Predator 459cc 16 HP + pump size?

Hello all my name Robbie and I’m starting to make some real money doing residential homes and flat work. I had a 4.2 GPM harbor freight pressure washer with a 420cc engine and have decided to move up to a larger unit that could push a 20 in BE surface cleaner that I already have. I’m really looking to gain more gallon per minute and I kind of fell into the brand new predator 459 CC big block electric start. I have it already mounted on the skid and I’m having real trouble figuring out what size pump I’m capable of utilizing. I would really like 6 gallons per minute at least. Does anyone have any suggestions or should I trade this motor in and go with the 670 V-Twin predator? Thanks for any input.

I just bought one of these. Seems like a good motor so far and there have been a lot of upgraded engineering aspects with this model as compared to the 420cc. I have a General TS2021 pump with a general ZGRS1000 gearbox between the engine and pump. It’s an awesome machine. The TS2021 will get you 5.6 GPM, that’s close enough to 6 you won’t notice. Heck, I went from the predator 670cc with an Udor 8 gpm and it can be hard to tell the difference sometimes. Unless you are doing a lot of flatwork, I don’t think the 8 gpm is worth it, especially given that you already have this engine.

That engine will get you 6 @ 25

Just food for thought: a 429cc 14hp Kohler is 13.4 certified hp…

GPM x PSI / 1100 = HP
HP x 1100 / GPM = PSI
HP x 1100 / PSI = GPM

Thank alot. Haven’t heard much about this motor. Sure seems like torque monster for it’s size.

Wrote that down!

@TexasPressureWashing is running one with an 8 gpm udor gear drive. Here’s the build sheet


Yes sir 7.8GPM at 2400PSI on 200ft of 3/8” hose.


Wait, you’re getting a verified 2400/7.8 after 200’ on a single cylinder?

Yah there’s just alot booty in these 459s. Very Torquey. I was worried sick about doing the 7.8 GPM odor so I downgraded to the 6.9 GPM with a gear reduction and you know it’s like it’s not it’s like it’s nothing it’s amazing freaking amazing.

To say that much money and to have such a little footprint so you’re not crowded and you know it’s so it’s not an EFI motor it’s not a igx700 you know you can tear it down you can fix anything and it’s just it’s just a really amazing piece of kit

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Yes. Udor CC 26/20 GR. Rated 6.9GPM @ 2900PSI. Seeing verified by multiple other people 7.8GPM @2400PSI

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What kind of results are you getting on flat work with it? I’ve got 2 GX390’s & have been tossing around the idea of adding something with more GPM, possibly the Allison 6.8.

Clean just about like a GX690 8GPM. We dialed that down to 2500PSI as well. So close it’s hard to tell.

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Really hoping to plumb this up in the bext week, but gotta finish trailer prep first. Allison 6.8 and their gear drive.


I’ve built this with an iGX800 and a Predator 670 so far. Note if you order the pump it come in a 1” gearbox shaft which is suitable for Predator 670’s but iGX800’s and GX690’s are 1 1/8” shafts and you must specify in the notes of the order. I would always recommend an iGX800 over a Predator or even a 690 but they’re harder to come by these days than usual. I’ve included several engine options on this build. 10GPM Build Video of Predator 10GPM Build in action:

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Do you know approximately how much PSI you’re pushing with that specific build?

Unfortunately not yet. Got sidetracked with my daughters health. Now I am almost finished. Maybe tomorrow. I expect 2700 + tho. Edit: Oops wrong answer thought you were asking me.

Haha totally okay! It’s cool seeing those types of numbers and this motor could probably push out the 5.6GPM 3500PSI pump I’m planning to get from Corbin’s build. Seems like a solid starter.

I have not had a psi gauge on it yet, but it definitely seems like it’s in the 3000-3500 range. I would bet it’s close to 3.5k.

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Thanks so much. Any modifications or additional parts that you had to put into it for it to run smoothly? If you have a parts list, that would be amazing!!!