Building own pressure washer

So I have the opportunity to get an Annovi Reverberi 4000psi/4GPM (XWA-M 4G40) pump and I have a 13hp horizontal shaft gas engine in my garage. What besides a mounting plate, belts, and pulleys would I need to make this work and is it worth it? Also, I would be relying on this forum heavily for expert advice on exactly how to plumb this thing

Buy a gear box. Then just slap it together with a few bolts


Gearbox, please explain? Could you link one that might be ideal? I’m assuming it is to increase or decrease the RPM/torque to a suitable tolerance so the pump may work correctly. Orrrr… is it to engage and disengage the pump?

Edit: looked it up… I see that would make it direct drive, I’m hearing belt driven is better?

Just like the pump in the picture uses belts and pulleys to step down rpms a gear box does the same. The advantage is it is easier to set up and takes up less space. You bolt the pump to the gearbox and the gearbox to the engine. Done.

@Sasquatch Is there a disadvantage to using a gearbox?

Probably a bit more costly than buying belts, pulleys, and platform. You’re putting a used pump on it? That’s kind of risky.

Agreed, it is risky. However, I can build this whole thing for just the cost of assembly parts as opposed to buying an already assembled washer with the same specs for $1000+. In your professional opinion, is this worth it? If the pump is bad/broken, couldn’t I just rebuild it?

Also… I need to google before asking some questions. Found out the pros/cons of belt drive.

It depends on what is wrong with it. I did what you are proposing and later had to replace the pump. Unless you are getting the pump essentially for free. I’d start with a new pump. Envirospec has some very good deals. Some include the gearbox.


The pump is freeninetyfree, that’s primarily the ONLY reason I’m considering this. The only downside for me is that I’ll be removing my 13hp engine off of my generator to make this happen. I never use the generator though (still literally brand new and never been run), but maybe I will someday so I’m hesitant to dismantle it for this purpose. My other option is to go buy a 670 from HF for about $350 and build it with that. I know EVERYONE hates on harbor freight, but I used one of their 8750/7000w generators with the 670cc engine EVERY SINGLE DAY for 8+ hours per day in 100 deg+ weather near Death Valley, CA for just shy of 6 months while living in my 5th wheel RV. It did break eventually, however, it was the pull cord that broke, and get this, they replaced it for free with no questions asked. Sorry for long rant, I’m just very pleased with that particular machinery purchase.

Ask ole @SchertzServicesLLC about his HF predator build. He had to do something different with the fuel system but he loves it. I’m building one this winter for a cold water machine just to rinse. My advice is to use a steel mounting platform and steel pump mounting platform and install an unloader block. Other than that go with what curls your toes man. AR pumps ain’t close to the best ,but I do have 2 comet pumps AKA (Allison) from envirospec sitting on my shelf for standby. Can’t beat $359 delivered. But UDor,legacy, the GP crown etc are definitely designed for heavy use

You won’t get a 670 for $350. By the time you get the extended warranty you’re probably at around $900. Maybe you meant their 420?

You can get a 6.8 gpm gear drive from Envirospec for around $500. I think @Patriotspwashing is running a few of the Allison pumps. There were complaints from some in the past about the owners of Envirospec. They’re under new ownership now. I ordered from them the other day and had to call to ask some questions. They were extremely helpful and friendly. They also upgraded me to UPS two day at no charge.


you’ll need an adapter to make it straight shaft as as generators are mostly, if not all conical shaft.


Yeah, if the pump is free I can see your point. Still a gamble but the buy in makes it attractive. :+1:

1 Like

Dan Galvin is a Good guy in my book. He was at the trade show in Branson Missouri, I’m thinking that’s why Envirospec is on this forum as well. All the hot water units are built from Largo from my understanding. But they have definitely changed their tune from calling house washers splash and dash ppl and are selling a lot of products dedicated to yall. Not the truck washing only store that they used to be in the past.

I spoke with a guy named Joseph. Very friendly, respectful, and let me know numerous times that he appreciated me. That was the first time I had dealt with them but they definitely earned my business.

1 Like

@marinegrunt you’re absolutely correct, I’ve been on this phone non stop on about 15 sites trying to plan this out and I got the two confused.

Well, I have bad news. I went back out to look at this thing and analyze it a little more and I don’t think it’ll be worth the hassle. Although I’d love to say that I custom built my machine and saved money, I don’t think this will be the case in this scenario. I think I’ll buy a new pump and engine to build this later on down the road. :anguished:

Is the pump bad?

Yes definitely, it’s seized up. It’s been sitting for a while and now I know why. It’s a pump from a military chemical decontamination unit. It’s been decommissioned due to the engine going out. Since it’s been sitting and not cared for, the pump is now seized. Almost like I can’t catch a break… maybe I should stop trying to save $$$ and just bite the bullet. However, I don’t have $5-10k lying around, I need to start from the ground up. People around here say that I MUST have a heated power washer and that I can only do residential with a cold washer and that residential is not going to make any money.