Cutting off Fins to Blower??

[BadGenetixx]

Hey Guys,
A friend of mine suggested that I could cut off every other fin to the 'blower' to cause less drag on my engine. I don't know if this suggestion was such a great one, especially if I've modified my engine to run much faster = hotter.

You guys think that this mod could affect the engine in a negative way??

And why do some people have metal blowers for their engines??

 

[mmisterbungl]

Hey Guys,
A friend of mine suggested that I could cut off every other fin to the 'blower' to cause less drag on my engine. I don't know if this suggestion was such a great one, especially if I've modified my engine to run much faster = hotter.

You guys think that this mod could affect the engine in a negative way??

And why do some people have metal blowers for their engines??

Tecumseh and Briggs engines have aluminum or cast iron flywheels. The reason yours is plastic is because it's probably a honda or a honda clone. The plastic fins just bolt on to the flywheel.

If you end up removing the governor and doing a bunch of high performance mods to your engine, the billet flywheels are a must since your engine will be spinning much past the intended RPM range from the factory. It's a safety issue.

This should explain everything - http://www.oldminibikes.com/forum/h...nor-your-engine-OldMiniBikes-please-read.html

This is what a stock flywheel looks like under the fins

And here is an aftermarket billet flywheel

 

[toomanytoys]

What type of engine we talking?

Some Honda/Clone guys cut off every other fin on the plastic fan.

 

[pickupman6]

Gettin hot shouldn't be a problem. These engines are made to be stationiory. As long as ur moving you'll be fine removing every other fin. Also sitting there idling u would be fine too because there's no load on the engine.

 

[Oldsalt]

Your gain by removing fins is about on par with a fat lady exhaling before she gets on a scale. Adding a lb. or so more tire pressure would have a much greater effect on performance. The amount of air that can be moved by the fan blades [even at WOT] is limited by the intake opening. The air entering the restricted intake hole cannot enter at any pressure greater than 14.7 psi. The atmospheric pressure at sea level. At very high RPM a flywheel with fewer fins would probably be pulling the same amount of air through the restricted intake [and costing the same amount of torque to pull it as if it still had all of its original fins]. To reduce the torque required to turn a air blower is easy. Limit the intake opening area.

 

[Oldsalt]

I'm disappointed. Thought surely there would be replies that would straighten me out on this. What I posted simply can't be true...or is it?

 

[Oldschool]

I'm disappointed. Thought surely there would be replies that would straighten me out on this. What I posted simply can't be true...or is it?

Sadly we are in agreement again.
Say something right wing and stuffy ( not about guns we agree on that too).

The fractional HP advantage if cutting fins is something you won't likely feel and if you do things that increase the real HP potential of the engine odds are your looking at Low RPM cooling issues aproaching 10 Hp.

Tried it.
http://s426.photobucket.com/albums/pp344/Dougwp/clone stuff/?action=view&current=100_9837.jpg
http://www.oldminibikes.com/forum/photopost/showphoto.php?photo=46218&title=000-0623&cat=500
went back to full fins...

 

[olajoe808]

Hey Guys,
A friend of mine suggested that I could cut off every other fin to the 'blower' to cause less drag on my engine. I don't know if this suggestion was such a great one, especially if I've modified my engine to run much faster = hotter.

You guys think that this mod could affect the engine in a negative way??

And why do some people have metal blowers for their engines??

This is a trick that has been used for years, since people started modifying engines. Depending on what mods have been done and the actual weight removed there are gains to be made- on the dyno and on the track- mechanically and psychologically. With the clone there is now a menu of flywheel options with the fins already removed for you. Some with adjustable timing built right in. The small mods such as doing this by itself may not seem like much. But when combining a bunch of small mods together they add up.

 

[Modding_out]

Your gain by removing fins is about on par with a fat lady exhaling before she gets on a scale. Adding a lb. or so more tire pressure would have a much greater effect on performance. The amount of air that can be moved by the fan blades [even at WOT] is limited by the intake opening. The air entering the restricted intake hole cannot enter at any pressure greater than 14.7 psi. The atmospheric pressure at sea level. At very high RPM a flywheel with fewer fins would probably be pulling the same amount of air through the restricted intake [and costing the same amount of torque to pull it as if it still had all of its original fins]. To reduce the torque required to turn a air blower is easy. Limit the intake opening area.

No your right old salt. Ever play with computer box fans?...same principle, if you block the air flow to one of the fans (intake side) the fan will not have any significant resistance and will immediately raise at least 500+ rpm. as soon as you lift the fan from the table...drop in rpm again from the drag of the air.

This is a inherit problem with impeller style vacuum/blowers (depending what you need it for...no air flow, no vacuum

 

[olajoe808]

No your right old salt. Ever play with computer box fans?...same principle, if you block the air flow to one of the fans (intake side) the fan will not have any significant resistance and will immediately raise at least 500+ rpm. as soon as you lift the fan from the table...drop in rpm again from the drag of the air.

This is a inherit problem with impeller style vacuum/blowers (depending what you need it for...no air flow, no vacuum

That's impressive!

 

[Oldsalt]

No your right old salt. Ever play with computer box fans?...same principle, if you block the air flow to one of the fans (intake side) the fan will not have any significant resistance and will immediately raise at least 500+ rpm. as soon as you lift the fan from the table...drop in rpm again from the drag of the air.

This is a inherit problem with impeller style vacuum/blowers (depending what you need it for...no air flow, no vacuum

If a large or small blower motor has an amp meter connected to its electrical leads it will quickly become evident that closing off the intake sharply reduces the amps. If no air is allowed to enter the housing the impeller will simply revolve the same air around in a circle inside the housing. No 'new' air, in that case, is need be accelerated therefore the energy requirement is greatly reduced. But the revolving air will get warmer because of the friction.

So if someone is selling flywheels with fewer fins [for more money that a stocker] he is able to do so because many don't realize a piece of masking tape on the intake hole will give the same effect.

 

[olajoe808]

Covering up the blower will work but then it'll over heat unless it's on meth.

 

[Oldsalt]

Sadly we are in agreement again.
Say something right wing and stuffy ( not about guns we agree on that too).

Sadly!! OK, I'll try my best to make a mechanical/engineering/physics subject into a religious/political issue, if you really insist.

How about this for "right wing and stuffy". It's the best I can do on the spur of the moment:

The so called scientific 'laws' that man has written that are suppose to govern 'fluid mechanics' [includes gases we are suppose to be discussing] are NOT man's laws. No matter how much the misguided masses that graduated from Liberal Arts Colleges and learned about the "Brotherhood of Man" and other Leftest, Pinko 'world order' ideas wish to believe 'MAN" is the lawmaker, they are again hiding from the truth. These are GOD'S laws. Holding hands with Joan Biaz and singing Kombala will not change the physical laws of HIS universe or put the authorship of the laws into the hands of man.

 

[olajoe808]

Hmm.... getting deep quick. Well winter is near , gotta get the logwood burnin, Another year anotha axe-to-grind.

 

[BadGenetixx]

Okay, thanks a lot for all the advice. I think I'm gonna go with the Billet Flywheel though, because of all the mods I've made to the engine already..but is it even worth it making all these mods to a GX160? It seems like every one else doesn't even mess around with these any more and are all using like GX390's or GX200's :shrug: Am i wrong??

 

[Oldschool]

Sadly!! OK, I'll try my best to make a mechanical/engineering/physics subject into a religious/political issue, if you really insist.

How about this for "right wing and stuffy". It's the best I can do on the spur of the moment:

The so called scientific 'laws' that man has written that are suppose to govern 'fluid mechanics' [includes gases we are suppose to be discussing] are NOT man's laws. No matter how much the misguided masses that graduated from Liberal Arts Colleges and learned about the "Brotherhood of Man" and other Leftest, Pinko 'world order' ideas wish to believe 'MAN" is the lawmaker, they are again hiding from the truth. These are GOD'S laws. Holding hands with Joan Biaz and singing Kombala will not change the physical laws of HIS universe or put the authorship of the laws into the hands of man.

My god is also in agreement with the laws of fluid mechanics....

And watch what you say to Joan, she's had a few drinks and pull of a spliff and she gets real ugly when she's messed up

 

[Oldsalt]

Okay, thanks a lot for all the advice. I think I'm gonna go with the Billet Flywheel though, because of all the mods I've made to the engine already..but is it even worth it making all these mods to a GX160? It seems like every one else doesn't even mess around with these any more and are all using like GX390's or GX200's :shrug: Am i wrong??

Valid thought. There is absolutely NO substitute for cubic inches. If you buy a cam and a flywheel and carb and rod etc, etc to 'mod' the 160 you will spend more money, get far less reliability, fool away a lot of time building an engine better spent riding, and it likely will not go as fast as you had hoped, and it will be a troublesome engine. Just step up and buy the bigger engine. Sure, if it is to be competitive in some particular division of racing you have no choice but to throw good money after bad. If it is a fun machine, in my limited view, you will be sorry you spent money on overpriced performance parts.

 

[Oldsalt]

My god is also in agreement with the laws of fluid mechanics....

And watch what you say to Joan, she's had a few drinks and pull of a spliff and she gets real ugly when she's messed up

That's incredible! But wouldn't it be in better taste to alter, for instance, a Pollard or even a Goya rather than a scene from the Sistine Chapel? Aren't you worried about what olajoe will say about it? This is even further afield than my quoted ramblings. At least I made some reference to air.

 

[olajoe808]

Okay, thanks a lot for all the advice. I think I'm gonna go with the Billet Flywheel though, because of all the mods I've made to the engine already..but is it even worth it making all these mods to a GX160? It seems like every one else doesn't even mess around with these any more and are all using like GX390's or GX200's :shrug: Am i wrong??

Absolutely, if you already own it. Unless ya got $700 bucks laying for a stocker 390.

 

[olajoe808]

That's incredible! But wouldn't it be in better taste to alter, for instance, a Pollard or even a Goya rather than a scene from the Sistine Chapel? Aren't you worried about what olajoe will say about it? This is even further afield than my quoted ramblings. At least I made some reference to air.

I'm disappointed. Thought surely there would be replies that would straighten me out on this. What I posted simply can't be true...or is it?

Well, I didn't really want to go here, but seeing that ya being olde an all and bent out of shape, with time running out, and not much of a societal benefit from a straightening out. That would be my guess :shrug: