# Engine size for Log Splitter



## Basso (Mar 29, 2007)

Hello,
I have a question about engine size for a log splitter. Currently, I have a log splitter that I built (20 years ago) and it has an 8hp B&S engine. The engine is old (but still has plenty of power) but it has some issues(won't get in to them right now).
Bottom line is that I would like to replace it with another electric start engine. Since the pump and engine are direct coupled to the engine, it seems that I will have to run a larger HP engine at the same throttle speed to keep the pump turning just as fast so I keep the same cycle time????? If that is true, then I don't gain anything by going with more HP than 8, since my current 8HP has never bogged down or lacked in power. I wonder what the minimum HP engine I could buy and still have plenty of power. Obviously, a smaller HP engine will cost me less money, which is a good thing !!!! The pump is either a 13.6 or 16 GPM 2 stage and a 4" x 24" cylinder. Any thoughts ????? Thanks
Basso


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## CaseyForrest (Mar 29, 2007)

If your getting it done with an 8 horse now, bumping up the Hp doesnt do anything.

HP is only determined by the GPM your pump puts out. You need 1/2 horse for every GPM on a 2 stage pump.


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## sawinredneck (Mar 29, 2007)

CaseyForrest said:


> If your getting it done with an 8 horse now, bumping up the Hp doesnt do anything.
> 
> HP is only determined by the GPM your pump puts out. You need 1/2 horse for every GPM on a 2 stage pump.



You are partially correct, and patially wrong. This is a complex idea that can go wrong fast.

Upping the engine size will increase cycle times, IF you are kicking the pump in and out of the second stage a lot. If you increase power to the pump you still have the same sysetm, but wont kick in the se stage as much so it willrun faster. Up to the point where you have enough motor it will never kick in the second stage. The two stage pumps "sense" the load on the engine and when that load is to great, it kicks in the second/slower rate.
But the post above is correct, if it works fine, and has for 20 years, why mess with success?


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## CaseyForrest (Mar 29, 2007)

sawinredneck said:


> You are partially correct, and patially wrong. This is a complex idea that can go wrong fast.
> 
> Upping the engine size will increase cycle times, IF you are kicking the pump in and out of the second stage a lot. If you increase power to the pump you still have the same sysetm, but wont kick in the se stage as much so it willrun faster. Up to the point where you have enough motor it will never kick in the second stage. The two stage pumps "sense" the load on the engine and when that load is to great, it kicks in the second/slower rate.
> But the post above is correct, if it works fine, and has for 20 years, why mess with success?



COme on Andy, I though you were smarter than that!!

A 2 stage pump doesnt sense anything about the motor. It kicks into the second stage based on pressure. Most are set to kick down when the psi reaches 600 or so. And PSI build-up is dependent on the type of wood you are splitting. Ash you may never reach 600 psi before it splits. Oak or Hickory you can bet the pump is going to kick down.


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## sawinredneck (Mar 29, 2007)

CaseyForrest said:


> COme on Andy, I though you were smarter than that!!
> 
> A 2 stage pump doesnt sense anything about the motor. It kicks into the second stage based on pressure. Most are set to kick down when the psi reaches 600 or so. And PSI build-up is dependent on the type of wood you are splitting. Ash you may never reach 600 psi before it splits. Oak or Hickory you can bet the pump is going to kick down.



AHHHHHHH, but you forget on most pumps that pressure is adjustable!!!!


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## CaseyForrest (Mar 29, 2007)

sawinredneck said:


> AHHHHHHH, but you forget on most pumps that pressure is adjustable!!!!



Not the kickdown pressure. The relief is adjustable on the valve.

The kickdown pressure is set inside the pump.

I could be wrong though. Itd be the first time, however!!!!


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## ray benson (Mar 29, 2007)

The 13.6 gpm 2 stage pump recommends a 6.5hp motor. The 16 gpm 2 stage pump recommends an 8 hp motor. The pump switches from stage 1 to stage 2 at a preset pressure( usually about 650 lbs) the manufacturer recommends this not be changed.
Specs off a 16 gpm Barnes pump
First stage 16 GPM @ 650 PSI
Second stage 4 GPM @ 2500 PSI


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## sawinredneck (Mar 30, 2007)

CaseyForrest said:


> Not the kickdown pressure. The relief is adjustable on the valve.
> 
> The kickdown pressure is set inside the pump.
> 
> I could be wrong though. Itd be the first time, however!!!!





ray benson said:


> The 13.6 gpm 2 stage pump recommends a 6.5hp motor. The 16 gpm 2 stage pump recommends an 8 hp motor. The pump switches from stage 1 to stage 2 at a preset pressure( usually about 650 lbs) the manufacturer recommends this not be changed.
> Specs off a 16 gpm Barnes pump
> First stage 16 GPM @ 650 PSI
> Second stage 4 GPM @ 2500 PSI





Can't a guy have an off night once in a while??????????????

Thank you for the correction Ray!


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## CaseyForrest (Mar 30, 2007)

sawinredneck said:


> Can't a guy have an off night once in a while??????????????
> 
> Thank you for the correction Ray!



HUH?? I corrected you first!!

HAHA!!


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## stihl 440 (Mar 30, 2007)

*splitter*

I know that a 26 ton splitter with a 8 horse motor is the perfect combo. I've ran my buddie's 26 ton iron and oak, with a 8 horse engine on it and it dosen't hesitate in hickory or twisted willow.       :hmm3grin2orange:


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