smart51
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| posted on 22/9/08 at 02:25 PM |
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trackday fuel consumption
I'm going to Silverstone on Wednesday. I've been looking at the track map and I reckon I can average 95 MPH so long as there's not
much traffic. The south circuit is 2 miles long so thats about 47 laps per hour.
At a push, my tank holds about 28 litres. I've averaged 20 MPG on previous track days. That works out at about 1.5 hours per tank full. On
previous track days, I've used a tank plus a gerry can in the morning plus most of a tank in the afternoon, spending about an hour on the track
at a time with perhaps a 20 minute brake between sessions. It works out at nearer 4 tanks of fuel for my day at Silverstone. £123 at my local
station or more like £145 at silverstone prices.
Have I got my calculations wrong or do I need a mortgage?
[Edited on 22-9-2008 by smart51]
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aka Keith
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| posted on 22/9/08 at 02:39 PM |
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I'd be inteested in this too.
I did Bruntingthorpe in May and I thrashed the poor girl all day, but I only used two tanks plus 5 litres. (I know cause I ran out of fuel a mile out
of the gates on the way home). I think I did 150 miles on track, but in the heat of the moment, I completely forgot to make note of the mileage.
If my calcuations are correct it was about 12MPG. 
Alternatively, if it is getting too expensive you can ask me to go out in front of you and act as a moving road block to slow you down 
[Edited on 22/9/08 by aka Keith]
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coozer
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| posted on 22/9/08 at 02:41 PM |
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I did 80 laps at Teeside last time out and over the 88 miles it used 45 litres...
1972 V8 Jago
1980 Z750
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smart51
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| posted on 22/9/08 at 02:48 PM |
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quote:
Originally posted by coozer
over the 88 miles it used 45 litres...
That's less than 9 MPG Do you have a hole in your fuel tank or is your mixture a bit rich?
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smart51
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| posted on 22/9/08 at 03:39 PM |
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I've rechecked my figures and a "perfect" lap should average 93 MPH. Silverstone South is a pretty fast circuit. 1g in the corners
makes Vale the slowest at 50 MPH, the dog leg bit about 70, Beckets and Stowe about 85, Ireland 90 plus Chapel and Club flat out. On the 4 straights
the car should reach 100, 110, 115 and 120 MPH. This assumes that, 1) I'm brave enough, which I'm not. 2) I don't make any
mistakes, which I will. 3) there's no slow traffic, which there will be. I guess my average lap speed will be somewhat less.
Even 80 MPH at 20 MPG is 4 gallons per hour or 18 litres per hour. Three 60 minute sessions in the morning and 3 40 minute sessions in the afternoon
gives half hour brakes plus lunch. Thats 400 miles or 3 1/4 tanks full. Perhaps I need shorter sessions and more brakes.
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andylancaster3000
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| posted on 22/9/08 at 03:46 PM |
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20mpg on a trackday?! You're obviously not trying hard enough! 
If you have managed that its very good going. From the experiences I've had it tends to be somewhere between 5-10mpg on an engine of this sort
of power.
[Edited on 22/9/08 by andylancaster3000]
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speedyxjs
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| posted on 22/9/08 at 04:18 PM |
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Do a search. Trackday fuel economy has been discussed on here many times before.
How long can i resist the temptation to drop a V8 in?
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JimSpencer
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| posted on 22/9/08 at 04:22 PM |
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Hi
Think you're a bit off the mark to be honest.
Think your lap times are very quick indeed, a GP car 'only' averages low 50 second laps round there.. normally a good road car would be at
least double that, so would expect a car like ours to be in the region of a 1m30s lap ish.. which is around a 80 ish average.
Next bit is you're not knackered after 20odd minutes you're either not trying hard enough or you're a GP driver in terms of
fitness...
Think in terms of a 20 minute run per hour?
Plus take whatever fuel consumption it does on the road and divide it by 3 and you'll not be far off, most race cars with smallish engines see 8
- 12 MPG.
So roughly 15 laps a run = 30 miles = 3 gallons (at an average of 10mpg)
x 6 runs a day = 18 gallons.
Be interested to hear how it goes on Thursday
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adithorp
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| posted on 22/9/08 at 04:26 PM |
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Morning session is 9am to 12.30 I think. To get 3x1hour sessions in in the morning your going to have 2x15 min breaks (you probably will need more
brakes before the days out). That won't give you time to top up the tank, never mind take off your helmet, have a piss, have a brew, check the
car. God forbid, someone wants to talk to you.
adrian
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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JoelP
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| posted on 22/9/08 at 05:12 PM |
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i couldnt even imagine a solid hour on track. I dont think i ever did more than 10 laps before letting the car cool, and usually only did 4 sessions
in a day. So 40 laps.
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Paul TigerB6
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| posted on 22/9/08 at 05:46 PM |
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quote:
Originally posted by smart51
That's less than 9 MPG Do you have a hole in your fuel tank or is your mixture a bit rich?
Naaahhh - he's running one of those thirsty car engines in his car. A BEC will probably be a decent amount less thirsty. My Zetec Tger S6 was
rubbish on fuel on track too, but then again i didnt care at the time!! Maybe I would now though at £5+ per gallon
A quick search earlier showed an R1 MK Indy doing 1m 23s around Silverstone South so something like 87mph average.
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PAUL FISHER
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| posted on 22/9/08 at 06:36 PM |
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I think your lap time will be around 1m 25sec's on the south circuit,average speed 83mph,its a quick circuit,but with some long straight bits,a
struggle for BEC, well driven GT3's etc will be passing you on the straights with ease,but don't forget the video to prove me
wrong
[Edited on 19/05/04 by PAUL FISHER]
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smart51
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| posted on 22/9/08 at 07:28 PM |
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Previous track days have all produced between 19 and 21 MPG. That's with 100% throttle at high revs all the time except when braking and
cornering. The only time I give it less than full effort is in the high speed corners. One corner at Cadwell park has a turn in speed of about 100
according to my calculator. It took me all day to build up from 80 to 90. The car wasn't bothered but my accelerator leg didn't want to
push.
As for the fast straight, I know the seven isn't too fast. At Mallory I was taking most things out of the hairpin or just after Devils, only
for me to start slowing over 100MPH and them to start overtaking back. Provided I get round Becketts and Chapel OK, I should hit the car's top
speed of 120 along hangar. The 911 GT3s and EVOs will still be full of beans at that speed.
My main target for the day is the M3. Its not that its a comparable car, It's just that BMW drivers hate being overtaken.
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Jubal
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| posted on 22/9/08 at 07:37 PM |
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As a rule of thumb, assuming no major stoppages, I always have used at least a tank and two 20L jerries on any open pitlane trackday. Sometimes more
if I'm really going for it.
I'm quite sympathetic to the car. I run 20-30 min sessions with good breaks in between.
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smart51
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| posted on 24/9/08 at 09:01 PM |
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Well, I had a nice day at Silverstone. It started off with my harness adjuster falling apart. Many thanks to AKA Keith for helping me swap over the
passenger harness. I had 4 sessions in the morning, none over 30 minutes, all stopped by the red lights due to an incident. I spent about an hour
helping AKA Keith fix his gear change in return.
My speed estimates seemed about right. 50 MPH through vale, flat out to 85 through club, 70 through the dogleg and 100, 110 and 115 down the smaller
straights, topping out at 120 down hangar. I reckon Beckets and Stowe are 85 MPH too. I tried 80 but slight adjustments to steering or throttle
showed that the car was at the end of its useful grip and I didn't like to go any faster.
Still, full throttle acceleration everywhere and top speeds of 120 still gave 23.7 MPG, assuming I did 35MPG from the petrol station to the track and
back again.
A few mechanical concerns and the fact that the petrol station was shut when I went brought an early end to the day. It was fun though.
Those Ultimas are fast aren't they?
[Edited on 25-9-2008 by smart51]
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