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How many miles to a tank of petrol


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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 by DOG_MORGAN
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Get 30-33mpg with the supercharger on the motorway. 

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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

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25mpg on a country drive with a stock Lucas PI with electronic ignition. 15-20mpg around Sydney.

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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

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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

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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

8B30A59E-335E-40CD-B5B8-0F7D0E740416.jpeg

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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

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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

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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

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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

 

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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

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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

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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 by Steves_TR6
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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

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Did a brim to brim used 3.24 gallons did 91 miles = 28 mpg well pleased with that. It was mostly A roads 

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