On my early 16v, I found that using Sainsburys Super unleaded 97ron gave=20 it that little more Ooomph, and the engine ran cooler with a slightly=20 higher boost (after a week or two of filling up), but consumption wasn't=20 any different. I think we were looking at about =A31-1.50 difference filling up at the=20 same place for both fuels, for a weeks drive.
--=20 Carl Robson Audio stream:
:) I knew that. I just wanted to see what the last poster would suggest, bearing in mind that a lot of older bigger engined british cars would have originally been designed to run 87 and 100 octane 4* and 5* fuels. Cars like the Rover P6 V8 should ideally have been run on 5*. Like when leaded became unleaded and dropped in Octane to 95ron, it became necessary to retard the ignition on the V8s to run the 4* 97 ron instead of 5* 100ron.
"Reasuringly expensive" :) as the advert goes.
Never tried it yet, I pass two Shell stations on the way to work and always use v-power which gives me 200 - 210 miles per tank (19.7 - 20.4 mpg) however the tesco stuff does come highly recommended over at scoobynet, its
90.9 round here - exactly the same as v-power.
Hey! Put a smiley when you are being smart, will ya. ;-)
But the switch from leaded to unleaded caused with some (much older) cars 2 other problems. Do you know which?
TDM
used optimax and bp ultimate in the old MR2 turbo and never put 95ron fuel in the car. the 98ron optimax gave it a well nice kick in the back over the bp ultimate at 97ron and was cheaper but there's f*ck all shell stations around!
What's it like for starting with that much advance ?
My crossflow's starter didn't like it when I was running that much, it's much better with the megajolt, I just set it to 8 degrees up to 1k revs and
16 degrees over 1k.
Well, there was valve seat recession from lack T.E.L as a lubricant. Although cars with alloy heads, although not designed to, usually could run unleaded with less advance due to lower octane.
Don't know what the other was.
You've got one :-)
The other is that valve wear at the stem and guides increased, some valves have said to be sticking, due to loss of the lubrification properties. Never came across one myself.
TDM
Only Rover V-8s made up until IIRC '72 needed 5 Star - I had a '69 3500 when it was phased out. And I didn't retard the ignition as it lost so much power. Just put up with some pinking. Post '72 cars were designed for
4 Star. But when unleaded became the norm you could still get 97 octane unleaded - BP etc sold it.
There's a third - especially noticeable with Rover V-8s. Unleaded seems to evaporate more easily than unleaded. That's what finally made me get rid of my P6 in the late '80s.
My dads old =A350 and welded each year P6 was wonderful. Ideally required 5* but ran OKish (i was a kid) on 4* but also had=20 listed in the handbook, tyre pressure ranges for 100MPH+ cruising. After scrapping the P6 when it had more weld than metal, he bought a=20 VX4/90 then a couple of years after that, a Chrysler 180. It all went=20 down hill with the next car though when he bought a Renault 20 TL (with=20 early electronic ignition that would start fine in any freezing wet icy=20 winter morning, but left you stranded on the hottest day of the year on=20 a warm restart).
Oh yeah, I know you could get super unleaded at some places as well as=20 premium, right from the start. But it was so rare, especially in a town=20 that as far as I can remember had 2 petrol stations in the 80's, still=20 only has two petrol stations, and they aren't the same two, they have=20 changed name and location.
--=20 Carl Robson Audio stream:
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