McJim Posted September 11, 2021 Share Posted September 11, 2021 Only started this thread because I've just got the Spitfire back from being retuned and was curious what mpg we would achieve running on the RBRR route. Katy and I did a trial run from Gartcosh down to the Tesco petrol station at Carlisle off the M6 J43 that we intend to use for Momentum petrol on the RBRR. We brimmed the tank at Tesco Cumbernauld with the intention to brim it again at Carlisle and again back at Cumbernauld. We kept a steady 65 to 75mph just keeping up with the traffic all the way down the M73, M74 and the M6 and averaged 32mpg, which surprised me how low it was. On the way back, we avoided the huge tailbacks northbound on the M74, due to bridge works from south of Larkhall to Hamilton and went cross country from Abington, through Lanark, Carluke and Newmains before joining the M8 and M73 back to Gartcosh. This time, we averaged 39mpg after keeping a steady 50 to 60 mph off the motorway and a lot slower through the towns. So, if we go with our worse case scenario of 32mpg, with the fuel stops we intend to make, we should have plenty of petrol to get round. The Spitfire performed faultlessly and we now have the joy of an overdrive that engages when we want it to rather than when it feels like it. A great day's driving and a useful shakedown for the RBRR. Jim. 1 Quote Link to comment Share on other sites More sharing options...
Rubce Posted September 11, 2021 Share Posted September 11, 2021 On this years Coast to Coast event we averaged 33mpg in our Stag over the 870 miles. Obviously the Mpg was much better on the M56, M60, M62 sections getting from Cheshire to the start at Flamborough Head and then back home again than what we got on the roads over the Yorkshire Moors and Cumbrian Fells. Based on that route mix I am hoping for 35mpg overall on the RBRR. Bruce Quote Link to comment Share on other sites More sharing options...
ferny Posted September 11, 2021 Share Posted September 11, 2021 I always got around 32mpg on a Triumph 4-pot - 1300 and 1500 varieties. I get 28-34 mpg out of what's in there now. I've just fitted a new FPR so hope to have a bit of a play with its settings and a tinker with the laptop on the way to the first control stop. Quote Link to comment Share on other sites More sharing options...
Rubce Posted September 11, 2021 Share Posted September 11, 2021 2 minutes ago, ferny said: I get 28-34 mpg out of what's in there now. I've just fitted a new FPR so hope to have a bit of a play with its settings and a tinker with the laptop on the way to the first control stop. FPR? Quote Link to comment Share on other sites More sharing options...
yorkshire_spam Posted September 11, 2021 Share Posted September 11, 2021 Fuel pressure regulator? Quote Link to comment Share on other sites More sharing options...
McJim Posted September 11, 2021 Author Share Posted September 11, 2021 Flatulance Performance Restrictor. Invaluable on the RBRR. Jim. Quote Link to comment Share on other sites More sharing options...
ferny Posted September 11, 2021 Share Posted September 11, 2021 Both aren't incorrect. But this is the item; https://www.advancedautomotives.co.uk/sytec-motorsport-msv-silver-adjustable-fuel-pressure-regulator-8mm--gauge-11839-p.asp Quote Link to comment Share on other sites More sharing options...
PeteStupps Posted September 11, 2021 Share Posted September 11, 2021 Good topic @McJim! I get a bit obsessed with fuel economy. On the 2018 RBRR my mk3 Spitfire miraculously averaged over 40 mpg, the best economy figures i've ever had. However it also got through a gallon of oil. Since then i've messed about with the cylinder head and exhaust so it's a bit perkier performance-wise but noticeably worse on fuel (also had a rebore so hopefully won't need so much oil). So I'm expecting something around 33mpg, but hoping for 35. Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted September 11, 2021 Share Posted September 11, 2021 Ought to be able to get upper 30s on a long run in a OD-equipped Spitfire unless really pushing on. 1500 typically a bit better than 1300 due to higher gearing. Nick Quote Link to comment Share on other sites More sharing options...
McJim Posted September 11, 2021 Author Share Posted September 11, 2021 In 2018, we were getting 38 - 40 mpg but we weren't pressing on since the engine sounded really rough. We were pushing on today but I have my suspicions that the tank wasn't brimmed before we set off. Still, with our planned fuel stops we won't be running dry (I hope). Our longest run between stops is 185 miles from Wetherby to Shell Dreghorn at Edinburgh but a good part of that is on roads like today when we averaged 39mpg, so not too bothered. Jim. Quote Link to comment Share on other sites More sharing options...
mikeyb Posted September 12, 2021 Share Posted September 12, 2021 Not RBRR specific, but my Mk3 with J type overdrive consitently returned 38mpg on along steady crusing runs with over 30mpg on shorter wiggly bits. It's a standard engine but the carbs were properly rebuilt some years ago. My Stag struggled has averaged 25mpg on the last few 10CR's that it has done, with the worst section dropping to 21mpg (mountains) and the best coming in at around 27mpg. It used to do better, but the carbs are now pretty shot and not quite set up for the tubular manifolds it now has fitted. A rolling road session highlighted this as well as the fact that around 30 of it's original horses were missing! I need to decide where to invest the money - do I sort out the twin Strombergs, do I fit a Stagweber or similar or do I move to efi? Quote Link to comment Share on other sites More sharing options...
Kevin R Posted September 13, 2021 Share Posted September 13, 2021 I have just done the NC500 in my 1980 Spitfire 1500 with overdrive - 1300 miles door to door, 2 up with luggage. The roads included 750 miles of dual carriageway and 550 of mountainous roads of which approx 200 miles were winding single track. Average consumption was 36.4 mpg and used a pint of oil. Picture was taken on a detour to Skye. 2 Quote Link to comment Share on other sites More sharing options...
richard w Posted September 13, 2021 Share Posted September 13, 2021 The 2 South Coast Runs I got around 30. 1200 ish miles each time on mostly quicker roads. Border Raiders (400 miles on the event plus about 500 to and from) was a bit less, something like 27-28, but on hillier windy roads. Quote Link to comment Share on other sites More sharing options...
RobPearce Posted September 13, 2021 Share Posted September 13, 2021 I think my Spitfire gave about 39mpg in Yorkshire last month, including the journeys there and back. That was being driven a bit more gently than it sometimes gets (SWMBO was with me and she's not a speed freak). It will be interesting to see what it gives on the Cambridge group's Peaks-Lakes-Dales run next week. Quote Link to comment Share on other sites More sharing options...
Matt306 Posted September 17, 2021 Share Posted September 17, 2021 My spit mark iv never had fuel issues on the RBRR probably similar to you are expecting. Quote Link to comment Share on other sites More sharing options...
poppyman Posted September 18, 2021 Share Posted September 18, 2021 On 11/09/2021 at 18:49, Rubce said: On this years Coast to Coast event we averaged 33mpg in our Stag over the 870 miles. Obviously the Mpg was much better on the M56, M60, M62 sections getting from Cheshire to the start at Flamborough Head and then back home again than what we got on the roads over the Yorkshire Moors and Cumbrian Fells. Based on that route mix I am hoping for 35mpg overall on the RBRR. Bruce I take it you will pushing the car part way Bruce :) Tony. Quote Link to comment Share on other sites More sharing options...
Rubce Posted September 18, 2021 Share Posted September 18, 2021 17 minutes ago, poppyman said: I take it you will pushing the car part way Bruce 🙂 Tony. I hope not!!!!! Quote Link to comment Share on other sites More sharing options...
Rutty Posted September 18, 2021 Share Posted September 18, 2021 On 11/09/2021 at 18:49, Rubce said: On this years Coast to Coast event we averaged 33mpg in our Stag over the 870 miles. Obviously the Mpg was much better on the M56, M60, M62 sections getting from Cheshire to the start at Flamborough Head and then back home again than what we got on the roads over the Yorkshire Moors and Cumbrian Fells. Based on that route mix I am hoping for 35mpg overall on the RBRR. Bruce Managed 37mpg in the Vitesse on the C2C pushing it fairly hard most of the time though the trip up the A1 to the start and back to Cambridgeshire was at a more steady 65-70 MPH. Interestingly on the last RBRR the 2500 TC only came in 1 MPG lower than a couple of 2000's I compared it with. 28 and 29 mpg from memory. The thought was the 2000 had to be pushed harder than the 2500 especially on the hills. At the end of the day its not about MPG its about SPG. ( Smiles Per Gallon) 2 Quote Link to comment Share on other sites More sharing options...
thescrapman Posted September 18, 2021 Share Posted September 18, 2021 On 11/09/2021 at 23:07, PeteStupps said: Good topic @McJim! I get a bit obsessed with fuel economy. On the 2018 RBRR my mk3 Spitfire miraculously averaged over 40 mpg, the best economy figures i've ever had. However it also got through a gallon of oil. Since then i've messed about with the cylinder head and exhaust so it's a bit perkier performance-wise but noticeably worse on fuel (also had a rebore so hopefully won't need so much oil). So I'm expecting something around 33mpg, but hoping for 35. Only 1 gallon of oil, on our first RBRR we used 5 I think it was. 1 Quote Link to comment Share on other sites More sharing options...
Roger Keys Posted September 18, 2021 Share Posted September 18, 2021 No idea. Dont care either! 1 Quote Link to comment Share on other sites More sharing options...
mole42 Posted September 19, 2021 Share Posted September 19, 2021 On the 2016 RBRR my Stag did 30mpg on the legs I was driving, 38mpg when it was my co-drivers turn. We were running a longer diff then, so I expect slightly more fuel this time. Quote Link to comment Share on other sites More sharing options...
Shynsy Posted September 20, 2021 Share Posted September 20, 2021 Our supercharged TR6 does low 30s mpg. Tend to fill her up at every stop just to be sure. tim Quote Link to comment Share on other sites More sharing options...
Radders Posted September 20, 2021 Share Posted September 20, 2021 On 18/09/2021 at 22:56, roger keys said: No idea. Dont care either! Best answer yet! Me neither! I never worry about how much money I spend on the things I really enjoy doing. 😊 2 Quote Link to comment Share on other sites More sharing options...
Lemon Hell Posted September 20, 2021 Share Posted September 20, 2021 I'm only getting around 24 mpg on a run in my VItesse ( Round trip to drivers meet) - running a little rich perhaps but apart from that seems in good tune - I'm happy but would be happier at 28! 🙃 Any thoughts? An oil change and a squirt of Penrite Semi Fluid Grease in the Trunnions next weekend and I'm as ready as I'll ever be. Quote Link to comment Share on other sites More sharing options...
PeteStupps Posted September 20, 2021 Share Posted September 20, 2021 22 minutes ago, Lemon Hell said: I'm happy but would be happier at 28! 🙃 Any thoughts Drive slower! 🙂 Quote Link to comment Share on other sites More sharing options...
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