Rated Horsepower

[tomtucson]

Kohler labels their engines by max horsepower, but the recommended horsepower is less, I'm guessing the other makers do also. I don't like it, they should rate the engine at the horsepower it supposed t run at but should this factor into the selection based on the pump requirement? If you figure your setup needs a certain horsepower engine do you really need a few more as a minimum?

 

[Vince Wood]

I had a Kohler 15HP with a General TS2021 pump hooked up with it. I blew that engine up right after I had got done cleaning some garages 1 year. I put a Vanguard 18HP on with the same pump and after 760 hours no problems so far.

I agree with you Tom, they should rate their engines at the horesepower they are suppose to run at.

Keep in mind that on the burners propane is alot easier to ignite that diesel causing less wear/tear on the engine as well. This is one reason you see alot of guys going to the 110 systems versus the 12 volt systems on the diesel burners.

I've learned it always better to go a little over with the horsepower than under. Before I got the Vanguard 18HP I had a Vanguard 21HP. They shipped the 21HP to my door COD but it was for $300 more than what I was quoted. I refused shipment of it and bought the 18HP locally on the same day.

 

[Russ Johnson]

That's why, in 2008, the Federal Trade Commission mandated that engines rated under 16 hp be relabeled. They found that "ideal conditions" horsepower usually isn't the same as real world horsepower. Now Honda uses engine cc displacement and Briggs uses gross torque output. I also noticed that Honda has derated their engines.The GX 610 is now 16.6, not 18, GX 620 is 18.1, not 20, and the GX670 is now20.5 instead of 24.

 

[810f250]

Tom remember we posted stuff about this a year ago, you asked why I wanted more (manufacturer) HP. Your statement is the very reason why.

Nigel, if you can eyeball the size of the pulleys with a tape measure or if they're stamped you can tell how fast the pump is turning by the engine rpm. Also I think you can get a good idea by what pressure you're getting with what size tip.You really want more horsepower? How much?

Ok, I see were you are going, true 20HP is for electric Horse Power not gas engine Horse Power, but I have never seen a "pressure pro" rated for 8 @ 3500 psi with a 20HP Honda on in. They all have 24HP with that pump rating.

( Note: Honda no longer post the HP rating on their new engines the have they displacement values , 620...(20HP*) and 670...(24HP*), they also bumped their warranty from 2 to 3 years)


The question is if the pumps are truly spinning at the exact rpms to give you the advertised gpms under load.


I was told that hydrotek get in some "hot water" for something similar on a government contract.

I now want a least a 34 HP Kohler, I only have a 30HP with a 120 Volt system. I rather have the reserve HP and run my system as an "industrial" unit.


Also look at the specs of a 34HP Kohler, the engineering, and read the fine print, do tell.....what do you see?



"Eye Ball", I did that, I just wanted something more hardcore "evidence". The strobe light would not lie, only + or - 1.5%

I also bought the strobe light, kids had fun moving in slow motion, but it would get put to business use sometime next month, I have a couple speed checks I want to make.

 

[810f250]

Here is the fine print from kohler engines:

Kilowatt (kW) and horsepower (HP) specifications for Kohler general purpose engines are calculated pursuant to the Society of Automotive Engineers (SAE) J1940 for horsepower ratings - calculated with the air cleaner and muffler removed, per the SAE standard. Actual engine horsepower is lower and affected by, but not limited to, accessories (air cleaner, exhaust, charging, cooling, fuel pump, etc.), application, engine speed and ambient operating conditions (temperature, humidity and altitude). The reason for this standard is to provide consistent measurement to customers who may want to control the intake and exhaust features of the engine. It is important to note that the power output of all Kohler engines is always as advertised. For more information, contact Kohler Co. Engine Engineering Department. Kohler Co. reserves the right to change product specifications,designs and standard equipment without notice and without incurring obligation.

That is one of the reasons I wanted the 34HP minimum on my system, but it was to late for me as the pw build was started, and the change order cost was over budget.



The better manufacturers of the industry mates pumps and engines based on:


HP = (GPM X PSI)/1100



but I have also seen literature with this one as well:


HP = ((GPM x PSI)/1460 ) X 1.5



I think if you setup your units with the second formula it is more an industrial setup.


Example: for an 8 gpm @ 3500 psi 12V machine

A cheaper machine would couple a 25 HP kohler

A descent machine a 27 HP kohler

The better machine a 30 HP kohler

then you have to remember the fine print above for all kohlers, HP is before all the accessories.

So if you have the budget a 34HP kohler minimum should set you straight, it would run many marathon cleaning jobs without a problem.


This brings me to another point, pressure washing manufactures typical pump setups are 99.9% of the times setup for non "marathon" use, because frankly 99.9% of us dont operate our units like that. (my definition of "marathon" operation is : frequent continuous cleaning, operation over days before you ever cut the machine off)

However I think if your budget allows, select a pump for your pressure washing unit based on continuous operation, it would be more of an industrial setup.

 

[homer]

In Defense of Kohler

I had a Kohler 15HP with a General TS2021 pump hooked up with it. I blew that engine up right after I had got done cleaning some garages 1 year. I put a Vanguard 18HP on with the same pump and after 760 hours no problems so far.

In defense of Kohler - and I like Briggs as well - we sell both - the problem was not with the 15 HP engine as I see it - it was with the company or person who coupled a 15 HP engine (of any make) with a TS2021. You are asking to much out of an under powered system. That pump requres a minimum of 17.81 Gross HP at max pump performance.

It should have had an 18 Kohler instead. If it did chances are that it would have lasted much longer that 760 hours.

John

 

[Chris Tharpe]

I agree, by looking at Root's website they recommend 12.7hp to run the blower I have, so I put a 13hp engine on it, it runs fine but when its under a load really pulling some water up it will start to bog down vs. pushing right through. I completely agree with overpowering something vs under powering it. I will be taking the 18hp out of my storage and replacing the 13hp with it.

 

[Scott Stone]

In defense of Kohler - and I like Briggs as well - we sell both - the problem was not with the 15 HP engine as I see it - it was with the company or person who coupled a 15 HP engine (of any make) with a TS2021. You are asking to much out of an under powered system. That pump requres a minimum of 17.81 Gross HP at max pump performance.

It should have had an 18 Kohler instead. If it did chances are that it would have lasted much longer that 760 hours.

John

Yep, John is right. To me, this is an elephant in the room observation. But then, no one made it.

Since I have machines that typically run a full five hours, before they are cut off for lunch, then started for another five hours, I would consider that industrial. I do prefer to have a few extra horsepower, and when I buy a pressure washer, unless it is for a very specifically designated task, I try and get the maximum horsepower I can. It does not happen that way all the time, but I try.

 

[Dollarspa]

Here is the fine print from kohler engines:

Kilowatt (kW) and horsepower (HP) specifications for Kohler general purpose engines are calculated pursuant to the Society of Automotive Engineers (SAE) J1940 for horsepower ratings - calculated with the air cleaner and muffler removed, per the SAE standard. Actual engine horsepower is lower and affected by, but not limited to, accessories (air cleaner, exhaust, charging, cooling, fuel pump, etc.), application, engine speed and ambient operating conditions (temperature, humidity and altitude). The reason for this standard is to provide consistent measurement to customers who may want to control the intake and exhaust features of the engine. It is important to note that the power output of all Kohler engines is always as advertised. For more information, contact Kohler Co. Engine Engineering Department. Kohler Co. reserves the right to change product specifications,designs and standard equipment without notice and without incurring obligation.

That is one of the reasons I wanted the 34HP minimum on my system, but it was to late for me as the pw build was started, and the change order cost was over budget.



The better manufacturers of the industry mates pumps and engines based on:


HP = (GPM X PSI)/1100



but I have also seen literature with this one as well:


HP = ((GPM x PSI)/1460 ) X 1.5



I think if you setup your units with the second formula it is more an industrial setup.


Example: for an 8 gpm @ 3500 psi 12V machine

A cheaper machine would couple a 25 HP kohler

A descent machine a 27 HP kohler

The better machine a 30 HP kohler

then you have to remember the fine print above for all kohlers, HP is before all the accessories.

So if you have the budget a 34HP kohler minimum should set you straight, it would run many marathon cleaning jobs without a problem.


This brings me to another point, pressure washing manufactures typical pump setups are 99.9% of the times setup for non "marathon" use, because frankly 99.9% of us dont operate our units like that. (my definition of "marathon" operation is : frequent continuous cleaning, operation over days before you ever cut the machine off)

However I think if your budget allows, select a pump for your pressure washing unit based on continuous operation, it would be more of an industrial setup.

great information (Nigel as always) and russ johnson and John...


so for my second unit soon I guess its unrealistic to run the honda 24 horsepower on 8 gallons...... based on previous threads ?

(The GX 610 is now 16.6, not 18, GX 620 is 18.1, not 20, and the GX670 is now20.5 instead of 24)

 

[810f250]

I agree, by looking at Root's website they recommend 12.7hp to run the blower I have, so I put a 13hp engine on it, it runs fine but when its under a load really pulling some water up it will start to bog down vs. pushing right through. I completely agree with overpowering something vs under powering it. I will be taking the 18hp out of my storage and replacing the 13hp with it.

Any pics Chris?

 

[Paul Kassander]

HP = ((GPM x PSI)/1460 )

If I am not mistaken that is the formula for electric motors.

 

[810f250]

HP = ((GPM x PSI)/1460 )

If I am not mistaken that is the formula for electric motors.

Yes Paul it is electric HP rating, but dont forget to multiply it by 1.5 to get the rating for a "standard" gas engines.

If you do that you would find that this formula yields a higher answer than the industry standard of HP=(gpm x psi )/1100.

 

[offdutyfireman]

I am firm believer in the kohler 25 horse for 8gpm. I have five of them. I do have one 16horse briggs mated to an 8gpm udor that runs all day long. If you are just washing houses or apartments and don't need the presssure, 16 hp is fine. I do love the sound of a kohler command rumbling though.

 

[810f250]

Couple other more things to think about with your HP requirement:

Engines runs "sweet" when new, years down the road that reserve HP may come in handy, .............or when your air filter has 20% life,................. or on those extreme hot days.



Spike pressure, if you have the operating head pressure at 3500psi on an 8gpm machine and your spike pressure is 10%,........ thats 3850psi briefly on the head, the engine has to supply the torque so it will not stall, that extra pressure is approximately 2.55 HP using (gpm x psi)/1100. Engines with healthy torque should pull through.

 

[810f250]

I am still waiting on General Pump to respond to the statement on their website, I did however get an email for the customer service manager Mr Cook, but it did not contain the information.

Today I asked the question to AR North America, Mr Al Stasny
Technical Manager.

I must say he was very helpful and we discussed much more than volumetric efficiency. He however did not have any graphs but did confirm that volumetric efficiency is affected by inlet line design and pressure.

Typically you can have a 5% to 8% increase in volumetric efficiency from a small negative (sucking/pulling) to zero (flooded) inlet, compared to a 30 to 40 psi pressurized inlet (he also said that over pressurization of the inlet has a negative side , 30 to 40psi is tested most efficient, I have also seen this on Cat Pumps website).

If you had to pressure feed a high flow pump like a General Pump TSF2021 (1750 rpm = 8.5 gpm) AR /General Pump and Cat Pumps all recommend a pump that is at least twice the rated output at a particular speed. So my TSF2021 needs 16gpm pump to feed it (lol!!), reason being it has to do with the acceleration the plungers experience during pumping.




The question now remains, what is our flooded pumps really pumping? Hummm!! ( MR Al said that in all the years experience, I was the only one he could remember that was concerned about volumetric efficiency, wow, I have nothing better to do, lol)

 

[swrest]

Hey all this Kohler talk... anyone need a muffler with < 1 hour on it will fit 18-30hp new 170-225 will sell for 100.00