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Unfortunately a plunger pump still requires a tight tolerance on its shaft, otherwise the leakage is significant relative to the size we are dealing with, and leakage = pressure loss and uncontrolled volume displaced. In larger sizes (say 3/8" or 10mm), a good fit maybe measured in a...

I started down the thought experiment path of a small 2 stroke diesel as a proof of concept before embarking on a much more ambitious mutli-cylinder model, and I've conclude (obvious to many) that the biggest difference between it and a normal IC or steam engine is primarily the fuel pump &...

I would very much like to see the drawing changes. I'm always looking at what improvements can be made, either to the method of manufacture or the design itself, Regards, Mike

Excellent work, maybe even inspire me to get off my but and do something with the J-5 castings I have aging in my workshop!

getting exciting. I'm following closely.

I've been waiting on FreeCAD (and by extension Ondsel) to release V1.0 with the big fix that has been missing (topological naming convention). Once that is out and in the mainstream I'll start investing time and energy in learning it and weaning myself off Fusion. From the looks of things I'll...

Do you have a check valve inline anywhere on the pressure measurement (ideally inside the plug)? Curious as the length of tubing may be significant enough to impact the CR and the max pressure achieved.

What is ideal? Low emissions (NOx), low particulates, max power, max efficiency, or an engine that starts and runs easily (i.e. fully controllable)? As a model engine maker, I'm going to aim for the latter, and maybe play in the other sandboxes later...not sure how many of them can be met at...

Many thanks to both minh-thanh and Roger B. for contributing to the public knowledge base. I'd like to ask a question about springs for injectors. It would seem that the main objective of the spring is to prevent opening of the injector until sufficiently higher pressure is achieved in the...

Keep the progress coming. Getting excited to see this thing come together.

Is it possible you had hydraulic lock or near hydraulic lock causing the head gasket to fail that quickly? If your injector got stuck open it would not take long to put too much liquid in the cylinder and get too much pressure. Any room left on the head for an adjustable pressure relief valve...

Hahaha, nice to see a bit of humor from people in industry once in a while. I'm sure I've got a bunch of the later one, the first would be nice to have but I would lose it in my shop!

Nice result. I like the translucent intake runners, I wasn't expecting to see little puffs of fuel mixture in them but seeing is believing. Adds an extra visual detail to the other externally exposed bits like the crankshaft and the camshaft

The plans were published in Model Engineer magazine. Started 25 January 2013. I think a subscription to Model Engineer will get you access to the archives and back issues but I'm not absolutely sure on that, maybe someone else can confirm that.

I haven't made a "PCV" before, but I think its really just a check valve, for low pressure - lets crankcase pressure out and prevents flow in. In your case the valve lies sideways, so either you need to really limit the lift of the ball to ensure its sucked back onto its seat, or you'll need a...

I am generally willing to post a response to a question or when being asked for advice if its a subject I'm relatively comfortable with. In other cases I've learned to shut up, as some who may be regular contributors are using forums more as a blog, and don't care to listen to advice given...

For a crankshaft of 10mm diameter, I'd look into 1144 "stressproof" here in North America, 1/2" diameter. Cuts really well. It has become my go-to steel for shafting. Typically does not need to be hardened after machining (i.e. machine directly to finished size) and is likely suitable for...

Any reason for Titanium other than maybe you had some or wanted an excuse to machine it (nothing wrong with that - more than half my projects are excuses to do something like that).

4 stroke radials have odd numbers of cylinders to keep the firing equally space - i.e. for a 7 cylinder: 1-3-5-7-2-4-6 back to 1....) An even number of cylinders results in 2 cylinders firing beside each other, introducing an uneven power pulse and vibrations (1-3-5-2-4-6 ->back to 1, 1 and 6...

Excellent work, not sure how I missed your progress previously. For the crankcase oil leakage issue, can you sneak in a one way valve into the breather pipes, making them PCV valves (i.e. let the air out but not back in)? It should help by making the case pressure much lower or even negative...