Fuel consumption

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Zuel
I see a lot of good points as well silly ones, though all good points all based around carbureted and fuel injected motors. But one area now one has touched yet is the type of fuel. Ever ones points have been based on regular pump fuel not racing fuel. For example we get a car stock take it out on the track run it dry to get the lap count and mileage. Now was that run done on pump or race fuel? Change the oil and then run it dry again. Now was it done in the same matter as before pump or race? We have no clue if it was or not. Now we tune the car adding power gains from 25% to 60%. Engine ECU has been remapped to give of the right A/F mixture. Do two more runs in the same fashion as before. , Would we get a better fuel range yes. You also have to take in your driving still as well in this matter don’t forget.

The reason why this is so race fuel burns faster, cleaner and cooler than pump gas due to the lighter weight and higher Octane mix, The typical A/F mixture for standard engines is 14.7:1 (14kg fuel / 1kg Air). Some typical race fuel allows you to have your A/F 12.7:1 due to its spark mark and heat range. Now hoping that PD has taken this to mind we’ll see a number of different fuel range for the cars that have been modified in GT5.

Sorry Akira you did say fuel type..:dopey:

It you want a better understanding on how it would work pick up a copy Bosch Fuel Injection & Engine Management. It helped me through school…
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Zuel
Yes it may seem on the rich for a modified engine but not for a daily used car. You may have left out that factor. An engine that hasn’t been modified will use more fuel to get the same power out than a modified engine would. You also blow up that engine putting all that fuel in it. Plus you got to take in account the Octane of the fuel as well.
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You will be lucky to find a non direct injection petrol engine street car to run WOT with a stoich AFR. Under normal driving conditions yes but under track/spirited conditions no way unless it was a large capacity low powered engine or a leanburn DI engine. Most street cars get down to around 12:1 and higher strung engines 11:1 only to reduce knock without taking out too much power robbing timing. A higher concentration of fuel past stoich (14.7 parts air : 1 part fuel) will not gain any extra power through fuel energy (extra fuel is wasted out the exhaust, often seen as black smoke common on small turbo engines) and is only there to cool the cylinders, this may gain a power increase only due to advancement of timing but not due to the extra energy in the fuel itself.
 
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Jay
You will be lucky to find a non direct injection petrol engine street car to run WOT with a stoich AFR. Under normal driving conditions yes but under track/spirited conditions no way unless it was a large capacity low powered engine or a leanburn DI engine. Most street cars get down to around 12:1 and higher strung engines 11:1 only to reduce knock without taking out too much power robbing timing. A higher concentration of fuel past stoich (14.7 parts fuel : 1 part air) will not gain any extra power through fuel energy (extra fuel is wasted out the exhaust, often seen as black smoke common on small turbo engines) and is only there to cool the cylinders, this may gain a power increase only due to advancement of timing but not due to the extra energy in the fuel itself.
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It's the other way around; 14.7:1 is leaner than 12:1, and is generally avoided since it's impossible to ensure a perfect mixture, such that lean areas may cause localised detonation; this has those further effects you mentioned i.e. retarding the spark timing via a knock sensor. Most cars run rich at full-throttle for safety and guaranteed power (extra fuel ensures all the oxygen gets used and the piston is pushed as hard as intended - Diesels are guilty of this, hence EGR which deposits unburnt fuel and soot in the intake tract and the particle "filters" that pick up the remaining soot and unburnt fuel and oxidise it fully.)

A stratified charge engine (e.g. achievable via direct injection, among other methods) allows for an overall far leaner mixture (approaching 20:1, for example) but the local charge (where the fuel is, e.g. around the spark plug) is much richer, probably still around 12-13 or so to 1.
 
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Yes, my bad I can't believe I also made the silly typo, I did mean 14.7 parts air.


Griffith500
A stratified charge engine (e.g. achievable via direct injection, among other methods) allows for an overall far leaner mixture (approaching 20:1, for example) but the local charge (where the fuel is, e.g. around the spark plug) is much richer, probably still around 12-13 or so to 1.
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The reason I removed lean burn/DI engines from my example.
 
arseneH
So may be for the internet game room, someone may host game with the following rule:

This is a fuel economy game:
Each of you will have one tank of fuel, no re-fuel is allowed. The one who first complete 10 laps of Nurburgring wins!
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That would be very fun...! A lot of diesels and Fiats in a race!
Of course, that would only work if the car halts when the tank gets empty.
 
Griffith500
It's the other way around; 14.7:1 is leaner than 12:1, and is generally avoided since it's impossible to ensure a perfect mixture, such that lean areas may cause localised detonation; this has those further effects you mentioned i.e. retarding the spark timing via a knock sensor. Most cars run rich at full-throttle for safety and guaranteed power (extra fuel ensures all the oxygen gets used and the piston is pushed as hard as intended - Diesels are guilty of this, hence EGR which deposits unburnt fuel and soot in the intake tract and the particle "filters" that pick up the remaining soot and unburnt fuel and oxidise it fully.)

A stratified charge engine (e.g. achievable via direct injection, among other methods) allows for an overall far leaner mixture (approaching 20:1, for example) but the local charge (where the fuel is, e.g. around the spark plug) is much richer, probably still around 12-13 or so to 1.
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I know for my Mustang, my tuner refused to allow the A/F ratio to go over 11.75:1 when under WOT. Anything over 12:1 with forced induction, and you are just creating a ticking time bomb.
 
YES YES YES!!!! It's about time I traded post with some real gear heads on this site. I'm sorry but it's true, I would love to talk with more if I can. It's never to late to learn more....
 
I did some further investigations on GT4's fuel consumption meanwhile.

(Remember GT4 is the last full Gran-turismo game which allows for measurements on this topic. GT5 Prologue does not simulate fuel or tyre-wear yet)

My analysis is only meant for getting conclusions on GT5 of which I hope that it will have realistic fuel consumptions.


So I called in my friend "B-spec Bob" also known as "Spongebob" and instructed him to choose 2 (production-) cars and take part in some races.

I told him to go around Laguna-Seca at different race-speeds for 30 laps and then pit-in to have a look on.. right.. his car's fuel consumption. (Events were Arcade, Tyres Standard N2's)


30 laps on Laguna-Seca makes a distance of 107 km (66.5 miles)


On his first race he took a Volkswagen VW Golf GTI (1976) 110hp. (A car I owned for myself once in real-life...)
For the first measurements I told him to go "slow race speed" (Remember in GT4 we are able to give instructions for speed on a

scale from 1 to 5) ("slow" is "1" in that case)



When he came in he had used 22 liters/units. (I assume its "liter" although its not specified ingame. But what else should it be? Gallons?

22 liters = 5.8 gallons

Thats 20.6 liters / 100 km
or 5.4 gal / 62.1 miles
or 11.5 mpg (miles per gallon)



The second race he went 30 laps on "full speed" ("5") and his laptimes decreased by 3 seconds.

He used 24 liters now

24 liters = 6.3 gallons

Thats 22.4 liters / 100 km
or 5.9 gal / 62.1 miles
or 10.5 mpg (miles per gallon)



Third race he took a Volkswagen VW Golf GTI V (2005) 200hp. ("slow race speed")

He used 39 liters

39 liters = 10.3 gallons

Thats 36.5 liters / 100 km
or 9.6 gal / 62.1 miles
or 6.5 mpg (miles per gallon)




Fourth and last.. (Volkswagen VW Golf GTI V (2005) 200hp. ("full speed")

He used 41 liters

41 liters = 10.8 gallons

Thats 38.3 liters / 100 km
or 10.1 gal / 62.1 miles
or 6.1 mpg (miles per gallon)


All in all, though considering this is racing and not creeping on a sunday trip I think these values cant be real. These races all took about 1 hour each so the average "racing-speed" was still about 100 km/h (62mph)

In my opinion fuel consumption in (at least) GT4 seems too high.
 
So on a 99 lap race that about 15 stops if my math is right ( doing all in the head while at work). Let's hope the modeling for the fuel is better this time.
 
Try doing manually a few laps on the Test Course at a constant speed of 100 Km/h in the tallest gear you can engage. You will see that consumption will be much lower, probably more comparable to what you had on your real life Golf.
You're not taking into account that B spec drivers run the engines quite hard, so even if the average speed on a twisty track is "only" 100 Km/h, fuel consumption will be high, because the engine will be used close to full power fur much more time than with the Test Course run at constant speed.
 
If GT4 uses units instead of litres or gallons it could be different for every car. Maybe you could let your friend do the same thing with a standard Supra RZ and a fully modified 1000 hp+ Supra RZ and a standard racecar like MB CLK DTM. If the differents with these are the same you can asume it are units depending on the car you use.
 
As far as I know more or less accurate test were performedand the results were posted in the GT4 forum a few years ago.
The most plausible unit for "fuel units" was liters.
However, each car had the same fuel tank containing 80 fuel units (liters).
 
I know my stock MX5 seemed to go forever on a tank whereas my 787B in some cases would run out of gas before it needed a tire change.
 
profi
Fuel consumption...

Yes it's only one single detail within the complete game, but an important one as I think.


I still here those arguments regarding visual damage of the cars ingame... "the manufacturers will not allow to show their damaged cars so we cant do that.." ...


Today the world is all about economic efficiency. Not only here in Germany.

So what will the car manufacturers say if their products fuel consumption is twice or triple as much ingame as in real-life ?

I dont think they would be happy... But still no one talks about it or thinks about it.


We do not know yet how it will be in GT5 but...

We (or at least I) do know how its been in GT4.


An example ? - In GT4 a 69 Chevrolet Corvette (fully tuned to 572 HP) consumed 49 liter for 100 kilometer (km). (average)

A bit much, isnt it?

The gas-tank of this car can hold 80 liters (ingame), so the range of this car is 163 km. A bit short, isnt it ? (Thats about 100 miles)

This is only one example but I soon realized in GT4 ALL cars had an exaggerated fuel-consumption.


GT5 Prologue does not give an indication on fuel so we can only hope that there will be an appropriate fuel consumption in GT5.

At least I hope so...
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Are u joking or what?
U think that 2 km per liter is too much?
A tuned corvette from 1969? LOL. I think its quite optimistic!

An Hummer at the max will do something like 0,5 km per liter.
 
Now the only way to settle this is for some of us whom are able to get their had on some of the car that will be in GT5 take it to one of the track listed in GT5 and test them our self ( which will never happen) or find some info with some test results and compare them to GT5 model.
 
Jay
Yes, my bad I can't believe I also made the silly typo, I did mean 14.7 parts air.


The reason I removed lean burn/DI engines from my example.
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Fair enough, but even with a stratified charge, combustion still occurs below the stoichiometric ratio; that's all I was saying. 👍
So technically, they needn't be excluded :)

As for these fuel figures, they seem reasonable enough. What's not so reasonable is the 80 unit tank for all cars. It's a bit silly, really.
Does fuel affect the weight / handling of the car in GT4? There's another important trade-off: tank size and fuel economy vs. inertia and centre of gravity etc.
 
With a EG6
This is a aspect of GT5 that is so borring id rather drown myself in a bucket of wallpaper paste.
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Then go do it then and leave us alone. You're not a true car nut so leave the forms. Just joking...
 
Zuel
Now the only way to settle this is for some of us whom are able to get their had on some of the car that will be in GT5 take it to one of the track listed in GT5 and test them our self ( which will never happen) or find some info with some test results and compare them to GT5 model.
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quite simple actually. Top Gear is useful here. They did an episode where they raced a bunch of cars around their test track with 1 gallon fuel to see how far they would go at race pace.

The Top Gear test track will be in the game, and the cars they used I'd imagine will be too (at least one or two of them anyway).

Ferrari 599GTB, Lamborghini Murcielago, Aston Martin DBS, Audi R8, Mercedes McLaren SLR

I'm not up on what will be in the game, but I'd imagine all of these will be. So you know what their fuel mileage was running full out on the top gear track, and then you can figure out the fuel economy running full out on the top gear track in GT5. Voila.

Assuming of course that you can figure out what the "unit" of fuel actually is.
 
Pedal-Force
quite simple actually. Top Gear is useful here. They did an episode where they raced a bunch of cars around their test track with 1 gallon fuel to see how far they would go at race pace.

The Top Gear test track will be in the game, and the cars they used I'd imagine will be too (at least one or two of them anyway).

Ferrari 599GTB, Lamborghini Murcielago, Aston Martin DBS, Audi R8, Mercedes McLaren SLR

I'm not up on what will be in the game, but I'd imagine all of these will be. So you know what their fuel mileage was running full out on the top gear track, and then you can figure out the fuel economy running full out on the top gear track in GT5. Voila.

Assuming of course that you can figure out what the "unit" of fuel actually is.
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Well, you drive as far as it took to use that gallon (UK, not US...) and then read off the fuel gauge :dopey:

Good idea, though. It'll be hard to do accurately, but it'd be close, at least. 👍
 
but that doesn't tell you what the unit of fuel was. It tells you nothing, actually.

It could EITHER tell you what the unit of fuel is, OR what the fuel mileage is, but not both. Until you know the unit of fuel OR the fuel mileage in game, the test doesn't really tell you anything.
 
If you do go with realistic fuel consumption, know you won't be driving a Veyron for very long before a refuel.
 
That's when you drive the car flat out on a highway, though.
On a race track you don't normally get to use the engine at peak power for very long.
Range might end up being smaller (due to the lower average speed), but the driving time with a single fuel tank will be longer.
 
What episode was it so we can get the cars right, and was the WHITE NIGHT driving?
 
no, Stig didn't drive. They drove all of them at the same time. I know the three presenters drove, but dunno who the other 2 were. The list of cars was lifted from the episode list.

Series 11, Episode 1.
 
Would be nice if GT5 included information of fuel consumption atleast in a after race datalog, it is a big part of race strategy and accurate logged or realtime information could come in quite handy, especially when it comes to tuning or general vehicle choice for enduros.

IIRC GT4 or GT4P had a Prius event which did log fuel consumption where you were to finish two laps under a certain fuel limit.


Griffith500
Fair enough, but even with a stratified charge, combustion still occurs below the stoichiometric ratio; that's all I was saying. 👍
So technically, they needn't be excluded :)
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Indeed technically (the whole reason it doesn't missfire) but I was only referring to total AFR (I didn't make that clear I guess) as this thread is about fuel consumption. :)
 
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I don't care so much as to what they do in terms of amount of fuel consumption.

I just hope that in the physics engine, they account for fuel spent in the weight and center of gravity of the car. Take a NASCAR for example. With a full tank of gas, the car is at a heavier weight, with more weight towards the rear end, and the center of gravity pushed back. It can make the car quite a bit squirly in some instances because of that. But, as you burn off fuel, that center of gravity moves forward, and the car becomes lighter, making it faster. With a fuller tank though, you get more weight over the rear axel making the rear tires grip better.

It's all so dynamic, and PD has claimed that this new physics engine is going to be as real as it gets (or so they implied), so I hope this isn't something overlooked.
 
Jay
IIRC GT4 or GT4P had a Prius event which did log fuel consumption where you were to finish two laps under a certain fuel limit.
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I'm pretty sure it was GT Concept, and you had a diagram if I remember correctly telling you what the hybrid engine was doing, a novel addition to break up the normal racing events I thought.
 

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