Author Topic: Engine HP  (Read 8823 times)

bandmiller2

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Engine HP
« on: July 20, 2012, 01:45:25 PM »
Question for you techie types,reading post from our Aussie brother his ST-1 Lister is running at 1500 rpm's basically half speed half hp when he has a large load and the governor opens up will he pull more than 6hp from that engine or is it locked into that hp due to its speed.?? Thanks Frank C.
Fast cheap and easy are seductive sirens,its a rare man that does not court their pleasures.

dieselgman

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Re: Engine HP
« Reply #1 on: July 20, 2012, 02:19:11 PM »
Horsepower is exactly correlated to speed because only a fixed volume of air(oxygen) is available at a specific speed. Fuel volume is the only variable and the ratings or performance curves assume a maximum fuel mixture (properly working fuel rack).

I would not call an ST1 at 1500rpm half-speed (nor half horsepower) either.

dieselgman
« Last Edit: July 20, 2012, 02:20:52 PM by dieselgman »
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ronmar

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Re: Engine HP
« Reply #2 on: July 20, 2012, 03:11:33 PM »
Question for you techie types,reading post from our Aussie brother his ST-1 Lister is running at 1500 rpm's basically half speed half hp when he has a large load and the governor opens up will he pull more than 6hp from that engine or is it locked into that hp due to its speed.?? Thanks Frank C.

HP = Torque over time.  Fewer torque pulses in a given time period due to lower RPM = lower HP available...
PS 6/1 - ST-5.

Combustor

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Re: Engine HP
« Reply #3 on: July 22, 2012, 03:30:49 PM »
               The good news for our Aussie mate is that at 1500 rpm his ST1 will last forever, and with generator build spec,(heavy flywheel and gen spec governing)  it will deliver steady power.
       Don't recall an ST with a continuous rating above 2400 or 2500 rpm, and wow, are they noisy at that speed! Will need to keep it loaded if he is in cold country. Knew some 50Hz ST units
       that were happy pulling full rated load all day in the tropics at +44*c,  say 110*F?  Keep clean and serviced, they go forever.   Combustor.
       
Toys include- Lister CS 8/1, Lister VA SOM plant and some Aussie engines.
   "Old iron in the Outback" Kimberley, West Australia.

bandmiller2

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Re: Engine HP
« Reply #4 on: July 29, 2012, 01:31:05 PM »
I have seen a chart published by Lister that gives the HP derating at lower RPM's,from memory,my ST-1 is 12.5 HP at 3000 and drops to around 7+ at the 1800 I am turning it,But anyhow my question was answered  the governor can't give me more HP at a fixed RPM. Frank C.
Fast cheap and easy are seductive sirens,its a rare man that does not court their pleasures.

cylinderheadnut

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Re: Engine HP
« Reply #5 on: August 21, 2012, 11:45:00 PM »
What effect does turbocharging have on a generator engines output  at a set speed ?




dieselgman

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Re: Engine HP
« Reply #6 on: August 22, 2012, 01:37:39 AM »
What effect depends on the turbo, and other engine variables as well as air temperature... in most cases at least 10% to 15% increase, in some quite a bit more than that.
It depends on how much extra oxygen and also fuel you can stuff into her.

We have a Caterpillar 3304 model in common use here that comes in many flavors, all the way from a 60kW rating up to 120kW (same displacement engine) depending on turbo vs non-turbo and fuel pumps/ injectors and compression ratios used.

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bandmiller2

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Re: Engine HP
« Reply #7 on: August 24, 2012, 01:35:22 AM »
Today computers have much to do with a diesels horse power,you just program it in.Many years ago I worked in a truck fleet garage and it was my job to cut the balls of the new Detroit powered highway tractors.They came with n-65 injectors I had to put 55 back in.It was done on the grave yard shift away from prying teamster eyes,they would have fudged their rompers if they knew,and I hated to do it. Frank C.
Fast cheap and easy are seductive sirens,its a rare man that does not court their pleasures.

ronmar

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Re: Engine HP
« Reply #8 on: August 24, 2012, 04:03:18 AM »
What effect does turbocharging have on a generator engines output  at a set speed ?

Turbocharger output(boost) is more a factor of engine load than engine RPM.  Ever drive a turbocharged vehicle?  Try building boost pressure in neutral setting in the driveway...  It just dosn't happen.  Put it in gear and crack the throttle and the boost quickly builds to wastegate relief pressure.  

IF you think about this, it makes perfect sense.  What powers the turbo?  It is exhaust gas.  Reving an engine unloaded takes only a small fraction of the engines available HP, so very little fuel is added to rev the engine and not much exhaust gas is created.  Add load, you burn more fuel and make more exhaust gas, which in turn spools the turbine which builds boost.  

So in answer to your question, a turbo on a fixed RPM generator does the exact same thing it does on any other engine.  It increases power output.  How much is a factor of all the things DieselGman mentioned and of course the mechanical limits of the engine...  
« Last Edit: August 24, 2012, 03:00:25 PM by ronmar »
PS 6/1 - ST-5.