I’ve run a 5.5/3k belt-drive machine with a Honda GX390, but Honda has a big gap in it’s engine lineup, and when I upgrade in the spring, I’m looking at putting together a gear-driven machine myself with the following goals:
At least a 6.5 - 7.5 GPM at 2400-3000 PSI performance target
Single-cylinder Engine form factor with built-in fuel tank
(before suggesting a typical 8/3.5k V-twin retail unit, trust me when I say that won’t work with my build concerns at this time)
The GX390 is rated at about 11.5 HP. The next step up in Honda’s lineup currently appears to be the GX630 V-twin at about 20.5 HP. While I wish there was something comparable in Honda’s lineup, that gap means I’m weighing the Pedator 459 vs. DuroMax 500. Pretty similar specs so far as I can tell. Predator 459cc claims just under 16HP, 24.5 lb/ft. Duromax is marked at 20HP, but I don’t really buy it, with 500cc claiming 23.9 lb/ft, it’s likely also about 16, or maybe at best just under 18 HP in reality.
Reading on this forum and elsewhere led me to consider the Udor CC26/20GR or Allison TSG-6835G.
The Udor pump (without the GR) is rated at 1450 RPM, and the 2.2:1 gear reduction of that motor calculates to about 1635 RPM, so if I’m understanding, spinning the pump faster increases the volume over the rated 6.9 GPM, and according to @TexasPressureWashing an observed performance of about 7.8/2.4k after 200’ of 3/8" hose.
Curious if anyone has experience with a build like this with the DuroMax 500, and also with the Allison TSG-6835G from Envirospec? I can’t find as much detailed information the TSG-6835G pump/GR unit, other than a stated 1650 RPM, 6.3G/3.8k. What kind of performance has been observed from this combo, in comparison to the 459/Udor combo above? How does this Pump compare to the Udor on the Predator 459?
I say put that rig to work & save your nickels until you can upgrade properly. And make sure it says Honda on it or leave it at the store. A broke down rig puts out zero GPM.
Definitely Chinese built, nowhere near the quality of Honda. There is a reason Honda makes more 4 stroke engines than anyone else in the world. I usually run the duromax for 500-700 hrs then replace due to the fact I don’t want to risk downtime.
What does ‘upgrade properly’ mean, exactly? Seems there’s a lot of eventualities to pursue.
I don’t disagree about the reliability of Honda, but there’s that large gap in their engine lineup I mentioned, hence looking elsewhere. That 16-19 HP range in a single-cylinder engine format seems illusive. Yamaha, Robin, Vanguard, Kohler, all top out at about 14HP from my research thus far.
Just saying 5.5 ain’t nothing to sneeze at but a v twin is your most logical next step if you do flatwork at all. I would just roll with what you have but if you have a wad of cash burning a hole in your pocket, there are always lots of deals to be had in the classifieds this time of year. Why is a v twin not an option?
I have a 2k lb. limit on my trailer and tow vehicle. I’m trying to maximize my flow for residential flat work while keeping the mass down with a single-cylinder form factor.
A great deal of my work thus far has been flat work. Many of the residential jobs I complete are pushing 3k sq ft of Driveway/walkway/patio. I’ve been running a 5.5G/3k at right about 2k PSI with a 19-inch Whisper Wash, and I’d like to work as fast as I can within the vehicle limitations I mentioned above. It feels painfully slow to complete this with my current setup. I’m hoping moving up to at least a 7G flow will let me move to a 24-inch surface cleaner and rinse faster too.
One thing to keep in mind is that, typically, when your flow goes up your pressure will go down. Now, there are some pumps out there that can achieve good numbers in both categories but those pumps will usually require more HP than most single cylinder engines can produce.
An 8.5/3500 Pressure Pro skid only weighs about 250lbs. Full gas tank will add some weight but overall you’re only looking at about 15% of your capacity with a V twin engine that can do it all.
You can run a single cylinder engine and spin a pump a bit faster like @CHogue has done but you’ll be sacrificing pressure for flow. If you don’t have the pressure to lift the heavy stains out of concrete you could always go heavier with your soap mixtures but you’ll need to be very cognizant of runoff and nearby vegetation.
I started with 4gpm & moved on to the Predator 459 with 6.8gpm pump. House washing sped up but driveways slowed down. After the muffler fell off on the 8th or 9th job I ordered a GX630 & it let me open my unloader up all the way which sped up houses & concrete. Underpowered engines will squander flow or psi depending on how the unloader is set up. 2000 lbs is a lot to work with. My rig, trailer & all is barely over half that.
@CHogue Interesting, thank you for your perspective. What (pump) RPM do you run them with that belt setup, and what kind of PSI are you setting at the unloader at the faster speed, since the specs for the 5638 I’m finding state 5.6G/3.5k at 1450 RPM?
I’m looking to do gear driven but still good knowledge.
@DisplacedTexan Right. I know I’m chasing a balance point, and added HP will be necessary to drive both numbers up. GPM x PSI / 1100 = HP Then there’s the targeted pump RPM for it’s rated output.
Thus far I’ve not encountered any concrete stains requiring more pressure than my current machine can provide, which at max is about 2600 PSI at the end of 200’ of 3/8" hose. While I’m sure those needs are out there, for typical residential concrete, what’s the highest you really need to go?
If my business grows past a certain point I’ll be looking at major upgrades anyway, that will negate all of this, like a hot water unit pushing 8+GPM, which I would think would be more beneficial for truly stubborn concrete stains than pure pressure from a cold unit, no? Not in the cards for now, regardless.
At this point I’m leaning towards the Udor pump for the higher potential flow over the Allison which is rated for higher pressure.
I run right at a 2:1 pulley ratio, so right around 1800 pump rpm. I set the unloader on this combo till the engine starts having trouble maintaining rpm, after 200ft of hose it is usually about 2800psi. Still does well cleaning residual concrete. If you do a good bit of flat work I would bite the bullet and invest in a 8gpm V twin setup, you won’t be disappointed.
7gpm will be slower than what you’re getting now if you go up to a 24" You’ll move faster keeping the 19" until you get up to an 8gpm with decent pressure. Part of the reason you’re slow is 2k psi not quite strong enough. Need to get it up to around 2500. That will do a couple of things for you, one of which is give you more lift on your SC.
@Racer My 19" WW surface cleaner can get 2400 PSI out of my current 5.5/3k, I’ve just been experimenting with tip sizes and it has some slightly larger tips installed currently that put it about 2k, so it’s not for a lack of power that I’m currently seeing that pressure.
Isn’t the base math 4-inches of surface cleaner diameter per GPM? By that a 24-inch should be fine with a 7 GPM, correct? At any rate I plan on continuing to run the 19-inch surface cleaner in the interim anyway. My WW has casters so the lift isn’t really a thing currently.
More than the speed of the surface cleaner I feel like rinsing is what’s really the slowest aspect of my flatwork right now, and I’m hopeful that jumping up to around 7 GPM will give me a bit of a boost there as well, without risking running the system dry on my smaller buffer tank.
