Lotus Elan and Lotus Elan Plus 2 Forums

The major problem with ethanol in fuel for an elan is the impact of volatility and operation when cold. Ethanol has a high heat of vaporisation which cools the intake and inhibits fuel vaporisation and low RVP ( tendency to vaporise to make a a air fuel mixture which burns) this can lead to poor formation of the fuel air mixture in a carb engine when cold. A high pressure fuel injection system works much better. The changes in fuel density with ethanol also affect air fuel ratio in a carb engine much more than in a fuel injected engine ( or not at all in a FI engine with a feedback sensor)

At low concentrations of 5 to 10% no real issue with the above and also no real issue in terms of engine component fuel system component life with most modern fuel system seals and other plastic and rubber components or alloy items. Keith on the Sidedraft central continues his quest for better performance with increasing ethanol in US gasoline but he is looking for 40mpg and fuel injection like performance not does it run or not. If ethanol concentrations get to around 20% or above in a carb engine you will start to need to make signficant changes to the jetting to make it work

Water contamination of the fuel supply chain becomes more of a problem as ethanol dissolves water lying in the bottom of storage tanks ( and car fuel tanks) and carries it through to the carb where it can cause problems. Additive may help this situation but you would want to undestand exactly the chemistry behind what they do before spending good money on them

I am no expert but spent a lot of years running a plant making motor gasoline as one of its by-products so understand a little of the issues around fuel blending

cheer
Rohan

Wow!

Thank you Rohan. Excellently presented and explained.

Peter

Having formerly worked for Shell, I forwarded the post to one of the fuels guys I know. His comments follow:

I don't know the current ethanol qualtity of road fuels, some countries have done it for years others have never done it, it will be different in the UK to the US and may even vary by state - if indeed there is any.

The general principles in the article are correct though - it is common to blend fuel differently for summer /winter conditions, particulary if there is a significant temperature difference between the seasons. More "light ends" - i.e. high volatility- components are added to the winder mix to ensure it ignites when cold.

If you live somewhere warm all year it probably makes no difference.
Similary keeping the tank close to full when storing it - with the cap on - will limit loss of the light ends.

Dan

Hi There

For UK readers,

I've just come back from a run in the Plus 2 after filling up for the first time with Tesco Super Unleaded 99 Octane (?1.09 per litre). It's really good and the car's running noticablly better than it did on the Esso Super I had been using.

Andy

I've always used Tesco Super Unleaded (99 Octane) in my Sprint - and add sufficient lead additive to make it about 105 octane.

The car appears to me to go a lot better that way.

Super Unleaded makes my X-Type go much better as well.

when I store the cars for the winter [ mid Nov to end of May ] I put 8 oz of rubbing alcohol in each full gas tank of to absorb moisture from condensation in the gas ---the tanks don't leak and start up in the Fall is a matter of simplicity and driving until the first fill up is no problem ---gasohal aside from the shitty mileage has not been a problem here --no gas line deterioration or aluminum damage in the carbs or pump fuel damage --at the last rebuild the piston tops and bores were fine ----sounds like some one is selling pixie dust --] hi test is an advantage but 86 octane works for me ---ed

Quote:
"I've always used Tesco Super Unleaded (99 Octane) in my Sprint - and add sufficient lead additive to make it about 105 octane."

Brian,

That's interesting.

I spoke to Castrol's tech dept. 2 years ago, and they said that additional additive made no increase to the octane rating,
no matter how much you dump in.

Whoose product are you using, please ?

Regards,
Stuart.

Stuart,

The additive is made by ELF.

I started using the product last year following a discussion at a CL meeting. I have to admit that not everyone was convinced of the additive?s ?magic? powers and that it would make a difference, but I did percieve an improvement with the additive.

Perhaps I?m kidding myself by believing the ELF statement of an octane increase ? but as I?ve bought it I shall continue to use it.

Stuart,

I came across this leaflet at Aldon this week - thought it may be of interest:

reminds me off the days when Moly slip would drive a car to the start line at Shannonville race track during lunch break --drain the oil from the sump -add 3 one pint cans of Molly and drive around the track for a half hour while the track announcer enthusiastically claimed it was a magic oil treatment ---------secret was there was still a full oil filter and lots of oil in the galleys and in the Head ----so they were just driving around down a quart -----sold product though -- ---ed