Gear drive vs Belt drive

Sorry if this been asked i searched but didn’t find the answer. Does a gear driven pump need more HP than a belt driven pump to put out same gpm and psi?

No. Same formula

Thanks im looking at getting on of the Kohler 14hp engines and Udor.7gmp, 3500psi pump. How do you think that would work for house washing?

Most likely will get this pump to be safe

That would be a great pump for house washing for a 14 hp engine. You’ll need to get an unloader as well since it doesn’t look like it will come fully plumbed.

I plan on getting a K7 and GP high draw injector.

I installed that pump on a Honda gx390 and it works great. You need an unloader as mentioned (block mount it), intake fitting, and I’d get pump rails as well. Also a heads up, they don’t ship with any gear lube so get some 80/90 gear lube from your local auto parts store too.

14 Hp will not run that pump. It’s been said a thousand times on here but I’ll tell you how to do the math.

Gpm x (times) psi =
Take that number and divide my 1,100 and it will give you the required horsepower.


22.27 hp required for that pump.


Will not run the first pump described (7x3500)

I had another pressure washing company try to sell me his equipment about a week ago he said he had two units for sale 10gpm@5000 psi . That got my interest ! Then he showed me a picture. They were powerd by the older 24hp Honda’s . I tried to explain the math to him but he was convinced he was rite.

Tell him you want to see it fill a 5 gallon bucket in 30 seconds with a pressure gauge at the wand reading 5,000 psi. If he can do it you had better buy it because it’s a miracle machine that is breaking laws of physics…

1 Like

This guy was not interested in logic. He actually worked for a local vendor. Before starting his own business. So he knew more than me and I just wanted to get my chem and get away from him.

After running the numbers that’s why i decided on the second pump. I already have a 5x8 trailer and a 100 gall buffer tank. just need to get my list of hoses and fittings.


My personal suggestion:

Get a 5.5 Udor for your 14hp engine, make some money with it, then get a 24+ hp engine with an 8 gpm Udor on it. That’s what I did, and I’ve never regretted it.


Did you build your 8gpm unit?..I thought I remembered you having both gear drive pumps. How do you like house washing with 8gpm compared to 5.5?

I put the gear driven Udor on my 5.5 machine and the 8 is a distributor assembled belt driven machine. They both work flawlessly. Housewashing with the 8 vs the 5.5 is night and day different, but the 5.5 is just fine. I still use the 5.5 about 30% of the time because a lot of my customers have old, weak wells.

1 Like

Udor has the hp requirements for every pump in a table on their site plain as day. Chris is unequivocally right, but you don’t even need to know math more often than not to know a 14 hp engine will not nun that pump unless you want 1800-2000 psi. Might as well by an electric.

1 Like

While doing research i read this post that’s why i asked the question. it didn’t seem right but what do i know.


Innocentbystander4 GPMJun 2
One of those kohlers @Steve linked with an undor 7gpm would be a great machine for a single operator.

The pump i linked above is 5 gpm is there a different one that’s 5.5 i should be looking at. Will you notice the .5 gpm difference?

Nice…I’m now getting used to a 5.5 over a 4…big difference when it comes to rinsing. I’m curious to try an 8 to see the difference. What injector do you use for DS for the 8?