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DuroMax XP18HPE 18 HP Electric Start
- Thread starter Armilite
- Start date
besides math? They literally took the peak torque measurement and plugged it into the torque/rpm/hp equation at MAX RPM to give an inflated hp number. Last time i checked, these industrial 4 stroke engines make peak torque at 2200-2500 rpm, not @ peak hp rpm, which is 3600 rpm. Given their supplied data for torque and a little common sense, and a simple formula. This thing only makes 11-12.5 hp out of the box. Sorry duromax but your probably going to get a class action lawsuit just like all the other big names (honda, briggs). One significant pro is that you can actually buy one, then when they get sued for doing what other engine manufacturers have done (puffing the numbers), then you can be part of the lawsuit settlement and get CASH BACK! wohoooo!!!
I just bought this engine,..
I was pleasantly surprised to open the box, spin around to the back& see a ten bolt side cover vs the typical GX-390/420 setup
For what i am building the additional bracing in the side cover is a big benefit
The engine ~does~ displace more than the GX390/420’s and simple logic tells you yes it is capable of more hp and torque?,.. how much more?,.. who knows,.. and who cares
With the stroker crank this engine is easily turned into a 460cc, but again, why?,... gains are not massive..
From what time i have spent on harbor freight’s offerings and Lifan’s offering, this latest Gen2 Duromax440 is a very impressive mill ESPECIALLY at the $289 delivered price with el. start and ability to re-charge a starting battery
I really am impressed with mine
Anyone who will tell you a Honda 390 in stock form puts down the same numbers as a 420 or 440 clone i would suspect is cc’ butt’hurt, but that is merely my opinion
I was pleasantly surprised to open the box, spin around to the back& see a ten bolt side cover vs the typical GX-390/420 setup
For what i am building the additional bracing in the side cover is a big benefit
The engine ~does~ displace more than the GX390/420’s and simple logic tells you yes it is capable of more hp and torque?,.. how much more?,.. who knows,.. and who cares
With the stroker crank this engine is easily turned into a 460cc, but again, why?,... gains are not massive..
From what time i have spent on harbor freight’s offerings and Lifan’s offering, this latest Gen2 Duromax440 is a very impressive mill ESPECIALLY at the $289 delivered price with el. start and ability to re-charge a starting battery
I really am impressed with mine
Anyone who will tell you a Honda 390 in stock form puts down the same numbers as a 420 or 440 clone i would suspect is cc’ butt’hurt, but that is merely my opinion
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.
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.
65ShelbyClone
Member
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.
FTFY. They can say whatever they want because there are no consequences. If it gets bad enough, they just change the name, maybe color, and keep selling 'em. Go on Alibaba and it's impossible to know what you're looking at because frequently the engine specs are totally wrong also. Many can't even do inch conversions properly.
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.
I may have not re-read all the posted from the start~ AND I UNDERSTAND WHAT YOU ARE TRYING TO SAY, my point is merely it is a 440, a 440 is bigger than a 390, or a 420, PLUS has the beffier block w/ 10bolt sidecover.
The 440’s and 460’s make more power, its simple physics~ thats why you stroked and bored your 389cc to a 460.
(30 hp 65+mph LOL)
https://www.youtube.com/watch?v=sTBq3bRRQqE
I know i know~ i’ll beat you nay’sayers to the punch~
“I can make a dyno read whatever i want”,.. or.. “yeah but who’s dyno”
Here is a damn near stock UTI GX390 laying down 18hp, yes revving past 3,600 rpms to do so
I know i know~ i’ll beat you nay’sayers to the punch~
“I can make a dyno read whatever i want”,.. or.. “yeah but who’s dyno”
Here is a damn near stock UTI GX390 laying down 18hp, yes revving past 3,600 rpms to do so
Had to ship my 440 back, found some shipping damage that concerned me. Mine was $259 at the time id i recall, now to re-buy they are up to $296. Oh well still a steal for a 440.
I decided not to stroke this one after all, not putting the longer rod in either. Mill the head is it, i have a 306TQ cam i could move over to it but im on the fence if i even want a cam in it.
This motor is going to be essentially an endurance motor, hopping it up a little but i want my “regular work” on the motor to be oil changes, adding fuel, and cleaning the air filter.. (occasionally check valve lash)
Over building and continually breaking due to it because you are pushing the limits of a generator motor~ the novelty of that has worn off.
Edit:
To clarify the shipping damage was done in route, not at all uncommon in all clone sales,.. my first Lifan 420 from HD i also had to ship back.
The quality of the 10bolt Gen2 DM was very very impressive. DuroMax got a bad name promarily because of one powerwashing moron on youtube that bolted two 16’s to a powerwashing trailer with absolutely no rubber shock absorbtion spacers and his fuel tank brackets cracked.
I will re-order the 440 i’m just watching to see if prices dip again to aid in offsetting the ARC rod (stock length)
I decided not to stroke this one after all, not putting the longer rod in either. Mill the head is it, i have a 306TQ cam i could move over to it but im on the fence if i even want a cam in it.
This motor is going to be essentially an endurance motor, hopping it up a little but i want my “regular work” on the motor to be oil changes, adding fuel, and cleaning the air filter.. (occasionally check valve lash)
Over building and continually breaking due to it because you are pushing the limits of a generator motor~ the novelty of that has worn off.
Edit:
To clarify the shipping damage was done in route, not at all uncommon in all clone sales,.. my first Lifan 420 from HD i also had to ship back.
The quality of the 10bolt Gen2 DM was very very impressive. DuroMax got a bad name promarily because of one powerwashing moron on youtube that bolted two 16’s to a powerwashing trailer with absolutely no rubber shock absorbtion spacers and his fuel tank brackets cracked.
I will re-order the 440 i’m just watching to see if prices dip again to aid in offsetting the ARC rod (stock length)
BLACK DEATH
Member
Any updates on the 440?
I’ve seen them $230 with pull cord only.
I’ve seen them $230 with pull cord only.