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landy1
07-15-2012, 04:33 PM
I couldn't see anywhere to introduce myself, so I'll just post here anyway.



2.25, 3 bearing crank, petrol Land Rover, 109 Safari 1972.

The Mission.

To gain extra engine power, keep combustion temperatures down and improve mileage, whilst running 95 Octane unleaded petrol.

This is a bit long winded, but it’s worth it.

Let’s start with basics.

The Land Rover engine, was designed to run on very low octane petrol, usually in very high temperature areas, like Africa. It was never a sports car, but would get you there eventually, usually with heavy loads either on the roof rack, or in it and on roads that would finish off most other vehicles. It has always done surprisingly well, if you like travelling at speeds up to 60 mph. In Africa it didn’t matter. On modern roads however, with modern cars, it’s not so great. It struggles up one hill after another, until your nerve goes and you are forced to pull over in order to let the build up of traffic go past.

So, you can either fit a much larger engine or buy something newer. Or………if your budget is limited and you like tinkering, you can resolve the problem.

I’ve always been fascinated that Land Rover can take a large engine and make it produce such a small amount of power, say next to a car engine. I discovered that in their rush to make it run on so low grade fuel, they threw out the need to produce power. They also didn’t think that the gearbox would take the strain, although people have been putting Rover v8’s in for as long as I can remember, without much of a problem.

An old fashioned way of increasing engine power and performance, is to have the head skimmed. I had 100 thou (About 2.5 mm) skimmed off mine. You may think that’s not much, but it’s about all you can do without the rockers touching the cover. Quite what that does to the compression, I’ve never bothered to work out. It was 8:1. but the power increase is dramatic.

The next thing, was to sit down and work out the camshaft opening and closing positions. On normal engines, the top dead centre of the engine shows the camshaft balanced at the mid way point. Not on Land Rovers. They backed it off by one tooth, so it wouldn’t allow so much fuel/air in and to reduce top end power. (Not necessary for off road vehicles). Problems arise when both the inlet and exhaust valves open late. The exhaust valve is still open when the piston is on its way back down for the inlet stroke and the inlet valve is still open when the piston starts to come back up ready for the compression stroke. ( Later engines have a redesigned camshaft profile, which goes some way to addressing that problem).

With the engine sucking in more air and fuel and the higher compression, I had to fit a larger exhaust silencer and rear pipe. I also had to increase the air filter size. Both problems were sorted by fitting 6 cylinder parts, which are larger.


Next, the ignition timing. On standard engines, tickover is at 0 degrees, and 2000 revs should be 20 degrees BTDC. All Land rover 2.25 petrol engines, will run on these settings. However, for some reason I have yet to understand, some like more advance and some don’t. Hence the factory settings. I used to run mine on 6 degrees on tickover and 26 degrees at 2000 rpm.

Now the problems.

When 4 star 98 octane leaded fuel was removed and everyone started to run 95 octane unleaded, engines had to have the valves and seats upgraded, and the ignition timing knocked back until it stopping pinking (knocking or pinging). Most Land Rover owners didn’t even notice the change. Sadly, I did. The engine temperature went up even though I’d backed off the timing. The exhaust became jet black and sooty, all because unleaded fuel burns much hotter and faster than leaded. (That was the whole point of leaded).

One way round it was to use super unleaded petrol, but the cost is quite steep after a while and I’m not sure what damage, both to the environment and the engine, adding sulphur, amongst other things, does. (Especially at 16 to 18 mpg). Another way, is to use water injection, but is rather expensive to set up and you need to find room to fit a water tank.

I came across another route. It was a cheap version of water injection that fitted into the vacuum pipe on the carburettor. The idea was that it would ‘cool’ the charge of air/fuel, thus enabling the ignition timing to be increased.

The problem with this type of water injection, is it doesn’t deliver water when you most need it. Full throttle. If you’ve ever driven a Landy, you spend most of your time at full throttle, otherwise you don’t go anywhere, especially up hill. The vacuum only sucks up to about half throttle.

HHO.

I bought a 21 plate unit, bottle and bubbler off Ebay, waited for about 2 weeks for it to arrive from the States and fitted it. I added KOH until 20 amps showed on the ammeter and fired it up. Not much happened. It produced bubbles, is about all I can say.

Not to be disheartened and left as a sceptic, I had to find out why it wouldn’t work. Most people explain that their modern cars have to run a weaker mixture and the oxygen sensor has to be fooled. I haven’t got any of that, so to weaken the mixture, I bored out the venturi in my carb, by 1 mm. (Now it’s a 28mm venturi Zenith 36IV).

This did not much either, other than improving the fuel consumption at full throttle, but giving me some half throttle problems as it was too weak.

After working out that what it really needed, was a cross between the water injection and the hho, I decided it needed to pick up water vapour along with the hho. I put an air stone I got from a fish water tank into the bubbler, forcing the hho through it. Now, it produces smaller, but more bubbles and it attracts water from the bubbler on its way to the air intake. You can actually see that the air intake pipe from the bubbler is filled with water vapour, in a similar way that boiling a kettle under a surface does.

Because of the lack of height in the engine bay, I decided to use a small plastic fuel pump, (which came from New Zealand) to force the KOH mixture round the system, thus reducing the need for any more than 10 amps, to make the system work. Because it pushes the mixture through the stainless steel plates, more of them are in contact with the mixture.

What it is has actually done, is to increase the octane rating of the fuel.

The difference is astonishing.

I find I can run the ignition timing at 14 degrees advance, before it even considers pinking, (so I run it at 12 degrees to make sure), the engine temperature is cooler (it barely gets any hotter than when the thermostat opens) and the engine runs properly. The exhaust is now back to that lovely pale grey that tells me the engine is burning correctly. On a trip to Pembrokeshire in Wales, fully loaded, with camping gear, trailer, dogs etc, it did an average of 19 mpg. Quite what it will do down a motorway, at a steady speed, I can’t say, but I look forward to finding out.

One last point, I have found, that ever since we’ve had all this rain and flooding in the UK, I can actually turn the system off, as the humidity in the air, does roughly the same thing.

Jon.