Jonathan Kay

.. the sourcing of additives to increase the octane of fuel for the Merlin engine shortly before hostilities is an often overlooked and underestimated critical factor in Battle of Britain. It's very unlikely that the Hurricanes and especially the Spitfires tangling with the Bf109s would have been able to hold their own without the power boost the higher octane delivered. I have the story somewhere in my military history library... Setright is very good on the technology, including the 100 Octane fuel upgrade. I reread the Merlin chapter in Hooker but it doesn't add much. There's a discussion on WW2AircraftNet with some of the relevant official papers on the change. What do you recommend on the strategic and geopolitical aspects of fuel and additive availability and selection? Thanks Jonathan PS: And my congratulations on not assigning combat superiority to the British fighters in 1940!

Mmmm... data. Thanks Jonathan

Where do you want the socket? (Mine is in the vertical aluminium sheet above the passenger's legs, and I punched a new hole there.) ...how does the transmission tunnel cover come off ? There don't appear to be any fixings, is it likely to be held with just Velcro ? If you can't see a pair of screws in the sides at one end it's probably just pressed into place. Try pulling harder. If you want to remove it the handbrake lever needs to be vertical. I bought a complete socket kit with fuse and plan to run it directly to the battery terminals. Do you want USB charging? If so I recommend buying a socket that offers that rather than using an adaptor. Jonathan

i used to see that sometimes, but they always got through. Have you checked that you're below your limit? Jonathan

Interesting. The Wikipedia description of tyre geometry and this table might help, but the latter doesn't show the middle figure (which looks like an aspect ratio) the same way... ... but here's a calculator that specifically includes that Michelin nomenclature. Jonathan

Are you going to change the alternator before that service? Still need to explain the clicking. Could be the battery not having enough oomph from the lack of charging by a duff alternator. After that's replaced I'd check the battery voltage at rest, during cranking and at 3,000 rpm as part of the acceptance of the work under warranty. Jonathan

However, CC protect access to the ecu with a pin number and after some further discussion with CC, they said they would collect it for return to the factory. IIRC some Members have a workaround for that. Jonathan

Do you want the extra interior space of an SV? Five speed box (because of the overdrive) and appropriate axle ratio for touring. There are several recent discussions of wheel size which should help: 1, 2. I'd start by deciding the tyres you want on wet public roads.Jonathan

In case anyone's puzzled by the engineering, chemistry and physics underlying this discussion, and its previous versions, here's an attempt at a summary, corrections and additions welcome: Premature detonation is a problem in piston engines. Compression ratio is one of the determinants and limiting factors of thermodynamic efficiency. For a given octane number or similar, and other things being equal, there's a limit to the achievable compression ratio before premature detonation occurs. A higher octane number allows a higher compression ratio. Some engines detect premature detonation and change things if it occurs. (Has anyone established whether any factory Caterham engines have knock sensors?) But fuels with higher octane ratings don't necessarily* have any more usable energy per unit volume or per unit mass. Fuels with higher octane ratings are more expensive per unit volume.After that it gets difficult and might be controversial: There's a shortage of evidence that higher octane ratings than needed to avoid premature detonation give greater power, economy, or any other benefits. There's a shortage of evidence that any fuels keep engines cleaner than any others.Can anyone provide more on 1 and 2? (And why aren't there lots of studies out there? They aren't hard to do on eg fleets and could easily be done double-blinded.) * It's probably worth adding that it's not implausible that the composition of some fuels that have higher octane ratings coincidentally do have more usable energy, but I haven't seen that any studies of that for ordinary road fuels as opposed to trick fuels used for records and racing, see Setright above. Jonathan

I saw 110 Octane on one of the pumps when I filled up at Lake Havasu in the US. Never knew you could go that high before I saw it. I presume is is mainly used for the powerboats on the lake. The availability of high octane fuel and the understanding of how to make it was a major part of the development of aircraft engines. And different countries took very different approaches up to 1945. There's an excellent description of this in Setright's "Power to Fly: History of the Piston Engine in Aviation". Highly recommended. Jonathan PS: Yes, of course there's lot about the Merlin.

Good morning, gentlemen. SNARK! Jonathan

Could be fuel starvation from inadequate breathing at the tank. The next time it happens take the filler cap off while the engine is still running. Do you hear a rush of air, and does the engine immediately start to run better? Jonathan

I toured to Germany, and found no problem getting 98 in any country on the way, but while in Germany it was rude not to use the 105 that was on offer Do you think it made any difference? Jonathan

Next step is penetrating fluid rather than WD-40. Jonathan

If you're lucky at least one expert will be along very soon. 3. About 3 months ago engine would not start at petrol station and blew the 20 amp ECU fuse (apparently normal ish) changed to 30 amp fuse ECU no power for about an hour This has happened to lots of others and IIRC 30A (or (25A) is now recommended. I think that probably isn't related to the other problem(s). They think it is a top end issue and suggested that i take head off and check the valves. What upgrades would make sense if i am stripping the engine down Are you thinking of doing it all yourself or paying someone else? What upgrades would make sense if i am stripping the engine down While you're waiting: DVA's pages on the K series, and upgrades. Jonathan

... and greater rotational inertia. But why greater *rolling resistance? Jonathan * Not clickbait but I ought to say that the arguments are... well-rehearsed. :-)

Also does anyone have a notion as to the cost of a new set of coolant hoses for an X-flow ie Samco silicone or the standard rubber and which type is advised? Silicone hoses last longer and come in pretty colours. Classic Silicone Hoses £78. Members seem happy with all three suppliers of silicone hoses. There's a Club discount from one of them. Jonathan

Of course it could have been poor quality, or dirty fuel, but I never went back to standard unleaded again. What does the factory say for your engine? Once we know how could we persuade you to rerun that experiment, but with 95 RON fuel from a high turnover supply in the UK? £5 wager that it doesn't run as badly as it did that time, takings to NtL? Jonathan PS: Following that interesting discussion about Ricardo, here's a photo (I don't have a schematic diagram) of the E-35 variable compression test engine that helped him unlock the problem of fuel quality, and his own thoughts: http://www-g.eng.cam.ac.uk/millennium/achievements/ricardo/images/th-R34.jpg During the 1914-18 War, I came into contact with Sir Robert Waley-Cohen, of the Shell Company, who, at that time, was chairman of a committee dealing with fuel supplies. To him I told of my experiments on detonation, of the very great importance I attached to it, and of my belief that it was largely a function of the fuel. He immediately sent me samples of a wide range of fuels of different origin, which I tried out on my supercharging engine, and I was able to show him very great differences in their behaviour as regards detonation. Of these sample fuels, by far the best was one hailing from Borneo. He told me to my amazement, that hundreds of thousands of tons of this particular petrol were being burnt to waste in the Borneo jungle merely because it did not comply with the existing specification as to specific gravity. On the strength of these observations, he invited me to undertake, as soon as the war was over, a comprehensive research into the behaviour of liquid fuels. This, then, formed the first piece of large-scale research undertaken at our new laboratory at Shoreham."

That should work, but it's a lot of mass and volume. Have you checked the thread on the electrical sender is the same? How about the multimeter approach: On the Caterham measure the resistance at a couple of temperatures. Move the sender and the multimeter to the S2. Put the multimeter where you can see it. Will need a new long lead. Keep an eye on the resistance compared to those known values.Jonathan

Just checked the Assembly Guide and Handbook and can't find any specifications or advice... what does the factory say? Agree with John, but sceptical about being able to detect any difference in performance even if it exists, because of uncontrolled variables and all those cognitive biases.... unless it's done blinded. And travelling with others offers you the perfect chance to do that. They toss a coin to decide what goes in, and you write down your findings without knowing what it was. Then on your last evening you break the code. Jonathan

Thanks. Well done. Jonathan

:-) Jonathan

That should be OK. I'm trying to think of a suitable battery or power supply... Or you could use a multimeter. How does the usual gauge work? How much does the supply voltage vary once you're up above idle? Jonathan

Did you find the cause? Jonathan

What is it about track driving that makes the difference, please? Thanks Jonathan