Unleaded fuel

driver · Post by **driver** » Fri Feb 17, 2006 12:40

Hi to everyone in Excel land,
I was wondering what the situation with
Excels and unleaded fuel is. I assumed that the Excel would not take unleaded and there has been a lot of discussion on the old forum about the best way to go fuel wise. But I have seen some cars on ebay where the owner claims that they will run on unleaded. There is one there now.

Cheers,

Rob

Steve C · Post by **Steve C** » Fri Feb 17, 2006 12:47

Excels are fine on unleaded, they have tough valve seats. They generally prefer the higher octane super unleaded, unless you want to back off your timing a little.

ps. Anyone else noticed that Tesco 99 octane has been replaced with 97 Super instead??

driver · Post by **driver** » Fri Feb 17, 2006 15:12

Thanks for the info Steve.

Rob.

amarshall · Post by **amarshall** » Fri Feb 17, 2006 15:19

Most of the debate was about which unleaded to buy - general opinion/experience seems to be that Optimax is the best for the 907/912 engines.

Some of us, however, don't have easy access to consistent supplies of any one particular branded fuel so there was some discussion of which additives to use to boost octane or if we should just go for the nearest high-octane/LRP available.

There was concern about mixing LRPs since it's difficult to determine what the additives are (phosphorous, manganese etc.) and mixtures can be bad news.

My own preference is to buy any old 95RON and add the appropriate amount of Castrol Valvemaster Plus, that way I can be fairly sure that there is not likely to be a mixture of additives in the tank (and I have a stock of CVP since I run a Westfield with an unconverted X-Flow sometimes too). For longer high speed journeys, I get the tank as empty as I can and make a special trip for Optimax.....

CapnBob · Post by **CapnBob** » Sat Feb 18, 2006 11:52

Can't really comment on the fuels available in the UK, however. SE engines have Nicasil liners. Fuels with high sulfur content are not suitable with Nicasil.

Often (here anyway), sulfur is one of the additives used as a economical way to boost the RON of lower grade fuels.

A few pennys saved on fuel doesn't go far on an engine rebuild.

Ozzy_UK · Post by **Ozzy_UK** » Wed Feb 22, 2006 10:54

i assume that you guys running optimax or BP Ultimate will still add Lead Repleacement treatment?

or can you just run optimax/BP Ultimate pure?

Oz.

JohnJ · Post by **JohnJ** » Wed Feb 22, 2006 10:57

I just use Optimax in mine, runs just fine with it. I only use 97 when I'm absolutely desperate, but as I always refill at a quarter tank, that's rare.

Lotus-e-Clan · Post by **Lotus-e-Clan** » Thu Feb 23, 2006 12:59

ditto for JohnJ's comment.

amarshall · Post by **amarshall** » Thu Feb 23, 2006 13:00

Lotus's own engines were designed to run on unleaded. No lead replacement needed, no lead needed.

dpr59 · Post by **dpr59** » Thu Feb 23, 2006 20:24

Back on the road next week and straight to the Shell garage for a full tank of Optimax.

Following advice on a previous post I also add Redex for upper cylinder lubrication. Something about using the choke washing the upper cylinders and increasing wear on the nickosil.

Also carry octane adative when I'm away from home, just incase I need to fill up on other than the good stuff.

A 5th gear program last series should on a dyno that in a tuned engine the higher octance fuels did make a difference and that Shell's was better than BP's.

tonyjones1968 · Post by **tonyjones1968** » Sat Feb 25, 2006 13:56

For those of us who like to use castrol valve master,check out this guy on E.BAY Chequer Plate Supplies he has loads of it for sale in handy packs not leaky bottles!!
Or just enter fuel adatives for alternative types......T.J

Ozzy_UK · Post by **Ozzy_UK** » Mon Feb 27, 2006 12:13

incidently i emailed lotus about this...

their official line is:

97 RON is minimum, but Unleaded is fine as long as its 97 RON+

Oz

micha · Post by **micha** » Mon Feb 27, 2006 18:04

all, not only lotus engines, all engines with aluminium heads come with (hardened) valve seats, so all engines can use unleaded, as long as the octane is ok. 95 is ok as long you setup the iginition on "later", 98 would be perfect. we have both here in germany at every fuelstation. the one is called "super" (95), the other "super plus" (98) and since a few time also these higher-octaned new fuels, like optimax...a waste of money...

also nicasil-coated cylinders have nothing to do with leaded or unleaded. the lead in the past was ONLY as a lubrication for the valve seats.

all other stories are bullshit. and all these "magic" things called fuel-saver or octane-booster, too.

a big advantage of unleaded is, that it keeps all your engine cleaner than with leaded-fuel.

test it, control your valve clearance on the beginning more frequently and you will see that everything runs well with unleaded.

Dougie · Post by **Dougie** » Mon Mar 13, 2006 20:40

Steve C wrote:
ps. Anyone else noticed that Tesco 99 octane has been replaced with 97 Super instead??

Put 20 quids worth in today at Tesco in Horsham (West Sussex), and they were still promoting the 99octane. I think my 87 SE seems to be running better on this, than it did on Optimax.