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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

RPM of small gas engine



 
 
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  #11  
Old April 4th 09, 06:27 AM posted to rec.crafts.metalworking
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Posts: 464
Default RPM of small gas engine


wrote in message
...
On Fri, 3 Apr 2009 19:42:00 -0600, "SteveB"
wrote:


"RoyJ" wrote in message
news:HOCdndtvvOKtA0vUnZ2dnUVZ_rmdnZ2d@earthlink. com...
Standard small engine (single cylinder, 4 cycle, 3 to 14 hp) rpm is
3600,
some later engines run a few hundred RPM faster.


The 4 cyl. Continental on my SA 200 welder runs at 1450 rpm.

Steve

But that is not a "small engine"


Sorry, but previous posters included 4 cyl engines.


Ads
  #12  
Old April 4th 09, 06:47 AM posted to rec.crafts.metalworking
external usenet poster
 
Posts: 16
Default RPM of small gas engine

On Apr 3, 3:43*pm, "Karl Townsend"
wrote:
I just bought a trash pump without the gas engine.http://tinyurl.com/d3qj5f

What RPM do I spin it at?

FWIW, I hate small gas engines. Nothing but trouble. I'll use a 3 phase
motor for this job.

Karl


_________________________________________________


3000 RPM .

Need to start on Propnae . Exh is routed around to heat liquid fuel
and
to "regenerate" heat into the intake .
Then switch to liquid , turn off propane .


Japan cant sell machinery in U.S. ,
Jap' makes motors in China , China trademark . missing the Jap name

Price is highly subsidized .
13HP motor has a balance shaft and retards camshaft to lower
cranking PSI , for easy starting .



  #13  
Old April 4th 09, 12:22 PM posted to rec.crafts.metalworking
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Posts: 3,104
Default RPM of small gas engine

How about a VFD?

A 3600 RPM 5 hp. may be hard to find. I'll start shopping eBay for a 5hp.
VFD. Didn't really want to put this much $ into this job though.

Karl


  #14  
Old April 4th 09, 10:58 PM posted to rec.crafts.metalworking
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Posts: 2,005
Default RPM of small gas engine

DAGS

Powerhorse+pump+RPM

http://www.google.com/search?hl=en&q...ay&btnG=Search

3400-5500 RPM depending upon size and engine used, based upon a quick glance
at the search results.

--
WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"Karl Townsend" wrote in message
anews.com...
I just bought a trash pump without the gas engine.
http://tinyurl.com/d3qj5f

What RPM do I spin it at?

FWIW, I hate small gas engines. Nothing but trouble. I'll use a 3 phase
motor for this job.

Karl



  #15  
Old April 5th 09, 12:45 AM posted to rec.crafts.metalworking
external usenet poster
 
Posts: 163
Default RPM of small gas engine

"Karl Townsend" wrote in message
anews.com...
How about a VFD?


A 3600 RPM 5 hp. may be hard to find. I'll start shopping eBay for a 5hp.
VFD. Didn't really want to put this much $ into this job though.

Karl




A 3450 RPM should be easy to find, and work well enough. The 150 drop in RPM
will not affect the GPM enough to notice. Plus you not need the VFD.
Greg

  #16  
Old April 5th 09, 12:47 AM posted to rec.crafts.metalworking
external usenet poster
 
Posts: 428
Default RPM of small gas engine

On Fri, 3 Apr 2009 17:43:36 -0500, "Karl Townsend"
wrote:

I just bought a trash pump without the gas engine.
http://tinyurl.com/d3qj5f

What RPM do I spin it at?

FWIW, I hate small gas engines. Nothing but trouble. I'll use a 3 phase
motor for this job.


If you want to use an electric motor you can go a bit smaller - If
it calls for 5.5 HP gas engine, you can probably drop to a real 3 HP
electric motor - a 5 HP would spin it without breaking a sweat.

For some reason small gas engines are rated at gross HP, and when you
subtract the power used to run the cooling fan...

And find out the optimum speed for the pump head - probably 2,400
RPM to 3,600 RPM range common for gas engines.

This style pump head is meant to direct-mount onto a certain tapered
crankshaft tail normally found on gasoline engines - which you are NOT
going to find on regular electric motors. The pump impeller has the
female of the tapered shaft with the lockbolt, and the tolerances when
it's all bolted together is critical.

Pool pumps and stationary pressure pumps are built to bolt to a
standard C-face pump duty motor with straight keyway shaft, not these.
If you search, you can probably find a semi-trash style pump made for
an electric drive - just like you can find prerssure washer pumps
built both ways.

If you really want to go electric with that particular pump head,
you need a pedestal adapter for the pump. It has the proper tapered
shaft with center bolt, a pedestal in the middle with two shaft
support bearings and and bolting face at one end to mount the pump, a
mounting foot built into the casting, and the other shaft end has a
straight shaft with keyway to mount a standard drive pulley or a
Lovejoy Coupling.

Thern you vary the pulley ratios to drop the speed a bit from the
3,450 RPM of the electric motor to the ~2,400 RPM that the pump head
really wants.

-- Bruce --
  #17  
Old April 5th 09, 12:53 AM posted to rec.crafts.metalworking
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Posts: 163
Default RPM of small gas engine

"Greg O" wrote in message
...
"Karl Townsend" wrote in message
anews.com...
How about a VFD?


A 3600 RPM 5 hp. may be hard to find. I'll start shopping eBay for a 5hp.
VFD. Didn't really want to put this much $ into this job though.

Karl




A 3450 RPM should be easy to find, and work well enough. The 150 drop in
RPM will not affect the GPM enough to notice. Plus you not need the VFD.
Greg


Here is one for example, EBay #120391225187
Greg

  #18  
Old April 5th 09, 12:59 AM posted to rec.crafts.metalworking
external usenet poster
 
Posts: 163
Default RPM of small gas engine

"Karl Townsend" wrote in message
anews.com...
I just bought a trash pump without the gas engine.
http://tinyurl.com/d3qj5f

What RPM do I spin it at?

FWIW, I hate small gas engines. Nothing but trouble. I'll use a 3 phase
motor for this job.

Karl



Karl, I have repaired a ton of small engine powered pumps over the years,
3-8 HP, and I have ONLY seen engines running at 3600 RPM. No other RPM's,
just 3600.
Look for a electric motor running about 3450 it will work fine running
direct drive. No belts, no VFD needed. You will more than likely need to
build a mount and shaft setup to mimic the gas engine that would normally be
supplied with that pump.
Greg

  #19  
Old April 5th 09, 03:02 AM posted to rec.crafts.metalworking
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Posts: 762
Default RPM of small gas engine



For some reason small gas engines are rated at gross HP, and when you
subtract the power used to run the cooling fan...


Not really, we have run these small engines on a legitimate dyno at one
of the major lawnmower mfg facilities. (They paint their stuff red) The
engines tend to put out less than the engine mfg lists: something like
95% of the nameplate number down to not much over 50%

But the real reason you need a larger gas engine than electric is that
the gas engine has no additional torque capability, an electric motor
does. A 20% overload for 1 second will kill a gas engine cold. Same
overload on an electric motor will cause a surge in input power, not
much else.


And find out the optimum speed for the pump head - probably 2,400
RPM to 3,600 RPM range common for gas engines.


I'd expect ANY pump in this class to be set up for 3600 rpm. It's the
standard speed for both gas and electric motors.

This style pump head is meant to direct-mount onto a certain tapered
crankshaft tail normally found on gasoline engines - which you are NOT
going to find on regular electric motors. The pump impeller has the
female of the tapered shaft with the lockbolt, and the tolerances when
it's all bolted together is critical.


The OP listing clearly states "3/4 inch straight shaft with keyway"

Pool pumps and stationary pressure pumps are built to bolt to a
standard C-face pump duty motor with straight keyway shaft, not these.
If you search, you can probably find a semi-trash style pump made for
an electric drive - just like you can find prerssure washer pumps
built both ways.

If you really want to go electric with that particular pump head,
you need a pedestal adapter for the pump.

A lot of work with no benefit.

It has the proper tapered
shaft with center bolt, a pedestal in the middle with two shaft
support bearings and and bolting face at one end to mount the pump, a
mounting foot built into the casting, and the other shaft end has a
straight shaft with keyway to mount a standard drive pulley or a
Lovejoy Coupling.

Thern you vary the pulley ratios to drop the speed a bit from the
3,450 RPM of the electric motor to the ~2,400 RPM that the pump head
really wants.

-- Bruce --

  #20  
Old April 5th 09, 10:41 PM posted to rec.crafts.metalworking
external usenet poster
 
Posts: 428
Default RPM of small gas engine

On Sat, 04 Apr 2009 21:02:46 -0500, RoyJ
wrote:
Bruce wrote:


This style pump head is meant to direct-mount onto a certain tapered
crankshaft tail normally found on gasoline engines - which you are NOT
going to find on regular electric motors. The pump impeller has the
female of the tapered shaft with the lockbolt, and the tolerances when
it's all bolted together is critical.


The OP listing clearly states "3/4 inch straight shaft with keyway"


O Rly?

I read the eBay listing referenced as a tapered shaft with an end
hole for a lock bolt. Sure you looked at the right page? They :do:
come both ways.

-- Bruce --
 




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