I see this DuroMax XP18HPE 18HP@3600rpm, Electric Start. Says 440cc, but (92mm x 66mm) = 438.9cc. Any Good/Bad things with this Brand. $289. 8.5cr.
With that said, If i was a betting man, I would bet 10 grand that the "18hp" duromax engine makes extremely close to the 13.5 hp in the real world. The world where math and physics apply. Not China where fudge factors and lies apply.
Brian, the problem is that the major brands are reporting per SAE standards for either gross hp or net hp output, and duromax is not even doing the math correctly. If you want to know how much net continuous hp a stock industrial 4 stroke engine should put out at the rated 3600 rpm, just divide the cc's by 32.5.
For example, lets try that with a 6.5hp predator 212, 212/32.5=6.5hp
338/32.5=10.4hp
389/32.5=11.96hp
420/32.5=12.9 hp
440/32.5=13.5 hp
460/32.5=14.1hp
So these are pretty close to real world horsepower. With testing methods for small industrial engines, you can run them without an airbox and without a muffler and get about a 10-11% gain in hp numbers just because you are removing the restrictions.
Additionally, if you use standard correction instead of SAE correction, you can inflate the numbers by an additional 3-4% from observed hp.
On top of all of that, if you use an older SAE test standard (pre 2013) you can advertise the engine output at a much higher rate than what you measured, as long as the measured hp output is 85% of the advertised output.
And finally, with duromax, you can take the peak torque number (that occurs at 2200-2600 rpm), then plug it into the hp=(tq*rpm)/5252 and instead of saying that the rpm is ~2200-2600 rpm, you say that the peak toruqe occurs at 3600 rpm, which we all know is physically impossible with these small industrial 4 stroke engines that are designed to run from idle to 3800 rpm. They always peak at 3600-3800 rpm in horsepower, and they always peak at 2200-2600 rpm for torque.
With that said, If i was a betting man, I would bet 10 grand that the "18hp" duromax engine makes extremely close to the 13.5 hp in the real world. The world where math and physics apply.Not the world where fudge factors and lies apply.
Think of it this way, a 614cc honda gx610 V TWIN engine makes 18 hp... a duromax single cylinder engine with only 71.6% of the displacemnt is not equal to a honda gx610 v twin... Its laughable how much the numbers are inflated with duromax.