This is our belt reduction drive and propeller combo for the Harbor Freight Predator 22 engine. It's a great power package for a mini-airboat or hovercraft. See more details at lonestarhovercr...
I built a 2 man air boat with one of these motors. I used direct drive with a 2 blade prop and I got 125-130# of static thrust with mine and would push it about 30 MPH. The only problem is their 22 Hp only use a 1" shaft to others use a 1 1/4" shaft for 22 HP and I broke my shaft off. I had used it for one summer with no problems the next spring I fried it up in my yard and the shaft broke off so direct drive I WOULD NOT USE. your set up looks very good to use good job.
Thanks Don. The only shortcoming we've found with the Predator 22 hp is the 1" shaft. We'd prefer a 1-1/8" or 1-1/4" PTO. Even if a direct drive prop is slightly out of balance, it can break a 1" shaft. But with the reduction drive, we haven't had any reports of broken shafts.
Don Elliott good advice. Whatever bearing used, it's gotta be ball - or tapered roller thrust capable of handling 250 lbs sustained thrust minimum..think 2:1 safety factor min, on critical systems
I know the below is an old thread, but perhaps this will be of help to someone... I found the thread below while searching for crankshaft replacements for the HF Predator 670cc (22 HP) engine. Coincidentally, I am also a commercial pilot, CFI, CFII, Multi-Engine, etc. I was re-powering a commercial leaf vac (aka 'truck loader) that was to be used for my own private residential use. So not a lot of extended use. To economize about 1/2 price on an engine, after a lot of internal debate and review reading, I went with the HF 670 engine, rather than a comparable Briggs + S Vanguard (commercial) engine of approx 2.5x the price of the HF engine. I did the re-power, but missed the leaf falling season. So other than some test runs, the unit was put away for the winter. In the spring, went to do some experimental / trial running of the new set up. Within 1.5 hrs use, the crankshaft sheared at the output shaft. On inspection at the break point, a cheap cast crank. Being past the 90 day warranty period, HF's position was... ohh.. so sorry... but you're on your own. On further review research, others are having the same 'cheap materials' problems with these engines. Compounded by lack of parts availability (not that these engines now seem even worth the effort to rebuild). These is no way, none, I would ever use one of the engines in a aeronautical capacity. I would not even use one again in a leaf vac capacity... where my feet are always on the ground :) Hope this is of help. Cheers - Jim
I’ve got a Harbor freight gasoline powered power washer with the smaller predator engine on it,,,I’ve used it in the summer in near 100° heat and use it hard,,, for about two years now and it runs like a champ,,? I keep the oil changed and run Kohler10/ W 30. 4 stroke engine oil in it
Nobody else responded so I will, from what little I know, 5500 is way to fast, from my research it looks like 3000 is optimal and about the max for this size and style prop. At 5500 the prop would probably just have cavitation if it didn't come apart first
how many hours do you get before you chew all the teeth off that tiny gates belt? other redrives use 1/2" belts per every 10hp with no cog belts for a reason. start up & shutdown there is a lot of torque differences on the 2 shafts. with a grooved belt there is a small amount of slip that minimizes belt wear. On a cogged belt all that energy is absorbed by the belt witch greatly increases belt wear.
Lots of people use cogged belts on redrives, including on most hovercraft. We have hundreds of hours of runtime with no visible signs of belt wear. We use the most conservative service factor from Gates and then derate by an additional factor of 2 to allow for startup/shutdown loads. The belt must be properly tensioned and there are practical limits on the size and weight of prop you can swing to lessen the energy absorbed by the belt.
Sir, i am just knowing this, how much cost to buy in this enginne and also let me know please, price this black propeller. I am from Bangladesh. Thank you.
Lots of people use direct drive and it works well except for rare occasions where it can result in a broken crankshaft. But larger propellers create more static thrust, and there's an upper limit on the prop size you direct drive safely. By reducing the speed you can swing a much larger prop and generate more static thrust from the same engine.
Aircraft engines, with a six foot prop, are limited to about 2500 RPMs. Prop tip speed becomes supersonic and the shockwave trashes thrust, snaps propellers, and sends vibration through the engine and airframe.
There's a maximum theoretical static thrust you can get from a prop of any given diameter. It turns out that a large prop (which moves a lot of air more slowly) generates more static thrust than a smaller prop (which moves a smaller amount of air more quickly). So you can design a small prop with wide blades to use all of the power from the engine, but it still won't generate as much static thrust as the same engine running a larger prop. This gets more complicated on aircraft, where you trade off static thrust (and climb rate) against cruise speed. But for airboats and hovercraft, which are all very slow compared to most aircraft, we can just design for maximum static thrust.
@@faw3511 , a propeller shaped like that (a long chord with a short radial length) would have high tip losses and would lose efficiency as a result. There are also higher shock loads transmitted to the prop with a direct drive. You can run a shorter prop at higher rpm, but you won't get as much thrust. You could also reduce the rpm even more, run an even larger prop, and get even more thrust, but that would take up a lot of space. It's all a balancing act, and you need to decide what's right for your application.
How is the ultraprop working out for you? I had one on the first Ultralight trike i built, and they were pretty loud, but they were tough, and did work, I see some changes from the 20 year ago one
The original ultraprops are on the louder side, but we've found that most of our customers prioritize low cost over low noise, so they're still very popular. On many drives though, including the one in this video, we're using the newer ultraprop 2. It's a quieter and more efficient airfoil with a more rounded leading edge and aerodynamic twist. It's worth checking out if you haven't looked at the ultraprops in a while.
PRDMRE yes absolutely. The spray and sand we sometimes kick up can erode the leading edges of a wooden prop quickly, but these composite props hold up to the punishment very well.
It would be pretty top heavy but very fast in a straight line. This entire setup weighs about 125 lbs, but it also fits the lighter Predator 420, which is about 40 lbs lighter.
@@LoneStarHovercraft sorry i was wondering if the gear reduction goes down for boats ,could it be reversed for a eletrical generator im trying to design a prototype model and needed imput
We're about to add details on our website, but the 2.2:1 unit is identical to this one except with a much larger upper pulley. We get fewer requests for the higher ratio, so we make them to order.
You can run it up to the max rpm of the prop, which is 3300 rpm for this particular prop. That would correspond to an engine speed of 5400 rpm. In practice we usually run it quite a bit slower to reduce noise though
LoneStarHovercraft for the cost of that predator you could easily pick up a reliable used 800cc rotax v twin that’s liquid cooled, fuel injected and makes 80 horse. With that much horsepower on tap any weight gain would be negligable.
Yes, we mostly run stock motors. Besides the billet rods and flywheel, some people are also changing out the cam, upgrading the springs, and putting on a mikuni or similar carb to help the engine breathe better. We haven't looked too much into aftermarket parts for the Predator, but I know many of Honda upgraded parts will fit since this is basically a GX670.
This would be great for an ultralight as long as it doesn't push you over the weight limit. Total weight of this setup is 121 lbs before any engine mods.
