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A billet flywheel because the OEM cast one may and has disintegrated under higher RPMs of modified engines.


The 8HP Predator modified ST824 suffers zero engine power issues. The engine hardly changes RPMs at all. But, there is a lot of belt slipping when large quantities of snow or wet/heavy stuff are tackled.

The stock Predator is just fine until I come up with a way to significantly reduce the impeller belt slippage.


From my experience, the Predator engine is far smoother, quieter, and just sounds so much more well put-together. In a little more than nine days I've put 7.9 hours of actual snow blowing on the machine. I'm very satisfied.



As mentioned above, the belt is the current limiting factor in getting all that engine power into thrown snow.

Are you completely sure your belts didn't get wet?
Are those belts raw edge? From what I read last week raw edge belts grab better and can transfer more power. The original belts were raw.
 

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Discussion Starter #22
Then, I wondered if anyone has put a charger and/or electric start on the Predator 301cc engine:


That's all I need... Another big time/money sink project.
 

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Discussion Starter #23 (Edited)
Are you completely sure your belts didn't get wet?
Can't say for 100% sure. But, the slippage is pretty constant and predictable when hitting bigger snow bites or heavy street plow cast-off.


Are those belts raw edge? From what I read last week raw edge belts
grab better and can transfer more power. The original belts were raw.
Doubtful. I just sourced the larger size needed for the engine swap from the local NAPA. Looks like I'm a gonna have to source a raw edge example.

Thanks for the pointer!
 

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Can't say for 100% sure. But, the slippage is pretty constant and predictable when hitting bigger snow bites or heavy street plow cast-off.



Doubtful. I just sourced the larger size needed for the engine swap from the local NAPA. Looks like I'm a gonna have ta source a raw edge example.

Thanks for the pointer!

I'll help anyway I can.
Im tempted to put the hmsk100 on it because it's stronger but like I said before it'll still have the same crummy carb etc. I've been around many hmsk engines and they all run the same (not quite right).

The belts aside, your impression is the 8hp predator is noticeably stronger than the 8hp tecumseh was? I assume the tecumseh was in good shape?

Just trying to get a good comparison.
 

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Discussion Starter #25
The belts aside, your impression is the 8hp predator is noticeably stronger
than the 8hp tecumseh was? I assume the tecumseh was in good shape?
Yes. The Predator should also take to running a bit faster in stock configuration better than the OEM Tecumseh. And hop-up parts are easily obtained for the Predator series.

Raw edged belt ordered. Although, it won't get here until March...
 

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Pull up the owner's manual *.pdf off the Harbor Freight web site and get the 420cc base dimensions from the back of the manual. Keep in mind, the diagram is not to scale so go by the listed dimensions and measure... The 301cc 8HP engine barely fits on the flat part of the engine deck and the 420cc motor is a bit larger base-wise. In stock configuration, the 8HP Predator does cause some belt slippage when hitting drifts and such. The 420cc would be worse. 8HP is kinda the limit without redesigning the impeller belt drivetrain.

Hell, even a Predator 5HP motor properly massaged can get up there in HP -- via billet flywheel, rod, valve springs, etc. So, the same modifications on the 8HP will eclipse the stock-configured 420cc example.

Eventually someone is going to produce a super-charger for these Chinese screamers.
I've seen a couple people wedge a 420cc onto an st824... I think the bolts will fit but the engine will hang off. I'm OK with that haha.. And whats the deal with the belts slippage? Isn't that a tension related issue and not an engine related issue?
 

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I've seen a couple people wedge a 420cc onto an st824... I think the bolts will fit but the engine will hang off. I'm OK with that haha.. And whats the deal with the belts slippage? Isn't that a tension related issue and not an engine related issue?
Tension sure, but a certain size belt is only going to handle a certain amount of power.

Do you have any pictures of the 420cc on an 824 machine? It sure would be nice to have the charging system etc that comes with the bigger engine.
 

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Tension sure, but a certain size belt is only going to handle a certain amount of power.

Do you have any pictures of the 420cc on an 824 machine? It sure would be nice to have the charging system etc that comes with the bigger engine.
I made this post asking about doing a 420cc swap. I'm waiting for it to go on sale at harbor freight.

Here's a picture someone posted of the bolt spacing in that thread for a honda engine with the same bolt pattern. The bolts are on the edge, but they should fit.

176099
 

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Discussion Starter #29
As stated previously, the 420cc footprint is slightly larger. When installing the 301cc engine I did have to grind angles on the bolt head hex flats to avoid interference with the 45° bend in the engine deck at the edge allowing the studs to stand straight. If someone has done it previously, then obviously, it can be done.

As for getting all that power transmitted into throwing snow, Ariens did have issues with their greater-than 9HP setups necessitating the double-belt upgrade kits. No such kit exists for the ST824. So, we're on our own engineering wise unless someone has documented a fix. Power that can't be transmitted is the same as no additional available power.

There's only one way to test whether or not all that power is making its way into throwing snow. Stuff the nose of the blower into a big heavy pile of fresh street plow cast-off and see if it stalls the engine. If the engine doesn't stall when overloaded, the choices are: The belt is slipping. The impeller design is too small. The test isn't inputting enough heavy snow.

Also, see previous post concerning a YouTube presentation on installing charging coils and an electric starter on the 301cc engine.
 

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As stated previously, the 420cc footprint is slightly larger. When installing the 301cc engine I did have to grind angles on the bolt head hex flats to avoid interference with the 45° bend in the engine deck at the edge allowing the studs to stand straight. If someone has done it previously, then obviously, it can be done.

As for getting all that power transmitted into throwing snow, Ariens did have issues with their greater-than 9HP setups necessitating the double-belt upgrade kits. No such kit exists for the ST824. So, we're on our own engineering wise unless someone has documented a fix. Power that can't be transmitted is the same as no additional available power.

There's only one way to test whether or not all that power is making its way into throwing snow. Stuff the nose of the blower into a big heavy pile of fresh street plow cast-off and see if it stalls the engine. If the engine doesn't stall when overloaded, the choices are: The belt is slipping. The impeller design is too small. The test isn't inputting enough heavy snow.

Also, see previous post concerning a YouTube presentation on installing charging coils and an electric starter on the 301cc engine.
Agreed.
There is a benefit to using a stronger engine than the belts can handle. It could be run a lower rpm which would both be easier on the ears, and the engine.

A 3.5" pulley which I would expect should grab better than a 2.75 would give 1100 rpm impeller speeds at 2800 rpm and it would also give 1400 rpm at 3600 rpm if the need is there. Unless of course that single belt just can't do it.
 

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Discussion Starter #31
Agreed.

There is a benefit to using a stronger engine than the belts can handle.
It could be run a lower rpm which would both be easier on the ears, and
the engine.
Design and engineering are always a, "Pick your poison," proposition of trade-offs...
 

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@Russell Stephan So I’ve been dealing with some belt slippage on my snapper 1030. The engine is plenty healthy and torquey and the impeller gearing is quite low. But in heavy snow throwing distances suffer even with impeller seals.

My though is why does my Honda with a big motor and high impeller speeds have ZERO slippage. It might have something to do with the large drive pulleys having greater surface area or maybe Honda uses better belts or BOTH.

Honda uses a bando w800 belt for the auger system. It certainly works great, but there is one higher line of belt the w1000. Once you dial in the most appropriate belt length, maybe try a w800 or w1000 belt of the correct size and see how it performs.

 

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@Russell Stephan So I’ve been dealing with some belt slippage on my snapper 1030. The engine is plenty healthy and torquey and the impeller gearing is quite low. But in heavy snow throwing distances suffer even with impeller seals.

My though is why does my Honda with a big motor and high impeller speeds have ZERO slippage. It might have something to do with the large drive pulleys having greater surface area or maybe Honda uses better belts or BOTH.

Honda uses a bando w800 belt for the auger system. It certainly works great, but there is one higher line of belt the w1000. Once you dial in the most appropriate belt length, maybe try a w800 or w1000 belt of the correct size and see how it performs.


Maybe I'm seeing wrong but it also seems like hondas have weaker smaller engines than other brands. Do they handle wet snow better as well or only dry stuff?
 

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Maybe I'm seeing wrong but it also seems like hondas have weaker smaller engines than other brands. Do they handle wet snow better as well or only dry stuff?
Weaker, No.

Smaller, in comparison to the most recent offerings from the Chonda world yeah they generally have smaller displacements. They also have hydrostatic transmissions so displacement is not a non issue.

In regards to wet snow. It was the first chute design using a collar at the base to eliminate snow spray that effected wet snow performance in HSS machines.
 

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Well.
I had a brilliant idea for a few minutes of converting the impeller/auger to a chain drive with an adjustable clutch to limit torque.

Then I realized there would be no way to stop it under normal conditions. :rolleyes:
 

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Discussion Starter #37
I had a brilliant idea for a few minutes of converting the impeller/auger
to a chain drive with an adjustable clutch to limit torque.
Have a gander earlier in the thread where I link to a YouTube video about installing a charging coil and starter on a 301cc Predator engine... Just before that I provide a link to a electro-mechanical clutch used in commercial lawn mowers.

Although, I would doubt charging coils would be enough to lock up the clutch. But an alternator... ;-)
 

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For what it's worth I noticed there's also a Predator 5500W generator that uses the 301 engine.
The general rule is 2HP per KW and the Tecumseh 10HP was used on some 5000W generators. Also, from what I've found the Tecumseh HM100/HMSK100 was rated something like 15.5ftlb @ 2600 while the Predator 301 is rated 14.9ftlb but they didn't specify an RPM but I would assume 2500RPM.

Very strange that a Harbor Freight engine would perform better than the claims. Isn't it?

Meanwhile we've got shop vacuums that claim to be 6HP when they're lucky to be a sixth of that.
 

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Interesting info I’m a follower.
Mounting a larger motor isn’t the hard part- a simple motor mount plate would solve that issue. You could either weld the plate or bolt it to the tractor. It seems that most of the issue is finding a belt the proper size. I do remember a thread on here that the belt was 1/2” too long why not just mount the motor 1/2” higher then finding a belt isn’t the issue. I get the belt guard will need modified, but that too isn’t a very hard thing to do.
 

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Interesting info I’m a follower.
Mounting a larger motor isn’t the hard part- a simple motor mount plate would solve that issue. You could either weld the plate or bolt it to the tractor. It seems that most of the issue is finding a belt the proper size. I do remember a thread on here that the belt was 1/2” too long why not just mount the motor 1/2” higher then finding a belt isn’t the issue. I get the belt guard will need modified, but that too isn’t a very hard thing to do.
They sell a riser kit for the belt guard so that isn't an issue.
 
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