# V4 steam engine - based on CFellow's opposed 4



## crueby

Just finished a V4 engine based on CFellow's wonderful opposed 4 engine. Used his basic layout and valve arrangement, with a few things changed: swung up one bank to make it a V, changed the gears to a ladder chain, went to a 2-stroke cycle (though swapping the valve rod and top gear would make it a 4-stroke like his), and upped the bore to 3/4". Makes a great sound (dont think the camera picked that up that well - in person it has more pop to it, sort of like a gas engine). The flywheel is from another engine, and does not fit that well - wobbles a bit, but I couldnt wait to fire it up. The valve springs took some experimenting to find ones that were the right strength and size - found some in mechanical pencils that worked fine once shortened a bit.

photo attached, here is a video clip as well:
[ame]http://www.youtube.com/watch?v=_CsfD9YcKeg[/ame]


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## cfellows

Wow, very nice. Doesn't sound like it's hitting equally on all cylinders. Is that just the video? You can check by feeling the air coming out of the exhaust pipes...

Chuck


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## crueby

You may be right - one of the exhausts has less air. Maybe that ones spring needs tweaking, or the valve ball in it is sticking. I had to play around with most of the springs to get it to run at first. With the ones in there now, it has a pretty good pressure and speed range, though if I crank it up too high it seems to stutter - probably not able to return the valve quick enough. Did you see that kind of behavior?


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## b.lindsey

Nicely done crueby...the "V" gives it a nice appearance too. Thanks for sharing the viedo.

Regards,
Bill


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## Wrist Pin

That is a sweet design!
Do you have a link to the original thread?


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## CaptSensible

I love it! Love it love it love it! The chain for the valves and V configuration are making it very tough and James Dean-ish, if James Dean was a miniature engine. It goes in a steam roadster, 2 seats and maybe one set of golf clubs. Whistles as it tears down the highway. ;D


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## crueby

James Dean stoking a boiler.... Brando, maybe, but Dean?! 
It could look good in the Munster-mobile too.... would need more flames.


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## cfellows

crueby  said:
			
		

> You may be right - one of the exhausts has less air. Maybe that ones spring needs tweaking, or the valve ball in it is sticking. I had to play around with most of the springs to get it to run at first. With the ones in there now, it has a pretty good pressure and speed range, though if I crank it up too high it seems to stutter - probably not able to return the valve quick enough. Did you see that kind of behavior?



Sorry, I missed this. Yes, the type of spring makes a lot of difference. A stronger spring gives you a higher top end, but also requires more air to make it run, even at lower speeds. Also, won't idle as slow with a stronger spring. I've been noodling around with a design where air pressure returns the slave valve, but don't have it finalized yet. If I get it to work, it should greatly improve the speed range since it would act like a weak spring at low pressures and RPM's and like a strong spring at higher pressures and RPM.

Another thing that would help would be variable timing on the camshaft. Advancing the cam timing at higher RPM's would improve the top end. It would not only "fire" quicker, but would shut off the air supply sooner giving the slave valve more time to close.

Chuck


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## crueby

I really like the idea of the air-return - something sort of like a
gas-return on a rifle maybe.


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## vincex

hi, can someone help me and send me the blueprints of a model engine like this?

[email protected]

thanks ..


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