I’m assuming you understand the principles of how a log splitter works, so I’ll just jump into the specifics. If this is Greek to you, Google is your friend.
Most here, including myself, have found that a 4” cylinder running at 3300 - 3500 psi is about all the force we will ever need to split any piece of firewood. These machines are variably badged 22 - 25 ton, and 90%+ of them come with a 200 cc motor and an 11 gpm 2-stage gear pump (often overspun to 120% of rated RPM) yielding a cycle time of roughly 11 seconds. Choose your favorite color, avoid some of the ergonomic problems of a few brands (like an exhaust that points in your face), and they’re pretty much all the same basic hardware. These usually cost $900 - $1100.
Then there are those who, without really thinking things thru, decide they need something more. They buy a 28-ton machine, which is the same stupid 200 cc motor with 11 gpm pump, but running a 4.5” cylinder at a much lower cycle speed. This is the worst choice you could make, IMO... the extra 6 tons of force buys you nothing, and the slower speed is just a frustration.
One step up from that, you have the 35 ton (5 inch cylinder) machines, and these usually come with a 16 gpm pump. Some of the cheaper ones will still have the 200cc motor, which will never work well, that motor does not have sufficient horsepower to drive 16+ gpm. Properly configured ones will have at least 300cc of motor, and some of these can even come close to the cycle times of the 4” machines, as (5/2)^2/(4/2)^2 = 17/11. But they cost much more, and if you’re running the same cycle time, what good are they? I’ve never drug home any piece of wood that my 22-ton splitter couldn’t split with ease, and I’m splitting more wood than any 3 average hearth.com members, almost entirely oak, ash, elm, and hickory.
Another issue that should be mentioned here is weight. We all like to feel like we’re getting good quality and value, and there’s a tendency to want to buy the heaviest machine we can afford. But then we want to move that machine a few feet at a time to keep stacking off the splitter as we work, without the bother of hooking it to the tractor, and wish we had something lighter. There is absolutely no reason, IMHO, to buy an insanely heavy machine for home use. You will just be hampering your own productivity, by making it too difficult (or impossible) to move it around your splitting area, as you work.
Going the other direction, there are the “fast cycle” machines, made by companies like Iron and Oak. Here, they take the 22-ton chassis (200cc / 11 gpm), and stick a 3.5” cylinder on it, and re-badge it 19 tons. These things are great, but you will hit some wood they can’t split, from time to time. I used one of these for a few years, before upgrading to 22 tons, and can say that the 4” cylinder is the threshold level to split any piece of firewood I ever encounter. These 19-ton “fast cycle” machines are a great option for those doing solely softwoods, or for those who don’t mind avoiding gnarly stuff, but they’re not for me.
Finally, we come to my favorite option, or at least the most affordable compromise to it, but first a disclaimer: I’m not suggesting you do this, I’m just saying what I did. In other words, don’t cut off your fingers, claim Ashful told you to make your splitter faster, and then come crying to me. Proceed at your own risk. My favorite configuration is a 4” cylinder on a 16 gpm pump with 300+cc of motor, which will give you 22 tons of force with an 8 second full-cycle time at 3600 rpm. I find the cycle times of the typical 22-ton machine (11 gpm) too slow for my work pace, and I really missed that “fast cycle” Iron and Oak machine I had been using before buying my 22-ton machine.
I built my own by removing the motor, pump, and all under-sized lines and fittings from my 22-ton Speeco (TSC Huskee) machine, and replacing with a 344cc 3600 rpm vertical shaft Intek and 16 gpm pump. I suppose you could do it with much less work by starting with a (35-ton?) machine already having the right motor and pump, and just “downgrading” the machine to a 4” cylinder from eBay.
I actually bought a motor with electric start, so I could run a cord to my tractor for cold starting, and I’m glad I did. Cold-starting a 16 gpm machine is no small feat, in January. Once the machine is warmed up, re-starting it with the pull cord is easy.
I’m still waiting for some nut to put a 22 gpm pump on a 4” cylinder, as I had originally planned to do when I hot-rodded my own splitter, and hit 6-second cycle times. But that would require a custom cylinder with SAE-10 or 5/8” ports at mucho $$. If you’re sticking with stock 4” cylinders (SAE-8 or 1/2” ports), you’re pretty much stuck at 16 gpm, and 8 second cycle time.
There are obvious safety concerns with making your splitter faster, so I make no claims or assumptions about your ability to run this thing, you are working at your own risk. But I believe the cycle time you will achieve with this rig is no faster than the “fast cycle” machines already produced by companies like Iron and Oak, check me on that.
There are those here who will argue that an 11-second cycle time is plenty fast for them. What can I say, they work slower than me. If you’re retired, or like to relax while splitting, maybe disregard all of this. That’s not me, I like to hustle when getting my work done, so I have enough of my day left to go sailing or do something fun with my family.
Summary: 22 tons is a minimum requirement, any more is usually a waste. Shop on speed first, you will hate a slow splitter, if you have any time constraints on your splitting work.
