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Avg fuel MPG?

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VelodromeRacer

VelodromeRacer

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I realize this is a loaded question with a million factors that effect it but I have a question for the racers out there...

When you prep for a race, do you fill the fuel cell all up or just enough fuel (and weight) to run the race?

What is an expected avg. race MPG? I ran some testing a few weeks ago and I know I ran 16 laps before I filled the fuel cell again. It took 2 gallons or so and the track is a 1.77 mile track so without looking at warm up time or cold pit distance, I averaged around 14mpg...sound close?

DO I just fill her up and not worry about it...(can't count on a yellow or something to add distance and I don't want to run out of fuel....

Thoughts?
 
Of course I am talking about a Bugeye with a 948 engine..I imagine a 1275 will be somewhat similar?
 
It depends on a lot of things, but I guess I'd get between 9~11.
What engine mods have you done? Approximate HP, gear ratio, etc?
Jeff
 
A couple of years ago (last time I checked mileage), I was getting approx 15 mpg with a 948cc race engine (Jeff, you know which engine) running either 4.55 or 4.88 gears and 20x8x13 Hoosiers. That was on a tight and twisty 1.5 mile track.

One huge factor in mileage is the amount of time spent at WOT (wide open throttle). In turn, that is going to depend on the track -- how many turns, how many straights and how long are they, etc.

If I was just starting out, I'd fill the cell, then refill after a session. Use that data along with how far you went to arrive at a starting figure, then refine from there.

Lastly, on our track, I seldom start a race with the cell more than half full. Carrying weight that is not needed doesn't make a lot of sense to me.

Tim
 
Fuel shouldn't be left in the fuel cell for a long period of time. It helps make the job of draining the cell easier if you burn up most of the fuel on the track.
 
I guess, based on Tim's comments that my mileage was better than I'd guessed. I usually would start out with a full cell in the morning for practice/qualifying, and just keep an eye on it afterwards. If I thought I'd be at bingo fuel at the end of a race, I'd add a couple of gallons just in case.
It also will depend on how close you want to push it to minimum weight.
In a previous thread, Nial said the fuel consumption with his 1500 Spridget was in the 6 gallon per hour range.
Yes, Tim, I know which engine! /bcforum/images/%%GRAEMLIN_URL%%/grin.gif /bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif
Jeff
 
What I do and see most folks do is make a device to measure fuel in inches, a piece of wodden dowell will work nicely, I took a piece of wooden dowell,and with a hack saw, cut notches in it at one inch intervals. I then add fuel by using the measuring stick, see how much fuel I use in a gven amount of laps. I fill my cell to amount of fuel I think I need for a given session or race with about a 2" safety margin. Hope this helps.
 
Hap, do you have the foam insert? How do you measure the level if you do. I think I heard of someone melting a hole in the foam with a hot pipe as the tank was new. (Obviously before the tank ever seen fuel)
 
Lou, I melted a hole in my foam to stick my cell. If you've already had fuel in there, you can mark a spot on the foam, remove the fill plate and the marked chunk of foam, then cut a hole where you've marked it.
Jeff
 
I am running the 4:55 gears, have Hoosier A70-13 and a pretty modified race engine. I too have the foam insert so I figured that a stick wouldn't work. The Putnam PArk track I tested the car at has 1 long straight and a mix of shorter sections with 10 turns. I started with a full cell and than marked my fuel just after running 16, 1.77 mile laps and filled it again, which took just over 2 gallons, hence the 14 MPG figure.
 
Hap Waldrop said:
What I do and see most folks do is make a device to measure fuel in inches,
Click to expand...

That's the beauty of the ATL 8 gallon cell. It's 8" deep, so 1 inch = 1 gallon. Even <u>I</u> can do the maths on that one! /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
Jeff
 
Sounds like a pretty good setup for Putnam.
I've never run the Hoosier A70's, but I run Hoosier 20x8x13 slicks on the race car. I've got Hoosier Street TD's on the vintage car, and love them. The vintage ride, alas, isn't a Sprite.
Jeff
 
Jeff, No fuel yet, Just got the tank installed. I thought I'd heat up a piece of 1/2 or 3/4 copper pipe with my torch and melt a hole threw the foam. I think I heard you make this comment before. (Thats where I remember it from I believe.)
 
I can't remember what I used to burn the hole in the foam. I think it was just a piece of 1/4" rod, moved around a bit. Just be careful and don't go into the cell itself.
Jeff
 
FYI: My 1500 Spridget burns about 6 gallons an hour.

Most of my speed averages per lap are around 70 mph, so I'm getting approx. 12 mpg.

My car has an 8 gallon ATL cell.

When I've run our 4-Hour in this car, I have to make two fuel stops or I run out of gas.

It is set up pretty rich, and of course, it is about 50% bigger than a 948

The 1275 Sprite I occasionally co-drive burns about 5 gallons an hour.
 
I burn 2-3 gallons in most sessions (20-25 minutes) with more on tracks with higher average speeds and vica versa. After verifying consumption during qualifiers I try to run the feature with just enough fuel plus a little bit more but am always thinking about how foolish I would feel if I ran out of gas during a race.
 
Thanks gang. It makes me think that my 14 mpg is right on. I also have a 8 gal ATL cell..I may have to look into the wood stick idea. Doesn't the foam insert have a metal part or clip that is visible from the filler neck when the cap is removed?

Aeronca65T, 4 hour events huh? Man I about burnt up just practicing and running 20 minute sessions...hardcore!
 
blkcorvair said:
Hap, do you have the foam insert? How do you measure the level if you do. I think I heard of someone melting a hole in the foam with a hot pipe as the tank was new. (Obviously before the tank ever seen fuel)
Click to expand...

I done it a couple of ways over the years with different cars I owned and worked on, I actually made a area to put the stick in by cutting the foam, or you can just measure right through the foam, most just do it that way, it compresses quite easily and doesn't really tamper with your results.
 
12mpg, Imperial gallons, which is 9.6mpg American. That's a big motor though, 2,138ccs., not a Spridget.
Each lap of Mosport is about a litre, 3.8 litres per US gallon, lap distance 2.5 miles, 2 minutes per lap so 75 mph.

Street driving 25mpg, gentle cruising 28mpg (Imperial.)

Your mileage may vary....
Simon.
 
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