Genset Power Quality Improvement?

[AJ1G]

It looks like that I can not run our Frigidaire front loader washing machine on our backup generator.  It will fill and drain, and sometimes will agitate, but will not go into spin.   After chasing down some info on this issue, it looks like the washer's solid state direct drive drum motor speed control does not like the power quality from the Generac 17.5 genset.  I have not looked at the waveform on a scope yet,but apparently high speed two pole consumer grade machines like mine are known to have lots of brush noise and harmonic content that can trip up solid state motor drives.  More ominously, many of the newer oil fired furnaces also don't like running on generator power, and we are likely going to need to replace our aging Beckett/Burnham, which has run just fine on the genny, sometime in the next few years.  Baderus furnaces, which is a brand we are considering,  were specifically mentioned as having problems with genny power.

No problems running any other household motor loads off the genny, including the matching Frigidare dryer, which of course has just a simple single speed motor and a electro-mechanical timer.

Some postings have suggested trying to filter out some of the brush noise and harmonic distortion with  nominal 380 micorfarad non-polarized caps across the washer circuit AC line to neutral.  Anyone on here have any experience with doing this?  Wheres is a good source for a big cap like that? Will connecting a pair of polarized electrolytics at about 400 uf at 450 VDC in series with their negative terminals tied together work as a non polarized cap substitute?  I can recall doing this on a smaller scale for making speaker crossover networks, but am kind of leery of doing this across 120 or 240V AC lines.

Hopefully the filter can also get rid of the washer motor drive related EMI which really trashes up the HF and AM BCB spectrum.  I could not find any indication on the washer or in its owners manual to indicate that it is compliant with any FCC EMI criteria.

[Opcom]

The load presented by a given appliance can be quite bizarre. A brute-force line filter might help, especially if you set it up to eliminate the specific annoyances. I would not rely only on capacitors, but some inductance, a CLC filter, or a paralleling choke might help.

The design of the alternator makes a big difference. Most of the smaller ones regulate the voltage by means of a capacitor across the stator of the exciter, with increasing RPM also increasing the voltage.

There are also genset rotor designs that tend to eliminate harmonics, which is a big issue with sensitive electronics, and also designs that do a good job balancing the power through the stator when only one side of the 120-0-120V output is loaded heavily.

Most sets can benefit from power factor correction capacitors when running motors whether capless induction types (with centrifugal start switch)  or something with a bridge rectifier and variable speed drive.

With a scope and a voltage isolation transformer as well as a well-terminated current transformer, you can observe many of these artifacts and problems and work to correct them.

I bought a 6KW diesel (Lombardini) powered Gillette generator, which has the AC end made in the USA and is specially wound and has a slightly twisted rotor to eliminate harmonics and distortion and equalize the draw so that more than 1/2 of the juice can be drawn from only one side of the 240V output without causing more harmonics and inefficiencies. For a few years it ws installed on an M35 communications truck, and operated some very odd loads from real bad power factor induction motors to electronic ballast fluorescent lamps. It was extremely satisfactory. The Gillette site explains a lot about generator power and its quirks for odd loads, that might help. http://www.gillettegenerators.com/

One thing you can do if running a 120V load from a 240v machine is to use an autotransformer so that both sides of the 240V are used equally. You can also use a "balancing coil" such as that used to gang single phases on variacs, to better enforce equal load sharing. It's basically a 1:1 low voltage high current transformer.

Hope these suggestions help, but first, get out the scope and transformers and look at what is really happening in your application.

Have a look here to see the waveforms, as a guide. (ignore a complaint about voltage being low, it was an infant mortality on the capacitor)
http://www.bunkerofdoom.com/mil/m35/gen/test1/index.html

in case anyone is interested in one way to add a genset to a large-ish truck, there are some details:
http://www.bunkerofdoom.com/mil/m35/gen/index.html

[WA3VJB]

Hi Chris, hopefully this latest storm in your area isn't bringing down YOUR power like apparently it has done for other Connecticut customers.

We've had good performance on a generator powering a 2010 Armstrong oil furnace (forced air, not boiler) that replaced a 30 year old model after I started worrying about potential cracks in the heat exchanger box.  It runs on 120VAC service. There is an electronic control module that acts on the nozzle spray rate, initial startup mixture, and timing of the two speed 1/2hp electric blower motor.  

None of that seems bothered by whatever's coming out of the Generac for waveform and frequency, even when a fridge kicks on while furnace is running.  Downstairs fridge is on one leg of 240VAC single phase street power, the upstairs fridge is on the other leg. No difference in furnace happiness when either or both fridges kick on and run.

In fact, the only casualty we've suffered on generator power is a Hall-effect fan motor in a bathroom shower vent.  I heard the difference in motor noise but disregarded it.  Eventually it quit working and I had to replace it.  Stays off now when we're on generator.  Same for the full-size bedroom ceiling fans, protectively.

As for an autotransformer, I tried one on a 120V load but was concerned about the thermal issue -- the core laminations got unreasonably hot after a while, probably from frequency/harmonic content.  The device I was running on it did just as well when directly connected.

[Bill, KD0HG]

Chris: Put your load on the generator and view the output waveform on a scope.

If it's highly distorted, there's your problem and there's likely nothing that can be done. Don't waste your time trying to filter harmonics with caps. Sell and replace the generator.

Last year I dealt with the same problem at a broadcast site, but on a larger scale. I had previously installed a new solid state transmitter that uses a switching power supply. The site generator was maybe 30 or 40 years old. Well, the power went out at the site last winter and -surprise- the generator refused to power the transmitter, even though it was loafing at maybe 40% of rated output. I had never tested the new transmitter on the generator, assuming it would be an easy load.

I looked at the waveform of the generator with the load and it was pure distortion. I contacted the manufacturers involved as well as power quality consultants and hit a dead end. There is no solution to waveform distortion other than replacing the generator with a modern one, sorry to say.

This was a known issue with backup generators powering computer data centers with their switcher power supplies and motors, turns out I wasn't the first to get burned by this problem.

Good luck,

Bill

[W1ATR]

Yep. Went thru the genset craziness when last years Oct storm hit. After Hurricane Irene hit in the end of Aug last year, people ran out and grabbed generators wherever they could. When the Oct 2011 snowstorm wiped us out, I started getting the calls almost immediately. Most everything in their houses would run except the heating equipment. After the first few stops to see if they were even wired right, I came back to the house and grabbed my little Fluke 190 handheld scope and made up a fast adapter so I could plug it right in to these gennies. The next few stops were no heats on gen power. What I found was the flood of inverter type gennies look more like a dirty saw tooth than a sine wave with a ton of noise at the peaks and some even had a small voltage showing up on the neutral (usually only a few volts, but that's enough for a lockout). This is bad news for modern day heating equipment that checks the incoming mains before it even tries to start up. Heating equipment electronics is advanced about to the point where OBD1 was in vehicles back in the 90's. (In other words, very simple) The heating equipments brains see that voltage showing on the neutral, and would kick an idiot light suggesting L1 and L2 are reversed. A Trane furnace on a Honda brand inverter gennie I looked at responded well to my clip lead jumper from neutral to ground. Hit the reset, and it fired right up. Electrically acceptable? No...Warranty void? Yes... but it was a woman in her 80's in a cold house. If I did fry it, I have boards for it in stock anyway. Worth a risk and it worked out fine. Her power came back on 7 days later and I went back to reclaim my jumper lol. A better gennie took care of her problem this last storm.

Back on subject, lol. The alternator type gennies were mostly an easy fix. Out of 20 or 25 stops over the course of that storm, I got probably half or better of them working right to get the heat turned back on. The problem is the frequency is way off and the heating equip brain sees that. Upon checking them, (Fluke 87, Hz setting, probes right in the 110 outlet, and gennie unloaded.) most of them were  showing anywhere from 40Hz to 80Hz. It was only a matter of tweaking the engine speed back into range to get the needed 60Hz at the outlet. The gas they were setup with, and the gas people put in them must be different. Most were running too slow, but some needed to be slowed down. Once that magic 60hz is hit, the heating equipment would stop locking out and run normally. The smaller air cooled jobs are cheap two pole alternators and need to run at 3600rpm. the larger water cooled mounted units were usually 4 pole alts and they run at 1800rpm. A slight tweak of the idle while watching the frequency and all was happy regardless of the other noise showing up on the sine.

To Chris. Buderus boilers are hit or miss with today's gensets. I've had them run fine on no name chinese gennies, and fail on high buck mounted Kohler gensets. Go figure. It's a great boiler, but the Logamatic controller tends to puke on gennie power and line surges, and it costs about a grand to replace it. If you want to go triple pass, I would suggest a Burnham MPO-IQ and a SuperStor indirect tank. The control package seems to be more durable and forgiving to line problems (I haven't replaced any yet). Efficiency is the same, and any replacement parts are easy to find.

Food for thought, 73       

[N0WEK]

All this makes me appreciate my 12 year old Crown boiler. All it's got is a 24 volt transformer, a relay, the circulation motor and a vent damper motor. They all together draw only 90 watts and I can run them on a small 175 watt inverter and my boat batteries. I've got my furnace power on a regular grounded 120 volt plug which makes it easy to switch the furnace to alternate power. I don't let the standby load sit on the batteries, I just heat up the boiler now and then when I need the heat.

I've been meaning to automate the process with a separate thermostat in the basement which turns on the inverter, which in turn pulls in a relay that switches the furnace to the inverter and turns it on. With the standby thermostat set about 10 degrees below normal it'll never activate under normal conditions but will keep the house from freezing with minimum battery draw. I'm going to add a couple of deep cycle batteries to the system for a couple of other loads and radios.

[W4EWH]

I have not looked at the waveform on a scope yet,but apparently high speed two pole consumer grade machines like mine are known to have lots of brush noise and harmonic content that can trip up solid state motor drives.  More ominously, many of the newer oil fired furnaces also don't like running on generator power, and we are likely going to need to replace our aging Beckett/Burnham, which has run just fine on the genny, sometime in the next few years.  Baderus furnaces, which is a brand we are considering,  were specifically mentioned as having problems with genny power.

That's a tough one: it's easy for me to say "stick with the old", but the newer furnaces are so much more efficient that sometimes you can't afford not to change. 

Here's a step-by-step process that worked for me:

• Find out what it would take to "Winterize" your home to the point where you can let the temperature fall below freezing for long periods of time. Basically, you'd be draining all the water out of anything that will be in the "frozen" part of your home, including the heating pipes.
• Make a candid examination of your age, fitness, lifestyle, and experience. Decide if you are able to do that needed work, on short notice, under time pressure.
• During a cold night in winter, preferably when the XYL is out of town, turn off the heat. Time how long it takes for your home to get to 35 degrees Fahrenheit, and decide if that interval is long enough for you to set up alternate heat: space heaters, kerosene heaters, etc.: whatever it takes to keep the pipes from freezing.
• Prince the alternative heating units. Remember to include the storage costs for the kerosene, if that's what you're planning to use. There are high-output motorized Kerosene units that will heat an entire home, albeit with a lot of smell, but they're made to be used on job sites with less-than-perfect power. You might be able to use electric "space" heaters to keep the pipes from freezing, depending on the capacity of your generator.
• Decide if you'll use alternative heaters to heat a portion of your home, or if you'll heat the whole structure with portable units, or if you want you regular furnace to work from the genset. If you choose to use the furnace during power outages, you'll need to order non-electronic controllers for your new furnace so that they will work with your generator.

I hope this sheds more light than heat. Or, come to think of it, maybe vice-versa. 

Bill, W1AC

[Jim, W5JO]

[

• Prince the alternative heating units. Remember to include the storage costs for the kerosene, if that's what you're planning to use. There are high-output motorized Kerosene units that will heat an entire home,

Kerosene is an expensive alternative fuel.  It is no longer commonly available in bulk and is very expensive in 5 gallon containers at farm stores.  Last winter I saw 5 gallon cans selling for over 50 dollars.  There is one place within driving distance that sells bulk and last year it was about $4.25 per gallon.

One might be better suited to buying a heater that uses those propane bottles that are available in a lot of locations.  Here you can find them at some convience stores along with HD, Lowes, hardware stores and all farm supply stores.  You can even find it at RV parks and supply stores.   A high BTU Kerosene hearter will need about 2 gallons for an 8 hour period where as the propane versions can be used for longer periods of time on the bottle.  The side benefit of the propane type is there isn't the smell.

[ke7trp]

You just need a power conditioner. search amazon. I dont know the current requirements of the washer but you can look that up and get a model that fits the bill.  A decent one WILL provide a steady output to the washer.

C

It looks like that I can not run our Frigidaire front loader washing machine on our backup generator.  It will fill and drain, and sometimes will agitate, but will not go into spin.   After chasing down some info on this issue, it looks like the washer's solid state direct drive drum motor speed control does not like the power quality from the Generac 17.5 genset.  I have not looked at the waveform on a scope yet,but apparently high speed two pole consumer grade machines like mine are known to have lots of brush noise and harmonic content that can trip up solid state motor drives.  More ominously, many of the newer oil fired furnaces also don't like running on generator power, and we are likely going to need to replace our aging Beckett/Burnham, which has run just fine on the genny, sometime in the next few years.  Baderus furnaces, which is a brand we are considering,  were specifically mentioned as having problems with genny power.

No problems running any other household motor loads off the genny, including the matching Frigidare dryer, which of course has just a simple single speed motor and a electro-mechanical timer.

Some postings have suggested trying to filter out some of the brush noise and harmonic distortion with  nominal 380 micorfarad non-polarized caps across the washer circuit AC line to neutral.  Anyone on here have any experience with doing this?  Wheres is a good source for a big cap like that? Will connecting a pair of polarized electrolytics at about 400 uf at 450 VDC in series with their negative terminals tied together work as a non polarized cap substitute?  I can recall doing this on a smaller scale for making speaker crossover networks, but am kind of leery of doing this across 120 or 240V AC lines.

Hopefully the filter can also get rid of the washer motor drive related EMI which really trashes up the HF and AM BCB spectrum.  I could not find any indication on the washer or in its owners manual to indicate that it is compliant with any FCC EMI criteria.

[Bill, KD0HG]

I realize not realistic everywhere, but no one mentioned coal, wood or pellets for backup heating?

Bill

[KM1H]

I always start my genny with at least a 200W resistive load as the waveform looks a lot better. It runs the hot water furnace fine which has a lot of SS control circuitry.

It does not like the 3/4 hp deep well pump but it eventually fills the tank at about 210V at the pressure switch. Been working that way for 23 years.

[Todd, KA1KAQ]

The alternator type gennies were mostly an easy fix. Out of 20 or 25 stops over the course of that storm, I got probably half or better of them working right to get the heat turned back on. The problem is the frequency is way off and the heating equip brain sees that. Upon checking them, (Fluke 87, Hz setting, probes right in the 110 outlet, and gennie unloaded.) most of them were  showing anywhere from 40Hz to 80Hz. It was only a matter of tweaking the engine speed back into range to get the needed 60Hz at the outlet.   

I've got a late 30s/early 40s Onan W3S 3kw set like this. Plug in the frequency meter, adjust the mechanical governor until the desired number is reached. The only issue comes into play is the loading down of the genny which of course causes it to drift off a bit.

My question for you Jared and other folks who service or have gensets sitting there full of gas for extended periods is how well does the new ethanol mix gas hold up for you? I've noticed a problem with it gumming things up much, much faster than pre-eth gasoline in small engines here. Makes a good argument for diesel in my view. Treated properly, diesel can supposedly last for upwards of 7 years?

[WQ9E]

Todd,

Be careful of the diesel now also.  Proper treating and storage will avoid the algae growth problem but a lot of diesel is blended with soy now and this does not age well.  Pretty soon finding pure diesel is going to be just as difficult as finding non-ethanol gasoline.

For typical use the soy blend is good because it improves the lubricity which was reduced during the sulfur removal process.  But it doesn't age well.

For any long term diesel storage make sure the tank is full to reduce the amount of water contamination from changing air temperature.  Do NOT use the old style diesel water treatment for modern HPCR (high pressure common rail) injection systems.  The modern systems depend upon a very good water separator and some of the old treatments were designed to emulsify and pass through rather than drop out water.  It wasn't really good for any system but it is death to modern systems.  Given the very expensive fuel system damage resulting from water there is a high likelihood that coverage for this will be excluded from the standard auto insurance comprehensive coverage in the near future and you will be at the mercy of the selling station making good on damage from contaminated fuel.  Injection system repair can easily exceed $6,000 on a modern light truck diesel-one of the reasons I will probably be going back to gas power for my next pickup.  It sounds like the newest DI version of the small block Chevy should return pretty good highway mileage if you don't need the maximum towing capability of a diesel.

[WU2D]

A little off the subject but we had the same problem with UPS's accepting power from generators at work. We went to dual conversion UPS types and these are much more forgiving and turn nasty voltage into nice.

It is interesting that the most common UPS types basically will not even come on line if the power frequency or voltage or sometimes the shape are not correct. 

[KB2WIG]

The following link may be of interest.

http://pure-gas.org/

I've found a few local stations that sell the garbage free gas oleen.... The problem is that the stuff is 91 octane, so the price is high. There are stabilizers available for long term storage of gas.


klc

[Jim, W5JO]

For long term storage of alcohol gas, take a look at sta-bil marine.  There are a couple more but in the long term ethanol will damage the engine.  Funny thing about the government is small engine manufacturers said to not use it until recently.  Some one stomped their toes and now they are saying up to 10% is fine, but the EPA will now specify 15%.

You can filter the alcohol by letting the gas sit and separate,  then carefully pour the gas off.  It will take about a week for it to separate.  The alcohol absorbs water in unsealed tank which causes rust and  all sorts of problems.  If you choose to use it just be sure to agitate the gas before running the engine so the alcohol will be absorbed.

[W1ATR]

The alternator type gennies were mostly an easy fix. Out of 20 or 25 stops over the course of that storm, I got probably half or better of them working right to get the heat turned back on. The problem is the frequency is way off and the heating equip brain sees that. Upon checking them, (Fluke 87, Hz setting, probes right in the 110 outlet, and gennie unloaded.) most of them were  showing anywhere from 40Hz to 80Hz. It was only a matter of tweaking the engine speed back into range to get the needed 60Hz at the outlet.  

I've got a late 30s/early 40s Onan W3S 3kw set like this. Plug in the frequency meter, adjust the mechanical governor until the desired number is reached. The only issue comes into play is the loading down of the genny which of course causes it to drift off a bit.

My question for you Jared and other folks who service or have gensets sitting there full of gas for extended periods is how well does the new ethanol mix gas hold up for you? I've noticed a problem with it gumming things up much, much faster than pre-eth gasoline in small engines here. Makes a good argument for diesel in my view. Treated properly, diesel can supposedly last for upwards of 7 years?

Hiya T. Sadly enough, our fuels today are so lousy, I would have to say 6 months to a year in a sealed container for gasoline or diesel. I only have a few small engines, and a couple of bikes for my gasoline consumption, so I'll fill up a can or two when I buy diesel for my trucks. I keep these cans filled right to the top and the cap screwed on tight. They live in a cool place out of any sunlight and I haven't noticed any degradation. I found that using sunoco 94 keeps the little motors in much better shape, but none the less, if they're not going to be used for a while, I'll drain the tanks, and run them till dry. The only fool proof long term, storable generator fuel is going to be propane. If the tank doesn't leak out, then the stuff will last forever. The obvious downside is being able to get a refill during a power outage, so a large tank would be in order. A full 500g underground tank, (or above ground if you have a place to hide it) will last a long time if used conservatively to run a small (say 15,000w) mounted genset.

J

[WA3VJB]

What passes for street gas today is piss poor for storage.

The ethanol component really attracts water. In time, the witch's brew separates, and the water settles to the bottom of the tank and will rust it. It also can corrode fuel bowls and carburetor jets. The alcohol hardens the fuel flow diaphragm in some of the more simple lawn-mower type engines.

That's at 10% ethanol. There's a push by industry toward 15%, oh great, and some of the proposals would leave it up to the retail pumps to make sure it's labelled properly or else it could cause damage. Right.

The collector-car hobby was among the first to identify the problem. But then the power boat community started seeing problems after winter storage. Figures I'm in both categories. Some boaters say it only took 3 or 4 months for the problem to come up, especially the hardening of older rubber fuel hose. I noticed that in our 1988 boat, but the latest one has the type that resists alcohol.

So now, where the advice had been to top off a stored car's tank or a boat's gas tanks to avoid water from condensation, the winterizing checklist now includes DRAINING as much of the gas as you can. For the old cars here I load up on race gas from the local track. Lots of tetraethyl lead, and NO friggen' ethanol. Expensive, but lots cheaper than carbureators and gas tanks on 40+ year old cars.

http://www.racegas.com/fuel/1

For the generator here I leave it empty but use a 6 gallon portable boat tank, filled up every couple weeks and drained down into a needy car when time's up. When the power goes out, we drain it into the genset, and we're set to go. Buys enough time to fill the other hand tanks to prepare.

Good advice posted on here for the "marine" type of Sta-Bil. There are two flavors of that too, both are dark green instead of the regular Sta-Bil which is pink/red, so read the label carefully. I bought some online that was NOT the full protective kind that I got at a local boat store.

[Opcom]

The set here, a 40K Mankato, has a day tank holding about 30 gallons. I keep it full and run the set about once a month to heat the fuel and circulate it through the big filter. Today, even the red offroad diesel may have all kinds of bio-garbage in it.

It may not be possible to keep steel tanks from rusting but there might be plastic or aluminum alternatives which are acceptable by law.

The surface appearance of these issues could be construed by paranoid people as that the government doesn't want anyone storing fuel. or ammo. or... There is at least one crank on the shortwave ranting about all of it.

I used to be able to drive about 10 miles south of I-20 and get unadulterated gasoline. Now the nearest location is 55 miles. I really believe it is fascist for the government to force me to use adulterated fuel and to pay extra for the privilege of being overcharged for the added low-energy swill.

[N0WEK]

The set here, a 40K Mankato, has a day tank holding about 30 gallons. I keep it full and run the set about once a month to heat the fuel and circulate it through the big filter. Today, even the red offroad diesel may have all kinds of bio-garbage in it.

It may not be possible to keep steel tanks from rusting but there might be plastic or aluminum alternatives which are acceptable by law.

The surface appearance of these issues could be construed by paranoid people as that the government doesn't want anyone storing fuel. or ammo. or... There is at least one crank on the shortwave ranting about all of it.

I used to be able to drive about 10 miles south of I-20 and get unadulterated gasoline. Now the nearest location is 55 miles. I really believe it is fascist for the government to force me to use adulterated fuel and to pay extra for the privilege of being overcharged for the added low-energy swill.

If you want high quality, stable, leaded, unadulterated gas just go to the local airport and  buy 100LL Avgas. Only problem is the $5 par gallon price tag.

[W4EWH]

If you want high quality, stable, leaded, unadulterated gas just go to the local airport and  buy 100LL Avgas. Only problem is the $5 par gallon price tag.

Whatever happened to 80/87? Would 100 octane risk damaging a generator engine?

Bill, W1AC

[Todd, KA1KAQ]

The Onan manual says 68-74 octane for the W2C/W3S which is a late 30s design. I'd always though older = higher octane.

TNX for the fuel assessment, Jared. Six months seems about right, although I seemed to notice the varnish/gumming up to be more of an issue by then, whereas untreated fuel appeared to stay viable longer. My neighbor is an over-the-road mechanic for Caterpillar, has the big truck with 4 ton crane, genny, welder, etc. He had warned me about the issue Rodger mentions, though not in specifics. He says they've had to go around and pump out/filter large tanks full of diesel for customers to remove contaminants of this nature. Sounds like yet another example of the Green Weenies good intentions exceeding their actual knowledge on the matter. Big surprise.

So it appears there is no longer a simple answer. Gasoline which used to remain useable and reliable for a longer period of time no longer does. Diesel which could be left for years no longer can. I'm not big into conspiracy nonsense as far as the gov't trying to control us, seems instead like more of the typical 'we know what's best for you' stupidity related to the overall dumbing down process.

Including a few pics of the Onan. Its governor arm for adjusting the frequency(original point of the thread) can be seen above the carb in the last photo. Slab used to have one of these old beasties, so we've exchanged a lot of email about it. Has a leak in the original honeycomb radiator from a mishap in '85 that needs repair, and an overall clean up & re-lube. It's the perfect genset for Vintage Field Day or light(3kw) backup use.

[WQ9E]

Higher octane fuel in general isn't a problem.  The octane rating is simply a measure of its resistance to detonation at higher cylinder pressure.  Using octane below the required amount, especially in older engines without some sort of knock sensor/timing retard system, can lead to rapid and very severe engine damage.  But having higher than required octane is generally fine although a waste of money.  The caveat is alcohol is a great octane booster and is often used for that purpose (but not in av gas).  Since the BTU content of alcohol is lower you may also have reduced power in these older gensets-in addition to the other alcohol negatives listed earlier in this thread.

As engines get older the required octane number may climb as deposits in the cylinder head reduce cylinder head volume resulting in a higher effective compression ratio.

The cetane rating, applicable to diesel, is nearly the opposite of the gasoline octane rating.  A higher cetane rating indicates the fuel will combust more rapidly which is desirable.  

And I agree with Todd, conspiracy theories may be fun but applying Occam's razor leaves stupidity as the most probable explanation of the negatives of "green fuel" along with  special interest support of the alcohol content mandate and subsidies.

[N0WEK]

If you want high quality, stable, leaded, unadulterated gas just go to the local airport and  buy 100LL Avgas. Only problem is the $5 par gallon price tag.

Whatever happened to 80/87? Would 100 octane risk damaging a generator engine?

Bill, W1AC

There is still some 80/87 out there but most airports won't dedicate a truck to it since many of the lower powered aircraft can use auto fuel with the required paperwork and it's much cheaper. The 130/145 Purple gas is long gone except for one batch a year that's made for the Reno Air Races. The rest of the year the warbirds are running at reduced manifold pressure with 100LL.

I've run Avgas in the mower now and then when I had some left over in the fall when I stop flying the self launching glider and it runs fine. My old pre-catalytic Datsun truck loved the stuff. Just don't go lower in octane than recommended. Of course the leaded stuff will kill the catalytic converter in anything that has one.

[Todd, KA1KAQ]

I recall burning 100-something octane in my '72 TR-6. Our tiny regional airport was user-friendly for locals, so I could drive out on the ramp and get filled up now and then. Was pricy compared to the 39-46 cent civilian gas so didn't do it too often. Seems there was an issue of nozzle fitting the gas filler (which had an aircraft-style cap, ironically) with one of the trucks, so I just loosened the clamp on the rubber collar connecting it to the tank neck and could slip it on and off easily.

It always made the car run much smoother & stronger, and cleaned things out nicely.

As to my old genny, I was more amazed at how low the octane rating is for it. I guess the high compression/high octane/combustion phase hadn't kicked in back then. More of a 50s-60s thing?

It sure would be nice if they could sell a pure gas mix for gensets and such, like off road diesel and so on. If there was a concern for over-road use, they could always color it as with the diesel.