Rick G 14 Report post Posted November 16, 2003 I have a 13hp Honda direct drive with a Comet pump that puts out 4.5 @ 3500. I am breaking this unit down and rebuilding the engine and I would like to go with a 3000 psi @ 6gpm or more pump. I will keep the Comet as a back up. Is this possible with 13hp? I know I would be better off with an increase in hp but I must work with what I have. I thought of converting into a belt drive. Realizing I must have the proper ratios for the pulleys I don’t see why this would be to difficult? I have been told it would be. Anyone have tips on converting direct to belt? Brands of pumps? Warnings or cautions? What do you all think the best why to reconfigure this unit to maximize the GPM? Thanks Rick G Share this post Link to post Share on other sites
Mike Williamson 198 Report post Posted November 17, 2003 I imagine it would be possible, but not recommended...You're way too low for that..you need 18-20hp... IF the engine could turn the pump fast enough to put out that much gpm at 3000 psi, I would think it would be way overworked. I have my doubts it would even do the job, you would possibly wind up back where you started, with a lower gpm and psi than you're shooting for. Share this post Link to post Share on other sites
Michael 14 Report post Posted November 18, 2003 ALL pumps are positive displacement....this means they move the same amount of water every stroke at a set RPM. ALL pumps are rated at maximum RPM for the weakest component. Overspeeding the pump will give you more GPM but WILL void the warranty. Direct-drive pumps run at 3450-3600 RPM, going any faster is not possible because of the limits put on the engines. Horsepower is directly related to flow, to get more of the latter you need more of the former. Using a formula for Electric Brake Horsepower (an international standard of measure) you arrive at the following... (Flow X Pressure) / 1,460 = EBHP (6 X 3000) / 1,460 = 12.33 ELECTRIC horsepower. In order to get to a "real world" comparison you must multiply that number by 1.5 to arrive at gasoline engine horsepower required or 18.5 hp; which you do not have. Some people will try and convince you to use a slightly different version of that formula (Flow X Pressure) / 1,100 to allow for the diffences in relative efficiency. DO NOT USE IT. This formula is based on theoretical performance figures with every component working to theoretical perfection in standard conditions. There are no international standards regarding gasoline engine performance; just look at the difference in SAE, DIN and JAS horsepower figures for automobile engines. Hope this helps? Cheers. Share this post Link to post Share on other sites
Brian Keating 14 Report post Posted November 18, 2003 Michael, Is it possible to get a higher GPM from a gear drive pump than a belt drive? I have a gear drive 13.0hp honda with a cat pump. It is rated at 4.5 GPM at 3500psi. The same belt drive is rated at 4.0 GPM at 3500psi. Share this post Link to post Share on other sites
