JowettTalk

I read about Ian Roxburgh using higher octane petrol in his Javelin (Drummond refers to this in the latest Jowetteer October page 25) and it set me wondering!
I don't have hardened valve seats in my heads, just the standard heads.

Would it be beneficial using higher octane petrol in my case or would it be beneficial only with "up-rated" heads?

Thanks

Paul

Paul, I think for the milege that we do each year and the fact that you are not rallying the car or fast motorway journey's that it should not make a lot of difference. I use Shell V-Power as I find it a much cleaner fuel compared with Supermarket offerings. The difference in price is offset with a slight increased MPG and better running.

Now I know that I have modified heads on the Jupiter but it must be nearly 10k miles since I adjusted the tappets.

PS. Tap in post to you today. Please use either the copper of the fibre sealing washer that you feel most comfy with. Don't over tighten the tap into the head.

Drummond

Thanks again Drummond

Paul

I tend to treat Napoleon to high octane petrol. I couldn't really say whether it's made a difference to his running, mind you. I always use high octane in the first fill of the Spring, when he comes out of hibernation, then intermittently throughout the rest of the season. I've not had to do the tappets since he was recommissioned (and I don't think anyone else has done them either!), but not done anywhere near as many miles as Drummond. At a guess, he probably does around 1k/year.

Amy.

If using modern unleaded fuel, i.e. that generally available everywhere, there is now no connection between fuel octane rating and valve seat recession. The only tiny positive influence may be because the engine does not have a high enough compression ratio to take full advantage of the high octane fuel and unburned particles pass out into the exhaust cooling the valves in the process. In our case this is likely and can be beneficial towards easing the damage, if any, occuring between valve and seat. But measurable over how many decades I wonder? In modern cars, potential exhaust contamination causes alarm and despondency because the car is fitted with a catalytic converter. Hence precise fuel injection, engine management systems and an MOT test that checks it is all working properly. Interestingly, most (old) tests that I am aware of showed an improved mpg for all types of cars using a premium fuel so don't imagine you are losing a particularly significant part fo your wallet down the exhaust. It is now some years since I retired from the oil industry - certainly before ethanol really became an issue. If lead was not used to raise octane, increased severity of refining processes could be and this certainly used to be the case with Shell V Power (though I stress may or may not be now). However, octane can be improved by a greater of inclusion of ethanol and here both petrol manufacturer and customer are at the mercy of of policy makers. Ethanol problems are of course discussed at great length in classic car circles and to my mind represent a greater threat than the loss of lead. My personal opinion is that there are benefits in using premium fuels - though I doubt the issue of detergent is one of them - but it would be nice to know if that fuel contains the same percentage ethanol as regular, before jumping out of the frying pan and into the fire.

Nick

Just out of curiosity petrol in OZ is approx $1.50 per litre . Autogas 72 cents. Whats your local fuel price , wherever you are reading this from?

in switzerland is sfr 1.74 is £ 1.18...... 95 octane

peter

Petrol & Diesel Prices in Scotland certainly vary such a lot but here in the Edinburgh area average prices are £ 1. 34p for 95 Octane and £ 1.41 for 97 Octane.
Diesel is on average 7 p per litre more expensive. Supermarket fuel ( junk ) can be sources from 1.31p per litre.

Drummond

Prices across the USA have been $3 lowest and most $4 for regular 87 octane. Diesel is 40c more.

please state LITER or Gallon.... Liter will be the best !! thanks

peter

Well these Americans use neither as they have small gallons. Just seen regular here in Fort Smith Arkansas for 2.98$.

1 Liter = 0.264 us gallon 1 us gallon = 3.785 Liter

and also the octan is important
in the state the regular ist 87 octan
in GB and switzerland the regular is 95 octan
just made same home work:

1 Liter in us 0.49 £ 87 octan
1 Liter in australia 0.90 £ ??
1 Liter in switzerland 1.19 £ 95 octan
1 Liter in GB 1.34 £ 95 octan

US is the land of cars
GB is the land of Walking

peter

The international spelling is LITRE, liter is in the USA. I believe that the different Octane numbers are due to different test methods. In Prince George BC, Canada, the current price for (regular) 87 Octane fuel is $1.59 per litre.

Petrol at my local varies from 91 octane to 97 octane.Don't know if other brands are any different.

1 Liter in us 0.49 £ 87 octan
1 Liter in australia 0.90 £ ??
1 Liter in switzerland 1.19 £ 95 octan
1 Liter in GB 1.34 £ 95 oct

peter[/quote]

sorry Robin fairservice , in switzerland and Germany we spelling it "Liter" my english is not as good as a english person - sorry !
peter