# why does the impeller modification work?



## bcjm (May 29, 2015)

I have not done mine yet. Just curious why does it work? The only thing it does is preventing the snow gets to the back of the impellers. Does the snow in the back increases the friction so the impeller does not spin as fast? If that is the case I should hear the engine RPM goes down as well (assuming the auger belt is tight) but I don't.

I believe it works just don't understand why.


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## 43128 (Feb 14, 2014)

it close up the gap between the housing and impeller fan. as the impeller goes around, the rubber wipes the housing clean which eliminates the ice buildup that causes clogging and poor throwing distance


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## bcjm (May 29, 2015)

You would think something this easy all manufacture should be doing it.


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## E350 (Apr 21, 2015)

Could the good impeller to impeller/housing seal also be pressurizing the chute to more effectively pump out the more-solid water (i.e., snow)? 

(Sorta like a potato gun?)

I know that close impeller to housing tolerance is important on jet skis.

Which also have an impeller/pump to more effectively pressurize and pump out the liquid water.


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## Vermont007 (Mar 29, 2015)

It's my theory that in closing that gap, we're extending the portion of the blade which is actually moving the fastest; and maybe giving it a little more inertial power with the added weight of the bolts, washers, nuts (and rubber).

I know that my MTD performs at its best when it is given the most work to do; and at its worst when it's sitting around idling, or barely lifting any snow.

It's still important to NOT park the unit with a blade parked at 6 O'Clock where it might freeze in place.


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## bad69cat (Nov 30, 2015)

Vermont007 said:


> It's my theory that in closing that gap, we're extending the portion of the blade which is actually moving the fastest; and maybe giving it a little more inertial power with the added weight of the bolts, washers, nuts (and rubber).
> 
> I know that my MTD performs at its best when it is given the most work to do; and at its worst when it's sitting around idling, or barely lifting any snow.
> 
> It's still important to NOT park the unit with a blade parked at 6 O'Clock where it might freeze in place.


I think that's part of the reason the leave a gap..... also they can have sloppier tolerances in the construction and not worry about any rubbing issues....


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## bcjm (May 29, 2015)

E350 said:


> Could the good impeller to impeller/housing seal also be pressurizing the chute to more effectively pump out the more-solid water (i.e., snow)?
> 
> (Sorta like a potato gun?)
> 
> ...


I don't think that is the reason since the snow will seal the gap. You will have a similar pressure, not initially but after you use it.


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## Paul463 (Nov 4, 2014)




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## RedOctobyr (Mar 2, 2014)

bcjm said:


> You would think something this easy all manufacture should be doing it.


I don't think it's as easy/cheap as it might first appear, for manufacturers to close up this gap. My thoughts, from another impeller mod discussion yesterday: 
http://www.snowblowerforum.com/forum/general-snowblower-discussion/86193-3-stage-worth-extra-money-3.html#post936098


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## bcjm (May 29, 2015)

Paul463 said:


>


I like be able to explain things scientifically. We are all different I guess.


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## bcjm (May 29, 2015)

RedOctobyr said:


> I don't think it's as easy/cheap as it might first appear, for manufacturers to close up this gap. My thoughts, from another impeller mod discussion yesterday:
> http://www.snowblowerforum.com/foru...3-3-stage-worth-extra-money-3.html#post936098



We did it (add the kit) in less than $20. I am sure manufactures can do it for less.


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## Vermont007 (Mar 29, 2015)

RedOctobyr said:


> ". . . I don't think it's as easy/cheap as it might first appear, for manufacturers to close up this gap . . ."


And costs are encountered in many ways AFTER the sale.

Manufacturers have to consider the whole market, and whether this enhancement would attract more buyers. Are they sophisticated enough to appreciate the change ?

And questions about "fitment" and noise during the break-in period after the sale.

And potential scratches that may be created earlier in the product's life.

Some portion of this production line is never even used by the people who initially buy it. I have a Sister-in-Law in Kansas City who, with her Husband) bought an expensive unit three years ago, and have yet to use it even once. 

Manufacturers have to have consider the Lowest Common Denominator in the Market when they decide on what features to include in the basic product.

Let me add that the "Heated Hand Grips" on my MTD (branded as White Outdoor Equipment) were standard when I bought it, as was the complicated JoyStick for one-handed directional and pitched Chute Control.

In the case of the Heated Grips, they were too expensive to include as a standard and weren't appreciated to be bought as an option.

And the JoyStick was discontinued because it was abused and was too expensive to repair while under Warranty, and requires "some" maintenance/attention afterwards..

But in both cases, I'm glad I bought while those features were included as standard . . . . I appreciate both of them.

I think including well fitting metal or rubber tipped Impeller Blades would result in a mess of whining from too many buyers who'll never be satisfied.


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## skutflut (Oct 16, 2015)

bcjm said:


> I believe it works just don't understand why.


I don't know all the physics of it. I would only compare it to a water pump. If the vanes of a pump do not seal, less water will be pumped, and a lot will blow by the vanes.

I put the kit in my machine just this year. I have dealt with wet snow and slush in the past and the snowblower didn't really do very well with this kind of load. Really wet sloppy stuff would go about 2-4 feet and land where I needed to blow it again. Water would pour out of the joint between the chute and the deflector. 

I got to used the machine twice so far this year. First event was 4" wet sloppy snow, and a low pile of EOD stuff mixed with salt and whatever else the town plow put there. It was wet enough and thick enough that it just kind of landed in a pile, then sagged into a 3 inch layer of goop.

When I got into fallen stuff, it went 15-20 feet, far enough that I did not have to revisit it. Slush under the snow and all. No clogs. The stuff from the EOD goo contained even more water, and even the water went through the chute a good distance and out of harms way. .There was a lot less water pouring out of the chute joints. I was very happy with the results because it beats the **** out of trying to move that stuff with a shovel.

The second event was about 3 " of dry snow. That went probably 25-30 feet. It can go farther, but there really wasn't enough snow to keep the bucket full. I never really had any trouble with moving dry snow, it always blows far enough that its gone and forgotten.

I conclude that if you only ever get dry snow, the kit probably wouldn't make that much of a difference. With wet heavy slushy stuff, sealing the gap and eliminating the blow lifts the material out the chute and makes a big difference in performance, and the shovel stays in the garage where it belongs.


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## bcjm (May 29, 2015)

I agree that the amount of snow it throws is less but the distance should be the same. The distance is highly depends on the speed of the impeller. Unless the impeller speed changed otherwise the distance should be the same.


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## Vermont007 (Mar 29, 2015)

bcjm said:


> ". . . Unless the impeller speed changed otherwise the distance should be the same . . ."


But the tip of the Impeller Blades "IS" traveling faster than it did before the blade was extended with the modification.

The Impeller's RPM may be the same but the distance traveled around the circumference in the same amount of time is greater because of the increased blade length; ergo the blade tip is traveling faster.


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## bcjm (May 29, 2015)

The snow is not thrown from the tip of the impeller. The center of the snow ball mass does not change.


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## nwcove (Mar 2, 2015)

wish i could find the specs on my mtd, im sure it had " impeller tip speed" listed in ft/sec. not sure why it would be in the specs if it had no effect on performance ?

wrong machine......sno tek, impeller tip speed @3738 ft/sec


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## Normex (Feb 21, 2014)

#1-


bcjm said:


> I agree that the amount of snow it throws is less but the distance should be the same. The distance is highly depends on the speed of the impeller. Unless the impeller speed changed otherwise the distance should be the same.


#2-


bcjm said:


> We did it (add the kit) in less than $20. I am sure manufactures can do it for less.


#3-


bcjm said:


> The snow is not thrown from the tip of the impeller. The center of the snow ball mass does not change.


 1- bcjm The farthest the snow is throw from the vane the fastest it gets thrown no matter if it is only 1/4 to 1/2" longer.

2- You have to understand the manufacturing cost process is measured in cents per unit while a dollar cost per unit is prohibitive on such a small part from a manufacturer's point of view. It would be even a headache to try to offer this feature as an option.

3- If you observe the shape of the vane, it starts with the width smaller near the center and or shaft to wider at the end of it so likely the engineers figured this aspect that the centrifugal force will force the snow outward as it leaves depending on the friction factor at play.

take Care All

Norm


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## skutflut (Oct 16, 2015)

It may have something to do with the plume coming out of the chute. If the plume is larger, ie more volume of snow, it stay together longer whereas a low volume tends to break up sooner in the breeze and doesn't seem to get as far. 

As far as wet stuff goes, centrifugal force sends it to the impeller walls and if there is a gap there, water and slush will find it and go down hill. Snow, not so much. 

It would be interesting to make a video of the impeller with and without a kit working in wet sloppy stuff to see whats going on in the impeller. Probably would need a decent high speed camera, with zoom to get in close without getting the operator in close.


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## Geno (Nov 29, 2011)

I think their is several things to look at: why it works was hit on already probably they all come into factor. if a water pump fan were to loose the ends of its blades a car will overheat because the water can't circulate fast enough but rather just get churned around. certain conditions the snow or portion of it will do the same. Just keep slipping back on the outer edges. Of course packing snow is different but it stands a better chance of being thrown out (and farther) if the impellor cavity is got more volume of snow in it and no place to go but out and with the increase of speed added. As far as why not all made that way.. could be patent factors.. cost is definitely involved and warranty issues may be higher too? bit more stress on gear box, ect. Idealy I'd like them all made that way and have the machine built accordingly..but.. $$$


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## Blackfin (Jan 25, 2016)

Two things at play I believe.

Increased tip-speed by virtue of extending the effective blade tip out 3/8-1/2". For a 12"-diameter impeller the tip speed at 1000RPM is roughly 603.2 inches/sec. This is about 50.26 ft/sec. If you extend that by just 1/2" and are able to maintain 1000RPM your tip speed increases to 654.5 in/sec or 54.5 ft/sec. An increase of 4.3 ft/sec doesn't sound like much but it actually is quite an increase in the best velocity the impeller can impart on the snow (i.e. 8.5% more.) 

I don't think this has as much of an effect as the second reason though:

Increase efficiency: By closing the tolerances up we are closer to making a centrifugal _pump_ than the centrifugal _blower_ the factory supplies. Similar centrifugal pumps like water pumps, turbochargers and centri superchargers work as well as they do because they run incredibly close tolerances between the blade tips and the enclosure; leakage past the blade tips is minimal. The OE snow blowers (aptly named as it turns out) are pretty crude.

I love the ingenuity on the part of some of the guys putting kits in. Some extend the tips just a bit further and let them basically wear into the housing surface. Some advanced turbos come with a teflon coating at the compressor wheel interface; during operation, the compressor wears away only enough of the teflon to produce a near-air tight seal. These guys are effectively doing this with their snowblowers -- er, snowcompressors -- and that's cool.

I think the gaps are intentional for (mostly) incompressible things like sticks and rocks and that makers don't want to have users worry about more wear items like that (the shave plate is enough...)


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## YSHSfan (Jun 25, 2014)

bcjm said:


> I agree that the amount of snow it throws is less but the distance should be the same. The distance is highly depends on the speed of the impeller. Unless the impeller speed changed otherwise the distance should be the same.


This is not true on my experience mainly with Honda and Yamaha. If you are blowing 3-4" of snow they will throw the snow 15-25 feet, but if they are blowing 10+" of snow they can throw it 30-50 feet. 
Not only the impeller tip speed (determined by impeller rpms) determines the throwing distance but the volume that is getting moved as well.


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## YSHSfan (Jun 25, 2014)




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## E350 (Apr 21, 2015)

Blackfin said:


> I think the gaps are intentional for (mostly) incompressible things like sticks and rocks and that makers don't want to have users worry about more wear items like that (the shave plate is enough...)


My limited but personal observation:

Honda HS1132TA (smaller impeller gap) = impeller blade easily freezes to the impeller housing = more throwing/pumping performance, requires more owner attention.

Ariens ST1032 (big impeller gap) = impeller blades do not easily freeze to the impeller housing = more reliability, with less owner attention.

Isn't this a classic engineering design trade off?

Reliability vs Performance.


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## bcjm (May 29, 2015)

bsblowersfan, thank you for the videos. They are very educational.


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## Golfergordy (Oct 29, 2014)

It's just simple math that needs to be applied to the following hypothetical snowblower impeller:
Let's say a rotating steel impeller has a radius of 6". The circumference of the circle made by the outer edge of this rotating impeller = 2 X 6" X 3.14 = 37.68". At 4000 engine rpm, the impeller probably has a slower rpm, so let's say it's 500 rpm. The speed of the outer edge of the steel impeller is then calculated to be 37.68" X 500 rpm = 18,840 inches per minute.

If you add an impeller kit, the added piece of rubber (attached to the steel impeller) may stick out 0.5" beyond the outer edge of the steel impeller. The circumference of the circle made by the outer edge of the rotating rubber = 2 X 6.5" X 3.14 = 40.82". The speed of the outer edge of the rubber is then calculated to be 40.82" X 500 rpm = 20,410 inches per minute, which is 8% faster than the pre-impeller kit speed of the outer edge of the steel impeller. 

If the modified impeller (with kit installed) now travels at a faster outer edge speed than the pre-modified impeller, at the same 500 rpm, the snow should be blown farther. I've seen some people comment that the added weight of the impeller kit should slow down the impeller's (engine's) rpm, but the engine's governor senses the engine speed slowing down, and then opens the throttle a bit to bring in more fuel, and the rpm goes back to the set rpm, but the engine will burn a bit more fuel in the process. 

By installing the impeller kit, the more you close the gap between the outer edge of the impeller and the impeller housing, the better the impeller kit should improve throwing distance.


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## bcjm (May 29, 2015)

I am not convinced that better throwing is due to the speed increase of the impeller tip. If you have something so small that always leave the impeller from the tip then yes. But you have a huge snow mass the is filled in the paddle area. They all leave the impeller at the same time. The speed of the mass can not be calculated based on the speed of the tip.


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## bcjm (May 29, 2015)

Also, the body of the impeller housing does not change. Everything is against the housing before going into the chute. They should have the same speed.

Imagine you have a tennis ball thrown by the paddle going into the chute. The ball is against the housing no matter how close the paddle is to the wall.


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## E350 (Apr 21, 2015)

Dudes, seriously, it is likely more like an air/water pump with the impeller/housing seal modification than it is without it.

Which would explain why a taller chute would throw farther.

Just like a longer barrel increases rather than reduces the velocity and thus the range of a bullet. (A bullet is also propelled by air.)

I guess the empirical way to test this theory would be to put an airplane telltale wind sock over the chute and run it dry, both before and after installation of the impeller/housing seal.


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## bcjm (May 29, 2015)

Air pump/water pump/gun barrel are all in a seal chamber. The chamber pressure and the time it can push the bullets determine the distance. The snow on the hand is open to the atmosphere, pressure does not (or very little) play a role here.


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## Blackfin (Jan 25, 2016)

I think both play a role but that the closure of the gap is the dominant factor.

The impeller is a centrifugal type: any snow that gets into the impeller is immediately moved toward the blade tips by centripetal acceleration and turbulent air flow. I don't think much snow exits the chute having been hurled from the inner portion of the impeller. Indeed, an impeller design like this:










shows that some manufacturers don't see much value in impeller blade material except at the edges. Extending the tips gives decent percent increase in tip-speed which can only help the throwing of snow.

But given that the snow is being hurled toward the outside of the impeller, a gap between the stationary housing and the impeller whizzing by a 50 feet per second or more can be seen to be a bad thing if you want the thing to actually _pump_ snow out. 

There's a "velocity gradient" between the tip (50 ft/sec) and the housing (0 ft/sec relative); snow impinging on the stationary housing just gets dragged past the gap by friction and doesn't get thrown out until "later". Friction between the housing and the snow and friction between particles of snow could mean some pretty significant "leakage" through a 1/2" gap. Closing that gap to zero (or actual) zero is likely where the bulk of the improvement comes from.

IMO


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## bcjm (May 29, 2015)

Oh I am not denying closing the gap improves the performance. I am just wondering why.
There must be something more than the "speed of the tip" or "the pressure" it creates.


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## Geno (Nov 29, 2011)

*just little simplicity note:*

I'm sure all would agree that faster the snow leaves a cavity or space by force of an impellor the 'less' chance it is apt to get stuck or clogged up. And that increase speed subsequently throws it farther too. The results from this is what the owners of such are witnessing. Now how do you get the snow to discharge faster.. By adding a extension on the blade that (a) increases the tip rpm (b) decreases the amount ,if any, snow to slip pass the impellor blade and down into the next chamber of the impellor..and as such that one is doing the same. This is eliminated and the positive results above are added to create a far better functioning piece of equipment. I don't know how better this can be explained?


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## James972 (Feb 5, 2016)

Blackfin said:


> I think the gaps are intentional for (mostly) incompressible things like sticks and rocks and that makers don't want to have users worry about more wear items like that (the shave plate is enough...)


but with no gaps rocks, sticks etc would be more likely to be thrown out and not clog machine?

Does clog mean impeller stops or chute plugs while impeller turns?


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## Vermont007 (Mar 29, 2015)

I don't think this thread will come to a soft landing until long after the snow melts and we proclaim that Spring has arrived.

Ideally, someone will apply for a Federal Grant so that it could be studied _ ad infinitum _ !

I'm simply glad that the process works; I've got other problems that concern me more today.


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## bcjm (May 29, 2015)

I used a tennis ball as an example. Are you saying by increase the length of the impeller a tennis ball will leave faster? The object is already against the wall of the housing. The speed will not change.


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## James972 (Feb 5, 2016)

bcjm said:


> Also, the body of the impeller housing does not change. Everything is against the housing before going into the chute. They should have the same speed.
> 
> Imagine you have a tennis ball thrown by the paddle going into the chute. The ball is against the housing no matter how close the paddle is to the wall.


yes but with the mods you are sweeping clean closer to chute all the way up thus preventing build up and clogs, and, throwing farther


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## bcjm (May 29, 2015)

James972 said:


> yes but with the mods you are sweeping clean closer to chute all the way up thus preventing clogs and throwing further


Agree. 

I just don't buy the idea that the snow traveling faster by increasing the tip.


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## James972 (Feb 5, 2016)

Blackfin said:


> . Closing that gap to zero (or actual) zero is likely where the bulk of the improvement comes from.
> 
> IMO


or perhaps the snow in the gap, in effect, freezes into place and you get tight tolerances that way?


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## nwcove (Mar 2, 2015)

bcjm said:


> Agree.
> 
> I just don't buy the idea that the snow traveling faster by increasing the tip.


ok.....but now take the mod to the opposite direction .....take an impeller and cut the tips back by an inch and see what happens when you decrease tip speed AND allow for more cavitation in the " snow pump" housing.


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## Blackfin (Jan 25, 2016)

bcjm said:


> I used a tennis ball as an example. Are you saying by increase the length of the impeller a tennis ball will leave faster? The object is already against the wall of the housing. The speed will not change.


The problem is that snow that is against the housing has nothing but residual momentum from when it was in contact with the impeller to move it along. Because of the 1/2" gap the impeller tips will always be moving faster than, say, a snowflake or piece of ice "against the wall of the housing."

If the tip is extended _to_ the housing then everything in the tip's path will be moving at the tip velocity, that is, faster than if the tip was still 1/2" away.

The fact that the tip is further from the axis of rotation and thus moving something like 8% faster is just icing on the cake, so to speak.


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## bcjm (May 29, 2015)

ok. This is my last post. Some people are sick of the this conversation by now. 
We can all come to our own conclusions why it works.


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## Sid (Jan 31, 2014)

This has been a great discussion on the air gap. My own question is would it an advantage for me to increase the length of my chute to get the snow to be thrown a longer distance, as mentioned in post #29 [I think]? I don't care about diminishing returns, I'm retired, and have a little time to spend on it.
Sid


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## E350 (Apr 21, 2015)

Vermont007 said:


> Ideally, someone will apply for a Federal Grant so that it could be studied _ad infinitum _!


 It has already been studied _ad infinitum_.

Unfortunately, however, the Honda engineers whom Robert has likely forwarded the link to this thread to (and whom likely have had a good laugh) don't seem to want to stop the fun by telling us what the results of their experiments are. 

Likely same thing with Mary and her engineers at Ariens.


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## E350 (Apr 21, 2015)

nwcove said:


> ok.....but now take the mod to the opposite direction .....take an impeller and cut the tips back by an inch and see what happens when you decrease tip speed AND allow for more cavitation in the " snow pump" housing.


UH OH!!! *nwcove* mentioned the "C" word. Where density of the medium and air pressure in the turbine is reduced.

Cavitation is the buggaboo of everything I do in the water, white, or otherwise...


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## James972 (Feb 5, 2016)

bcjm said:


> Agree.
> 
> I just don't buy the idea that the snow traveling faster by increasing the tip.


well it does travel a little faster for sure but more importantly in the perfect place, namely, along the impeller housing and chute wall to scrape it clean, help avoid build up, clogs, and to throw snow farther, ....I think.


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## nwcove (Mar 2, 2015)

E350 said:


> UH OH!!! *nwcove* mentioned the "C" word. Where density of the medium and air pressure in the turbine is reduced.
> 
> Cavitation is the buggaboo of everything I do in the water, white, or otherwise...


lol....my world outside home was/is in the water /wastewater world.....the "C" thing is brutal without doubt. it is interesting ( and applicable to this thread) to watch pump performance on a scada system go south as impeller clearances get larger due to wear.


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## cpchriste (Jan 19, 2014)

Thank you Blackfin post 31 & 41 - I finally get it. 
The high velocity snow coming off the impeller is impeded by the slow velocity snow slowly shedding off the impeller drum/gap. The bigger the impeller gap, the more slow snow enters the chute stream, thus slowing the entire discharge velocity.
Seems so simple once it's made clear.


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## Spectrum (Jan 6, 2013)

The story behind the part:




Blackfin said:


> I think both play a role but that the closure of the gap is the dominant factor.
> 
> The impeller is a centrifugal type: any snow that gets into the impeller is immediately moved toward the blade tips by centripetal acceleration and turbulent air flow. I don't think much snow exits the chute having been hurled from the inner portion of the impeller. Indeed, an impeller design like this:
> 
> ...


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## Marty013 (Mar 14, 2014)

i thnk part of the reason is thers less snow... re-pumped... without impeller kit.. some snow gets tossed round in the housing before it gets ejected... less of that with the kit added i figure... therego.. snow has less time to slow down the impeller before it gets ejected... my 2 cents

now.. why the powers that be dont offer this standard... well... NEW machines have closer tollerances to begin with... so putting something to scratch up the paint is making it easy for rust to latch on and cause major issues.. without even considering possible strains on driveline components( gearbox.. belts etc)


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## Golfergordy (Oct 29, 2014)

bcjm said:


> I am not convinced that better throwing is due to the speed increase of the impeller tip. If you have something so small that always leave the impeller from the tip then yes. But you have a huge snow mass the is filled in the paddle area. They all leave the impeller at the same time. The speed of the mass can not be calculated based on the speed of the tip.


I think you will agree that if the tip speed is increased, then the mass of snow speed will also be increased, but I don't know how to calculate by exactly how much it will be increased. Don't forget to consider that the last part of the impeller to touch the snow mass (before the mass heads up the chute) will be the tip.


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## Terrance (Dec 28, 2015)

Paul463 said:


>


Mopar is called Sure Grip.

Posi-traction is a Chevy term. It is sacrilege to say posi and plymouth in the same sentence. :banghead::2cool:


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## Golfergordy (Oct 29, 2014)

bcjm said:


> Also, the body of the impeller housing does not change. Everything is against the housing before going into the chute. They should have the same speed.
> 
> Imagine you have a tennis ball thrown by the paddle going into the chute. The ball is against the housing no matter how close the paddle is to the wall.


Even a tennis ball will be thrown farther! As the tennis ball leaves the impeller housing and is thrust into the chute, the last part of the paddle to touch it will be the tip, and if the tip speed is increased, then the speed of whatever the tip touches and is throwing into the chute will also be increased.


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## Golfergordy (Oct 29, 2014)

E350 said:


> Dudes, seriously, it is likely more like an air/water pump with the impeller/housing seal modification than it is without it.
> 
> Which would explain why a taller chute would throw farther.
> 
> ...


Yes, E350, the impeller also provides air pressure beneath the snow mass, which is part of the force propelling the snow, and with the impeller tip being closer to the housing wall, this pressure should be increased. I'm not sure how much force is provided by the air pressure, however, because there is a lot of room around the sides of the impeller paddles for the air to blow by.


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## Golfergordy (Oct 29, 2014)

Blackfin said:


> I think both play a role but that the closure of the gap is the dominant factor.
> 
> The impeller is a centrifugal type: any snow that gets into the impeller is immediately moved toward the blade tips by centripetal acceleration and turbulent air flow. I don't think much snow exits the chute having been hurled from the inner portion of the impeller. Indeed, an impeller design like this:
> 
> ...


Blackfin - I had to read your post a few times, but you are right on. The mass of snow between the impeller tip and the housing (in the gap) is moving slower than the snow directly in the impeller's path, thus slowing down the average speed of the entire mass of snow particles. By reducing this gap, the average speed of the snow mass isn't reduced as much, so throwing distance must increase.


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## Golfergordy (Oct 29, 2014)

bcjm said:


> I used a tennis ball as an example. Are you saying by increase the length of the impeller a tennis ball will leave faster? The object is already against the wall of the housing. The speed will not change.


When the impeller rotation brings the paddle into a position in the housing so as not yet ready to thrust the ball into the chute, the ball will be touching both the housing wall and the impeller paddle. It will touch the paddle at a point approx 1 3/8" away from the housing wall (2 3/4" dia. tennis ball). As the impeller rotates further, and the tennis ball exits the impeller housing and enters the chute, the last part of the impeller that touches the tennis ball will be the tip of the impeller paddle. The faster this paddle tip is traveling, the faster the tennis ball will exit the chute. Also, I think you should have used golf balls in your post instead of tennis balls.


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## Golfergordy (Oct 29, 2014)

bcjm said:


> Agree.
> 
> I just don't buy the idea that the snow traveling faster by increasing the tip.


I don't think you can argue with the math - increasing the tip dimension (radius) from the impeller shaft MUST increase the tip speed, at a constant rpm. If the tip speed is increased, then the snow speed must also be increased.


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## James972 (Feb 5, 2016)

Golfergordy said:


> Also, I think you should have used golf balls in your post instead of tennis balls.


marbles or peas or sand would be better still since snow is not one piece like a tennis ball. I'm guessing the advantage of the kit is that it sweeps clean the impeller housing and the chute where you would have the build up that leads to eventual clogging. Plus, if the snow is going faster in that area all the better to prevent build up and throw farther.

I still don't know if a clog means the impeller stops or the chute gets plugged and the impeller keeps turning?


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## nwcove (Mar 2, 2015)

the chute plugs, impeller keeps turning but cant do its job, the blower becomes a plow with rotating parts.


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## Vermont007 (Mar 29, 2015)

James972 said:


> I still don't know if a clog means the impeller stops or the chute gets plugged and the impeller keeps turning?


"Clog", at least for me, has meant when the Chute has become packed with slush . . . . almost solid like ice (which I'm sure it would become if allowed to linger there too long)..

All the while the clog is present, my Engine, Auger, and Impeller would continue operating, performing no work, until I stopped them and cleared the clog.

Not anymore.


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## Paul463 (Nov 4, 2014)

Terrance said:


> Mopar is called Sure Grip.
> 
> Posi-traction is a Chevy term. It is sacrilege to say posi and plymouth in the same sentence. :banghead::2cool:


Never saw that movie?


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## tpenfield (Feb 24, 2015)

Interesting discussion, sorry that I have only caught up to it now. A few of points that I will add . . .

Tennis balls and snow are different. If my driveway were covered a foot deep in tennis balls, I would probably use a Golden Retriever to clean them up rather than a snow blower 

I have 2 snow blowers - An older Toro 521 and a new TB 2410. . .

- The old Toro would out throw the TB any day of the week in any conditions (even before I did the engine swap).

- I did do the impeller mod on the TB (see my thread in the maintenance section).

- When I did the impeller mod, I compared the Toro impeller and the TB impeller (see pics in my mod thread) The Toro impeller has a very close tolerance to the housing, probably 1/8", and the impeller blade tip is much like a clever.

- The TB has/had about 3/4" clearance between the impeller blade and the housing. The blade tip is/was also rounded. As soon as I saw the difference between the 2 machines, I knew why the TB did not throw snow as well as the Toro.

- The videos posted earlier in this thread pretty much cover it. 

- The combination of larger clearance and rounded edge of the TB impeller, give the snow a place to go around the blade and avoid being thrown out the escape chute of the housing.

- Various brands of snow blowers differ in their impeller design and housing clearances, but . . . The key factors in impeller efficiency is the tightness of tolerance and the shape of the blades.

- Adding the impeller mod kits tend to address both of those issues for designs that are not as efficient as they can be. I am not sure why some companies design their blowers with less efficiency, but they do.

- The modification kits, for the most part, improve the efficiency of the impellers by reducing the gap between the housing. They do some for the shape of the blade, if the shape is a problem, like on my TB machine.

- I reduced the 3/4" gap of my TB 2410 impeller/housing down to about 1/4" by installing the modification kit and the thing now throws snow like a monster. Why ??? because less snow can escape its fate since the tolerance between the impeller and the housing is now tighter.

- I could probably add an impeller kit to the Toro (which already has a tight tolerance) and see no improvement, since it is already an efficient design.

That's my story


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## E350 (Apr 21, 2015)

Terrance said:


> Posi-traction is a Chevy term. It is sacrilege to say posi and plymouth in the same sentence. :banghead::2cool:


*Terrance*: I think you should cut him some slack. It was just a "limited slip" up...


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## Bob E (Jun 9, 2014)

Golfergordy said:


> Yes, E350, the impeller also provides air pressure beneath the snow mass, which is part of the force propelling the snow, and with the impeller tip being closer to the housing wall, this pressure should be increased. I'm not sure how much force is provided by the air pressure, however, because there is a lot of room around the sides of the impeller paddles for the air to blow by.


Air pressure? More like snow pressure.


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## Geno (Nov 29, 2011)

I really think we took this to the limit.. every reason has been brought up from top to bottom and sideways. If op needs more on this then what was brought up then I guess a blower needs to be tested against a stock one in a lab with engineers testing every conceivable step.. with and without the rubber kit installed. just my humble opinion of course.


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## Paul463 (Nov 4, 2014)

As an aside, impeller tip clearance works on more than just snowblowers. Back in my dairy farm employment days when filling silos we'd get the fill pipe (60 foot tall) plugging all the time with a 100hp tractor on the blower (think 60" diameter snowblower impeller). We reset the paddles on the impeller to about a 1/16" (they were around 3/8") clearance to the housing and had no more problems. Same deal with the forage chopper, set the knives close to the housing and it would blow feed right over the back of the wagon if you weren't paying attention. With the clearance large it would be lucky to reach the middle of the wagon.


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## E350 (Apr 21, 2015)

Bob E said:


> Air pressure? More like snow pressure.


 *BobE*: Now you're probably going to tell me that there is no low pressure (no suction) on the auger side of the turbine too? 

Gee, it just seems to me that there would be a pressure differential between the turbine intake and turbine discharge...


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## Bob E (Jun 9, 2014)

If there was it could suck the snow right off the ground like a vacuum cleaner. Try dropping a snowball down the chute and see if the air pressure blows it away before it hits the impeller.


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## Blackfin (Jan 25, 2016)

There is definitely movement of air but as a fan (versus a compressor) the impeller is incapable of generating more than small amounts of pressure differential.


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