Running a pi on modern fuel

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Binny
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Running a pi on modern fuel

#1 Post by Binny » Fri Jun 18, 2021 11:31 am

I'm about to convert my pi back to a standard Lucas injection set up however I have a couple of questions regarding this.

Firstly will the Lucas system run happily on modern unleaded fuel or will it need an additive to provide lubrication of the metering unit?

Secondly will modern fuel affect the rubber seals and O rings in the system? I know replacement seal/O ring kits are available for the metering unit and Lucas pump but don't know if these are Viton which resists the ravages of Ethanol.

Thanks in advance for any advice.

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Re: Running a pi on modern fuel

#2 Post by johnnydog » Fri Jun 18, 2021 1:32 pm

I have never converted any of my Triumphs to an 'unleaded' head, and since the demise of unleaded fuel, I have always used an additive. My preferred choice is Millers VSP which is Manganese based. Initially it was just classed as lead replacement affording protection against valve seat recession, but with the added benefit of adding 2 RON to the octane rating. With the introduction of ethanol to fuel, they introduced Miller's VSPe which helps stabilise fuel and protects the fuel components of the ravishes of Ethanol. I use it in all my Triumphs, and whilst I don't do great mileages every year, I have never had any problems at all. I do use it in conjunction with Super Unleaded - either Shell V Power, or over more recent years Tesco 99 Momentum which has good reviews within performance car circles. I use Shell V Power or Tesco 99 Momentum in my V8 Audi RS4 and that runs equally well on both fuels (obviously without the additive!!!).
In the Triumphs this effectively raises the octane rating to 101 RON, which, considering the PI was originally designed for use with 100 octane fuel, is as good as you are going to get!
I tow a caravan too with the Triumphs and I never get any pinking and they are all set 'to the book' factory ignition / timing settings all without electronic ignition.
Following the lockdown last year and resultant lack of use of the Triumphs, the fuel in them was 12 -18 months old and they ran perfectly well when I brought them out of hibernation, but the additive I use helps to preserve the fuel and protects against the harmful effects of ethanol, as unleaded fuel on its own goes stale in a matter of months as well as the harm it is doing the metal and rubber components.
So in short, I run them as they are with Super Unleaded plus the additive / octane booster and I have had no issues as a result in 21 years of using it.
There may be other additives that do exactly the same, but Millers VSPe is my preferred choice being Manganese based, increasing the octane rating AND giving Ethanol protection, and it is easy to dispense either in a bottle per 40 litres of fuel or concentrated for the chosen dosage against the fuel you are putting in. I find it easier to just add a bottle with 40 litres of fuel. Being a PI, I wouldn't want the fuel level getting too low, so adding 40 litres of fuel at a time is a easily manageable amount without the car being on fumes.
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Re: Running a pi on modern fuel

#3 Post by Charles H » Fri Jun 18, 2021 1:43 pm

Agree with Johnnydog and also have used Millers VSPe with Shell Super with no problems with either the PI or hard worked rally car. They both have not had hardened valve seats fitted. I understand that metering units, and pump and injector seals are now Viton. Unless you are fitting a second hand un-rebuilt unit, the seals will be Viton.
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Re: Running a pi on modern fuel

#4 Post by wild bill » Fri Jun 18, 2021 7:00 pm

Like John and Charles,I use a quality additive, the name of which escapes me as the car hasn't moved in nigh on two years! :oops: I thoroughly recommend the Tesco 99 Momentum fuel, use it in Triumph and Mini.What I was recently recommended was Costco top grade petrol as it is meant to be the best available ,and cheaper.I put this in the Mini for the first fill of the year-and it picked it up straight away.I also use Costco Diesel fuel, it also is very good, the difference in performance, pulling, and MPG is noticeable.Well priced too.P.S. No connection to Costco or Tesco apart from taking our hard earned.....
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Re: Running a pi on modern fuel

#5 Post by Binny » Mon Jun 21, 2021 8:30 am

Thanks for those informative replies - it's much appreciated.

I think I'll rebuild the metering unit and Lucas pump with new seals and 'O' rings.

Then it's just a question of draining half a tank of twenty years old LRP out of the tank!

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Re: Running a pi on modern fuel

#6 Post by david_lall » Tue Jun 22, 2021 4:55 am

I've covered over 80,000 miles in 15-years in my PI often towing. It does have an unleaded head from a 2500 S and the metering unit is from Prestige Injection where Malcolm machines from new one of the internal parts specifically for unleaded fuel.

Modern fuel does present running problems at high temperatures, it's something I sometimes struggle with in my highly modified MG 1300 but in the PI all is fine. I do run with a Lucas pump but having done my homework decided to fit from the very beginning a very low pressure {2 - 3 psi} electronic Facet pump between the tank and the Lucas pump. My pumps are also fed directly from the battery with a higher spec cable and relayed via the bulkhead safety switch.

It's an estate, I've always avoided running the tank down to less than a quarter and have never experienced any vaporisation issues
David Lall

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Re: Running a pi on modern fuel

#7 Post by johnnydog » Mon Jul 05, 2021 10:39 pm

Another benefit in my opinion of using Millers VSPe fuel additive is that it currently offers protection against E10 unleaded fuels containing up to 10% ethanol content. Current unleaded fuel is E5 (5% ethanol) which is due to phased out in favour of E10 which is bad news for older engines that were not designed to run on this fuel. This basically means that when availability of the current E5 unleaded fuel is reduced in favour of E10, without any form of fuel protection in older cars will lead to harmful corrosion of metal components in the fuel system.
It is suggested that a small amount of E5 will continue to be available for older cars, but as we saw with the demise of leaded fuel in 2000, any garages supplying it basically held the classic car owner to ransom pricewise, before it was phased out completely due to very low volume sales probably being one reason. I imagine it will be a similar situation with E5, making an suitable additive offering protection against E10 a more attractive proposition.
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1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
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1973 Mk2 2.5 PI in Sienna Brown
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Phil T
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Re: Running a pi on modern fuel

#8 Post by Phil T » Tue Jul 06, 2021 2:24 pm

My understanding is that it is only the 95RON fuels going to E10, the higher octane ones will stay E5.

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Re: Running a pi on modern fuel

#9 Post by johnnydog » Tue Jul 06, 2021 4:53 pm

Phil T wrote:
Tue Jul 06, 2021 2:24 pm
My understanding is that it is only the 95RON fuels going to E10, the higher octane ones will stay E5.
I sincerely hope that is the case, although I clearly remember the promises about leaded petrol remaining available for classic car owners after 2000, but that was relatively short lived....
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1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

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Re: Running a pi on modern fuel

#10 Post by david_lall » Fri Jul 09, 2021 6:27 am

Phil T wrote:
Tue Jul 06, 2021 2:24 pm
My understanding is that it is only the 95RON fuels going to E10, the higher octane ones will stay E5.
Agreed - the higher octane fuels can't be achieved with E5 so if you want to avoid E10 just use higher octane fuel.

V-power seems to be less stable than the others btw, Mini racers using V-power still use octane boosters but the Esso high octane is imho pretty good
David Lall

1972 Triumph 2.5 PI Estate Royal Blue
1968 MG 1300 Saloon Connaught Green
1978 Carlight Casetta Caravan
http://carlightrestoration.blogspot.co.uk
1995 Lada Riva 1.5 Estate Cherry

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