Author Topic: Freelance Inline Twin  (Read 37117 times)

Offline ThomasM

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Re: Freelance Inline Twin
« Reply #165 on: October 18, 2017, 03:54:00 PM »
Congratulations for this engine !

When i first saw your crankshaft with the parallel moving pistons and therefore the equal firing order i was wondering if a 180 offset and unequal firing would sound better.
Now i know that i was wrong.
The engine sounds fantastic and the clean technical look is also perfect.

Best regards,
Thomas

Offline Rustkolector

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Re: Freelance Inline Twin
« Reply #166 on: October 18, 2017, 07:01:37 PM »
Yogi,
It sounds like you’re getting reasonable splash in your crankcase. Regarding oil type, in my opinion engine oils are better for model engines than machine and hydraulic oils. My particular concern with the latter oils in 4 stroke model engines would be crankcase moisture retention in wet sump designs. Keep in mind our engines never get up to normal engine operating temps so ~30 degrees above ambient is all you can expect in a model engine crankcase. Moisture production and retention is significant especially when the engine is new. Machine and hydraulic oils are formulated to allow water and crud to drop out and be retained in the engine. Engine oils provide detergents and water dispersants to keep crud and water in suspension allowing it to be observed (turns milky) and easily removed by draining.

Regarding oil viscosity, I built a slow speed engine that allowed me to install Plexiglas inspection covers on both sides of the engine to observe oil splash vs RPM. As you might expect, 5w-20 engine oil splashed better than 10W-30, which did better than SAE 20, etc., so the lower viscosity the better in my experience. Also, oil surface tension in a cool running oil system becomes a significant factor when evaluating effectiveness of a small splash system.

I just finished a 180 degree slow speed twin. I am getting quite fond of its John Deerish sound and I especially like the lack of heavy crankcase pressure pulsations. Watch out for the latter in the 360 degree crank design. A check valve design breather to control pressure is almost mandatory.

Jeff

Offline yogi

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Re: Freelance Inline Twin
« Reply #167 on: October 18, 2017, 10:04:15 PM »
Thanks for the compliments, guys!  :cheers:

Jeff, good input on the oil. Thank you! I will take that into consideration.
I was contemplating a 180 degree crank for a while, but then settled on the 360 crank. I'm sure that would really sound cool too...


Yogi




Online Art K

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Re: Freelance Inline Twin
« Reply #168 on: October 19, 2017, 12:43:35 AM »
Yogi,
I read your bit about using ISO 68 which I recognized as hydraulic oil. I wouldn't personally use it in place of motor oil and thankfully Jeff gave a very definitive reason why.
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline fumopuc

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Re: Freelance Inline Twin
« Reply #169 on: October 29, 2017, 07:53:55 PM »
Hi Yogi, I am late to the party, nice sound. Congratulations for this well made engine.
Kind Regards
Achim

Offline yogi

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Re: Freelance Inline Twin
« Reply #170 on: March 29, 2018, 09:22:58 PM »
Progress on the engine has been painfully slow, but I finally have some parts to share.  :atcomputer:

Next, I'll be working on the cooling system, staring with the pump.

I started with some gear stock, parting off two blanks.



To ensure both gears are exactly the same width and flat, Brian (toolznthings) helped me out with his surface grinder.





The finished gears, with the shaft installed.



The pump housing is milled from bronze.







... so is the rear cover...





The finished pump housing parts:



With the gears installed.



And the pump installed on the engine.




Thanks for following a long and stay tuned for more...
Yogi


« Last Edit: September 21, 2018, 05:18:20 PM by yogi »

Offline Perry

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Re: Freelance Inline Twin
« Reply #171 on: March 29, 2018, 11:03:15 PM »
Great looking parts yogi. I've used J. Howells design of magnetic driven impeller water pump on mine twin engine.

Regards Perry

Offline kuhncw

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Re: Freelance Inline Twin
« Reply #172 on: March 29, 2018, 11:11:16 PM »
Yogi,

Very nice job on the pump.

Thanks for the update.

Chuck

Online Art K

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Re: Freelance Inline Twin
« Reply #173 on: March 30, 2018, 02:51:45 AM »
Yogi,
Great to see progress. I haven't made a water cooled engine, so haven't needed to struggle with the idea of impeller or gear. What were you planning for the radiator?
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline toolznthings

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Re: Freelance Inline Twin
« Reply #174 on: March 30, 2018, 10:18:36 PM »
Thanks for the honorable mention ! It's about time you got something done !  :stickpoke:

Pump came out super nice !
Thanks for the visit !
Brian

Offline Dave Otto

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Re: Freelance Inline Twin
« Reply #175 on: March 31, 2018, 01:11:13 AM »
Nice work on the pump Yogi, it looks great!


Dave

Offline Rustkolector

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Re: Freelance Inline Twin
« Reply #176 on: March 31, 2018, 04:32:49 AM »
Yogi,
Great project and nice looking pump. What type of shaft seal are you using in the pump?

Jeff

Offline Brian Rupnow

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Re: Freelance Inline Twin
« Reply #177 on: March 31, 2018, 01:48:10 PM »
Very impressive engine. Looks great and runs great. Congratulations.---Brian

Offline yogi

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Re: Freelance Inline Twin
« Reply #178 on: March 31, 2018, 05:20:45 PM »
Thank you everyone for the kind comments! It's very much appreciated.  :cheers:

Art, the jury is still out on the radiator design. I'm contemplating either a built up bar stock radiator inspired by Jerry Howell's design, or a PC cooler radiator. Right now I'm leaning towards the PC radiator. Stay tuned, I guess...  ;)

Jeff, I'll use a O-ring for the shaft seal in the pump.


Yogi

Offline kuhncw

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Re: Freelance Inline Twin
« Reply #179 on: March 31, 2018, 10:51:58 PM »


Hi Yogi,

What is the diametral pitch of your pump gears and what size shaft did you use?

Also, how did you cut the blind holes in the pump body.  I'm guessing you plunge cut them with an end mill?

Thanks.

Chuck