A good idea that works, and has additional benefits in keeping operating temp more stable.
If accessories could kill… MPG
- Thread starter InlineDave87
- Start date
"...Automatic trans these days are more efficient and some even surpass manual trans (or so they say)..."
yes, the stats have shown a decade or so that autos now surpass manual.
At one time (remember Mr. "MPGs" a stang owner here?) we hada list: a/c v open window, tires/tyres, belts, pumps, rotating parts lube, etc, etc.
There wasa comment w/each: Ex - windows win till over 45 mph, p/u truck tailgate down no, tonneau .5 mph, etc
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aussie7mains
Famous Member
OK, then how come the trucking industry has largely gone to Automated manual transmissions rather than full auto? Losses is the answer, every bit of fuel consumption counts for truckies.
It is largely due to initial step-in cost and secondly the cost to rebuild the automatic is tremendous over the standard. Plus, if you lose a gear in the automatic your done for a week or ten days; the standard you still might get your load in.
I think Paccar is one of the bigger truck builders catching on an adding more automatics to their front-line trucks. Many of your city municipalities, public as well as school transportation run automatics, fuel cost is negligent.
automobiles, from the international auto writers (IDK - "Motor Trend", ASR Mag, Road'n Track or whatever their names are) have been reporting on it a good while. Common knowledge (I'd say, but I'm pretty common).
Sorry, friend, I know nothing re: the big rigs. We're talkin "cars" here. May B you're talkin what's on the bent8 Oz super cars? Sounds like what's ona buncha drag cars here now (company starts w/"L"?) where they just hita lever-like shifter - https://www.summitracing.com/parts/...MIwpXG2sKmgQMVwfXICh1logq3EAQYBSABEgKdovD_BwE - w/o need to depress clutch (well - rally cars, may B some 'drifters') also called "sequential manual"? But, a digression, opposite of MPGs...
Also weight was the primary reason when I was in the industry '80's-'00's. The Allison autos then were much heavier than the Eaton manuals. They proved dependable in bus applications, but the big trucking companies stayed away from them for uniformity in their fleet repair shops, the cost, weight, and unknown durability in the high-load semi application. I don't remember fuel economy being a big playing card.
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I just saw this.
Your numbers would be correct if the alternator is 100% efficient.
The automotive alternators used in vehicles from the 1960’s up to present have an efficiency around 50 to 55%. Some more, some less. Some of the most efficient alternators are used in heavy trucking and busses.
Normally, about 1 HP is needed for every 25 amps of power generated by an automotive alternator.
Below is some information on Delco alternators. Efficiency numbers are also listed. The efficiency numbers normally go down when the alternator gets hotter. High temperatures in the engine compartment is one of the reasons for drop in efficiency numbers.
Alternators by Model Family | Delco Remy
From brushless designs with fewer moving parts to remote sense to improve battery charge time, Delco Remy technology is second to none. We continue to leverage our experience to provide our OE and aftermarket partners with innovative solutions for today’s vehicle electric system challenges.
www.delcoremy.com
It’s known that in general, 24 volt alternators have higher efficiency numbers than 12 volt. Some newer alternators are using square wire wound on the stator and rotor. This helps, but generally a 12 volt alternator will be less efficient than alternator with a higher voltage output.
Here is some good reading:
There are advantages upgrading to a G3 alternator. Most alternators are more efficient at lower output than being near fully loaded. If possible, upgrading to a G3 gives a slight edge in efficiency to older F150’s because the alternator is not working is hard when maintaining voltage when the truck is cruising on the highway. And the G3 tends to be more reliable because its working less.
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aussie7mains
Famous Member
Higher voltage, lower current for equal power, lower current, less losses. This is why 24v is used. think of the HV transmission lines, 330KV. Still efficiency of under 60% is quite low compared to AC generators for 50Hz, which can generally be up over 90%.I just saw this.
The automotive alternators used in vehicles from the 1960’s up to present have an efficiency around 50 to 55%. Some more, some less. Some of the most efficient alternators are used in heavy trucking and busses.
Alternators by Model Family | Delco Remy
From brushless designs with fewer moving parts to remote sense to improve battery charge time, Delco Remy technology is second to none. We continue to leverage our experience to provide our OE and aftermarket partners with innovative solutions for today’s vehicle electric system challenges.
It’s known that in general, 24 volt alternators have higher efficiency numbers than 12 volt. Some newer alternators are using square wire wound on the stator and rotor. This helps, but generally a 12 volt alternator will be less efficient than alternator with a higher voltage output.
Here is some good reading:
Exactly,
A good friend and I started a microcogeneration forum in 2009 and we did an experiment. We both purchased the same make, model and horsepower engine. He used a 7.5kw generator head and I used a 12.5kw generator head. We both operated them 1 to 1 ratio. He direct coupled the 7.5 with a love-joy coupling, while I used an 8 groove K-belt setup. We both ran the engines to overload and we were surprised that the larger head belted to the engine engine out-pulled the 7.5 direct coupled head setup by 982 watts. Even if our numbers were off 35% because of the differences in the engines output, 638.3 watts is still pretty impressive. Some members in the group thought the direct coupled, smaller head would out pull the larger belted head due to less friction loss on a smaller fan, smaller bearings and less rotational mass. The study showed that generator heads are generally more efficient not being pushed to full output.
To this day, when I build a genset. I normally oversize the generator head for an application and de-rate it by using a smaller than required breaker to prevent engine overload.
A good friend and I started a microcogeneration forum in 2009 and we did an experiment. We both purchased the same make, model and horsepower engine. He used a 7.5kw generator head and I used a 12.5kw generator head. We both operated them 1 to 1 ratio. He direct coupled the 7.5 with a love-joy coupling, while I used an 8 groove K-belt setup. We both ran the engines to overload and we were surprised that the larger head belted to the engine engine out-pulled the 7.5 direct coupled head setup by 982 watts. Even if our numbers were off 35% because of the differences in the engines output, 638.3 watts is still pretty impressive. Some members in the group thought the direct coupled, smaller head would out pull the larger belted head due to less friction loss on a smaller fan, smaller bearings and less rotational mass. The study showed that generator heads are generally more efficient not being pushed to full output.
To this day, when I build a genset. I normally oversize the generator head for an application and de-rate it by using a smaller than required breaker to prevent engine overload.
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aussie7mains
Famous Member
Generally what I've found is that with alternators, the bigger they are the more efficient they are, this is in the above 50kw. this could accont for the difference you found, you I take it were unable to determine the input power from the engine, also there is no quaranty that any two power uinits are the same, this is especially true of petrol engines. The difference you have quoted is about 12% which would be within the spec of most petrol engines (plus or minus 10% output) Diesels are generally better than this. I was involved in specifiying and building standby gensets for telephone equipment in PNG, most of them were over 35kva, they ran direct coupled at 1500rpm (50Hz) 3 phase and 240v. The larger ones were mostly caterpillar although some had a variety like Leroy Somer, Mecce Alta even some Australian local units. The smaller sets with single phase alternators were less efficient. We were not overly concerned about fuel consumption as most only ran a 1000hrs a year at most.
The engines used were Changfa S195 single cylinder liquid cooled diesels.
The Chinese diesel turned out to be very efficient 100% loaded. I don’t have the g/kWh numbers, but it was up there with some of the best small diesel engines made. The engine didn’t do very well at all lightly loaded. With our experience, in testing, with the diesel engines we’ve used, most got better numbers when fully loaded.
The Chinese diesel turned out to be very efficient 100% loaded. I don’t have the g/kWh numbers, but it was up there with some of the best small diesel engines made. The engine didn’t do very well at all lightly loaded. With our experience, in testing, with the diesel engines we’ve used, most got better numbers when fully loaded.
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aussie7mains
Famous Member
Yes generally true, if you get the BSFC curves they usually bottom out around peak torque, and above 75% load. Ive also messed around with natural gas engines, mainly in busses and trucks, the curves were similar there, One 9.6litre renault engine was getting 40% thermal efficiency on gas, which was as good as when on Diesel. The standby sets I was involved with were mostly Lister air cooled engines, but i prefered Deutz, especially the 912 series. Some of the cheapie engines like the Ford Dover engines were pretty good too. i did one caterpillar d353 engine, bloody huge thing, came out of a NASA tracking station, was orignaly 60Hz, but we slowed it to 1000rpm to get our 50hz. Heres a question for you, why did north America go with the 60hz, 110v split phase sysetm, when just about the rest of the world is 50Hz 240-250v.
Because we didn't mind spending the money on the extra copper it takes to run a lower voltage, split phase system.
Same with automobiles. Why did we have the 400 to 500 cu in V8 powered very heavy land cruisers while the rest of the world had more economical forms of transportation.
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aussie7mains
Famous Member
Hmmmm. And now we pay for it.
Nikola Tesla developed alternating current (AC) which was in the late 19th century, he invented 3-phase 240V AC. His concept was to combine three phases of power to account for voltage fluctuations. By Tesla's calculations and testing, 60 cycles per second was the most efficient power supply frequency. Also at that time there was also the Big Battle over the type of power that was going to be used for the first Power Grids and which would be the best. Mainly this was by Tesla and Edison over using Tesla’s AC power or Edison’s DC power. Edison tried to show that AC was much more dangerous using up to 750 volts to publicly electrocute many animals from Dogs and Cats to even a Horse and Elephant. In the end Tesla’s AC system won by being far more efficient in transmitting power longer distances without having as much Voltage losses. However Tesla also did compromise some to lower the Voltage to 110 volts and 60Hz to work with the existing 110 volt Edison devices that were being made as well as for safety. Europe even started out by mirroring this original US standard of 110V/60 Hz., however after World War II, they switched over to the 220V/50 Hz, even though their higher power at the lower 50 Hz. frequency is up to 20 times less efficient, I have always wondered why they did that. Our current 120 volt / 60Hz. Standard was set back in in 1967.
aussie7mains
Famous Member
We run the 50hz 3 phase here, with our own standards, but some states differ in voltage, but generally 240v, We have an east coast grid that runs right along our east coast, there are many coal fired plants, but with our uptake of rooftop solar, there are times when that carries the entire load without anything from the thermal stations, which mainly become frequency stabilizers. We have NO nuclear, despite be one of the worlds largest producers of yellowcake, although there is a push to use it now. IMO we have left our run for nuclear too late, it would take 20years before a single watt was generated, and its the NIMBY thing that would make it extra difficult to do. Renewables have a big head start in this regard, and the technology and materials needed are MUCH simpler. As to the SNR generators, only the Russians have really done it with anything land based. 20 times less efficient????
Back then in the 1890's with the common Arc and Incandescent Lighting they were using they found there was also less Flicker at 60 Hz. I also heard that they later found out that a clock is also more accurate on a 60 Hz frequency (60 minutes, 60 seconds). For an Electric Motor the basic, RPM is in direct proportion to Hz. If you decrease the power supply frequency, the motor will slow down and if you increase the frequency, the motor will speed up. So the RPM change is proportional to the Hz change. The primary difference between 50 Hz, and 60 Hz. is, that 60Hz is 20% higher in frequency. Example a 60Hz motor will run 20% slower on a 50Hz power supply, this also results in 20% less power and that’s where the up to 20 % less efficiency comes from. It’s been said that AEG in Germany (an Edison Founded company) choice of 50 Hz. was for convenience relating to a more of a "metric-friendly" number rather than 60Hz., still there was also that Battle between Tesla and Edison too. AEG had a virtual monopoly and their standard spread to the rest of Europe.
aussie7mains
Famous Member
Yes i know the relationship between frequency and RPM, this mainly applies to 3 phase squirel cage motors, but going slower does not reduce efficiency, or neccesarily power. You guys also have this strange (to us) system where you bring in single phase at 240v then use a centre tap transformer to spilt that into two legs at 120v with opposite cycles, we dont do this. We have 3 phase supply to some homes and most business at 415v (across phases) but we split the phase so that one house might be on the blue phase, the next on red, and 3rd one on white, the other leg being neutral. We also have an earth. Some rural areas use a SWER, single wire earth return, cheaper. Most appliances are single phase and our normal outlets are limited to 10a, however we do have 15a outlets for small welders and AC units for example. EG I have a lincoln powermig 180c welder, it uses a 15a outlet at 240v, I think the US ones have to go to the 220 supply. The metric friendly might explain some. But all electric stuff was always metric. Do the USA still use BTUs in calculations, thats a unit that is very difficult to use.
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Bronctopia
Well-known member
Yes, but mostly just in HVAC (Heating, Ventilation,Air Conditioning trades, NOT High Voltage Alternating Current!)
Since a BTU is 1.055 Kilojoules, and nobody notices 5% more heating, it is our most Metric adjacent "customary unit".
Since a BTU is 1.055 Kilojoules, and nobody notices 5% more heating, it is our most Metric adjacent "customary unit".
Hi aussie7mains, yes our Residential Single Phase Power systems consists of 3 Wires coming into the Breaker Boxes all across America and I believe its is that way also in all of North America. I mostly know the California, Arizona, and at one time North Dakota areas and have seen many other states they can have some differences in their local or state codes however they will still work the same. It has two 120 Volt power legs and a common the Breakers will plug into these two power Legs and its a fairly simple system and wiring its been this way as long as I can remember when I started working at a young age with my Dad in his construction business. So to get a 240 Volt Circuit in 20, 30, 50 Amps you only needed 2 120 Volt Legs and the Common for many years, now days the Building Codes says you need to have 4 Wire 240 Volt Plugs. Our common Household, Office, Garage, Light Industrial use 110 Volt Plugs were only 2 wires up until 1964 when we went to the 3 Wire Grounded Plugs in 15 or 20 Amps 120 Volts in 1965 in my area. We do have the big 220 to 240 Volt welders which is what I used for a long time and is still what I have however we also have the smaller 15 or 20 Amp MiG & Arc Welders that are much more common now days and they do work great for the small to medium size jobs. Most of my experiences were with Residential Electric but we also built and repaired many Industrial Buildings too so I have some experience with 3 Phase up to 660 Volt and I do like it it's abilities I even had tried unsuccessfully several times to get 3 Phase on my Residential property's. I also got to experience using the 220 50 Hz. when I was stationed over in Germany in early 1970's and my Stereo equipment I bought over there had the Duel Voltage that you had a Slide Switch on it to change it from one to another. X2 yes we do have BTU's used for the Heating and Cooling Trades though I have installed quite a few Gas and Electric Heaters and several Heating and Cooling Systems I am more of a novice when it comes to doing those kind Calculations which they want the systems sized correctly now days for the best performance.
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