of teams.

[poe21]

I still find it funny that a weekend AUTOX racecar has to worry about fuel economy. When I race in my own car, I come in with 1/4 tank of gas just for less weight. If you can make it on whatever gas you're holding, then that should be enough in my opinion. It's not like autox is depleting the world's gasoline stash, nor is it a sport where pit stops are crucial.

[TorqueWrench]

Woooh, I can stop having a heart attack now. Good to know that is being revised.

[Mazur]

How is E85 accounted for in all this? If it's based on purely volume, then are the E85 guys just SOL?

[Zac]

there's a correction factor for E85 based on the energy content per unit volume.

With regard to the formula, I saw that a couple months ago. I figured it was a mistake based on that discontinuity. But I don't know how happy I would be if I was a still a student working on a design competition and the organizers made a big change to an objective function pretty far into my design/build cycle.

[Michael Royce]

Sorry guys, Kaley is correct. There is a typo that we missed in the proof reading. The correct version of the equation in D.8.22.1 is:

If Vyour is less than Vmax then the following equation will be used to determine the fuel economy score:

FUEL ECONOMY SCORE = 100 x (Vmax-Vyour)/(Vmax-Vmin)

Where:
Vmax is the volume of fuel that produces a fuel consumption of 26 liters/ 100 km.
Note - For an Endurance Event distance of exactly 22 km, Vmax is 5.72 liters (1.51 US gallons).
Vmin is the smallest volume of fuel used by any competitor
Vyour is the volume of fuel used by the team being scored.

in other words, the score is a straight line between 100 points at Vmin and zero points at Vmax.

If Vyour is greater than Vmax then the equation used to determine a negative fuel economy score will be the same as 2009. The equation given in the 20010 Rules is correct.

[Mike Cook]

For a minute there I almost thought 4cylinders would have a chance again. Darn!

[Thrainer]

What chance? You don't need to win fuel economy to win the event. Besides that, fuel consumption doesn't solely depend on the engine.

I'd say it doesn't look so bad, but you have to do your homework.
http://www.formulastudent.de/u...FSG_Fuel_Results.pdf (http://www.formulastudent.de/uploads/media/2009_FSG_Fuel_Results.pdf)
http://www.fsaustria.at/filead...f/FuelEfficiency.pdf (http://www.fsaustria.at/fileadmin/pdf/FuelEfficiency.pdf)

There are quite some singles that consume more than the efficient 4 cylinders (Zurich, Stuttgart, Perth). My concern is not fuel consumption, but the fact that the small cars can be so fast with so little power.

With our GSXR600, we went from 5.71 l of petrol in Italy 2008 to 4.15 l of E85 (2.96 l equivalent) in Hockenheim 2009 while at the same time improving power delivery. The weak point was our cooling system, which wasn't taken care of well enough.

Regards,
Thomas
AMZ

[Tobias Hoernig]

In Italy 4cyl engines have a real chance to win fuel http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Mike Cook]

I think Formula SAE is the most successful of all the SAE design series because its the most fun. It's my personal opinion that if we make it not fun, people aren't going to want to do it, at least not to the extent they do currently. Adding events like fuel economy (where it actually has a significant effect on the results), sales presentation, cost, really snuff the life right out of the competition. I mean honestly, I've yet to meet a single individual who get really pumped up about any one of these things. I also don't necessarily think that these things make any of us better engineers. Anyways, like I said, this is only my personal opinion but I think it explains why formula hybrid, future truck, etc. were never really that successful.

[Muad'Dib]

I totally agree. Most teams (including ours) don't even take any of those factors into account. We don't have time to tune the car for fuel economy, if we get some points great, if not too bad. It really sucks that it's worth 100 points though. It's really just a way of SAE to call itself 'green.' A weekend auto-crosser would never care about fuel economy. A auto-cross course is, what normally about a mile? Even if you get 8 runs in (unlikely) if you got 2 miles to the gallon it would still only cost you like $12. It's stupid.

[TorqueWrench]

Fuel economy is one of those real world events that I have seen bug a lot of people. Personally, I think it is pretty important. With everyone today trying to go green in industry, companies are fighting for every last bit of fuel economy then can get. In motorsports, you can just see what Audi did in LeMans with the diesel if you doubt fuel economy having a big impact. So while a weekend autocross racer won't care about fuel economy, it is one of those things you have to think about after you graduate.

I do know UB competed in 08 and got second in fuel economy with our Briggs V-Twin. That car had a pretty good fuel table done, but spark was never touched due to lack of dyno access. People all the time say that fuel economy comes down to tuning time, but if that is any indication I think how your powertrain is developed has just as much of an impact as anything else. While I cannot say fuel economy was a top priority while doing work, I did pay attention to simulated outputs while doing most of the development because it is part of the competition that we are designing for. Every year during the first design meetings where we set vehicle and subsystem level goals, fuel economy of the engine package always came up as one of the deciding factors.

I certainly didn't mind needing to purchase less fuel when it was coming out of my own pocket a few times and we ran through a five gallon tank in a weekend doing testing.

[Bemo]

First you should take into account that the fuel rules at FSG aren't the same as at the other events. There your average lap time is in the formula, so if you're going faster you can use more fuel to get the same points.

I think fuel is an important part of the event. If a team isn't able to perform well in fuel because of a lack of manpower not enough testing time or whatever, they can still take part in the event but they won't have a chance to win.
I also think that the formula in the 2010 rules is much fairer is it is linear. In the past you didn't get much benefit if you improved your fuel economy if you weren't among the top teams in that discipline. With the new rule a team which improves from 5 to 4.5 l will have a fair benefit from their efforts.

A fact is, that also with the 100 points in fuel it is still possible to win events with 4-cylinder engines (as everybody could see this year ;-)
Just have a look on the winners of this year. The events in Michigan, UK, Germany, Italy and Japan were all won with 4-cylinder cars (I'm not sure about the other US comps) so I think nobody can say it got impossible to win with that concept.

[RenM]

i think fuel economy makes engine tuning more fun. Of course i prefer power over economy but as you are forced to look for both its more challenging and very rewarding if you meet your goals.
And honestly Cars that weigh less then 250kg should never use more then 4.5l.

The 2009 rule favoured 1 cylinder cars but for 2010 no 4-cyl team can complain anymore.

[Tobias Hoernig]

3.25l with a 279kg car and a Yamaha R6 (2005) http://fsae.com/groupee_common/emoticons/icon_smile.gif