Berni Models.com - A website about design and building scaled working F1 cars.
Showing posts with label Spark plug. Show all posts
Showing posts with label Spark plug. Show all posts
Sunday, 7 December 2014
Saturday, 29 November 2014
Fire up!!
Finally the engine is alive! the recent weeks have been really busy at work, leaving not so much time for hobbing and delaying the fire up. But at last the final bits were assembled and after a few mods to the fly wheel the engine run for first time.
The progress from the previous post have only been a new flywheel and the preliminary exhaust manifold. As you can see the engine is fixed in a very crudely manner, which will be changed to make it safer to operate and extra stuff around it (gas tank, etc) properly secured. Obviously the white cable will go away too.
I will make a better and longer video and post it after everything is adjusted. It is mainly tuning the carburettor settings to achieve the full performance that hopefully is in it.
The progress from the previous post have only been a new flywheel and the preliminary exhaust manifold. As you can see the engine is fixed in a very crudely manner, which will be changed to make it safer to operate and extra stuff around it (gas tank, etc) properly secured. Obviously the white cable will go away too.
I will make a better and longer video and post it after everything is adjusted. It is mainly tuning the carburettor settings to achieve the full performance that hopefully is in it.
Monday, 27 October 2014
Progress
Almost there! just last checking to do and all will be set for the first fire up!
The spark plug was tested with quite nice results as shown, and for sure the spark will be powerful
enough to ignite the fuel-air mixture.
Another development was the assembly of the carburettor inlet onto the engine head. This part is made in RP (Rapid prototyping). In particular, the material of choice is RP SLS Carbon, and was outsourced. The cost was £23 for 1 off.
The spark plug was tested with quite nice results as shown, and for sure the spark will be powerful
enough to ignite the fuel-air mixture.
Another development was the assembly of the carburettor inlet onto the engine head. This part is made in RP (Rapid prototyping). In particular, the material of choice is RP SLS Carbon, and was outsourced. The cost was £23 for 1 off.
Sunday, 21 September 2014
Spark plug
The spark plug is finally finished. The requirement for a custom spark plug is due to the design of the combustion chamber. In order to get the maximum port area the valves use the maximum area available. The off the shelf spark plugs are too big to allow such big valves and so a custom spark plug was required.
The body of the spark plug is made from stainless steel, which is turned, milled and threaded, and finally swaged to capture the insulation components and electrode. The thread is M5, and extra long thread section reduces the chances of wearing out the thread on the engine head. In the V8, I would probably opt to have a wire insert to reduce even further this risk.
The insulation materials are machined from Macor, which is a machinable ceramic. It machines quite nicely, but because of its brittleness one has to be extremely careful. Wall thickness's in some cases is <0,5mm. On the thread section of the spark plug, the diameter of the insulation is Ø2mm and electrode Ø1mm. There are two ceramic parts in this spark plug, with a flange that gets locked by the swaging process. To achieve a leak prof part, adhesive is added during assembly, which seals any void produced by machining tolerances.
A dedicated swaging tool had to be made to press the collar onto the ceramic insulation. There is not much pressure anyway, as the adhesive also helps keeping the bits together and did not want to crack the delicate ceramic material.
Another tool required is the special 4,5 mm spanner socket that is used to fit the spark plug onto the engine head. This is made form a M6 x 120 cap head bolt which cut down in length. The spanner socket for the spark is broached onto the stud section with a custom made broaching tool. The tool is quenched to achieve the required hardness.
All in all, only a few details are left to make: installation of ingnition system (CDI), test bench, carburator assembly.
The engine is looking good so far!
The body of the spark plug is made from stainless steel, which is turned, milled and threaded, and finally swaged to capture the insulation components and electrode. The thread is M5, and extra long thread section reduces the chances of wearing out the thread on the engine head. In the V8, I would probably opt to have a wire insert to reduce even further this risk.
The insulation materials are machined from Macor, which is a machinable ceramic. It machines quite nicely, but because of its brittleness one has to be extremely careful. Wall thickness's in some cases is <0,5mm. On the thread section of the spark plug, the diameter of the insulation is Ø2mm and electrode Ø1mm. There are two ceramic parts in this spark plug, with a flange that gets locked by the swaging process. To achieve a leak prof part, adhesive is added during assembly, which seals any void produced by machining tolerances.
A dedicated swaging tool had to be made to press the collar onto the ceramic insulation. There is not much pressure anyway, as the adhesive also helps keeping the bits together and did not want to crack the delicate ceramic material.
Another tool required is the special 4,5 mm spanner socket that is used to fit the spark plug onto the engine head. This is made form a M6 x 120 cap head bolt which cut down in length. The spanner socket for the spark is broached onto the stud section with a custom made broaching tool. The tool is quenched to achieve the required hardness.
The engine is looking good so far!
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