Had a 10 horsepower Little Wonder leaf a blower and the original briggs 305cc 10 horsepower engine failed on the connecting rod big end. Ended up repowering it with a Harbor Freight predator 301cc 8 horsepower engine as I was mainly interested in matching the CC's more so than the fake horsepower ratings. It required some shimming to move it back and the new engine is slightly taller so the mounting plate had to be rewelded and shortened. Upon getting the engine up and running in fully assembled I noticed that when trying to run it at 3600 RPMs the governor is nearly wide open and when I push the governor arm wide open I can get 3780 out of it. This tells me the engine is underpowered for this application but the Briggs engine must have been also as it didn't last very long. As long as the oil is checked and changed regularly in the cylinder fins are cleaned out regularly would there be any durability concerns running this engine that close to wide open throttle to maintain the manufacturer's rating of the impeller.
Lil wonder blower repower. Concerned about engine life.
- Thread starter Fordiesel69
- Start date
Yep, and your oil of choice will also be more critical running at those RPMs.
Blower impellers are designed to put a full (or nearly full) load on the engine at it's governed speed. Price/market considerations dictate that the manufacturers not over-power their blowers. Because of this, blower engines tend to have a short service life. IMO you don't have a problem here.
Correct the 420cc was a monster and we would have had to really get creative with the fabrication. I could have ordered better engines online and had one shipped but I wanted it locally. Most blowers of this size have 7/8/9 HP engines by subaru, Honda Clones, and very few with genuine GX series honda. The max I have seen is a GX390.
I hope my explanation was clear. If I reach in and override the governer arm, and open the carb to WIDE OPEN, the engine is only capable of spinning 3780RPM. The engine cannot accelerate any further.
I know im taking a gamble with the predator 301, and I know you can get bad luck with bad metalurgy, but I really need this one to last 5 or so years. The briggs blew up twice, seemed like 5-6 years. The first time the rod snapped but the crank was OK. This time it had too much aluminum transfer and everything inside shredded up. And this is a residential used unit.
What is a good oil selection? Becuase we have cold temps here in Erie, was thinking a diesel 15w-40 or a 5w-40, maybe a 10w-40 motorcycle oil.
I hope my explanation was clear. If I reach in and override the governer arm, and open the carb to WIDE OPEN, the engine is only capable of spinning 3780RPM. The engine cannot accelerate any further.
I know im taking a gamble with the predator 301, and I know you can get bad luck with bad metalurgy, but I really need this one to last 5 or so years. The briggs blew up twice, seemed like 5-6 years. The first time the rod snapped but the crank was OK. This time it had too much aluminum transfer and everything inside shredded up. And this is a residential used unit.
What is a good oil selection? Becuase we have cold temps here in Erie, was thinking a diesel 15w-40 or a 5w-40, maybe a 10w-40 motorcycle oil.
Run it, if it blows up spend more money on the next motor. I'd go with a good 5w-40 diesel oil, you could run a 15w-40 if you let it warm up before going to work.
You may not understand how a blower works then...to get the airflow it has today, you MUST spin the shaft at least the same as the stock engine. If you "up-power" this, and want lower engine speeds you would have to also add a gear box.
I think OP made a good choice...If it were mine, I would wire it wide open for some more "umph" and run whatever synthetic I had laying around from my other vehicles (most likely a Euro Spec 0w-40 or Delvac 15w-40)
What Oil were you using on the Engine that Failed?
Its not actually mine. Its a friends. Harley, royla purple, or valvoline 20w-50.
I see a lot of those push blowers with blown engines, and some that are several decades old. What I've noticed is that since they run at full load and wide open throttle, they are very sensitive to oil level and quality. Each one that I have seen failed was from a blown connecting rod, and each failure had signs of oil starvation. I replaced the engine on one recently (8hp Briggs flathead) and when the customer went to test run it, the first thing he did was tip it up towards him so the engine was on an angle. Sure, easier to push, but if done for long periods of time will starve the engine of oil.
A few thoughts:
1) If you can get 3780 wide open, the fan is not loading the engine fully. That additional 180 RPM is 5% more RPM but likely requires 10-15% more HP. Centrifugal compressors, which is what this is, have a steeply curved power/RPM graph.
2) Adjust your governor to achieve the RPM you want. You may want 3600, or you may want some other RPM for your own reasons...
3) Choose an oil with at least a 3.8 HTHS, better still if HTHS approaches 4.5 or so. Hard working air cooled engines may operate at an oil temp above the 100ºC/212ºF rating of say, 10W-30 (with 30 being the 100c viscosity). HTHS is far more important here.
4) I'd consider using 5W-40 Rotella T6 or the Mobil 1 equiv TDT or other synthetic 5W-40 choice. If you are going to choose a 15W-XX oil, also consider M1 15W-50. It will still start easily in cold weather and warm up won't be problematic.
5) Grab your trusty Harbor Freight thermocouple and measure the oil temp immediately after hard use. This can help you determine just how much viscosity you need.
1) If you can get 3780 wide open, the fan is not loading the engine fully. That additional 180 RPM is 5% more RPM but likely requires 10-15% more HP. Centrifugal compressors, which is what this is, have a steeply curved power/RPM graph.
2) Adjust your governor to achieve the RPM you want. You may want 3600, or you may want some other RPM for your own reasons...
3) Choose an oil with at least a 3.8 HTHS, better still if HTHS approaches 4.5 or so. Hard working air cooled engines may operate at an oil temp above the 100ºC/212ºF rating of say, 10W-30 (with 30 being the 100c viscosity). HTHS is far more important here.
4) I'd consider using 5W-40 Rotella T6 or the Mobil 1 equiv TDT or other synthetic 5W-40 choice. If you are going to choose a 15W-XX oil, also consider M1 15W-50. It will still start easily in cold weather and warm up won't be problematic.
5) Grab your trusty Harbor Freight thermocouple and measure the oil temp immediately after hard use. This can help you determine just how much viscosity you need.
Oh I forgot the mention, the coldest temp for starting will be 40 degrees F. So I think I can get away with a 15w-40 diesel oil to keep it uniform with his diesel tractor. This should give an HTHS higher than 3.8 but less than 4.5, in addition to still being able to start it cold. With the last weeks of fall weather, it can get into the 20s at night but he will have a heated garage. Also this blower will never run in the summer months, just september, october, and sometimes into november. Usually for runtimes between 2 to 4 hours per use.
https://buffaloturbine.com/
2 to 4 hours per use, I have this Little Wonder with a 13 HP Engine that I was using on a 1-acre property for like 30 minutes a time. I got tired of pushing the thing and ended up getting an Echo Backpack Blower. Here is what is ironic, come July 2025 I cannot use my Backpack Blower anymore. We have some law here against backpack blowers, but I can still use my weed eater and chainsaw.
JTK
$100 Site Donor 2025
Cool re-power! Looks great.
Predator 212cc fan here. It is powering a 24" Ariens Sno-Thro. I run it WOT from the instant it fires til I shut it off by running it out of gas. I imagine the larger ones also have a low oil shutoff. .
Yeah. I like this. It’s going to word hard but @Cujet nailed it, it’s not totally maxed. Run at 3600 rpm or if you’re feeling gentle, adjust it down to max 3400. The heavier oils discussed are good choices. Having oil in it is the most important, and not being overly thin under high heat (looking at you, m1 5-30 in super hot OPE). That’s a nice refit - I’d enjoy it.
That sounds like alot of outboard boat motors. Would an oil for boating work?
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