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Donnie740 | 04-04-2008 01:42 AM
I'm looking for some advice on getting a generator...checked out a few models today at the local hardware depot, but I'm not too sure where to start when evaluating them. Hopefully I can get some answers here for my questions.... What kind of output is sufficient for an average house - - is 1000W too little, is 4000W overkill? What kind of gas consumption can I expect - - will I need to install a storage tank in my yard? How many items can I run off it - - will I need to keep switching to appliances or can I run a bunch of electrical cords & splitters for several appliances? What brands are the most dependable and which ones should I be avaiding?

nub | 04-04-2008 02:26 AM
Re: Best generator to get? Ok, if your gonna use gas, hondas are decent yamahas are good and check out the various makers like coleman and others that use yamaha motors and honda motors , you can check out northern hydralics they have a line they push that utilize honda motors and vanguard motors, vanguard motors are very good also they are an overhead valve Briggs & Stratton, BTW Nissan makes a very good generator also....I use Diesel generators. All right, then you need to figure out your load, go around and get the wattage or amp ratings off everything you plan to run....remember 1amp=110 watts....for most homes 4000watts isn't any to big , and remember any thing with a start capacitor will take roughly 3 times it's run rating , so if it's rated at 3000 watts or 3-4 amps it will take darn near 3 times that to get it started then the load will drop waaaay down to it's run rating , to common items in this catagory are well pumps and air conditioners , so keep that in mind. And one other thing if your gonna have this thing runnin behind your house make sure it's relatively quite, I've had regular old construction site generators like nissans ,yamahas and hondas that were quiter than some of the generators home depot sells for stand by, so if you can try to listen to a few different models....and remember to use fuel stabilizer in it if you think your not going to use all the fuel .Lastly don't buy anything you can get parts for or serviced easily.....you don't have to spend a bunch of money to get a pretty darn good generator .

nub | 04-04-2008 02:41 AM
Re: Best generator to get? You can make a double ended male cord and run the power backwards through a standard three prong recepticle, problem is than your not going through your sub panel/ breakers sooooo I really shouldn't suggest that but I did it some years back cuz I figured the generator had a breaker on it anyway, they all do , but if you have a 20 amp breaker on the generator and you have a problem in say a 10-15 amp circuit your gonna overload that circuit and cause an overload or worse yet FIRE ! Best way is to get a manual or automatic transfer switch and wire it into your main panel . The transfer switch is expensive and that may cause you to buy one brand over another depending on the price of generator & transfer switch, also some are 3 wire and some are 4 wire ,as I remember 3 wire transfer switches are much easier to wire in......HAVE FUN !

Fullpower | 04-04-2008 02:57 AM
Re: Best generator to get? "BEST" is a tough generalization to make. For a "small, portable unit" the HONDA ES (inveretr) series is real good kit. VERY QUIET, fuel efficient. they come in 1,2 and 3 KW sizes. You really need to provide more information in regard to your application. how long of run times do you anticipate? do you want thsi to be a permanently mounted, hardwired standby device to run the whole house, including Air Conditioning, washer/dryer/hot water, kitchen appliances, well pump? this could easily require a 20 Kw machine, for an all electric kitchen. Or are we talking about keeping a few lights and the refrigerator running with a portable unit for a couple days? for such a scenario,a couple five gallon gas cans and a 3 kw honda inverter style generator will suffice. the two BIG energy hogs in a domestic environment are electric hot water heaters, usually 4500 watts, and electric clothes dryers, around 4000 watts If you can do without those items, your generator requirements are much easier to fulfill.

bsdetector | 04-04-2008 06:57 AM
Re: Best generator to get? Build a "hybrid" electric generator for superior fuel economy.

Silver Bullet | 04-04-2008 07:19 AM
Re: Best generator to get? Building on what the others have said. People usually start from the wrong end of things in deciding on what generator to get. Decide on your fuel source. There are 2 parts to this - availability for your situation and your intended usage. #1 Gasoline - harder to store large amounts for long periods. Generators are smaller and less expensive per KW. Can it run on ethanol if you happen to live in a grain farming region? #2 LP/NG & hybrids - easy to store in large tanks or hook up to a piped in supply. Less energy per unit than gasoline. Will piped in supply be avail. during shtf? Many of the fixed placement "whole house" generators use LP/NG. Most portable gasoline models can be converted. #3 Diesel - easy to store. Diesels tend to be larger & more expensive. Are much more rugged and longer running than the others. Biofuels as an alternative when commercial sources are gone? Realistically size your load. Do you just want to power the fridge and a few lights? Add a window AC? Maintain your current lifestyle during an outage? Larger loads can often be rotated - run the fridge for a few hours, then use your power tools, then the water heateror sump pump... You also need to account for high start-up energy draws of inductive (motor) loads. Most effecient use of gen. fuels is to charge up a battery bank while also running your large loads. Than use an inverter to power a few lights and the tv/computer/radio. This type of setup can also utulize alternative but non-steady energy sources as available - ie. solar, wind. Remember, realistically size your load. Too small a generator will fry if overworked. Too large a generator capacity will waste fuel. Short term needs (ie after hurricane, blizzrd) & less than 10KW (no central AC or heat or large pump) #1 will suffice quite well as will the others. As a guideline, 5 gal. gas will run a 5KW generator for about 10-12 hours on about a 50% load. A 12KW maybe 6-7 hours. A little 1KW Honda EC could go for days (with frequent fill-ups of it's tiny tank.) Longer term use and/or larger loads. Need to stick w/ 2&3. NG/LP most convenient when available. Diesel engines are the only reasonable option for long term (many weeks to months) continuous running. Once you've decided on your fuel source than you need to start worrying about what options you want/need on the genny. And then you have to learn why a 5KW generator is not a 5KW generator - or whatever size you are looking at.

Tn...Andy | 04-04-2008 07:23 AM
Re: Best generator to get? Quote:
Originally Posted by Donnie740 (Post 1044815) I'm looking for some advice on getting a generator...checked out a few models today at the local hardware depot, but I'm not too sure where to start when evaluating them. Hopefully I can get some answers here for my questions.... What kind of output is sufficient for an average house - - is 1000W too little, is 4000W overkill? What kind of gas consumption can I expect - - will I need to install a storage tank in my yard? How many items can I run off it - - will I need to keep switching to appliances or can I run a bunch of electrical cords & splitters for several appliances? What brands are the most dependable and which ones should I be avaiding?
You need to decide how much you want to run at any one time....add up the wattage of the items, then add a start up surge fact of about 20%, and that will tell you what size you need. IF you want to run "large ticket" items like electric water heater, clothes dryer, stove, AC, any kind of electric heat, you're probably looking at 10,000 watt generator MINIMUM. I have an 8kw ( 8,000 watt ) and it will handle the house less stove, AC, etc....I could run either the dryer or the water heater ( since changed to propane ) alone with the rest of the house, but not together. NEXT, you need to decide how long you plan to run it. Is this a 'temporary' deal.....like a few days or week/two at most, and just once in a blue moon ? Then you could get by with a smaller one, and 'rough it', living by switching different items around. A smaller, portable type will do you.....I wouldn't bother with a 'tank in the yard' unless you go with propane models.....which you could still hook up via a quick disconnect type hose. IF you plan to live like the grid power never left, you need a permanent mounted standby type generator, probably 10-12kw or bigger, and a permanent fuel tank.....and a deep wallet.

90%RealMoney | 04-04-2008 11:55 AM
Re: Best generator to get? Quote:
Originally Posted by Donnie740 (Post 1044815) I'm looking for some advice on getting a generator...checked out a few models today at the local hardware depot, but I'm not too sure where to start when evaluating them. Hopefully I can get some answers here for my questions.... What kind of output is sufficient for an average house - - is 1000W too little, is 4000W overkill? What kind of gas consumption can I expect - - will I need to install a storage tank in my yard? How many items can I run off it - - will I need to keep switching to appliances or can I run a bunch of electrical cords & splitters for several appliances? What brands are the most dependable and which ones should I be avaiding?
It's a good thing you inquired about this. If you ran out and bought a 1000 watt generator, you'd be able to run your blender to make some cocktails with! LOL! Seriously though, like everyone said here, HOW much of your house do you want to be able to run? I bought my parents the Yamaha equivalent to the Honda EU 3000, for their 5th wheel trailer rig. They only use it when they can't get hookups somewhere. I think I paid about $1700.00 delivered, from a dealer on Ebay. There are dealers on the internet with some very good prices, and free delivery sometimes.

money matters | 04-04-2008 01:09 PM
Re: Best generator to get? Most gensets are not longterm propositions. IOW, they will not hold up to extensive use. I have seen Hondas fail under consistent use in under 6mos. The Honda warranty is good; if you can get it honored in a SHTF situation. The main problem with gasoline and consumer quality gensets is they run at too high engine speed. You want a 1600-1800rpm motor for long life. RV gensets are made very heavy duty, but very costly. Onan is excellent. A diesel fueled genset will be the longest lived solution. If you are looking for an energy solution; think alternative energy. Solar panels or Windturbines produce DC current reliably, but are fairly expensive. Best way to use a genset is for charging deep cycle storage batteries, then you need an inverter unless you will run 12 or 24v DC appliances which is feasible. The genset should run a 60-100amp battery charger for maximum value from your generator. Look also at propane appliances for dryer, cooking, water heater. There are no free lunches, although with a rooftop solar collector for pre-heating your hotwater you can come close. With about $20,000 you can buy enough solar panels to get 1500watts at 24v DC. It is very possible to run fluorescent lights, energy efficient refrigerators and freezers, use propane or wood cookstove/clotheslines and live off the grid. Without storage batteries and a quality inverter your are just wasting your money by not spending enough.

Tn...Andy | 04-04-2008 01:18 PM
Re: Best generator to get? You must be shopping in the wrong place, MM......I bought 2100 watts worth of panels last year for 11k.....they are at 24v DC. Totally agree with the speed on the generator.....most of the cheap ones SCREAM at 3600rpm for their output. Find an 1800rpm one if you want a longer lasting one.

buff01 | 04-04-2008 01:52 PM
Re: Best generator to get? Quote:
Originally Posted by bsdetector (Post 1045077) Build a "hybrid" electric generator for superior fuel economy.
I hope this is a joke!

____hoot____ | 04-04-2008 10:50 PM
Re: Best generator to get? Just bought a chinamart 2 cycle 1000 watt unit on close-out sale for $89.95. It didn't like starting it, but it will run my 7 amp big refrigerator. Eight hours on a gallon of gas. Think I can survive on it by switching the loads around: battery chargeing, food storage[frig and small chest freezer], water pump,lighting, small tools, etc. Not for long term, but I think I could get by for a couple months on it and say 20 gallons of stored gasoline. Only weighs 40 pounds, so I can cut and run with it easily, also. i'm cheap

bsdetector | 04-04-2008 11:39 PM
Re: Best generator to get? Quote:
Originally Posted by buff01 (Post 1045808) I hope this is a joke!
Nope. 12 volt Generator charges battery bank then shuts off, battery bank supplies power to inverter, inverter runs loads. Works like a hybrid electric car. Uses a lot less fuel.

nub | 04-05-2008 12:00 AM
Re: Best generator to get? Quote:
Originally Posted by bsdetector (Post 1046845) Nope. 12 volt Generator charges battery bank then shuts off, battery bank supplies power to inverter, inverter runs loads. Works like a hybrid electric car. Uses a lot less fuel.
BD what your talking about is typicaly an alternater ran by as mall motor at low rpms although you don't have to run at low rpms, the reason for alternator over small generator is alternators make more power at lower rpms....these setups have been historicaly used for recharging small battery banks in off grid home systems...I built one once, it's around here somewhere....I also have an army surplus model made by chrysler it's a 24 volt screamer. My home system is now 48volts ran through a big sine wave inverter.

Ghost Recon | 04-05-2008 11:56 AM
Re: Best generator to get? for anyone on a budget: back in 1999 I bought a 1800 watt Mitsubishi. Put it on my back screened/glassed in porch and drill a small hole through the wall close to the floor. Ran a couple of 14 gauge extension cords through it. I've got enough juice to power the fridge, lights, fan, computer or tv etc. For heat I fire up a kerosene heater and/or my Vermont Castings gas heater. This setup works well and I've been very comfortable in every power outage.

90%RealMoney | 04-05-2008 12:16 PM
Re: Best generator to get? Quote:
Originally Posted by Ghost Recon (Post 1047285) for anyone on a budget: back in 1999 I bought a 1800 watt Mitsubishi. Put it on my back screened/glassed in porch and drill a small hole through the wall close to the floor. Ran a couple of 14 gauge extension cords through it. I've got enough juice to power the fridge, lights, fan, computer or tv etc. For heat I fire up a kerosene heater and/or my Vermont Castings gas heater. This setup works well and I've been very comfortable in every power outage.
Thats basically what I am set up for. I bought a Honda 3500W generator off Ebay. It was at a local pawn shop, and was for pick up only. I got it for $700.00. It's probably 5 or 6 years old, but was never used/looks brand new! We can have some wicked storms/power outages up here in Northern Ca. It'll run my fridge/ freezer, tv, computer. I'd like to get one of those nice standby generators, that'll run on gas or LP. Actually, Yamaha makes a 12,000 watt portable type that has a tri fuel conversion on it. It's only around 3 grand.

ipatent | 04-19-2008 11:23 PM
Re: Best generator to get? I have an Airstream trailer that I haven't used in years sitting in my yard. If TSHTF, I could use the fridge, which will run on propane. It also has 12V appliances that we could get by with. If things really get bad in our area, I just hook it up to my F-250 and relocate.

goldsilverman | 07-31-2008 11:34 PM
Re: Best generator to get? Quote:
Originally Posted by Sukhoi_fan (Post 1045031) "Best" is relative, based upon your intended usage. Some folks consider something like a Listeroid to be "best" for their application. http://www.generatorsales.com/LISTER_all11.asp?page=1
Thanks for the link, Ive been looking for this for the past 30 mins.

mick silver | 07-31-2008 11:41 PM
Re: Best generator to get? when you go shoping for one look at lowe;s tell them you seen it cheaper , say a hundred or so off some were else they well match the price

TTAZZMAN | 08-01-2008 12:39 AM
Re: Best generator to get? It would really help If Donnie would post back as to a few things. #1 fuel type #2 How much of his house does he want to run #3 Budget #4 intended useage I have several generators (construction company) from towable diesels to suitcase carry around generators. i live in a area that we typically lose power in the winter mostly due to ice storms and heavy snow...and the portable generator i use when my house goes down is a Honda 6500 inverter style generator set up with a remote fuel tank and hose. They are expensive but are the most efficient gas portables i have found since they only run as fast as your demand, they produce very clean sinewave power so you dont have to worry about electronics. and they are the quietest generators i have found. I have run up to 10 days continueous on one, and got about twice the advertized fuel economy. simply outstanding. we use the 240 outlet and power the whole house panel, of course i shut off the breakers to the Electric Range-Electric Clothes dryer etc. If a person needs a summer generator large enough to start a 3ton+ ac unit then you will need something in the minimum 10,000watt range, if i were doing a whole house one it would be 17,000watt one. the inverter style generators are substancially more expensive but well worth it in my opinion for those that dont know a inverter generator turns a DC alternator which only turns as fast as the amp demand requires.....then it runs the DC current thru a inverter to Make it into AC power http://www.hayesequipment.com/eu6500is.htm now if a person is going to power their house for the next 10yrs.....i would build a generator house and go with a listeroid diesel

killer2021 | 08-01-2008 01:03 AM
Re: Best generator to get? I always wanted to get a solid fuel biomass Stirling engine to produce electricity. I was thinking I could just burn whatever firewood was around and I would never have to worry about running out of gasoline/diesel fuel. I could also burn it in my fireplace to heat my dwelling or use it to cook food if I needed to. Turns out no one makes them. All the companies I've found that make 2,3,4,5 horse power Stirling engines either don't make them anymore or they went out of business.

nub | 08-01-2008 03:46 AM
Re: Best generator to get? Tazz, I wish I could say I'm all warm and fuzzy about the Honda 6500, I to own a const co.....I bought 2 of them about 10 years ago, carb linkage disintagrated on one and the gas tank on the other got rusted up on the inside and I had to have it repaired for some reason that now escapes me....but I don't doubt yours has treated you well. I have a 4800 watt honda in a sound inclosure I bought 20 years ago off a job site where it had ran 40 hrs. a week for 10 months, I must have put 500 hrs. on it after that and it still runs like a champ, I swear you can't kill it with a sledge hammer. Believe it or not I've had very good luck with Nissans and yamahas on the job sites I have a beautiful 1972 low RPM international (propane)straight six coupled to an english made marathon generator I don't use any more (to spensive to run)... it's a 30kw international with 155 hrs. on it that I purchased from the aviation commision. Propane is nowhere near as economical as diesel Then there are the low RPM diesels a 12 kw kubota , 12 kw Izusu and a 15 kw shanghi diesel with a marathon generator ,China diesels are very good once you work out the bugs, they are crude but very very heavy, I've grown to like them, just make sure they do not have a Chinese made generator on them, cuz they're junk. With all 3 of these diesels we service them every 100 hrs and they'll run a good 20,000 hours.There's a 35KW caterpillar on a trailer parked up the canyon that I retired after it threw a spark and damned near burned this place down Up the road at the original well site sits a 35 year old low rpm gasoline coleman 4500 watt generator....last year I drained the tank, dumped the gas out of the carb bowl added fresh fuel and got her to fire off .....they don't make um like that any more. The diesel perkins generators have a very good reputation , a buddy of mine sells them and says he doesn't even keep a parts inventory cuz they never fail.....I'm not surprised about the lack of a parts inventory, nobody keeps parts any more....."we'll have them for you in 3 days" yeah sure! Here's some advice .....check the output of your generator, check the cycles and volts.....to check cycles you'll need a meter that can read Hertz, and they get pricey. I recently puked a 1 year old well pump with a 6500 watt yamaha driven coleman piece of crap generator that I bought at home depot, it was running at 200volts instead of 220/240 and the cycles were at 58 instead of 60. I bought the less than stellar unit to leave down by the pump which is accessable from an old county dirt road, that way if a thief took a hankerin to lift it I wouldn't be out so much......some times I can't win for loosing.

Bushpilot | 08-01-2008 10:43 AM
Re: Best generator to get? I just bit the bullet and purchase a low speed lister with a 10kw head. It will run at 650 rpm and only burn just over a quart of diesel, WVO, or drain oil an hour. It will power my entire house including a small freezer and my fridge. I may have to shed some load to wash clothes though. The only downfall to the lister style engine is they weigh 800 lbs. Parts are easy to get and they are easy to work on. BP

markt | 08-01-2008 11:26 AM
Re: Best generator to get? Quote:
Originally Posted by killer2021 (Post 1218075) I always wanted to get a solid fuel biomass Stirling engine to produce electricity. Turns out no one makes them.
I have thought of building/selling them on eBay. They are really very simple engines with only a few moving parts. There is even a version that pumps water with the ball in a ball-valve as the only moving part. One could pump water up to a storage tank and later run it down over a waterwheel-generator. A 6000 watt unit could be very practical and reasonably priced...

TTAZZMAN | 08-01-2008 12:33 PM
Re: Best generator to get? NUB.. The honda 6500 inverter generator just came out within the last couple of years but Thanks for the heads up on the Honda, I havent had any issues with it at all BUT i keep it as my own personal generator and it never goes out on jobsites I also have a similar Kipor 6000 that seems to be working well, these inverter style generators in my mind are not built to withstand the physical abuse of a jobsite. they are more suited to RV or Portable home backup ussage. I would add for others that any small gas engine generator's life is directly perportional to maintence especially changing the oil after each usage, most use less than a quart of oil and dont have a oil filter and get run hours at a time. The inverter style generators is very new technology and is worth investigateing if a person hasnt been exposed to them before. they perform much differently than a typical generator the reason i like the inverter style gens for home backup is they are extremely quiet, and since they only run the speed based on amp load we found during a 9 day ice storm outage this last winter if we conciously tried to keep our power ussage down we could run on 5-6 gal a day because it was idleing most of the time especially at night. I agree on the construction site generators we have multiple diesel portables and trailer mounts various sizes. We have had great sucess with perkins diesel engines in Generators and other small equipment IE skid steers and excavators etc.

TTAZZMAN | 08-01-2008 12:42 PM
Re: Best generator to get? Quote:
Originally Posted by Bushpilot (Post 1218444) I just bit the bullet and purchase a low speed lister with a 10kw head. It will run at 650 rpm and only burn just over a quart of diesel, WVO, or drain oil an hour. It will power my entire house including a small freezer and my fridge. I may have to shed some load to wash clothes though. The only downfall to the lister style engine is they weigh 800 lbs. Parts are easy to get and they are easy to work on. BP
are you using the big single cylinder or the twin? and have you had the chance to confirm the fuel usage yet?

Tragedy Trousers | 08-01-2008 12:48 PM
Re: Best generator to get? Quote:
Originally Posted by Donnie740 (Post 1044815) I'm looking for some advice on getting a generator...checked out a few models today at the local hardware depot, but I'm not too sure where to start when evaluating them. Hopefully I can get some answers here for my questions.... What kind of output is sufficient for an average house - - is 1000W too little, is 4000W overkill? What kind of gas consumption can I expect - - will I need to install a storage tank in my yard? How many items can I run off it - - will I need to keep switching to appliances or can I run a bunch of electrical cords & splitters for several appliances? What brands are the most dependable and which ones should I be avaiding?
Good grief 1000 watts wouldnt run much of anything. 4000 watt min. My 6000 watt Pramac gen has a 13 gal tank which will run 12 hours and will power everything except the central AC and range.

BobS | 08-01-2008 12:56 PM
Re: Best generator to get? One of the issues with a Lister or Petter style engine from India or China is the EPA has set emissions standards on NEW engines (does not apply to those already incountry). http://www.epa.gov/fedrgstr/EPA-AIR/...y-24/a1118.htm Official EPA regulations http://www.dieselnet.com/standards/us/stationary.php Backround information on the regulations For long term use, it is my opinion that there is no better combination than a low speed Lister or Petter (Petter would be my personal choice) and a good generator head. I know of 4 on various locations in the US and Mexico where a Lister has been in use continuously since (the newest) 1933 or (the oldest-a Petter) since 1926, both without rebuilds-just oil changes and air filter changes.

jamesfrancisco | 08-01-2008 01:55 PM
Re: Best generator to get? If you want a reliable generator that you will be able to get parts for, buy an old Onan. Mine has 60,000 hours on it so far, and barely sips the oil. It can be converted for propane, and Onans are fairly widely regarded as the best available, amongst generator nuts like myself. It was built in 1977 and I can still buy every single part for it brand new. Try that with a Jap Crap generator.

Fullpower | 08-01-2008 02:48 PM
Re: Best generator to get? one word: PHOTOVOLTAIC

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jamesfrancisco | 08-01-2008 04:33 PM
Re: Best generator to get? Photovoltaic simply is not financially viable at the minute - even the companies who make them say it will be another 5-7 years before they are. Get yourself a nice Onan 5.0 CCK with the vacu-flo cooling, a basic set of spares such as points, plugs, etc. and it will outlive both you and your kids. 5Kw constant as rated, you'll be able to pull twice that from it no problem. And there is a huge parts network out there for them!

ruprick | 08-01-2008 04:54 PM
Re: Best generator to get? A good rule of thumb for fuel consumption is 0.5 lbs per HP per hour. I've used this in aviation my entire life and it is very accurate for most spark ignition engines. Example: 300 HP aircraft operated at 65% power.....300 x 0.65 x 0.5 = 97.5 lbs.....6 lbs per gal.....97.5/6 = 16.25 gal per hour...and that is very close to the book number of 16 gph. Some engines can approach 0.45 lbs/hp/hr....but 0.5 is a good estimate. This also applys to small engines...like gen sets and mowers and other power equipment. You can roughly determine your vehicle road load hp requirement using this estimate..... Take a typical car traveling at 70 mph and getting 30 mpg......70/30 = 2.3333 gal per hr........2.33 gph x 6 lbs per gal = 14 lbs/hr...using my rule of 0.5 lb/hp/hr......14/0.5 = 28 hp......thus this car requires about 28 hp to travel at 70mph. Most cars at 55mph will need between 10 and 15 hp.....so cars have way too big of engines for maximized mileage....but they "want" the extra power for passing, accelerating, hill climbing...... The perfect high mileage car wound be something like a GEO Metro or old VW Bug with about a 20 HP Diesel.....just dont try to climb any big hills...it can do it...but slowly..... If interested, you can do a coast down thest to determine your road load power.....take car and go 60mph....go to neutral and cost down to 50 mph.....measure time with a stop watch (assuming flat ground and no wind).....calculate KE at 60 and subtract KE at 50...divide by time.....you will get the power. I can provide units and exact steps if anyone wants.

Fullpower | 08-01-2008 05:37 PM
Re: Best generator to get? nice set of numbers ruprick, thanks for sharing the info. I would like to add typical brake specific fuel consumption figures for high speed turbo diesels in the .35 pounds per horsepower hour range. Also of interest is that AIR coooled long stroke engines are inherently more fuel efficient than water cooled, and short stroke designs.

BobS | 08-01-2008 05:49 PM
Re: Best generator to get? Quote:
Originally Posted by ruprick (Post 1219007) A good rule of thumb for fuel consumption is 0.5 lbs per HP per hour. I've used this in aviation my entire life and it is very accurate for most spark ignition engines. Example: 300 HP aircraft operated at 65% power.....300 x 0.65 x 0.5 = 97.5 lbs.....6 lbs per gal.....97.5/6 = 16.25 gal per hour...and that is very close to the book number of 16 gph. Some engines can approach 0.45 lbs/hp/hr....but 0.5 is a good estimate. This also applys to small engines...like gen sets and mowers and other power equipment. You can roughly determine your vehicle road load hp requirement using this estimate..... Take a typical car traveling at 70 mph and getting 30 mpg......70/30 = 2.3333 gal per hr........2.33 gph x 6 lbs per gal = 14 lbs/hr...using my rule of 0.5 lb/hp/hr......14/0.5 = 28 hp......thus this car requires about 28 hp to travel at 70mph. Most cars at 55mph will need between 10 and 15 hp.....so cars have way too big of engines for maximized mileage....but they "want" the extra power for passing, accelerating, hill climbing...... The perfect high mileage car wound be something like a GEO Metro or old VW Bug with about a 20 HP Diesel.....just dont try to climb any big hills...it can do it...but slowly..... If interested, you can do a coast down thest to determine your road load power.....take car and go 60mph....go to neutral and cost down to 50 mph.....measure time with a stop watch (assuming flat ground and no wind).....calculate KE at 60 and subtract KE at 50...divide by time.....you will get the power. I can provide units and exact steps if anyone wants.
FYI- good info-but you are missing a couple of items. If you want to get closer to the road load HP requirements, use the calcs from SAE J688. http://eogld.ecomm.gm.com/NASApp/med...tion&year=2004 The above link is an example application book of J688 applied to GM medium duty trucks. Best regards, Bob

BobS | 08-01-2008 05:52 PM
Re: Best generator to get? Quote:
Originally Posted by Fullpower (Post 1219061) nice set of numbers ruprick, thanks for sharing the info. I would like to add typical brake specific fuel consumption figures for high speed turbo diesels in the .35 pounds per horsepower hour range. Also of interest is that AIR coooled long stroke engines are inherently more fuel efficient than water cooled, and short stroke designs.
Yep, some are down around 0.32-0.33 #/hp/hr. (certain versions of the Cummins ISB, for example). As far as gasoline automotive engines, the current range is a bit lower then 0.50...actually closer to 0.42 (the GM EcoTechs lower than that, but is geared for performance, not economy). Best regards, Bob

ruprick | 08-01-2008 06:03 PM
Re: Best generator to get? Quote:
Originally Posted by BobS (Post 1219085) FYI- good info-but you are missing a couple of items. If you want to get closer to the road load HP requirements, use the calcs from SAE J688. http://eogld.ecomm.gm.com/NASApp/med...tion&year=2004 The above link is an example application book of J688 applied to GM medium duty trucks. Best regards, Bob
My rules of thumb are close enough for the girls I run with....

BobS | 08-01-2008 06:10 PM
Re: Best generator to get? Quote:
Originally Posted by ruprick (Post 1219103) My rules of thumb are close enough for the girls I run with....
hehehe...understood. Best regards, Bob

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