Hot Rodded Compressor

Remote

Observer
First, all this stuff is about a 3 year old Harbor Freight and a new (Jan) Master Flow 1050 Tsunami. The MF1050 has quite a few similar variants. The current HF unit is not worth fooling with.

Long story short, the best mods, (if you have any kind of other life) is to re-wire the thing and open up the ports. Everything else I did had minimal performance gains other than longevity.
I would not recommend these things for any more than filling tires as performance drops off rapidly over 40psi. They will go to 150 and beyond but at great cost in time and risk of melting the Polar Icecap.

Testing was done as follows: 4900' elevation, room temp (68 deg or so), powered from running truck/Optima, filling a 3.5 gal tank from 0-105psi and the most useful 0-40psi.
3 stages of development were tested in this manner, stock, with wiring and porting, and finally with "the works".

Results: 0-40psi, stock 56 seconds, with wire and porting 42 sec, all mods 37 sec.
Results: 0-105psi, stock 3min 38 sec, with wire and porting 3min 21 sec, all mods 3 min 15 sec.

This shows that most of the gains were in the "tire inflation" zone. If you want to keep a decent size tank filled and use air tools, these things are not the answer. Get a $200 Puma, divorce the tank, pump, and controls, and be done.
On the 1050 I run an 85psi on, 105psi off Viar pressure switch. This allows the use of a 10' power cable and a coiled hose/standard fittings without having to manually turn the thing on and off all the time while I check the tire pressure. Just pull off the tire chuck, the compressor pressurizes the hose to 105psi (in about 2 sec) and shuts off.

Here is the play by play.
Steps may not be in chronological order.

14g stock wire and 12g "Low Voltage Underground Landscape Lighting Wire" sold by the foot here at Lowes @ $0.56/foot
14gVS12g2.jpg


Ditch the fuse holder and replace with a quality one or better yet a $4 30a ckt breaker. Check all connections and re-solder any thing that looks weak. I was able to cram it all inside the end bell including the breaker. The relay will want to short against the end cap of the motor. I arranged the wires to lie between the two.
WIRING2.jpg


The surfaced head showing the opened up intake and exhaust. I left a thin web of material to help support a lighter thinner and flatter one from .003 feeler gauge stock. Look how crude the .006" stock reed looks compared to the .003" gauge stock. Red Loctite on the reed screws is good. The intake provided by far the biggest gain of the two.
2VALVES2.jpg


Head with beautiful new reed.
NEWVALVE2.jpg


Intake and exhaust drilled and tapped to accept 1/4" NPT manifolding and fittings, "color matched" of course. Drill out any pipe fittings used on the intake side to the id of the 1/4" pipe, makes a difference.
FRONT2.jpg


This is a HF unit with the head jacked up showing the piston with its dual (riveted in place) intake reeds. I'm working on porting that baby now. (Edit, the HF unit was merged into the 1050)
HFPISTON2.jpg


After testing the thing worked great but the 1050 motor would not restart against a head of any more than 30psi due to the higher compression. It just buzzed and made the cables get real hot. Apart came the motor. The plastic brush holder was warped due to the thermal cut out switch being jammed underneath. That’s how they built it. That put the brushes at an angle to the commutator, not good. I put the 1050 motor away for now and planned to swap in the HF motor.
BENTBHOLDER2.jpg


The HF motor suffered from the same thing and the armature was different leaving 2/3 of the brush hanging out over the end of the commutator. The solution was to install 5/16" stand offs under the holder and add two more mounting bolts to draw the holder parallel to the motor end plate.
FIXEDBHOLDER2.jpg


The 3 year old brushes had scored the commutator so on to the baby lathe to make it like new.
ARMATURE2.jpg


At this point, a picture is worth a thousand words, what a mess.
MESS2.jpg


Continued
 

Remote

Observer
The Finish

Now the differences between the 1050 and the HF were really adding up. Although from a distance things like the castings look identical, they are not. The HF motor makes the 1050 look like a toy. It has stronger magnets, better ball bearings, the armature had nice tight windings, there were the proper high dielectric insulators on the armature polls, a .1uf capacitor across the motor leads (cuts down arcing of the brushes) and the can was some kind of seamless tube that had been finished up on a lathe.
The bore and stroke of both are the same and the pistons are interchangeable.
In both units the crank throw was not inline with the cylinder. This caused a good bit of binding of the piston/cylinder on the 1050. It took 5/32" spacers between the motor (HF) and crankcase (1050) to get it right.
Finally, the HF heat sink was a light interference fit with the cylinder sleeve while the 1050 had 4 little bosses only allowing minimal contact. The 1050 heat sink is mostly to hold the head up. I used the HF heat sink in the "Frankencompressor".
CYLINDERS2.jpg


The final hybrid after proper painting and yes, the tips of the fins have been wet sanded to bright metal. Alert the Mall!
HYBRID22.jpg


And another
HYBRID12.jpg


The test rig
TEST2.jpg


One final observation. From to about 0-35psi these things really shine. Above that they just don't have the displacement to be of much good. I have read posts that claim 2.5 cfm @90psi, it just isn’t so. I would respectfully question the accuracy and method of their testing.
One more thing, I promise it's the last one, I ran a 0-30 psi test and it only took 24 seconds.

Questions, confused, just ask.
 

FlatlinesUp

Adventurer
WOoHOO!!! it's extra-BLINGY! :victory:

Nice job on the rebuild, and great work on the shiney bits.. there's no shame in making your work shine a little
 

bjowett

Adventurer
YES! Another after my own heart... if it does something, hot rod it. A couple years back I ported the pukey little compressor that I use with my quad for flats... what a difference in fill time when the pressure is under 7 psi. Too bad we can't easily mess with those reed valves (other than material/thickness).

My only criticism... that 90 egree elbow on the intake... velocity stack city my man!

Awesome post!
 
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RHINO

Expedition Leader
wow thats what i'm talking about. i guess i have a project for the work bench now.
 

Remote

Observer
My only criticism... that 90 egree elbow on the intake... velocity stack city my man!

Awesome post!

I actually did a bit of "flowbench" testing with the intake fittings. I kept drilling out the ID of the fitting until the rpm "note" stopped increasing.
 
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this may sound dumb but, will a 1/4" npt tap say that on it? i looked at tractor supply this evening and could find nothing that said that. would i be better served at lowes or home depot? do they usually come with the approprite drill bit?

sorry for the hijack.
 

soonenough

Explorer
this may sound dumb but, will a 1/4" npt tap say that on it? i looked at tractor supply this evening and could find nothing that said that. would i be better served at lowes or home depot? do they usually come with the approprite drill bit?
Yes, a 1/4 NPT tap should say "NPT" on it. I guess it could be labeled as "pipe taper" or "tapered pipe". The tap will have a visible taper to the threads, and should have 18 threads per inch. You just want to make sure you don't get a straight pipe tap or a normal 1/4"-20 or 1/4"-28 tap (although the outer diameter of a 1/4 NPT tap will be significantly larger than a 1/4"-20 or -28; it's actually closer to a 3/8" thread).

The drill size for 1/4 NPT is 7/16".

I can't say for tractor supply, but Lowe's and Home Depot should definitely have these (the stores here have them anyway). Or if you can't find them locally you can buy them online at any number of places like McMaster-Carr or Grainger

Here's a pic:

image.php
 
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thats what i needed to know. i will stop at home depot tomorrow. tractor supply had the 1/4 20's but not the npt. thanks for clearing that up.
 

CanuckMariner/Nomad

Love having fun 😊 in the 🌞 by the ⛵ and the ⏳
Nice post, Terry! but as the guy says you have way too much time on your hands. Nice bit of work though and you obviously know your stuff. Hope our trails cross again in the near future. Hi to the HB as well.
 

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