Crazy Air Compressor Idea

[Ricko1966]

One of the other threads someone is talking about hand sanding their frame. I happen to have a sandblaster big enough to do a frame or a car,just not enough compressor to run it for long periods. So here's where my broken brain figured,can I make a V8 small block into a 4 cylinder compressor. My thinking is make a intake gasket out of copper or aluminum copy a stock gasket but with no intake port openings. Pull all the rockers on 1 side put really really light springs on the exhaust valves,plumb all 4 spark plug holes through check valves into a common manifold which will plumb to an air tank with BOV to regulate pressure. Down stroke,vacuum will open exhaust valves and fill the cylinder,upstroke will push compressed air out of the cylinders. I know I'd have to put iifters in the lifter bores,and tack them. What am I not thinking off? Run on 4 pump on four it ought to make all the air I could ever use.

 

[CalSgt]

Never done it before, but here are my thoughts… just thoughts

why the need for lifters on the compressor side of the engine if no push rods.

use a super stiff springs on the intake valve and skip the copper gasket, the weak spring on the exhaust side would be the path of least resistance for the intake air anyways.

Two stoke reeds on the header tubes would probably work more efficiently than the weak valve spring idea. The valve would have to be removed and the guide hole welded or maybe just tapped and plugged with a bolt.

A large tube header on the compressor side (could even be mounted upside down) would be easy to clamp an air filter (K&N type) on if you cut the flange off.

An oil separator on the compressed air lines before the pressure relief valve would probably be a good idea.

I say go for it… if nothing else it would at least be entertaining

 

[Ricko1966]

Stiff springs on the intake, yep I like it. The reason for the lifter is just to block the holes in the lifter bores. Yea I thought of reeds actually thought of reeds for inlet and outlet but seemed like a lot more work than weak valve springs and check valves. On the exhaust ports,now compressor intake I figured a stock exhaust manifold with a couple inches of pipe on it and a clamp on air filter like on the ricer cold air kits. Yea thanks for the input.

 

[CalSgt]

I thought of the manifold with a stub pipe too but was thinking headers would be easy to work, would be less restrictive and would allow for a large filter with not much fab work.

If you think about it you will be running twice the amount of air through there because the compressor side is a two stroke.

Nother idea…

I wonder if anyone makes an affordable camshaft for the conversion.

A two plane intake manifold with the intake side blocked between the carb and valve and some plumbing from the intake runners to the compressor air filter.

A special cam could also help with reorganizing the firing order so the engine would run more efficiently and optimize lift, duration and LSA for air compressor purposes.

and another thought, get some rubber plugs that fit tight in the distributors plug wire holes so you’re not shocking yourself every time you reach past the distributor.

 

[Ricko1966]

Hmmm something to think about,regrinding the cam would definitely make this easier. Plug the intake runners on one bank with epoxy then drill and tap 4 holes for stubs and air filters. The more I think about it the more I like it.

 

[SirRobyn0]

@Ricko1966 My dad has a tire inflator, probably from? I really don't know 40s maybe. Anyhow that's not really important what is important is how it works. You unscrew one spark plug, screw the threaded end into the spark plug hole, and the other end to the tire valve. Fire up the engine and when that hole is on the compression stroke it over comes the shrader valve in the inflater and the compression goes into the tire. Even if you rev the engine up some. My dad use to like to pull the choke some to raise the engine speed, even still it was terribly slow compared to today's cigarette lighter operated inflators.

I think your idea is kind of cool for the compressor, and certainly the pressure is there inside the cylinder, but I don't think there is enough volume to make it work as you'd like, but I could be totally wrong.

 

[CalSgt]

@Ricko1966 My dad has a tire inflator, probably from? I really don't know 40s maybe. Anyhow that's not really important what is important is how it works. You unscrew one spark plug, screw the threaded end into the spark plug hole, and the other end to the tire valve. Fire up the engine and when that hole is on the compression stroke it over comes the shrader valve in the inflater and the compression goes into the tire. Even if you rev the engine up some. My dad use to like to pull the choke some to raise the engine speed, even still it was terribly slow compared to today's cigarette lighter operated inflators.

I think your idea is kind of cool for the compressor, and certainly the pressure is there inside the cylinder, but I don't think there is enough volume to make it work as you'd like, but I could be totally wrong.

This is actually a “thing” some manufacturers of high volume compressors for road construction build similar designs

 

[Ricko1966]

@SirRobyn0 I like it when I'm not inflating things I can use it as a flame thrower,we gotta figure out the ignition part though. Do you think guys like me are the reason they don't make those anymore?

 

[SirRobyn0]

This is actually a “thing” some manufacturers of high volume compressors for road construction build similar designs

Cool, didn't know. Thanks.

 

[SirRobyn0]

@SirRobyn0 I like it when I'm not inflating things I can use it as a flame thrower,we gotta figure out the ignition part though.

Yea right! As an adult I wonder what that did to the inside of the tire and if there was much risk, you know having gas vapor in a tire! You could just rig up something from an electric lighter or use the lighter like a pilot light. The V8 weed burner lol

 

[Ricko1966]

I'm pretty sure I am the reason they took all the good cartoons off!!!!

 

[GTX63]

One of the other threads someone is talking about hand sanding their frame. I happen to have a sandblaster big enough to do a frame or a car,just not enough compressor to run it for long periods.

Why not just add an extra auxiliary tank to your compressor? Not knocking your idea. I added a 30 gallon air tank to my existing 30 gallon compressor and it does everything I need it to.

 

[WFO]

We rented a jackhammer for work, that came with a compressor on a small trailer. The compressor was a Ford V8. One bank of cylinders had a normal head, and ran as a 4 cylinder, and the other bank had a custom looking head, and ran as the compressor.

 

[Hunter79764]

It can certainly work, just needs some thought on the front end. What's your compression ratio existing, and what pressure do you want to end up with? You would have to have at least 8:1 compression ratio to get a possible 120 PSI, but that would be at zero flow, basically. Higher compression ratio will allow actual flow at the higher pressure. Based on some light reading over here (https://www.polytechforum.com/welding/dumb-question-on-compressor-displacement-cfm-14544-1.htm), the short version I think is that anything you have over 8:1 compression (8:1 equates to 120psi:15 psi atmospheric pressure) is one main factor, and your displacement is going to be the other factor. Half of a V8 running in compressor mode is going to give offsetting factors (half the cylinders, twice the "compression" strokes) such that a 350 is going to give 350 cubic inches of swept volume (which is about .2 cubic feet) * RPM * Volumetric Efficiency * (and I think) (Compression Ratio (CR)-8)/CR to get your CFM at 120 PSI. Use 7:1 for 105 PSI, but blasting likes as high of a pressure as you can give it.

Edit to add:
Volumetric efficiency is probably between 0.60-0.80, depending on how soft the valve springs etc. Raising compression ratio could be done with clay etc in the combustion chamber, since it won't see much real heat.

 

[AuroraGirl]

We rented a jackhammer for work, that came with a compressor on a small trailer. The compressor was a Ford V8. One bank of cylinders had a normal head, and ran as a 4 cylinder, and the other bank had a custom looking head, and ran as the compressor.

Is it balanced or negligible vibrations maybe?