Berni Models.com - A website about design and building scaled working F1 cars.
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!
Friday 5 September 2014
Engine head progress 2
Hi there, it´s been a while after last post, but batteries fully charged after the summer break. Hope you all had a good time too.
The engine head has been assembled and is almost completed. All four valves, rockers, cam shafts are working together. All is left is the valve lapping and cups to be ground. I pretend to adjust cam clearance by grinding the cups, so each cup will have to be numbered according to its position and valve.
The valve seats were already cut with an HSS custom made tool. This tool is basically a countersinking tool with a pilot steam to achieve good concentricity with the valve guide. I am sure most of you use the same system.
I hope I can grind the cups and lap the valves this weekend, so I will be posting more pictures soon.
The engine head has been assembled and is almost completed. All four valves, rockers, cam shafts are working together. All is left is the valve lapping and cups to be ground. I pretend to adjust cam clearance by grinding the cups, so each cup will have to be numbered according to its position and valve.
The valve seats were already cut with an HSS custom made tool. This tool is basically a countersinking tool with a pilot steam to achieve good concentricity with the valve guide. I am sure most of you use the same system.
I hope I can grind the cups and lap the valves this weekend, so I will be posting more pictures soon.
Tuesday 29 July 2014
Engine head progress
This weekend I have made some progress with the engine head. The inlet and exhaust ports have been polished and valve seals have been pressed in. It all went quite nice together. I used some Dremel tools and polishing compound to polish the ports in the inside, with extreme care to not damage the mating surfaces for the inlet and exhaust and valve seats. On the pictures you can see the dedicated fixtures to press the valve seats and guides into the head.
The upper assembly with the camshaft carriers and little brackets has also been put together. As the top of the engine will be open, it will be possible to see any leaks or other issues inside the head. The brackets are only for the test engine as the V8 holds the cam shafts with the head covers.
The valves were almost finished, I just had to grind the top and bottom surfaces to final dimension. So they are ready to install. The material for valves is SS AISI 316.
During the week I expect to finish the bores for the cam shafts, including the bronze split bearings installation. Also the countersunk on the valve seats.
The upper assembly with the camshaft carriers and little brackets has also been put together. As the top of the engine will be open, it will be possible to see any leaks or other issues inside the head. The brackets are only for the test engine as the V8 holds the cam shafts with the head covers.
The valves were almost finished, I just had to grind the top and bottom surfaces to final dimension. So they are ready to install. The material for valves is SS AISI 316.
During the week I expect to finish the bores for the cam shafts, including the bronze split bearings installation. Also the countersunk on the valve seats.
Monday 21 July 2014
Lower engine assembly
I have virtually completed the lower assembly of the engine. The crankshaft is finished and finally assembled with con rod inside the crankcase.
You can see that the crankshaft has 6 holes on the counterweight area. These will be filled with tungsten bars. This is to adjust the amount of weight on the counterweight as well as keeping the inertia low. On the V8 one I might not do it as it is a lot of hassle as the tungsten is really hard to work with. I have to use a right angle grinder and because the pieces are so tiny it is quite a dangerous job.
The bolts to on the con rod are M2. I will replace the current stainless steel by 12.9 steel ones.
The cylinder liner is from a Lapped internal H7 steel off the self tube, that I turned to fit the aluminium engine block. It is not hardened but I hope it will be just fine for this test engine.
I am going to use gasket sealant, like Loctite 5800 as I do not plan to use any joints on between the crankcase and engine block.
You can see that the crankshaft has 6 holes on the counterweight area. These will be filled with tungsten bars. This is to adjust the amount of weight on the counterweight as well as keeping the inertia low. On the V8 one I might not do it as it is a lot of hassle as the tungsten is really hard to work with. I have to use a right angle grinder and because the pieces are so tiny it is quite a dangerous job.
The bolts to on the con rod are M2. I will replace the current stainless steel by 12.9 steel ones.
The cylinder liner is from a Lapped internal H7 steel off the self tube, that I turned to fit the aluminium engine block. It is not hardened but I hope it will be just fine for this test engine.
I am going to use gasket sealant, like Loctite 5800 as I do not plan to use any joints on between the crankcase and engine block.
Subscribe to:
Posts (Atom)