Le Mans car info needed

[slothead]

As a solo racer I run simulated multi-car races using recorded lap time data. One of my classes is the World Sportscar Championship series featuring Le Mans type cars from the mid-late 60's. In 20 car races 5 different teams are represented - Ford, Ferrari, Porsche, Lola, and Chaparral. Each team has 4 cars and in addition to recognizing the cars and drivers (Gurney, Donohue, Elford, etc.) that make it on the podium, points are awarded to teams to see which claims the series championship over several races.

As I endeavor to add more realism to the races I've just computed section time percentages for each car which will allow them to change speeds relative to each other throughout a lap as the simulation plays out. For example, one car may be faster on the back straight while another navigates the loop turn faster, allowing cars to catch and/or pass others at various places around the track. A 'real time' display allows me to track the current race order lap by lap and even see where cars are on the track at each time step during the simulation.

But, I'm hoping for even more realism by incorporating additional race factors. Next up is calculating fuel usage and tire wear lap by lap to determine when cars will need to make pit stops. To do this realistically I need to know what the fuel capacity was for cars like the Ford GT40, Porsche 917K, Ferrari 512M, Lola T70 MK3B, and Chaparral 2F. I don't need exact amounts, reasonable ballpark values will do. I also need decent estimates on fuel usage (mpg) and how long cars could go on a set of tires by car type.

Anyone know what good values to use would be? My research is starting here with the knowledge base at HRW. Any info, thoughts, or ideas folks have to offer is appreciated.

[War Eagle River]

Race car specs are easily attainable. Google it!

[slothead]

Doing an initial search and found some interesting commentary on the development of the GT40 and engine development specs but not much on factors responsible for pit stops. Did find this regarding north American version of GT40.

Fuel capacity:

159 liter / 42 U.S. gal / 34.9 imp. gal

Did the math and at 6.25 lbs @ gallon a full tank would weigh 262.5 lbs. That's more gallons and weight than I thought would be in a race car. For an endurance race carrying a lot of fuel would seem to make sense, but also creates a hazard in the event of a crash or mishap in the pits.

I don't know if fuel capacity was determined by the sanctioning bodies or left to the discretion of the teams. As for fuel consumption, the info on the same webpage (https://www.automobile-catalog.com/auta_perf1.php) was nonsensical as it listed city & hwy values ranging from 13.9 to 5.6 mpg. I would think a race tuned 7 liter engine would be very thirsty.

Additional input welcome.

[CG Slotcars]

Fuel capacity for the GT40 would have been the max for group 6 in 1967. All those cars most likely were at that size.....
In 1967 - the 2F pitted on lap 10 at the Nurburgring.... (And retired shortly after...)
For the sake of argument I'd throw out that at 150 miles - the tank was going to be empty..... so roughly 3.5 miles per gallon.... Which sounds correct for a 7L
Could be more - could be less, but that must be in the ballpark

[Scatman]

This might help. Click on photo gallery and follow the link.

[slothead]

Thanks very much CG Slotcars!

Two sources suggest 42 gallons is the fuel capacity, though for the era before modern fuel cells that sounds very dangerous. I might reduce that to 22 gallons and then try to work out a reasonable amount of time to get that amount of fuel in a car for pit stop length. GT40 engineers devised a way to change disk brake pads during a pit stop, so with a driver change, brake and tire change (when needed) refueling might not be the major determinant of pit stop length.

I think I will go with 3.5 mpg as the series average then do a little +/- for the various teams based on engines.

Any estimates from races at Sebring, Daytona, etc., anyone may know of are appreciated.

[CG Slotcars]

No problem!
The P4 has a 30 gallon tank...

I found this in some reading.... I think it was Wikipedia.... 1967 Lemans

There were no engine limits on the GTs or Prototypes. As before, the Groups were split up in classes based on engine size, there was a sliding scale of a minimum weight based on the increasing engine size (from 450 to 1000 kg for 500 to 7000cc) as was fuel-tank capacity (60 to 160 litres).

I can't seem to find the '67 FIA rule book. I thought the FIA used to have copies online - but not anymore it seems

You could probably get lap chart info from news coverage or you tube videos....

[slothead]

I could assign different size fuel tanks for different types of cars, then even things out with mpg values used. I'm guessing the 427 c.i.d. V8 Ford GT40 engine was very thirsty, while the Ferrari, Porsche, and possibly Lola were more fuel efficient. The Fly, Scalextric, and MRRC cars in my series are all very equal in speed so if Ferrari's had to make fewer pit stops it could be a huge advantage.

For simulation purposes the key will be to match fuel capacity with fuel usage so either all cars are making the same number of pit stops in a race, or the ones with fewer pit stops need longer stops to refuel and account for things like driver and tire changes, and other factors. The GT40 could have a larger fuel capacity allowing longer runs between stops, but then need longer pit times to refuel and change brakes. According to an interview with the chief engineer the GT40 was so fast down the long Le Mans straight it took massive braking for the tight turn that came after it, and the team struggled with keeping adequate brakes on the cars.

The more realistic factors that can be added to a simulation the better.

Thanks again for the input and feedback. All comments are welcome.

[Historiceng]

Just a thought, as well as slot cars I enjoy sim racing, on and off line. Some of the better "mods" are created with great research from incredibly dedicated enthusiasts giving great attention to detail. Rfactor 1 and 2 are excellent for well researched historic cars. iRacing is also well researched especially for oval tyre wear and fuel consumption, albeit not as many historic cars..
I would happily take some details in a session with a Lola T70 over 20 or more laps and let you know..
I think with the right Mods, this can work as I have often been asked for many details from the individual modders because of my restoration work with historic cars.

[slothead]

Based on the 7 liter GT40 having a 42 gallon tank and getting 3.5 mpg, I estimated what other makes might get. Assuming a similar metric applies across the board a 30 gallon fuel capacity for the Ferrari would match with a 5 liter engine. I don't know the engine displacement for Lola T70, Chaparral 2F, or Ferrari 330 P3, but have a formula set up for reasonable estimates. I'm also assuming the link between engine size and fuel tank size is meant to even out refueling across these makes of cars. At 3.5 mpg the GT40 could go 147 miles on 42 gallons, so the others must be in that ballpark.

It would be great if you could pass on some info from sim racing. I have done some online research but spend the vast majority of my computer time working out math problems in Excel spreadsheets. New info will automatically recalculate what I have now.

I just started working on tire wear calculations today using the assumption tires would not degrade significantly over the length of a fuel run. But I don't know that and also assume refueling and tire changes both dictated when cars made normal pit stops.

[Rleog]

Much of your car data can be found by using Google. Just typing “Chaparral 2F specifications” can get a link to ultimate car page.com and a listing of specs for that car. Chaparral used a 427 Chevy motor (6997 cc, 525 bhp) in the 2F.

[Maddman]

Various motors could be fitted into the Lola. Most were probably variations of a 5L Chevy. If you view Ford v Ferrari you can see that the Fords changed brakes just once during the race. The remaining pit stops were fuel and tires.

[Dogsbody]

Slothead, I'm sure you know this but software such as SlotTrak does refueling and tire wear. Go faster and use more fuel and wear out your tires quicker and so on. Both are adjustable independent of one another.

[slothead]

Reading posts about pit stops in digital racing or with programs like you mention is what got me thinking about adding them to my simulations. Linking mpg to mph makes a lot of sense but I haven't worked on a formula to do that realistically yet, but am planning on doing it as things evolve. Thanks to the discourse here I'm coming up with good base values as starting points.

[slothead]

Thanks to everyone for input and feedback. As a solo racer I lack the back and forth chatter among competitors that sparks a lot of upgrades. The folks here at HRW are my racing buds to help with that and I appreciate it.

I was looking up info about the Porsche 917 last night and the stuff on Wikipedia was very helpful. I use any Le Mans, Sebring, Daytona, etc. large engine displacement endurance cars in my series that raced between 1966 and 1973-ish so a single race report or year's data doesn't cover it all. The 917K didn't become a factor till '69 but in my series it gets to line up beside Ford GT40's from the mid 60's. In my mancave slot car pits the best that ever were, still are.

The 917K had multiple engines but I think I'll use 4.5 liters as the base size and work out fuel use from that. I haven't found a lot of info about tire wear yet but will come up with something reasonable. What I'm looking for are realistic factors that might make a car leading a race have to pit while some trailing cars might not have to - which is a part of real racing.