Other Hobbies and Projects

[Curious Kid]

I just finished a personal "junk yard war"-like project, turning an old 2-cycle engine and changed-out 1/3hp furnace air circulator motor into an air compressor. I was curious as to what kinds of things others have or think about doing in there spare time in "the shop" or even just around the house?

As far as the effectiveness of the compressor - it only builds-up 30psi, probably because of the volume of air space created in the compression zone (about the intake and output check valves, close nipples and tee, and the piston face at TDC...all because I didn't want to nor have the ability to machine the head and fashion a bolt-on with reed valves). The compression ratio then works out to just over 2:1 (not suitible for general air tool application). Either way it stands as a "personal accomplishment" of sorts, seeing somthing come to fruition from that which would otherwise be scraped.

[ February 06, 2006, 12:40 AM: Message edited by: 59 Vetteman ]

 

[Bret Chase]

spare time? *** is that?

 

[wavinwayne]

I go to work in my spare time.

 

[Curious Kid]

Spare time...well I figure just about everyone who contributes to this board does so in their spare time. Other commitments, family affairs,...I understand - priorities!

 

[Bret Chase]

I tend to tinker with my truck in my spare time (what little there is).. It's getting a new cam, intake and full exhaust w/ headers very soon. the rest of the time I'm either at work, sleeping or watching my 3 small children while my wife is at work. I'd take up more hobbies (or ressurect old ones) if I lived in a house (instead of an apartment) w/ a garage/shop. I work on my truck in the shop bay at work during off hours, not a place to bring a 4,3, and 9 month old

 

[Bret Chase]

I'd say you'd have gotten better performance if you'd started with say an old 4 stroke briggs engine. the 2 stroke design is what's holding you back. a head would be really simple to make, imho.. just get a piece of 1/2"+ thicker steel plate, use the old head to drill the bolt holes in the plate. then, remove the valves and put a check valve on the intake and one on the exhaust.. you could leave the stock head if you wanted, but the flat plate will boost compression and performance. I might have to try that.

 

[Curious Kid]

Bret - I thought it would've been better with a 4-cycle engine as well, perhaps even keeping the valves but changing out the heavy springs with light ones, then changing the cam turning ration to 1:1. Then I could just connect the pressure line to the exhaust outlet. I do wonder though how much power would be required to not only deal with the cam system, but also the pressurized oil system (for lubrication I capped the bottom end intake of the crankcase on the 2-cycle engine to allow for oil - a crewd oil bath/sling lubrication set-up). The 2-cycle engine is belt driven and set-up to run around 400 rpm.

Like you've said, changing out the head on a 4-cycle engine would probably be best to lessen the energy required to drive it, but still would be picky as for the type of "check valves" used - reed valves having the least compartment/compressible air space, and are what is commonly used in consumer retail air compressors AFAIK, unlike the screw-on brass check valves with sprung stem valves (found at the local hardware store), and large internal air space. I might try to fill some of the excess air space so as to boost the appearent compression ratio, and thus upping the pressure capability of the current set-up before putting it "on the shelf".

Perhaps I should have entitled this thread as just "Other Hobbies and Projects?" What say you moderators?

 

[Shannow]

Curious kid...next time, get an old VW engine, and turn two of the cylinders (two front or two back) into compressors.

 

[Master ACiD]

in my spare time i sell things on ebay. mostly cars. i buy local cars which are broke down for real cheap, sometimes free. fix them up and sell on ebay. right now i own 5 cars. 2 are broke down and need more work because they are ready to sell. 2 are my daily drivers, 1 is almost ready to be put on the auction block.
i also ebay alot of other stuff. anything that i can make money on. i just sold 7 oem toyota air filters in the last week. thats about $50 right there. also sold a couple tires for about $80 in profit. i figure it averages out that i make about $200 a week on internet sales between cars and other stuff. comes out to about $50 an hour because i only put about 4 hours a week into internet sales.

its a nice little side hobby that i enjoy. i also make money off it so that is a good bonus.

 

[The_Jeff]

master acid, were you cryptokid on this bbs in another life?

If not you should hunt him down, he has similar stuff going on.

I only notice this, out of envy for the toys in your yard(s).

 

[Bret Chase]

using the cam wouldn't work very well, as the timing for a compressor is completely different than for an engine. you want the cylinder to be exhausting the second the cylinder pressure is > than the tank pressure. this is why reed valves work so well in this application. I mentioned using plain old check valves, as most briggs type motors have ports with pipe thread already in them. I do agree that you need the smallest "combustion chamber" possible to make it effective. so leaving the valves in w/o the cam and putting reed valves in the plate head would probably be the most effective.

 

[Curious Kid]

Shannow, you just gave me a thought.

In another section there's a link about DIY displacement on demand which talks about deactivating 1/2 the number of cylinders in an effort to conserve fuel during cruise conditions.

Taking the above, how might it be that a hybrid system be made so that when the selected cylinders for deactivation become just so, the compression energies that would otherwise exist for those simply cutting off the fuel supply, were to store that compressed air into a tank, and then it could be later released...ah, scratch that thought as simply enguaging the cylinders that were once deactivated would serve to provide the required energy boost under increseing, high load demand.

It all comes full circle. You don't get more than is put in, often time you get less of that which you're looking forin the first place with every conversion!

I stumbled upon this engine design, and at a glance it looks interesting: http://www.revetec.com/ Note to Shannow - they're also located in Australia I see.

Also, thanks moderators for the heading change.

Take care everyone.

 

[Curious Kid]

I hear you Bret. I've since put the unit on the shelf after trying a little experiment to see if filling some of the excess space in the "compression zone" would do. I managed a 3psi increase in max pressure, however much else would be deemed very tedious and time consuming with the current set-up and possibly representing air-flow restriction.

The blower motor with it's rubber mounts, would also require some ridgid bracing/mounting modifications as the torque pulses from the compressive energies cause twist with rebound - rotational vibration. This would only increase with incresing pressure capability.

I've also begun to see indications of some oil blow-by/seepage. I wonder just how much cylinder blow-by may also be effecting pressure limits on top of everything else.

If I was to go any further with this project, aside from a compression check, possibly cleaning of the piston ring(s) and replacing the gasket material with other, I would make use of the original stainless intake reed valves, and fabricate an intake-exhaust manifold that threads in-place of the spark plug. Cylinder head milling would require my being totally satisfied with the mechanical condition and capability of the engine and electric motor.

It does run comparitively quiet next to those other consumer oil-free units that seem rather prolific in handyman outlets, which is a really nice feature IMO.

Master ACid - Nice to hear that you're getting some return on investment, other than personal satisfaction that is.