[DennisCNC]

I was wondering if a diesel engine would be something to consider to replace a ~60hp electric motor?
Anyone have experience in this field?
I just got this idea because the current building will not handle a motor that size. This is for future waterjet cnc. I'm just trying to come up with some numbers to see what the fuel cost will be to run a diesel engine at 50Hp for one hour?




Thanks

[Geof]

I have a 14kVA diesel generator which has run about 600 hours total at an average load of maybe 40%. During this time is has gone through about 1400litres of fuel which is about 370 US gallons. I was told when I bought this unit that it would use about 1 Imperial gallon per hour at full load so I guess my consumption about matches that.

The diesel is rated at 25 to 30 horsepower depending on the operating rpm; 14kVA is equivalent to 18.7 hp at 100% efficiency so I guess my engine is putting out around 20 hp assuming a generator efficiency of 90%.

So if you were running a 50 hp diesel at its rated output I guess it would go through about 2 gallons an hour maybe a bit more.

If you have natural gas at your building you might consider a gasoline engine with a natural gas conversionit could be less expensive in the long run. And quieter...do you know how noisy a diesel is? I do.

[cdlenterprises]

I've heard of a company that makes small gas turbines for home and business uses. They're called Capstone turbine. No idea what they would cost or if it would even work for what you're looking for but it may be worth checking them out...

http://www.microturbine.com/


:cheers:

[DennisCNC]

ut around 20 hp assuming a generator efficiency of 90%.

So if you were running a 50 hp diesel at its rated output I guess it would go through about 2 gallons an hour maybe a bit more.
.

That is a estimate that I came up with also, ~2 gallon per hour. Looks like it is a sound idea.

I can build a shed for the noise if it will help any?
The building did have natural gas a long time ago I will look in to that as well.

Thanks for the input!

[Geof]

....I can build a shed for the noise if it will help any?.....

I built a 'closet'. My unit is in the rear of my workshop in a small room. I built an enclosure in one corner of this room with holes through the exterior walls for cooling air. Two sides of the enclosure are the building walls, the third is 2 x 4's with a double layer of gypsum board inside and the fourth is 2 inch plywood. It is only four feet high and the top is plywood with carpet on each side.

Inside the main workshop many times the diesel cannot be heard because the mill makes too much noise. Outside where the coolling air goes in and out it is a noisy as a typical truck engine.

[VVINZ]

Has anyone looked at building the waterjet pump? Virg at www.brokenhammer.com

I sure do like the Diesel engine as the power source. I'm trying to go off grid and plan on using veggie oil for fuel.

[DennisCNC]

I built a few things before but with something like a waterjet intensifier things wear so you need replacements you will be making them, instead of cutting parts with the jet.
I don't think it is worth the time you will spend on R&D.

Great info, Geof!!

[mog5858]

well from what i know if u wont to replace a 60 ph electric motor i will need more hp then that. the genral rule is 10-1 for everyone ph in a/c u need 10 ph in gas to get the same work done. dose not matter if it is 3 phas or single. so in u shoule need something like 600 ph. the big proble with gas/ ng/diesel is that they do not have a Striate Torque line as compered to a electric motor that get peak torque at 1 rpm to running speed. that is why you would need a lager motor. sorry about the spelling men. i always was in the shop's room not the english one lol.

[DennisCNC]

^^ Some thing doesn't sound right, 60hp is 60hp if its gas or electric. You might get it at different RPM but you get the same amount of work done. Not sure how you came up with that rule?

[mog5858]

dennis hp is how fast u can do work and torque is how much work u can do that. when u are going to have a load on it u need torque not hp. a big rig only has aobut 300-500 hp but will have like 1200-2000 feet of torque. the one that i can note is that u look at air compser that will give u 8 cfm. it will have a 1 hp electric or u get it in gas it will be 10 or more to give u the same cfm. don't take my word for it look in the stores. look at the really big mining loader/shovles they are all electric cus a electric motor is more efishiont. your stander 350 v8 have 749 moving parts a electric motor has 1 so i shere u can see wich will have more Parasitic power lost form frishion. if i am wrong could u show me where thanks.

[DennisCNC]

Here is what I mean: http://cgi.ebay.com/MQ-Power-Whisper...QQcmdZViewItem

A 180HP diesel engine generator gives you 125 HP to work with. Thats a 55hp up in smoke. I was thinking of direct driving the hydraulic pump from the engine so that will be less loss.

[Geof]

....A 180HP diesel engine generator gives you 125 HP to work with. Thats a 55hp up in smoke. I was thinking of direct driving the hydraulic pump from the engine so that will be less loss.

I am not sure your '55hp up in smoke' is correct. When I was collecting information about generator output, engine size and things like that it seemed that the engine horsepower was quoted as the maximum the diesel could give but when it was driving the generator it could not run at the rpm corresponding to its maximum output.

For instance the diesel might output 180 hp at something like 2200rpm but connected to a generator it can only run at 1800rpm so the output is lower.

[DennisCNC]

I just looked at the label on the generator on eBay and came up with that, but you are right the motor will not be running at full RPM.

[Netjams]

I suspect in the water jet application the HUGE electric motor is needed for startup because the machine pump has such a restriction. You could probably use a 100 horse diesel to power it but you may have to setup some type of bypass or clutch to allow the diesel to gain enough rpm to develop it's horse power. Electric motors have a pretty flat torque curve so the power is there at lower rpm but gas/diesel that is not the case, they need to get to their working rpm before it develops it's torque.

A good example of the difference between electric and fuel is my motorcycle. I have a home built electric motorcycle. It was a 250cc gas with 20 hp and a top speed of about 65 mph. I converted it to electric with a 3 hp electric motor, it now has a top speed of 70 mph and the acceleration at is far better then the gas motor.


60 hp electric is a MONSTER! Even 100 hp diesel may not be enough.. But then again diesels have HUGE amounts of torque so it may work ok.