Fuel consumption rate for race engines.

[evelrod]

As an addition to my post on thread71-125393 and answering a query by Robert Reinking of the University of Arizona...
<

http://dakotacom.net/~reinking/Yellowcar.html>

From my engine figures the fuel consumption graph appears to be linear given the four points that I can supply.
It sure would be nice if other members could add a few more in the 200hp to 450hp range. Horsepower at the wheels, race weight (car and driver),engine displacement and fuel consumption.

1594cc Lotus Cortina twincam ~165 hp at the wheels---race weight of 2060 lbs., car and driver---Riverside Int. Raceway lap times 2:05 long course and 1:39 short course (this car retired three lap records at RIR)--- 10 gallons of race fuel per hour...
Same car with 139hp at the wheels 2:09's and 1:42's same tracks and ~9 gallons per hour.

<500hp tube frame IMSA Pantera RIR long course 24 gallons per hour...sorry I don't remember the weight, but it was pretty light tube frame and fiberglass...it was not my car, I was the "fuel guy" in the crew and I just ran the 'dump cans'.

1380cc Austin Cooper @ 110.45 hp at the wheels, 1730 lbs. race weight car and driver.
Based on three two hour races at Willow springs from 2003 to 2005... 7.2 gallons of Sunoco 110 per hour.

Rod

 

[Rob45]

Evelrod:
From your lowest two horsepower points, I calculate .38 lbs per horsepower-hour: almost identically the same for both! But far lower bsfc numbers for the two higher horsepowers:
This suggests that the "165 hp" car was making only 154 hp, and the *500 hp* Pantera was making but 369 hp.

But that can't be: race engine builders wouldn't dare over-state their power outputs, would they?

Finally, I'd say that .38 lb/bhp-hr is a very reasonable-looking number, and I would not be surprised if it had broad application to race engines in general. Four-valve engines might be a bit more fuel-efficient, turbocharged or supercharged engines a bit less so, and air-cooled engines or drag engines where fuel is used as a sort of a coolant considerably less so.
I cannot see, however, how car weight, etc, has any bearing on this, as long as the race car is being operated at maximum output near 100% of the time.

 

[evelrod]

That's the problem, Rob. Road racing is not 100% , indeed, I would guess it's nearer <80%---greater percentaqge in the smaller displacement and slower class cars(such as my current Austin Cooper), less in the 500/600 hp GTO and Proto class cars on road courses. Car weight is the major determining factor in acceleration off every corner...and... how long it takes to slow for the next corner!
The hp figures for the Locor were done in the early 70's at Ak Miller's (VERY reputable shop) in Pico and, on the Evanspeed Claton at AVO in El Segundo in 1984 (I think). I don't have the sheets any longer but I used these two engines until November 1990 at Las Vegas--- fuel mileage varried little over the years. I think it got a little better as I got older and slower ;-) . The "165" engine went on E-Bay about five years ago (somewhere back east) and I have the "mule" scattered all over my shop...maybe to rebuild one of these days. The Vic Manuelli Pantara was dynoed in Long Beach ??? that is why the approx 500---an educated guess---but I did put in two full cans each stop/hour when they could keep it running. The Mini was last dynoed on Evan's Claton at my shop on September 16, 2005, 1300'AMSL corrected to std norms.

Rod

 

[GregLocock]

F1 cars spend about 60-70% of the time on the throttle, from memory.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[ale58]

and this year, with V8 2400cc I've read Toyota estimates 90% full throttle for a Monza lap!

Alessandro

 

[JKart]

Interesting numbers gentlemen! How can we compare them to the 'accepted' good bsfc of ~.43-.45 (numbers for a Grand National 350 motor on the dyno ca. 1980)? Can we surmise that the lower 'road' numbers reflect the widely varying throttle opening on the actual race course vs the severity of the dyno pull?
JimK.

 

[evelrod]

Hmmmm. 1980? Problably can't. If my memory is not totally out of whack, in the early 80's I watched a dyno run on a ~350 Ford (for Elliot, I think) that was 'streatched' to maintain 7500 rpm for a "500" mile test at 100%. Now, a couple years back, I got a glimpse of a Superflow chart that showed a test run of a 366 Ford that had a lot of 9000 rpm numbers on it. Couldn't get a good look but, enough to see what it was!!!

Keep in mind, gentlemen, that I posted those numbers as a favor to another member...I am not totally convinced that you can compare my fuel consumption figures with a vintage Austin Cooper raced by a 66 year old to the figures from modern day NASCAR or F-1 engines...indeed, from ANY modern engine!

Rod

 

[JKart]

As far as bsfc, things aren't THAT much different today than what they were in...1972! I have a factory published dyno bsfc curve for the Alfa Romeo Giulia 1600 engine,the 89hp version. It ranges from 0.47(lowest) to 0.54(highest). I bet we can compare these numbers with ANY size 2-valve carb-fed engine and come very close (dyno cycle measurement, not actual road).
Alessandro, 90% full throttle around Monza?!Must be nice to get hold of such a telemetry printout and have it framed!
JimK.

 

[GregLocock]

Many F1 teams have that data on their websites during the season. Last year Renault were supplying a live feed to their website - flaky on my computer but a brilliant concept.

http://img243.echo.cx/img243/3267/compare2yr.jpg

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[ale58]

I can't find where I read about the 2006 full throttle percentage at monza but this confirm Greg Locock's good memory

http://www.f1.panasonic.com/en/news/news_050830_01.html

This year the cars will have 18-20% less power, it looks like the mix between vehicle dynamic performance - engine power - trak configuration is not well balanced.

I'm stopping here because i think to be a little off topic ...

Alessandro