Ok we've a race meeting this weekend with the hotrod. It has now got a redtop 16v with very peaky cams and twin 45s. We normally only do 16 laps but this weekend its 35 laps of .227 miles and the revs will be 6500 to 8000 pretty much constantly. Since we've not had it out for a complete race yet we don't know the fuel consumption at all and i'm a bit worried the tank might not be big enough for the race
How much do you guys think we'll need for this. Sensible answers only please.
I'll try and post after the weekend to let you know who got closest.

35 x 0.227 = 7.9 miles.

Even if you car only does 10mpg (quite possible with that engine on a racetrack - I'm guessing) you will only need 1 gallon of fuel.

If you had 2 gallons on board I would think you'd have plenty of reserve.

Right, just trying to work this one out!

With a warmup, my grasser with a stdish Vauxhall XE 16v on throttle bodies, uses approx 0.5 gallons of fuel for an 8 lap final. A lap is approx 1/4 mile so the final is 2 miles, so I'm getting around 4 mpg, which sounds about right. I would say you need to work on the basis of 3-5 mpg for a 16v on carbs and with peaky cams.

I's say for the 8 miles approx that you will do you would JUST make it on 2 gallons, but I'd want 2.5 galls (if not 3) in case of stoppages etc and prolonged warmup time.

JAG - there is no way you will get 10mpg on any race car unless its battery powered!

trying to think.. our xe race car will run for about 25-30mins on 5 gallons iirc, know this isn't hugely accurate but if using similar revs for the same period consumption should be about the same...

we were doing 50km races over about 20mins (+ warm-up, out lap, green flag lap and in lap) always still a bit left in the tank at the end...

car is 240bhp spec on 45's and red line at 7.8krpm

50k race = 30miles approx, so 2.5-3 gallons should be plenty based on our usage, which coinsides with what NS Dev says..

Ned.

[Edited on 19/5/05 by ned]

glad to see i've got you all thinking. We've got a 2.5 gallon tank so we'll see on Sat how it goes. Hope i make it down to the actual race (i'm just the grease monkey ) if so i'll let you know.

Fill it brimfull and you'll have about 2 litres left if there's no major holdups.

It's restarts that always get me worrying in grasstrack, I have a 1.25 gall tank so if the restart is past 1/2 race distance then it gets touch and go!

[Edited on 19/5/05 by NS Dev]

[Edited on 19/5/05 by NS Dev]

OK we made the finish, 4th place in the 30 lap final, will see how much it takes to top up the tank tomorrow (this is tomorrow).
However a 2 litre pinto with a 38dgas and a 2 gallon tank ran out of fuel with 6 laps to go
I reckon it must be severly overjetted for that to happen.
Total laps of track was
1 driver parade
3 warm ups
30 racing laps
1 lap return to pits
35*.227 miles
7.945 miles

4th! Not a bad result at all!

Have to say I have always admired hot rodders, I have no idea how the hell you can find a way through the field with so many cars on so little tarmac!!

certainly sounds like a good result!

Should be a couple of litres left I guess!

Well F**ck me with the rough end of a brush shaft the car only used 6 litres of fuel. I cannot believe it and neither can the driver or the other car that was down with us as it used a similar amount. As for the drivers they are all mental anyway and half of them don't need a space as they seem to make their own Still respect to them all cause i wouldn't do it. Well not after the last time

Jeez, you don't spend long at full throttle then!! My grasser uses 2.5 litres in 8 1/4 mile laps, and it's running fuel injection and is mapped spot on, so should use less per hp than carbs, and its a std engine!!!!!!!!!!!!!!

There is a lot of power in your engine going unused, at that consumption!!

To be fair, all my laps are flat out, at or near the rev limiter.

Just thinking aloud though, the engine in my grasser was previously fitted to my Opel Manta road car, and when thrashed as hard as "sensibly" possible on the road used to return 15 to 20 mpg, and up to 36 mpg "on a run"

The same engine and same fuel mapping are now returning 4mpg ish under race conditions!! Just shows how hard the engine is working when racing!!

400mtrs per lap round a football pitch on full throttle for 3/4 of the staights. Say say 150 mtrs per straight . So 3/4 of 300mtrs times 30 laps =roughly 4 miles out of 8 at full throttle so maybe it's not surpprising when you count it out.
Oh and a new joint lap record which must put the hotest lap at around 60MPH average Around a football pitch thats fast

Some of the class 10 grassers hit 100mph at the end of the straights, which are around 120metres........................on soil!!!!!!!!!!!!!

Mine is (currently, pending new gearbox) on the limiter for well over 50% of the track which is around 75mph.

Must really annoy everybody on here when I start wittling on about grassing, but I just love it!

Did anybody see the grassers in the live action arena this year at Autosport?? All the (non-grassing) audience around me in the stand just wanted to see them and forget the other oval classes after they came out the first time! The grassers were so much quicker than anything else (including the 700hp F1 stockers) that it was unreal! Managing to roll one in the small area was some achievement too!!!!!

[Edited on 23/5/05 by NS Dev]

missed autosport this year unfortunately but remember the live arena from the last time down it was amazing and i could have stayed there all day. Don't worry about raving on about your fave sport cause i know where your coming from You shpuld see the wife's face when a crowd of us start on about motorsport.

needless to say I'm a fan of all motorsport, but especially the "low ranking" clubby stuff, it's so much more fun.

Oval stuff in particular has such a good feel to it and is largely so friendly. I always try and get out and see a bit of Hotrods and also stockers every year (F1's at Coventry and Skeggy are pretty awesome!) and also love sprint meetings, love the "picnic" atmosphere at Curborough and it's only down the road for me!

Bit hectic with racing myself now but always still get out to see the other stuff too!