Author Topic: 20 cc Horizontal 2 Stroke Diesel  (Read 44478 times)

Offline gbritnell

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #285 on: April 14, 2019, 12:55:28 PM »
Although I haven't commented much on your build threads I am totally impressed with the experimentation and work you have been doing on both the injector and engine. I wonder if it would help to make larger flywheels to try and get the rpm's down? Even with gasoline engines flywheel diameter makes a big difference in low speed performance.
I know a diesel requires greater compression so it takes more inertia to get it past the compression stroke.
The model diesels on YouTube are capable of quite slow running and have what seems to be extremely large flywheels compared to the cylinder size.
I'm still following and learning a lot from your work.
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Online 90LX_Notch

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #286 on: April 15, 2019, 12:12:08 AM »

I'm still following along.  It's nice to see you back at it.

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Offline Art K

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #287 on: April 15, 2019, 03:27:56 AM »
Good to see you back at it. George is right you have done an amazing amount of experimentation on this engine. I agree with him on the flywheel thought. Most old engines you see have massive flywheels. Just a thought.
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #288 on: April 15, 2019, 05:40:21 PM »
Thank you all for your interest  :ThumbsUp:

George, I am mostly making this up as I go along. I agree that a bigger flywheel will improve slow running however the original plan for this engine was to power a model tractor which will restrict the flywheel size and will also probably require fairly high rpm. In the design of the big end I considered a maximum speed of 6000 rpm. If it would idle at 2000rpm that would be ok, lower would obviously be better. I am still not sure that I am getting combustion directly from the fuel injection or vis leakage past the piston and carburation  :headscratch: If it was direct combustion I would expect a much quicker start with a hot engine but there is always quite a delay and hence quite a quantity of fuel injected. The gunge that comes out of the breather pipe seems to thin to be the lubricating oil so there must be a significant proportion of diesel oil.

There was a compression ignition engine that used an ingenious trick to avoid high pressure injection:

Best regards