# What is maximum RPM?



## GreatCanadian (Feb 20, 2013)

I have a 2013 Platinum 30 with an American made Briggs and Stratton 342 cc engine What is the safe maximum rpm for this engine? Thanks.

GC


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## ToroGuy (Jan 12, 2014)

3600 rpm.


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## scipper77 (Dec 4, 2013)

For the sake of redundancy, 3,600 RPM's is standard for pretty much all snowblower, lawn mower, pressure washers, tillers, etc... (Air cooled 4 strokes).


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## JRHAWK9 (Jan 6, 2013)

I turned my 342cc Briggs on my old blower to 3,740ish per the R&D guy I know at Briggs.

My current 420cc Briggs on my Pro 32 is turning the same, as he said they turn 3,800rpms with those in generator applications.


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## RIT333 (Feb 6, 2014)

JRHAWK9 said:


> I turned my 342cc Briggs on my old blower to 3,740ish per the R&D guy I know at Briggs.
> 
> My current 420cc Briggs on my Pro 32 is turning the same, as he said they turn 3,800rpms with those in generator applications.



Are you sure that he issn't say 3600 for power generation applications ? That is, pretty much, the industry standard.


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## mkd (Dec 31, 2013)

3600 rpm + or - 50 rpm is what i thought!


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## 43128 (Feb 14, 2014)

3600 is what i would recommend, but you could probably safely go up to 3850, dont blame us if you blow your motor though.


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## Benny365 (Dec 4, 2013)

I ran my go-devil mud motor with a 35hp B & S engine at 4100 RPM all the time.

I guarantee you if B & S recommends 3600, It will not blow up at 3650 or 3700 or even 4000. the valves will start to float up over 4200 RPM.

I used to race go-carts and would run that up over 5400 RPM (5hp B&S), granted that wasn't stock but these little engines will hold together just fine


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## Shryp (Jan 1, 2011)

scipper77 said:


> For the sake of redundancy, 3,600 RPM's is standard for pretty much all snowblower, lawn mower, pressure washers, tillers, etc... (Air cooled 4 strokes).


For the sake of safety, most lawnmower engines can run at 3600 RPM, but are set to 3200 RPM because that is what "they" have deemed the max safe rpm for non commercial spinning lawnmower blades.


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## scipper77 (Dec 4, 2013)

Shryp said:


> For the sake of safety, most lawnmower engines can run at 3600 RPM, but are set to 3200 RPM because that is what "they" have deemed the max safe rpm for non commercial spinning lawnmower blades.


Is this true for both riders and push mowers? My only experience with push mowers is doing carb work but I am pretty sure my rider is set for 3,600. The 3,200 number is new to me however.

I can understand why push mowers would tone it down with the blade being directly driven.


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## JRHAWK9 (Jan 6, 2013)

scipper77 said:


> Is this true for both riders and push mowers? My only experience with push mowers is doing carb work but I am pretty sure my rider is set for 3,600. The 3,200 number is new to me however.
> 
> I can understand why push mowers would tone it down with the blade being directly driven.



yes, there is a certain tip speed which is deemed "acceptable" by big brother. The larger the blade the slower the blade revs in order to keep tip speed in the acceptable range.


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## Grunt (Nov 11, 2013)

I believe the tip speed is supposed to be below 19,000 feet per minute.

20" mower at 3600 rpm = 18,840

21" mower at 3400 rpm = 18,683

22" mower at 3200 rpm = 18,421


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## GreatCanadian (Feb 20, 2013)

43128 said:


> 3600 is what i would recommend, but you could probably safely go up to 3850, *dont blame us if you blow your motor though*.


That is why I specified maximum *SAFE* rpm in my opening post.


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## GreatCanadian (Feb 20, 2013)

My reason for asking this in my opening post has to do with my snow throwing distance. My next door neighbor has an 11.5 hp Ariens Deluxe 28 and he consistently throws snow a fair distance further than me. I have no belt slippage or any other issue I can think of. I believe my impelled speed must be slower than his. I am wondering if my RPM's are high enough.


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## RIT333 (Feb 6, 2014)

GreatCanadian said:


> My reason for asking this in my opening post has to do with my snow throwing distance. My next door neighbor has an 11.5 hp Ariens Deluxe 28 and he consistently throws snow a fair distance further than me. I have no belt slippage or any other issue I can think of. I believe my impelled speed must be slower than his. I am wondering if my RPM's are high enough.


Sounds like a case of "penis envy".


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## Shryp (Jan 1, 2011)

Check into things like impeller kits and pulley modifications. The impeller kits make them throw more efficiently and the pulley modifications can give you more impeller RPMs without over revving the engine.


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## GreatCanadian (Feb 20, 2013)

RIT333 said:


> Sounds like a case of "penis envy".


LOL, no. According to his wife I have him beat in that department!!


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## Geno (Nov 29, 2011)

Ditto Shryp.. I'd ask your neighbor if he has changed his pulley or added a Clarence kit.


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## GreatCanadian (Feb 20, 2013)

Geno said:


> Ditto Shryp.. I'd ask your neighbor if he has changed his pulley or added a Clarence kit.


No, he hasn't. His blower is bone stock. It's actually quite impressive the distance he gets with that 11.5 hp. It just seems to be tuned perfectly. Best blower on the street actually. I just assumed that mine should be at least as good. Distance is important where I live. He never has to move his snow twice, where sometimes I do. So yeah, maybe a mild case of penis envy!!


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## Grunt (Nov 11, 2013)

GreatCanadian said:


> No, he hasn't. His blower is bone stock. It's actually quite impressive the distance he gets with that 11.5 hp. It just seems to be tuned perfectly. Best blower on the street actually. I just assumed that mine should be at least as good. Distance is important where I live. He never has to move his snow twice, where sometimes I do. So yeah, maybe a mild case of penis envy!!


 Maybe sneak over in the middle of the night, and switch blowers?


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## 43128 (Feb 14, 2014)

throw on an impeller kit, if it were a tecumseh just for future reference, dont over rev it at all, they are extremely prone to connecting rod failures ands its not worth blowing a motor for an extra foot of throwing distance


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## scipper77 (Dec 4, 2013)

One thing I will say is that over reving the engine is favorable to changing the pulley size as a means of increasing impeller speed. But changing pulley size is safer. When you increase the impeller speed with a pulley swap you are reducing your mechanical advantage. This means that a little snow will go further but a lot of snow will bog the motor more easily. An increase of rpm's will also increase horsepower without a loss in mechancal advantage. OK technically I'm assuming an increase in HP, I have no dyno's or experience to back this up.

If you realistically want to turn that thing into an out of this world freak of nature I'd start researching mods that are done on the go-kart side of things. I know there are safe (but pricey) upgrades that can safely make smaller honda's and predators spin up to 8k rpm's. If there are similar upgrades for your motor or maybe an 11 hp predator you could have 18-20 hp output at high rpm's and need to do a pulley swap to slow down the impeller because the motor will be spinning at double the rpm's.

Since it is now officially the offseason/project season I want to push you to look into buying a second motor that you can hop up. swapping motors should be pretty simple so if the "motor" grenades you will still have a blower to use. Just a thought, I really only know for sure that a large aftermarket exists for the smaller displacement motors used in kart racing. I have no idea if this is a viable option for the larger displacement motors.


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## RIT333 (Feb 6, 2014)

Does someone have a suggestion of a cheap (<$15 range) small engine tachometer that could be used on 2 and 4 cycle OPE. I have seen some on EBay that would with a laser and it seems like you have to attach a piece of reflective sticker on the engine, and also some that work on vibration, I think. Which are more favorable, and what are the recommendation. I will probably use it less than 10 times in my life, so I really can't justify a "huge" investment...plus I am "cheap".


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## 43128 (Feb 14, 2014)

i forget whats its called but theres one you wrap around the spark plug wire i forget whats its called


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## RIT333 (Feb 6, 2014)

This one ?

Tachometer Hour Meter 2 4 Stroke Small Engine Spark UTV ATV Kawasaki Digital LCD | eBay


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## 43128 (Feb 14, 2014)

yup, thats the one


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