User talk:Andy Dingley/Archive 2011 November

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Distributor cap and carburetor

Hi Andy,

I'm again a bit further along the way of modelling the internal combustion motor; I expect to have it ready within a few months. However, I have some additional questions:

• Since I'll be using a magneto, do I still need a Distributor ? Or, do I just connect the magneto wires to the spark plugs of the cylinders in a 1-3-2-4 arrangement (see http://auto.howstuffworks.com/ignition-system.htm )

• For the carburetor: I looked into several carburetor types, yet having done some research, it seems that the carburetor needs to foresee in following specifications:
• firstly, I'd like the carburetor to be placed seperatly from the motor. Besides the mounting, the carburetor is thus also best kept small (ie with few float chambers/butterfly valves, venturis, ... )
• the carburetor needs to be simple/durable and reliable (used in a variety of models, including some aircraft designs later-on; a pressure carburetor is probably not needed though) Since aircraft would also use the carburetor, the choke lever needs to be manually settable (or automated, but the altitude/air density needs to be settable)
• the carburetor needs to be reasonably efficient
• a turbocompressor is used, so perhaps not every carburetor type can be used
• the carburetor type should be usable for both low power (40 HP) and high power (150HP) motors
• finally, I need full information for the carburetor on where each components sits, how it works, ...

User:KVDP 15:04, 21 September 2011 (UTC)

You need a distributor whenever you have more cylinders than ignition systems. It's a bit more complicated than that - several engines (two strokes for a long time, four strokes recently) use a separate coil for each cylinder, so don't need a distributor. There's also (4 strokes only, fairly rare) the "wasted spark" system where one coil does two cylinders. If you have a distributor and magneto, then the distributor is built into the magneto and isn't an obviously separate component (if a magneto has more than one HT outlet, there's a distributor in there).

The magneto design was http://www.undaerospace.com/cbt_files/virtualengine/Magneto/Virtual%20Engine.swf ; there seems to be a "distributor block" (14) in there. However, how do I connect the wires from this to the motor; ie top left wire-top right wire-bottom right wire-bottom left wire to cylinder 1-2-3-4 respectively (when the motor is oriented with the flywheel to the left); or do I connect it in a 1-3-2-4 configuration; ie top left wire- bottom right wire-top right wire-bottom left wire

That's a magneto with a built-in distributor. Distributors deliver sparks in sequence, so for an engine with a typical firing order, the connection wires are not a simple mapping from one to the other. It's fairly common for a distributor to have the numbers 1-3-4-2 (or 1-3-2-4) moulded into the cap as labels, in just that sequence. Note also that the phasing between engine and distributor is crucial - it needs to be within a few degrees of its position for the engine to run at all, ideally within less than a degree to run well.

Carburettors are obsolete for cars, because of emission regulations. The last one was, I think, a Yugo in the mid-90s. Even the tiny micro-cars like the new Tata use fuel injection. Carburettors are complex and expensive to make, so with cheap modern electronics, it's just cheaper and easier to make fuel injection. You also mention turbochargers (assuming you didn't mean a centrifugal supercharger), so this isn't a simple or low-cost engine. Scooters and small motorcycles still use carburettors, but even those are shifting to injection.

The technology should be appropriate; offcourse the financial cost matters greatly, but the efficiency and other important issues as durability, ... matters aswell. Also, the carburetor is needed anyhow for my designs as I use several types of fuels, ...

"Alternative" technology used to mean hippies doing things on the cheap, and usually badly, but "appropriate" needs to work instead. The technological and engineering reasons that make it appropriate for me to buy a sophisticated engine made on sophisticated machinery from a big factory in China work just as well for me in Europe as they do for someone in Africa or Asia. The world's most efficient steam locomotives (the work of L D Porta) were produced in Patagonia, South Africa and China, not in Manchester.

Carburettors suck. Electronics is now cheap, and fuel injection works better. For multi-fuel, it works a lot better.

I really don't like electronics since if they break, it's very hard to find what exactly ceased to function, and even harder (if not impossible) to repair. That said, I might need to use it anyway since I'll also incorporate direct injection.

User:KVDP 15:04, 3 November 2011 (UTC)

If you look at the people using alternative fuels, they're not using carburettors. Most are even using compression-ignition engines (like diesels) rather than spark ignition.

I don't think a carburettor would work badly in my system, although I indeed use several fuels (several setups are being prepared). This as the carburettor is only used with the starting fuel (it uses 2 fuels, and switches fuel after the motor has run hot). The starting fuel is ethanol.

The old Amal you mention however may be intresting as an alternative carburetor for use with wood gas. I'll look for schematics later-on.

UPDATE: I looked into the Amal carburetor you mentioned (all 3 types), yet it doesn't seem like this is of any use to burning wood gas. The thing I actually need is a "air gas mixes" (see http://en.wikipedia.org/wiki/File:Planet_Mechanics_wood_gasifier.png , L (not sure whether it's the correct name though). The problem I still have is that I don't know

• how exactly the part's shape is best modelled (not sure how it was done back in the 1940's)
• how the 2 valves work together (I'm guessing the L2 would be fixed to the gas pedal, but how does L2 and L1 work together; ie how does the linkage looks like)

User:KVDP 09:36, 8 November 2011 (UTC)

As for compression engines: indeed some people use them, but this is generally mostly with "inconsistent" and/or difficult to ignite fuels (ie biodiesel/pure vegetable oil, ...) Ethanol is allready very volatile, so I don't think it will give any problems to use a petrol engine. Actually, to reduce the heat (especially when running on pure nitrous oxide) I'm actually beefing up (aswell as simplifying) the cooling system. User:KVDP 15:04, 3 November 2011 (UTC)

in regards to the turbocompressor: I use a very basic type with no speed regulation or on/off capability; I redirect air from air pipes instead. Offcourse the turbocompressor is another part that increases cost, in the long run it is cheaper since more energy can be extracted, and the combustion occurs better aswell.

There is no place for a "simple" turbocharger (and please call it a turbocharger or turbosupercharger, not a turbocompressor - they're different) in a spark-ignition petrol engine. If you insist on forced induction, then it's a lot easier to achieve for a diesel engine. A diesel engine also has better efficiency at low power, which is useful for many "appropriate technology" tasks.

Turbochargers are primarily there to increase specific power (power for engine size) not to increase efficiency. They won't increase efficiency unless you have quite a sophisticated engine that can make use off this - in particular a really good fuel system, and that isn't a carburettor. If you use an engine with power control via a throttle, rather than fuel metering (ie "petrol like" rather than "diesel like") you also need a turbocharger with a wastegate. It's easier now to build a small diesel engine with direct injection and a no-wastegate turbocharger than it is to make a turbocharger and wastegate for a comparable petrol engine.

I use power control via a throttle, and indeed incorporated a wastegate to the (centrifugal) turbocharger. It's an easy system to understand if you see it (I'll let you know once it's done).

User:KVDP 15:04, 3 November 2011 (UTC)

Turbocharged engines need fuel control computers. They can't work without, certainly not efficiently. You can make these computers through fluidics (carburettors and pneumatic plumbing) or through electronics. It's nonsense to discuss on the internet (the product of vast cheap electronics) whether fluidic or electronic controls are now cheaper to make.

There are any number of carburettor explanations around - some might even be correct. Like I said, get a copy of Setright. Their function is easy to describe but hard to achieve - they mix a constant ratio (by mass, not volume) of air and fuel. The difficulty is that they have to do this over a huge range of airflow. The airflow is controlled by the throttle butterfly, which is usually made as part of the carburettor. The ratio does change a little, they usually over-richen the mixture deliberately during acceleration, but it's more of a problem to keep it consistently constant during the various changing conditions.

As to how the carburettor works, then that's far too complicated to explain in just a paragraph. Andy Dingley (talk) 00:05, 22 September 2011 (UTC)

For the carburetor; I understood the basic function of it; however I wanted to know which carburetor type I should take, and which manufacturer is best, considering my requirements. I was personally thinking on a variable venturi carburetor; which seems to include the SU carburetor and the Zenith-Stromberg. I need exact schematics though.

08:09, 22 September 2011 (UTC)

Carburettors aren't even made much any more. Burlen Fuel Systems still make spares for SUs (and Stromberg), but rarely new carbs. Motorcycle variable venturi carbs are mostly mechanical slides (like the old Amal) where the venturi is varied as well by the throttle cable (rather than the manifold vacuum on the piston). This is faster-acting (why motorcycles used them), simpler (why lawnmowers use them), but usually less accurate for fuel metering (why nothing else used them).

If you asked me to design an "appropriate technology" engine it would be an easy choice. Either use something already existing in a big factory (economics forces this) or else design a clean-slate design. That would have these characteristics:

• Compression ignition
• Electronic or mechanical injection, depending on market
• Multifuel capacity (electronic injection only) by an electronic user interface or self-switching based on internal sensors.
• Opposed piston, uniflow two stroke
• Phase lead between pistons, for better uniflow scavenging. This means a two crankshaft and geared design, not a bellcrank design like the Commer TS3
• Three or six cylinders, according to power needed, but not a modular design. Modular designs would be easy, but would require an over-engineered crank and geartrain for the smaller engine.
• Forced induction via a Roots blower. These have goood service lives, and can now be manufactured cheaply.

It would look a lot like this: File:Opposite piston engine anim.gif The two main differences would be compression ignition rather than spark, and a Roots blower rather than vanes.

An interesting engine from the 1940s is the en:Vincent marine engine (I really must write this). A highly-efficient petrol engine for lifeboats, with an unorthodox opposed-piston design. Very rare then and now, an engine-collector friend of mine has one. Andy Dingley (talk) 10:17, 22 September 2011 (UTC)

Thanks for mentioning this, but I'm mostly focusing on more popular (and somewhat simpler) designs. I used a 4-cylinder 16V, line engine and I'm sticking with this. The main reason is that this motor is very common and can be found on junkyards, ... Spare parts are also easily to find, and most car mechanics (even in depeloping countries) will be able to work on it. I'm just adapting it a bit so as to make it more robust and simpler.

User:KVDP 15:04, 3 November 2011 (UTC)

Category:Brunel's Cumberland Basin bridges

Hi. I don't understand why you've re-added Category:Bristol Docks to Category:Brunel's Cumberland Basin bridges. The latter is already indirectly a subcategory of the former, and what you've done has resulted in a deprecated overcategorisation. Rodhullandemu (talk) 19:03, 10 November 2011 (UTC)

The bridges aren't just an accident of geography, they form an integral part of Brunel's engineering works in making the docks. Like the underfalls themselves are important for the docks, not just part of the Underfall Yard.

The blind suppression of transitive categorization like this is a good idea in general, but there are many cases where they should remain - if there's also a distinct and separate relationship between the two grand- categories. I would contend that in this case there is such a link. Andy Dingley (talk) 13:31, 12 November 2011 (UTC)

Kettering

If you would read Charles F. Kettering House, you would observe that he lived in the city of Kettering. We place individuals into categories for places where they lived; if you want to remove Kettering the man from Kettering the city, you will need to remove Category:George W. Bush from Category:People from Texas, because he's originally from Connecticut and in Category:People from Connecticut. Nyttend (talk) 00:33, 23 November 2011 (UTC)

Yes, he lived there. So put him into Category:Residents of Kettering, Ohio. He's not "from" there though, he's from Loudonville (for which he's also correctly categorized). He lived in many other cities besides (Dayton most obviously), but you're surely not suggesting that he should be added to the "from" categories of each and every one! Andy Dingley (talk) 19:08, 23 November 2011 (UTC)