fuel consumption

[Don Merino]

Hey there..

Some time ago, I took a look at my online statistics and calculated an average fuel consumption of roughly 43 litres per 100km. Now, with the GTR and Formula cars and all, I'd say: No wonder.
What puzzled me though is that I spend most of my online time in the GTI. So on the next day I went online with the GTI, raced for some time and then looked at my statistics again.
IRL I drive a '96 Nissan Maxima 3.0 V6, and I do like to kick it up and down the hills around here like a maniac sometimes, with screaming tires and all...and of course I often enjoy the missing speed limits on the Autobahn... and in four years I never managed to burn more than about 12.6 litres/100km. Usually I need around 10 though.

Yet the GTI's 1.3l inline 4 somehow burns more than 30 litres per 100km. I wonder how? From my knowledge about engines (which isn't actually vast), I thought it wouldn't be possible at all to get that much fuel through the injection system of a 1.3l engine, regardless of how you drive.

[danowat]

8mpg?, maybe a little far fetched, but hey, its a game right?, also its still in Alpha, so there are things left to tweak.

Dan.

[Don Merino]

It's a game, true. But it's considered a very realistic game, isn't it? And looking at all the realism, I wondered why the fuel consumption would be unrealistic...
And since nobody else had mentioned that yet, I thought that it might after all BE realistic, and that somebody might to explain it all to me :).. Which is why I formulated my post the way I did.
Of course I could have asked "Can anybody explain to me why the hell the GTI would burn 30l/100km?", but I'm Mr Merino and, as you can see, I'm a little weird and I can't put things in simple sentences.

[tristancliffe]

I think 8mpg is about right for a 1.3 at racing speeds & throttles. My Lancia Fulvia race car (1.3 also) gets around 8mpg on the track. It makes about 135bhp.

[xaotik]

but I'm Mr Merino and, as you can see, I'm a little weird and I can't put things in simple sentences.

You might also be interested in this thread and the url it refers to ( http://www.lfsforum.net/showthread.php?t=97&highlight=fue), Your Weirdness.

[danowat]

I think 8mpg is about right for a 1.3 at racing speeds & throttles. My Lancia Fulvia race car (1.3 also) gets around 8mpg on the track. It makes about 135bhp.

Yes Tristan, but the GTI isnt a race car is it, its supposedly a road car.

Also, how did you exactly calculate the 30lt/100km figure?, I just did a quick calculation, and I worked it out to be 9.25mpg, which is maybe a little low for a 1300cc road car, but remember this car is driving in WOT conditions most of the time, heck a Lancer EVO will be lucky to better 4mpg when you drive it hard and thats only a 2000cc, albeit with a huge great leaf blower bolted on.

Bottomline for me, its a little low, but no miles out, not enough to say its wildly unrealistc.

Dan.

[Don Merino]

Well, I went to lfwsworld.net and took a look at "today's stats"....:)
I'll try it again today, ok?

And thanks for the link..



heck a Lancer EVO will be lucky to better 4mpg when you drive it hard and thats only a 2000cc

Wow...that's...insane.

[tristancliffe]

To be honest, the Fulvia isn't a RACE car, but a standard road car tweaked a bit. The rules are fairly strict in HSCC racing, and we have to run standard carbs and inlet manifolds (although you are allowed to do minor porting work if necessary). So standard road carbs = ~8MPG

[Don Merino]

Ah, you're talking about carbs there.
I was assuming the GTI uses injection.

I do believe in your 8mpg with a carburetor...but with injection?


I'm still shocked by the gas mileage quoted for the Lancer EVO...that's at the level of Formula-1 cars...or small cabin boats.

[Bob Smith]

Carburetion was better than fuel injection for a fuel years until they stuffed enough electronics behind it (i.e. EFI, rather than mechanical).

I think I read once that F1 cars get about 2mpg. Racing fuel economy and motorway fuel economy tend to differ somewhat. ;)

Top fuel dragsters get through fuel at an incredible rate, I don't have any data to hand, but IIRC it's multiple gallons for a single 1/4 mile drag. So you'd need to measure that in gallons per mile, not miles per gallon. But then 8000hp tends to do that.

[Don Merino]

I think I read once that F1 cars get about 2mpg. Racing fuel economy and motorway fuel economy tend to differ somewhat.

I've read 70l/100km somewhere, which is exactly 4mpg. But I don't remember when that was...It may also have concerned a certain race track...so in other cases it might be even 2mpg...

I am aware that a motorway is different from a raceway. I didn't want to extend my ramblings any further, so I just wrote something about enjoying the missing speed limits. As a matter of fact I once went from Nürnberg to Munich, that is 170km, in a bit over 45 minutes. I did need a lot of braking and accellerating there, with speeds between 140 and 240 km/h, so it shouldn't be that far away from racing. After all I was either stepping on the brakes or slamming the accelerator to the floor. And I needed considerably less than half a tank, which would have been 30 litres. Even then I'd have gotten 16mpg.

On the other hand, my engine isn't exactly overtuned with 193hp from 3.0l.


btw, are we talking about imp or US gallons?

[danowat]

I'm still shocked by the gas mileage quoted for the Lancer EVO...that's at the level of Formula-1 cars...or small cabin boats.

Yes, I am pretty sure that the FQ400 Evo was the leader of the worst fuel consumption figure at Top Gears test track for a while, untill they let the Ford GT lose on it.

As you say, 193bhp from 3.0lt is quite lesuirely, I dont think its a good idea to use that as a comparison.

I used to own a Mini with a MG metro turbo engine in it way, way back, and if I drove that like a hooligan, which I tended to do when I was young, I could get ugly, ugly fuel consumption out of it, that was only 1300cc, but it was forced induction of course.

Dan.

[W1LLSD4D]

Last Saturday night I recorded the Bathurst 1000 & I'm slowly working my way through it an hour of so each evening (after Mrs K has gone to bed) - not finished yet (50 laps left to ogo), so no spoilers please.

Anyhow, this morning I was trying to work out the fuel consumption from the commentary (so anybody with better information please speak up - I dont want to search for info in case I see the result).

So we have:

1. 1000 km race
2. 120 litre fuel tanks
3. Teams talked about a 4 stop race (so thats 5 tank fills)

so 1000 /120 / 5 / 1.60 * 4.54 = 4.8 mpg

Now thats for a big V8 & making lots of assumptions (some of which may be wrong).

[Don Merino]

I tested the GTI again now and got about 10mpg...must have had something else on my mind when I calculated those 8mpg last time :)

[W1LLSD4D]

, untill they let the Ford GT lose on it.

Dan.

A classic Top Gear moment when Hammond 'calculated' that the fuel tank on a Ford GT wasn't big enough to get Clarkson from home to the studio... :D

[OPK]

Once I calculated the mileage of the FZ50 road car...and was shocked because it was around 90L/100km...
I hope this will be fixed...

[96 GTS]

Top fuel dragsters get through fuel at an incredible rate, I don't have any data to hand, but IIRC it's multiple gallons for a single 1/4 mile drag. So you'd need to measure that in gallons per mile, not miles per gallon. But then 8000hp tends to do that.
As I recall, it's something on the order of 40 US gallons per run, that includes the burnout and the run. I have a magazine article somewhere with a bunch of Top Fuel facts, I should dig it up.

Back on the road car note, my '98 Chrysler Concorde has a trip computer that shows both instantaneous and average fuel economy. With a 3.2 235hp V6, I get between 2 and 4 mpg at WOT acceleration, which is how you race a car. As the original poster mentioned, he gets decent fuel economy on the autobahn. Cruising at a constant speed uses very little power, and thus very litle fuel, I've read an engine needs about 35hp to cruise at 75mph. Again using my car as an example, I can push the fuel economy up into the 30-40mpg range if I maintain a constant 80mph on a flat piece of road.

Anyway, pardon my senseless rambling, I'm very bored :D

[Vain]

Yes. The FZ5 is out of scale. I also calculated something along the lines of 90l / 100km.

Vain

[Rebeldevil]

I can't say I worry much about fuel economy when I'm racing. The needle points to E, I go fill up. That's all the thought I normally put into it.

[T.K.Jode]

Has anyone else noticed that leaving the car idle will not use ANY fuel?

I left a FXR sitting for 30-40 minutes... not even a .1% change.

[danowat]

TBH, I would imagine that fuel consumption is actual pretty difficult to program.

What you have to remember is that these systems are not complete yet, I am just glad that there is fuel use in there even though it may not be up to scratch yet.

Dan.

[Bob Smith]

Has anyone else noticed that leaving the car idle will not use ANY fuel?

I left a FXR sitting for 30-40 minutes... not even a .1% change.
Really? It does for me. Even back on 0.5L I remember the engine stopping about a minute after I'd parked up after a race had finished. It is of course very slow.

[Nick_ll]

Just gonna give a quick input here:
Once on a TV show here they tested an Infiniti G35 (call it Skyline if you wish) and they decided to check out how much fuel it would burn driven at racing speeds. Answer: 37L/100km.
Now it is said a Formula1 (using the current 3.0L V10 spec) does about 80L/100km, slightly varying depending on the team and track and other parameters.
I've also read somewhere that a
Viper GTS/R (racecar, was/is racing in the GTS class of ALMS and some FIA GT) was doing something along the line of 57 or 65L/100km, using a 8 liters V10.....

[Don Merino]

Welll...I see the difference between real racing and the "racing" that I do out in the country - after all, I don't accelerate to from 40km/h to top speed once every one-and-a-half minutes. And I don't keep going up and down between 100 and 140 during the rest of that time.
Furthermore, I've never actually tested how big the fuel consumption of my car really is when I kick it up and down those hilly roads I mentioned. I only noticed that the impact of these sprints on the average consumption was'nt really big. On the other hand, if I have twice the normal consumption for only 5% of the distance that I can cover with one tank, this impact wouldn't be big, and I would still have burnt 6 litres on just 30 kilometers.

So probably the devs are right about the fuel consumption of the cars...

[J.B.]

Here's a consumption map I found on the web some time ago. Nothing to do with LFS but still interesting.

Up the left is work per displacement per four strokes which is essentially the same as torque per displacement. The numbers on the graphs is the mass of fuel used per kWh. You have to read the graphs as if they were elevation lines on a map.

Go figure. :tilt:

[Bob Smith]

...so what am I looking at and what does it mean in relation to the discussion (if anything?)

[ayrton senna 87]

perhaps this explains it better

[Vain]

Now I understand! How clear it is! Thanks! Horray! :)

Vain

[tristancliffe]

Cheers Will!!! It's good to know there are people that can turn technical rubbish into useful information :P

[ayrton senna 87]

well, so many of my posts on this forum are useless, i thought i would make a useful contribution once in a while

glad i could be of assistance

[Mauni]

Quote:
Originally Posted by T.K.Jode
Has anyone else noticed that leaving the car idle will not use ANY fuel?

I left a FXR sitting for 30-40 minutes... not even a .1% change.


Really? It does for me. Even back on 0.5L I remember the engine stopping about a minute after I'd parked up after a race had finished. It is of course very slow.

I noticed this too today as I took my LX6 out of pits and left it there during qualification for about 20 minutes. No fuel comsumpted meanwhile... Maybe this takes effect only if you leave the pits and dont move your car...
Doesn't affect to racing so I wouldn't be too worried:shy:

[J.B.]

...so what am I looking at...

It tells you how much fuel the engine is using in all possible states of operation. For example in the point that is marked "7kW/80km/h" the engine is outputting 7kW at 2000rpm and is using 600g of fuel per kWh. Push the throttle more and you have to move up on the graph. The best efficiency is achieved at 2900rpm, very close to full throttle.

...and what does it mean in relation to the discussion (if anything?)

LOL, I'm not really sure. I just think it's interesting to see how fuel consumption works in the real world. Here are two things you could do if you were really bored:

1) calculate the fuel mileage for a full power, top speed run.

2)output a FZ50 (closest to v6) Blackwood raf to Excel and use the torque and rpm values to calculate the fuel consumption for the Opel V6 then compare with LFS.

I don't know a reason why this would be worthwhile though, especially since you would have to somehow get the jpg data into Excel first. :shrug:

perhaps this explains it better

I knew someone would get it without further explanations. :D

[speedfreak227]

Quote:
Originally Posted by T.K.Jode
Has anyone else noticed that leaving the car idle will not use ANY fuel?

I left a FXR sitting for 30-40 minutes... not even a .1% change.




I noticed this too today as I took my LX6 out of pits and left it there during qualification for about 20 minutes. No fuel comsumpted meanwhile... Maybe this takes effect only if you leave the pits and dont move your car...
Doesn't affect to racing so I wouldn't be too worried:shy:

i've run out fuel idling when i had my fuel set to be almost empty at the end of the race.

speedfreak227

[tristancliffe]

Generally speaking ANY internal combustion engine is most efficient at peak torque at Wide Open Throttle (WOT).

It's a huge influence on road car engine design and gearing considerations.

[skiingman]

Generally speaking ANY internal combustion engine is most efficient at peak torque at Wide Open Throttle (WOT).

It's a huge influence on road car engine design and gearing considerations.

I get really annoyed by people that don't get this important concept you've just hit on the head and assume throttling losses are small. One is a degreed engineer. Go figure.

In practice, many modern engines tend not to be least thirsty at WOT because of open-loop fueling. They tend to work best at that point right before the ECU goes open loop. Full throttle-closed loop is only some new EPA regs away for some of us. Not a good thing for an enthusiast. :)
...
Re: this thread in general:

I don't think the fuel consumptions for LFS are all that accurate, but I do think a lot of people that have posted here are clueless about the fuel consumption involved in racing....any motor burns a lot of fuel run flat out for any modicum of time.

I just calculated fuel burn for an FV8 on KY Oval because its the simplest case. Gasoline is assumed at 6.35lb/gal, therefore one liter is about 1.677lb, the FV8 world record setup burns 1.875 liters on one hotlap. With a BSFC of .4 (typical for modern racing engine, super high end motors may dip below this) the FV8 is calculated to be producing ~700hp. If you move the BSFC to black-smoke belching turbocar range, it seems more accurate. I haven't tested any other cars, itd be interesting to see the results.