Acorn Presser Idea

[lessersivad]

So here's an idea I've been debating.

I would like to have a bit more CFM from my air compressor so I was thinking about using a B3 as the compressor unit.

1.3 liters = approx. .045 cubic feet.


If the engine was spun at 1000 rpm's that should give 45 CFM which would be plenty of volume i would think for lighter sandblasting.


Thoughts on the engine configuration (in my mind anyway) would involve;

Making/fabbing a cam gear so a 1:1 ratio is acheived with the crankshaft.

Disabling the exhaust valves so they don't open.

Using the sparkplug holes and manifold them together to the tank going thru a check valve/pressure relief system like a normal compressor.

The above mentioned modifications should in theory allow the intake to open on every piston down stroke, compression/release of compressed air on every up stroke.

Retain the water pump and radiator to hopefully dissipate some of the heat caused by compressing air.

These are just some of the things I've come up with. Possibly use a 330 gallon LP tank for storage.

I would think a 240 volt 5 HP motor would spin this contraption OK.

Possibly my calculations are off and someone could explain where i went astray.

Thanks.

[mikeyjd]

Cool idea. No comment about whether it would work, but it sounds good.

[Christ]

Engines basically /are/ air compressors, to some extent. You'd need better ring gaps and possibly to raise the compression of the cylinders, though. As is, you'll only get something like a max 120PSI per cylinder if all's in good condition. Raise the C/R and you can get up to 200PSI reliably, and then you have problems finding cheap tanks that can handle the pressure. [Use an old propane tank rinsed with water].

A 5HP motor is more than plenty to do what you need to do. A few recommendations though:

Instead of using the stock head/cam assembly, remove the head and install a plate across the block deck with two threaded bosses per cylinder - one for a intake filter and one for the output, which would use a check valve per cylinder. This removes a bunch of parasitic losses and allows you to change the C/R [pressure output] based on spacer plates [stacked head gaskets] instead of having to mill parts to achieve higher pressures.

You shouldn't need liquid cooling as there is no combustible fuel being spent inside the engine. You will more than likely want to use either slightly heavier oil or an external oil cooler unit mounted to the cooling fan of the electric motor.

If you want it to be dual purpose, mount the flywheel back onto the crankshaft [also acts as a balance for the compressor] and glue large sandpaper rings to it in different grits.

Hm... not much else I can of. If you take off the head and do as I suggested, you wont have anything to turn the water pump unless you cut down a timing belt and lace it back together in the correct length [no tensioner would be necessary] but as I suggested earlier, liquid cooling shouldn't be necessary anyway. If you still want liquid cooling, you'll have to add passages for coolant transfer through the head plate.

Use 3/4'' or 1'' dia pipe for the intake and pressure lines. You dont' want pressure on the motor, you want it in the tank[s].

[Rocketman]

+2 on the plate style head with poppet or reed or checkvalves, whatever you can find. That will really bump the CR too. Don't try to mess with the stock valvetrain.

Alternatively. cut the head in half just right, retain two cylinders and use the other two as the compressor. No need for a motor to drive it then

[lessersivad]

Hmmmm....The plate does sound like an interesting idea.

I didn't even think about that as an option.

[Larry Hampton]

Years ago a guy in Oklahoma took a 460 and ran one side off natural gas and used the other side as a compressor to pump natural gas into a gas gathering system. Obviously not exactly the same thing, but it worked well and made him a lot of money.

[sketchman]

+2 on the plate style head with poppet or reed or checkvalves, whatever you can find. That will really bump the CR too. Don't try to mess with the stock valvetrain.

Alternatively. cut the head in half just right, retain two cylinders and use the other two as the compressor. No need for a motor to drive it then

This all sounds good, though you'd need an end piece of the head too to either support the cam gear or the dizzy, whichever end you chose.

[zoom zoom]

This is actually sort of entertaining. I know a guy that needs a compressor, and has a spare b3 laying around. The fact that the b3 has a v rib belt already makes it really interesting.

I'm thinking if you pull the exhaust rockers out, find some 14mm pipe threaded for the plugs pitch, and a one way check valve this would be doable. I wouldn't want to mess with the hassle of taking the head off and custom fabing a plate, 120psi is plenty especially if it spits it out that fast. Run a water hose from one barb to the other..heh..... I've only got a 2 horse motor but its one of those monster motors from way back, about as big around as a spare tire, spins at 1750 and the pulley sizes would be 2:1 or more, wonder if that would be too much?

[Christ]

2hp should be sufficient. The size of the motor makes little difference except that it won't overheat while being used.

If you use a ball valve on the spark plug hole, you'll have a strange issue with the exhaust valve. It'll pull on intake and push the air up through, then you'll have a dead cycle because the exhaust valve normally opens while the piston is going up and it'll be pulling vacuum against the check valve after pressurizing it. The point of the plate is to create a two-stroke setup, which all 'normal' compressors are. The plate is extremely easy to manufacture. You literally only need a 1/2'' thick steel plate and some taps/drills to make threads for the outlet pipes with high-pressure check valves in them. You use standard air-compressor filters, if you use oil-bathed filters you also need an air/oil separator. Use copper for the outlet tubing with a heat-sink on it, doubt you'll be moving this monster around much anyway. You want the coolest possible air to be going to the tank. Hot air carries moisture and is less dense. If at all possible, use the exhaust from the cooling fan of the drive motor to push air through a condenser unit that will handle the pressure you expect to see, such as a small version of an A/C condenser unless you have access to a high-pressure liquid cooler.

You can also use a single check valve with a compression release for no-torque starting, but this would require the motor to run at higher RPM since you'd be using combined cylinder pressure to pump the tank up. It has advantages and disadvantages, but I can't cite them right off my head atm.

This design and utilization has been worked up so many times, there's really no need to be inventive with it.

[Christ]

Edit to the last though - The single check valve only works on rotary air mills. It will not work on a piston-type compressor.

[getnpsi]

I think you need to put it on a trailer and pump peoples fields out that would make a lot of money portable flood saver especially right now

The options are endless when it is not cramped up inside engine bay

[lessersivad]

Chris, I've reread your last 2 posts and I'm having kind of a hard time wrapping my gray matter around it.

You wrote,
"If you use a ball valve on the spark plug hole, you'll have a strange issue with the exhaust valve. It'll pull on intake and push the air up through, then you'll have a dead cycle because the exhaust valve normally opens while the piston is going up and it'll be pulling vacuum against the check valve after pressurizing it."

So what you are calling a "ball valve" is the "check valve"?

If it is the check valve I guess I don't understand how the exhaust valve would open if the rocker was disabled. I would think the valve spring pressure would be enough to keep it closed. I could be wrong though.

In my original post I stated I was thinking of running all the sparkplug holes together via a manifold.;

"Using the sparkplug holes and manifold them together to the tank going thru a check valve/pressure relief system like a normal compressor."

You also stated this;

You can also use a single check valve with a compression release for no-torque starting, but this would require the motor to run at higher RPM since you'd be using combined cylinder pressure to pump the tank up. It has advantages and disadvantages, but I can't cite them right off my head atm."

I was planning on using the single check valve with a compression release/pressure switch like the one on my 2 cylinder compressor. As far as I know, it doesn't spin much faster than my 1000 RPM initially proposed speed.

OK, just for the sake of making sure I just went out to check the motor RPM and the pulley sizes on my current 'presser.

Motor RPM is 3450. Motor pulley size= 3". Compressor pulley size= 10". So the compressor is turning at 1036 rpm's while the motor is spinning at 3450 RPM's.

Also as far as I could tell my 2 cylinder compressor doesn't have a primary and secondary cylinder. Both appear (from the outside at least) to be the same size so my guess is they are both doing equal amounts of compressing air thru a single, center mounted pipe leading to a "T" fitting which has small tubing going to the on/off pressure motor switch that also has a pressure dump. The plumbing then feeds to the tank thru a check valve.

This leads me to your response;

"Edit to the last though - The single check valve only works on rotary air mills. It will not work on a piston-type compressor."

My last bit of information addresses this.

I'm not trying to be argumentative. I'm simply trying to understand your statements.

[lessersivad]

I think you need to put it on a trailer and pump peoples fields out that would make a lot of money portable flood saver especially right now

The options are endless when it is not cramped up inside engine bay

Haven't had "flood stage" rain around here. If i were to attempt it, we're getting into hydraulic/fluid compression then. I'm having enough of atime trying to understand "pressing of air"....LOL.

[getnpsi]

Oh definitely not inside the engine something on the belt or something coming offthe back come on now haha

[Christ]

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?