Acorn Presser Idea

[Christ]

In the case where you wanted to use it to move fluids, it would - and it would be very good at it. You'd have to use LARGE intake and vent tubes, an overpressure vent, and a very slow speed because the piston heads and rods weren't designed to sustain anything near 1,000 PSI [dynamic load] that you could very easily reach pumping fluids.

If you have to use it, it'd work for that. If you don't have to, a rotary or positive displacement vane pump will work /much/ better and with less risk to persons and the equipment.

[Edit: Replace 'fluids' with 'liquid' since we've gotta be technically accurate here. Air is a fluid.]

[lessersivad]

Check valve = ball valve. Diff names, same thing. [They're actually different, but perform the same function.]

If you disable the exhaust valves, that will work fine [using the spark plug holes] - however, You end up with two full strokes - one up, one down - that are doing nothing. Huge waste of energy right there. In fact, it halves your potential air-capacity [amount moved, not pressure].

This brings me to suggesting the plate solution - If you look at a compressor when it's apart, it's essentially an early-style 2-stroke engine with reed valves [instead of having the cylinder lining bored in different places, it has the 'holes' for an intake and exhaust valve that function with reed valves]

In the instance I suggested, you need a one-way valve both on the intake and the exhaust sides, so that it sucks in the filter and blows out the exit hole.

Using the head as a compressor unit can be done, it's just a gigantic waste of potential and energy use without modifying the cam to use the intake valve every 180*.

The twin cylinder you have is more than likely a parallel twin that's staged at 0* - both cylinders rise and fall at the same time. In this way, it wouldn't need a check valve on both cylinders, because they're both acting like a single, huge cylinder, pushing both their volumes through the tube at the same time.

Using a B3 similarly, you'd need a total of 2 check valves, with 1/4 and 2/3 tubed together and a single check valve on each line. If you mix 1/4 and 2/3, you end up with a compressor that does nothing, because it just pushes air back and forth between cylinders via the exit tubes until you're at very high speed, where you risk overheating and not moving much air into the holding tank.

I know the previous posts were a bit confusing, and I don't take your questions to be argumentative. We all gotta learn, right?

Thanks for the clarification on the terminology concerning the valves. I've always thought of a ball valve as the 1/4 turn type which has a sphere in the middle.

So after reading your response I kinda/sorta picture in my mind the need for check valves between opposing cylinders. It makes sense to me that the air would simply move from one cylinder to another. Pretty much "monkey motion" with no work actually getting done.

As for my current compressor I'm pretty sure that each cylinder reaches TDC opposite of each other. I would think the "exhaust" reed valves would act or serve as check valves to prevent the compressed air from moving back and forth between the cylinders. (But, I've been wrong before.)

I agree that disabling the exhaust valves would cause a certain amount of "lost potential" for compressing, under normal valve timing. This is why I originally presented the idea of a cam sprocket of the same diameter as the crank sprocket.

This would in essence turn the original 4 stroke engine into a 2 stroke compressor.

Piston travels down while intake valve is open then intake valve closes when piston is traveling up, exhausting compressed air out of the sparkplug hole. Then the series starts all over again.

I hope that makes sense.

This exchange of ideas without any "browbeating" is what I really enjoy about this forum.

EDIT; Does anyone have the recommended reading ,PSI wise, that should be seen during a dry compression test?

[Christ]

If you replace the cam and crank pulleys to make them 1:1 with each other, you'll have the intake opening every pull, but closing before the piston reaches BDC, still some lost potential there.

Remember that 360* to the cam is 720* to the crank, so if your normal intake event is 60* at the crank @ 2:1 and you reduce that to 1:1, you're only going to see a 30* intake event.

You could play with cam timing at that point to get different results, for instance if you're pulling vacuum against the intake valve as it opens, air will move in faster than it does just by cylinder pull for a second or so. At the correct speed and timing, you may be able to set it up to move /more/ air than it could under natural circumstances per revolution due to the helmholtz effect causing what amounts to 'supercharging'.

Much, much too involved for me, really. I know a little about it, but never found it necessary to study once I learned how to turn the engine into a compressor myself.

PS - You can probably sell the head and buy as many pieces of steel as you'll need to allow you to screw up a few times. Steel isnt' really all that expensive. Alum plate would work just fine, too.. and it has the added benefit of being a heat sink if you cut some grooves into it.

[zoom zoom]

What about adding one of these to each cylinder..

http://m.homedepot.com/p/Powermate-1-2-in-90-Degree-Right-Check-Valve-031-0094RP/202593086

[Christ]

That's what I was referring to when I said 'ball valve', actually.

There's just a steel ball with a spring on it in there. Pressure opens it, pressure holds it closed. No leverage or anything on it, just a ball and a spring.

EDIT: Unless it's the diaphragm type. Duno unless I open one. I scavenge them from old compressors though.

[Christ]

If it were me doing this, considering the experiences I've had with building compressors from junk, I'd seriously consider getting some 3/4'' or 1'' one-way valves and using copper or aluminum tube with heatsink foil on it, including a 1'' or larger inlet air filter per cylinder or a 2.5'' single filter on a inlet manifold oil bathed with an air/oil separator on the condenser line.

You're going to fill a 60gal cylinder in less than 2 minutes using this setup - engines are designed to move LOTS of air.

By comparison, my actual 50gal shop compressor fills in about 3-4 minutes to 120PSI from about 60 [turn on pressure]... it's a dual stage unit and the large piston is about half the size of the pistons in a B3. We're talking chinese scooter small.

[zoom zoom]

I'm not looking for max potential or anything fancy, I just want it to work. If the exhaust stroke is a dead stroke is it really going to hurt anything? I'm having trouble understanding what's going on with it that would make it not work.

[Christ]

Oh, it'll work, it'll just be terribly inefficient, generate excess heat [dead stroke with no intake air to cool the piston] and generate less than stellar pressure [longer pump time, lower max pressure].

Some company used to sell a 'flat repair' kit that consisted of a spark plug socket, a plug hole adapter with a air chuck and 30ft of hose, and a can of something remarkably similar to fix-a-flat. You put the chuck adapter in the spark plug hole and start the engine, let it run one cylinder down until the tire was full, replace the plug and be on your way.

Not really related, but this made me think of it.

[tooldude]

I believe you can make a compressor from an engine block if you work at it, and if you would run it with another Festiva engine on the two crankshaft pulleys and a belt I would sure contribute 5 bucks.

[zoom zoom]

Well I got the engine unbolted from the auto tranny and up on a stand, degreased it for an hour or two and was just playing around with it. It spins practically as easy as the compressor mounted on the tank right now without the spark plugs.

Thinking about it, I honestly don't know what it would hurt to just leave the exhaust rockers on and let it cycle as a regular engine. There's 4 strokes 2 up 2 down, intake, compression, power and exhaust... so the compression stroke would be the only one actually pumping up the tank, and the next power stroke would be creating a negative vacuum that lasts a whole couple milliseconds until the exhaust valve opens and neutralizes the air pressure. I don't know what kind of negative effects that will have but I want to hook it up and find out.

I was also kind of thinking that if I went ahead and took the springs off the exhaust valves, and cut them so that they barely hold the exhaust valve up fully seated, it would reduce the spring pressure, which could potentially allow the exhaust valve to open up and act as an intake stroke on the power stroke, then the next one the valve would shut when the piston is headed back up and work to compress the air twice per cylinder per revolution....but honestly right now I just want to try to make the thing work, period. I've got plenty of spare parts for heads, rockers valves, cams, springs, whatever to try stuff and if it doesn't pan out I can put it back to stock.


Anyway, come to find out, a 3/8" NPT pipe thread is close enough to the spark plug thread pitch that I think with some pipe tape and torque it will go in and stay in for a long time. I'll need 4x 5" peices of pipe, 4 one way check valves, 3 T fittings, and 2 90's....plus a couple pieces of small pipe to go between....I'll try to get something figured out at the hardware store tomorrow if I remember after work.

[jason_]

Kill the head, it's useless for this.

I called around and found then cheapest drop in reed valve assemblies. Milled a heavy plate of iron for them, and made a cheesy cover.

I did this exact same thing to a 955 inch inline 6 cylinder Cummins.
4 reeds per cylinder. All 4 are intake, and used injector hole with a check valve for out/supply.

Beeotch makes gobs of air.

I used water jacket, factory oil pump, plugged a few holes. Works nice.

I'd do it to my other 955, but that waters my garden and back yard once a month.



Sent from my rooted HTC Supersonic using Tapatalk 2 Pro

[Christ]

zoomzoom - You might have an issue with threading a bunch of stuff together with tee fittings to make a manifold for the spark plugs... Namely that you'll need to put a flare union between each tee fitting or you'll never get everything to thread together properly. [Unless you screw the nipples wayyyy too far into the head and then back each one out into the Tee's. That works, but it may leak too.]

Instead of using NPT fittings, try getting some copper flare fittings or a few quikconnect push-loks that will thread into the head, then you can use 1/2'' copper and you won't have the problem of needing [relatively expensive] flare unions.

[Tommychu]

Kill the head, it's useless for this.

I called around and found then cheapest drop in reed valve assemblies. Milled a heavy plate of iron for them, and made a cheesy cover.

I did this exact same thing to a 955 inch inline 6 cylinder Cummins.
4 reeds per cylinder. All 4 are intake, and used injector hole with a check valve for out/supply.

Beeotch makes gobs of air.

I used water jacket, factory oil pump, plugged a few holes. Works nice.

I'd do it to my other 955, but that waters my garden and back yard once a month.



Sent from my rooted HTC Supersonic using Tapatalk 2 Pro

Don't you mean 855? If Cummins ever made a 955 I've never seen one. And I've seen about 100 855/N14s...

[zoom zoom]

zoomzoom - You might have an issue with threading a bunch of stuff together with tee fittings to make a manifold for the spark plugs... Namely that you'll need to put a flare union between each tee fitting or you'll never get everything to thread together properly. [Unless you screw the nipples wayyyy too far into the head and then back each one out into the Tee's. That works, but it may leak too.]

Instead of using NPT fittings, try getting some copper flare fittings or a few quikconnect push-loks that will thread into the head, then you can use 1/2'' copper and you won't have the problem of needing [relatively expensive] flare unions.

Yea I was thinking about that, I wasn't sure how it was gonna work out, so I might see what lowes has in the plumbing department. Maybe some of those sharkbite things, or even 3/8" couplings on each cylinder, kind of depends on the space between fittings...I'm not sure how it will work, I think I need to try and use 3/8" npt size stuff so that I can use cheap check valves...?

Jason...I don't have a problem with drilling tapping cutting and fabbing a whole head/manifold but that's gonna be as expensive if not more than attempting what I want to do...if I just use the block it takes away the wow factor of having a complete engine mounted on top if a 60 gallon tank with a 100lb propane tank on tap for extra reserve. I know the prices of small pieces of steel, and I can imagine a piece of 1/2" steel stock will cost quite a bit more than $50 worth of pipe fittings...which i'd still need. Simple cheap and effective is all I'm after.

[lessersivad]

Zoom,

Good for you for running with the idea. i was simply debating it in my head but you took off with it.

I feel like such a slouch....LOL.