2 stage log splitter pump vs. engine size

[jas67]

I purchased the following pump:
22 GPM/650PSI for the first stage
Haldex Hydraulic Pump — 22 GPM, 2-Stage, Model# 1080035 | Pumps | Northern Tool + Equipment

To upgrade my log splitter, which currently has an 8HP Briggs engine
with an 8GPM pump. I have an "extra" 10 HP Yanmar single-cylinder air-cooled diesel engine that I plan to put this pump on.

Northern's website doesn't show an HP requirement for this pump, but
list the 11 GPM pump as requiring 5HP, and a 16 GPM pump requiring 8 HP.

These numbers match the formula that I found in several places of GPM
* PSI / 1500 = HP. 22 GPM @ 650 PSI (1st stage) gives me 9.53 HP. The 2nd stage of these pumps is 2500 PSI with a proportionaly smaller GPM rating, yeilding a similar, or less HP requirement as the 1st stage.

So, I purchased the 1057 pump shown above. Then I find this calculator on Surplus Center's website:
Burden Sales Surplus Center - Tech Help
22 GPM @ 650 PSI show 10HP needed to drive this pump. Great!

BUT -- then I read the comment on that page: "calculated for electric motors,double HP for gas powered motors".

This might explain why my splitter has an 8 GPM pump on an 8HP engine, instead of a 16 GPM one.

Now, after reading this, I'm having some doubt.

What are peoples' experiences with matching 2-stage pumps to gas/diesel engines?
Will my 10HP engine drive this pump OK.

I read some "customer comments" on Northern Tool's site where people run running their 11 GPM pump with 5 HP engines, so 22 GPM with 10 HP sounds doable.

Thanks,
Jay

 

[LanceH]

Jay,

I'm building a log splitter right now and am going through the same debate. My local Tractor Supply sells splitters that have an 11 gpm pump with a 5 hp engine. That same **** note on Surplus Center's hydraulic calculators page got me too! From the little bit of research I've done, I'd say that your 22 gpm pump is right on the bottom end of the range a 10 hp engine can handle.

I'm debating on buying a 11gpm Haldex pump off ebay to match on my 5.5 HP Honda Gx160, versus buying a 16+gpm pump and a knockoff Honda engine to speed up the whole operation. Do you have any experience with replica engines?

I'll keep looking for some more calculators. You could also try calling Northern to ask them what HP is minimum required.

-Lance

 

[tommu56]

I think the 8 hp would drive pump but at a lower flow.
I think the pump wouldn't put 22 gpm at full pressure it would be like 3-4 gpm at the second stag pressure.

tom

 

[jas67]

I ended up buying the 16 GPM pump from Surplus center. I chose this for few reasons.

1: My 10HP diesel isn't going to bolt on w/o some modifications, it is too tall, and the exhaust is on the wrong side for the way the current mount is. So, I'm going to wait until later to upgrade to this engine. 16 GPM is the largest the 8HP engine can take. This way, I can get faster cycle times now w/o a lot of time investment.

2: The 16 GPM pump will bolt to the pump mount that is currently on it. I'd have to buy a new mount for the 22 GPM pump.

3: When I do change over to the 10 HP diesel, I can raise the unloading pressure setting, so that the splitter can split more wood w/o needing to go to the slow/high pressure stage as much. With the 16 GPM pump, it will do the full extend (at the lower pressure) in 5 seconds, 1/2 the time it currently takes. I think that'll be fast enough. Plus, being able to do that at higher pressures means it can split harder wood w/o slowing down.