DOG_MORGAN Posted May 6, 2019 Report Share Posted May 6, 2019 (edited) Just been for for a run around Wales got 210 miles to 3/4 of a tank of petrol his that good thanks billy Edited May 6, 2019 by DOG_MORGAN Quote Link to post Share on other sites
Tim D. Posted May 6, 2019 Report Share Posted May 6, 2019 Get 30-33mpg with the supercharger on the motorway. Quote Link to post Share on other sites
aardvark Posted May 6, 2019 Report Share Posted May 6, 2019 32-33 mpg on a run around Germany a couple of years ago. Ahhh... the roads, the memories, the driving.... I love Germany. Cheers dave Quote Link to post Share on other sites
ianhoward Posted May 6, 2019 Report Share Posted May 6, 2019 All depends on driving style and roads... A steady motorway trip (70mph) I’ve managed 32mpg, but in mixed roads with slower traffic it’s more like 22-24mpg (P.I. with electronic ignition). I’m generally returning 25-26mpg with a refurbished MU from Neil Ferguson... Cheers Ian Quote Link to post Share on other sites
John McCormack Posted May 7, 2019 Report Share Posted May 7, 2019 25mpg on a country drive with a stock Lucas PI with electronic ignition. 15-20mpg around Sydney. Quote Link to post Share on other sites
SeanF Posted May 7, 2019 Report Share Posted May 7, 2019 I have done about 800 miles with a rebuilt engine and completely refurbished PI system (Neil F) but am only getting 18 - 19 mpg - getting about 145 miles before I need to re-fuel. Any suggestions as to what might be wrong? Many thanks, Sean Quote Link to post Share on other sites
brian -r Posted May 7, 2019 Report Share Posted May 7, 2019 Sean, I have never bettered 22mpg with my 1970 6 in the 7years I've had it and it came with all new injection equipment. 800mls is not a lot on a new engine it may well be still a bit tight. I can remember the day's when cars of this era were new and many in the trade would not consider the engine's properly settled in until they had done at least 1,000 to 1,500 mls Brian Quote Link to post Share on other sites
Waldi Posted May 7, 2019 Report Share Posted May 7, 2019 I have installed a permanent AFR sensor in the exhaust, with a gauge in the centre console. It is a means to check if the engine is running rich/lean. There are similar systems that you can stick in the exhaust temporarily. If so, that might be an option? Waldi Quote Link to post Share on other sites
rcreweread Posted May 7, 2019 Report Share Posted May 7, 2019 1 hour ago, SeanF said: I have done about 800 miles with a rebuilt engine and completely refurbished PI system (Neil F) but am only getting 18 - 19 mpg - getting about 145 miles before I need to re-fuel. Any suggestions as to what might be wrong? Many thanks, Sean Sean - have you thought about a higher capacity tank? If interested PM me. As a matter of interest, what is the supposed capacity of a standard tank? Cheers Rich Quote Link to post Share on other sites
rcreweread Posted May 7, 2019 Report Share Posted May 7, 2019 Hi everyone - I've since established that a standard tank is supposedly 48 litres but typically people can squeeze in just over 50 litres. I know of 66 litre tanks , if anyone is interested . Cheers Rich Quote Link to post Share on other sites
SeanF Posted May 7, 2019 Report Share Posted May 7, 2019 7 hours ago, brian -r said: I have never bettered 22mpg with my 1970 6 in the 7years I've had it and it came with all new injection equipment. 800mls is not a lot on a new engine it may well be still a bit tight. I can remember the day's when cars of this era were new and many in the trade would not consider the engine's properly settled in until they had done at least 1,000 to 1,500 mls Thanks Brian, That's good information. I do tend to have a heavy foot so that may have something to do with it. 7 hours ago, Waldi said: I have installed a permanent AFR sensor in the exhaust, with a gauge in the centre console. It is a means to check if the engine is running rich/lean. Thanks Waldi, do you have a link to the one that you installed? Rich, I think I'll stick with the standard tank for the moment, and hope to improve fuel economy Cheers, Sean Quote Link to post Share on other sites
Waldi Posted May 7, 2019 Report Share Posted May 7, 2019 Hi Sean, I ordered this one: https://www.innovatemotorsports.com/products/mtxl_plus.php I suggest to look at E-Bay and other sites for the best price including shipping. I also installed a fuse box with a ‘main’ fused relay in the passenger foot well for several auxiliaries like seat heating, AFR, USB plug, and possibly a future EFI addition. The relay is activated when I turn the ignition key. The sensor requires to be active (heated) once the engine is running otherwise it will be damaged so in this way I cannot forget. Regards, Waldi Quote Link to post Share on other sites
SeanF Posted May 7, 2019 Report Share Posted May 7, 2019 Thanks Waldi. Expensive bit of kit! Quote Link to post Share on other sites
Waldi Posted May 7, 2019 Report Share Posted May 7, 2019 Hi Sean, yes, it is, and there may be cheaper ones, but this one was recommended by several “popes” on this forum. So far, I’m not disappointed (albeit with limited use). Waldi Quote Link to post Share on other sites
Tom Fremont Posted May 7, 2019 Report Share Posted May 7, 2019 When the fuel/air ratio is spot on the cam duration determines fuel economy. CP cams won't do as well as CR cams and CC cams will deliver the best ( 40 mpg Imperial highway with O/D ). The 280 degree duration of the CP cam is an anomaly amongst its contemporaries, exceptionally long with commensurate fuel economy penalty. Best I've gotten with Weber DCOEs and CP cam is 32 mpg Imperial ( 27 mpg U.S. ) and that was at 60 mph average. Any LUCAS P.I. engine with the same cam which surpasses this has been tuned very well indeed. A vacuum advance function for cruising would deliver another 2-3 mpg I reckon. Others can chime in on this. The early emissions controlled TRs have this and gain another 16-18 degrees of advance under light throttle conditions. Tom Quote Link to post Share on other sites
Steves_TR6 Posted May 7, 2019 Report Share Posted May 7, 2019 (edited) My experience is an average itro 25mpg, best ever of 30mpg, and never below 20 for a whole tank. my car has a tuned pi engine, with i believe a racetorations 777 cam and bored +60. steve ps, car has a 123ignition tune+ distributor, and i’ve often wondered about using the vacuum connection to add a cruise advance function. by connecting a small vacuum pump via a dash mounted switch it should be possible to ‘engage cruise advance’ when on the motorway? Edited May 7, 2019 by Steves_TR6 Quote Link to post Share on other sites
Tim D. Posted May 8, 2019 Report Share Posted May 8, 2019 When I ran PI (CP) I used an AFR sensor extensively to get the fueling spot on. Even with this getting into the 30+ mpg range was a challenge. One issue was that you had to run rich at low throttle to address the transient lean spike you get on snap throttle opening because the PI system does not have an accelerator pump. Without this I suspect that fuel economy would have been significantly better. This made it all the more interesting when my current supercharger setup with a twin barrel Holley gave 30 + mpg, but I suspect that this is because the supercharger isn't pushing any mixture at cruise and it is running a triumph saloon cam. Cheers Tim Quote Link to post Share on other sites
Paul Hill Posted May 11, 2019 Report Share Posted May 11, 2019 Did a brim to brim used 3.24 gallons did 91 miles = 28 mpg well pleased with that. It was mostly A roads Quote Link to post Share on other sites
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