On Wednesday, August 11, 2021 at 2:18:27 PM UTC-4, David Billington wrote:
> On 11/08/2021 17:30, Ed Huntress wrote:
> > On Wednesday, August 11, 2021 at 12:16:02 PM UTC-4, David Billington wrote:
> >> On 11/08/2021 16:41, Ed Huntress wrote:
> >>> On Wednesday, August 11, 2021 at 10:43:51 AM UTC-4, David Billington wrote:
> >>>> On 11/08/2021 15:26, Ed Huntress wrote:
> >>>>> On Wednesday, August 11, 2021 at 10:22:24 AM UTC-4, David Billington wrote:
> >>>>>> On 11/08/2021 14:34, Ed Huntress wrote:
> >>>>>>> On Wednesday, August 11, 2021 at 6:46:01 AM UTC-4, Jim Wilkins wrote:
> >>>>>>>> "Ed Huntress" wrote in message
> >>>>>>>> news:3b15da1e-d6a3-4094...@googlegroups.com...
> >>>>>>>> On Tuesday, August 10, 2021 at 9:04:25 PM UTC-4, Jim Wilkins wrote:
> >>>>>>>>> "Ed Huntress" wrote in message
> >>>>>>>>> news:ffbab5f1-2afe-4225...@googlegroups.com...
> >>>>>>>>> On Saturday, June 26, 2021 at 10:31:56 PM UTC-4, bob prohaska wrote:
> >>>>>>>>>> Just how strong are built-up crankshafts? They're
> >>>>>>>>>> common in very small engines, some of which seem
> >>>>>>>>>> rather highly stressed. They seem less common in
> >>>>>>>>>> larger engines, but those I'm familiar with are
> >>>>>>>>>> high-production types where tooling costs matter
> >>>>>>>>>> less than per-part costs.
> >>>>>>>>>>
> >>>>>>>>>> For example, if somebody wanted to build a small,
> >>>>>>>>>> one-off diesel engine, say a 200cc v-twin, would
> >>>>>>>>>> a built-up crank have a chance? At the other end
> >>>>>>>>>> of the spectrum, are the cranks in very large marine
> >>>>>>>>>> diesels (think Emma Maersk) built up or monolithic?
> >>>>>>>>>>
> >>>>>>>>>> Thanks for reading,
> >>>>>>>>>>
> >>>>>>>>>> bob prohaska
> >>>>>>>>> Hi folks! I haven't stopped in for years, but I was so pleased to see that
> >>>>>>>>> the political stuff (which drove me out in disgust) seems to be just a
> >>>>>>>>> whimper now. If I was still writing about metalworking, I'd get back into
> >>>>>>>>> it. But I'm not, so I'm just saying "hello" and it's nice to see so many
> >>>>>>>>> of
> >>>>>>>>> you still around.
> >>>>>>>>>
> >>>>>>>>> Bob, I don't know of any unsupercharged diesel engines -- running on
> >>>>>>>>> diesel
> >>>>>>>>> fuel -- smaller than about 300 cc or so per cylinder. I'm not a diesel guy
> >>>>>>>>> and there may be some such engines, but that's what I've heard from diesel
> >>>>>>>>> people. They've told me that smaller cylinders quench too much to burn
> >>>>>>>>> diesel fuel without supercharging. Of course, you can "diesel" with ether
> >>>>>>>>> and maybe some other fuels, but that's something to check out. Those model
> >>>>>>>>> "diesel" engines that run on ether don't have injection, so purists don't
> >>>>>>>>> consider them to be "diesels." Just "compression ignition."
> >>>>>>>>>
> >>>>>>>>> As for built-up cranks, there were racing engines in the 1930s, and
> >>>>>>>>> probably
> >>>>>>>>> since, that had built-up cranks. SO I'd guess that they can handle the
> >>>>>>>>> torsional load if you get the press-fit right.
> >>>>>>>>>
> >>>>>>>>> Good to see ya'll, and without the vile political stuff!
> >>>>>>>>>
> >>>>>>>>> --
> >>>>>>>>> Ed Huntress
> >>>>>>>>> ----------------------------------
> >>>>>>>>>
> >>>>>>>>> Amazon offers several brands of a 196CC Diesel:
> >>>>>>>>>
> >>>>>>>>> https://www.amazon.com/Diesel-Cylinder-Cooling-Horizontal-3000RPM/dp/B0917PGV7W/ref=sr_1_3?dchild=1&keywords=small+diesel+engine&qid=1628643055&sr=8-3
> >>>>>>>> Yes indeed. If you look closely, it looks like they're all the same motor,
> >>>>>>>> with different paint jobs.
> >>>>>>>>
> >>>>>>>> --
> >>>>>>>> Ed Huntress
> >>>>>>>> ------------------------------------
> >>>>>>>>
> >>>>>>>> A disgusted Chinese design engineer told me their government encourages such
> >>>>>>>> unlicensed copying.
> >>>>>>>>
> >>>>>>>> They don't necessarily disprove the 300CC statement, perhaps being able to
> >>>>>>>> use cheap available fuel is more important than lost efficiency at their low
> >>>>>>>> power level. Quench may be less of a problem in a hotter-running air cooled
> >>>>>>>> engine.
> >>>>>>> Aha! Yes, hotter running is an interesting point. I also noticed from the Amazon detail listing that compression ratio is 22:1, which is at the high end. I wonder what it's like using a recoil starter with a 22:1 compression ratio.
> >>>>>> I had a Yanmar L40 which is similar but upright and that is 20:1
> >>>>>> compression ratio and was easy to start when the decompression lever on
> >>>>>> the head was used, I knew one guy that was strong enough to start it
> >>>>>> without its use. I suspect that amazon engine has one and if anything
> >>>>>> like the Yanmar it's the lever with the red knob to the right of the
> >>>>>> cylinder head in the last image.
> >>>>> The thermodynamics of these things has always interested me, but the reality is that it's usually over my head. How a diesel can start cold, at low rpm, with a reduced compression ratio, boggles my understanding of what is going on.
> >>>>>
> >>>> I think it was more to do with allowing the user to get the engine up to
> >>>> speed with the recoil starter. The start procedure was to set speed
> >>>> lever to run position, pull the engine over till it was on the
> >>>> compression stroke, let the start lead back in, push the decompression
> >>>> lever down, and pull hard to start. The decompression device reset
> >>>> automatically after that first compression stroke by which time
> >>>> hopefully you had imparted enough inertia to the flywheel that it would
> >>>> go through the next compression stroke itself at full compression and
> >>>> start. In the summer it would often start first time, in the winter it
> >>>> could take a few more pulls to get it running, that was UK summer/winter
> >>>> temperatures.
> >>> I'm still surprised that it worked, given all of the quenching going on with a cold engine and a (relatively) slow speed. But, hey, that's why I'm not an engineer. I have seen some other starting aids on larger diesels, like hot-tubes and even ether injection, but I have no experience with diesels and I don't know what constitutes contemporary and practical operating practices. Meantime, as much as I like small engines, I made a first leap this year and bought a battery-powered lawn mower, which I love (Ryobi 40V, 21"). Next, maybe an electric car. Just turn the switch, and hummm...
> >> A mate was giving me a tour of his narrowboat and I knew it was diesel
> >> but was surprised to see spark plugs, apparently a semi-diesel which due
> >> to the low compression ratio would be started on petrol and run until
> >> warmed up where it would be switched to diesel fuel. IIRC a Kelvin diesel.
> >>
> >> While not a diesel I have had a Cox 049 spontaneously start on me when
> >> idly flipping it over, no glow plug power connected, and it got quickly
> >> dropped onto the porch where it continued to run for a minute or 2
> >> bouncing around as the prop kicked it about. It was only the bare engine
> >> and prop, I had been holding the rear fuel tank until it started.
> >>
> >> Re the new mower is it one you push, ride, or a robotic one you can just
> >> sit back with a brew and watch it do its thing. I know someone with one
> >> and she loves it and it'll go back and park itself and recharge as required.
> > Ah, yes, I remember a small "start on petrol, run on diesel" engine from Italy many years ago. It was sold for general-purpose agricultural use and it was listed in the Sears farm catalog. This was back in the '60s. That was (maybe still is?) another of the schemes for starting small, or cold, diesels.
> >
> > The new mower is a self-powered walk-behind. It has two 40V, 6Ah batteries. It takes a half-charge on one to mow my small front lawn, and a half-charge to mow my smallish back lawn. I switch between them to discharge each battery by half before re-charging. It's quiet, powerful, and hassle-free. I'm not ready for the robotic ones, but I can see their appeal.
> >
> I suppose with diesel engines small is relative but IIRC the engine is
> like this Kelvin K2 https://www.youtube.com/watch?v=mY65XOQa45s . The
> narrowboat it's in is quite new but the engine is vintage, a big slow
> running lump, The boat's listing gives the power at 18hp.

That engine reminds me of something that Vera Lynn used to sing: "There Will Always Be an England." It's just hard, sometimes, to keep it running. d8-)

Or, as I once said after a tough day working on my MG, "England, the country of many oil cans."

--
Ed Huntress