| Author |
Message |
ralph7 (208.148.72.145)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 02, 2003 - 10:17 pm: | |
I went to the Carlisle car show today [in Pa] an talked to some bus owners [venders of car parts] an found an Eagle,owner who converted it in 1995 it now has 256,000 miles on conversion. Pulling a 18 or 20 ft enclosed trailer both units loaded with antique toys an car parts. He installed 8 elect fans [4? on rad. 4 ? on right side of coach] needs cross flow in engine compatrment an 1 Ford [flathesd v-8]fan with 8 blade not orig. 3 blade] in eng room,belt driven from crank. 8v71 with 10 speed an they run 55-65, but now health forces them to quit, they went coast to coast to swap meets. Now two dogs someone has gone an done IT!!! |
two dogs (67.30.23.90)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 02, 2003 - 10:24 pm: | |
lets hear it for our side....I'm not the kind of guy that says I told ya' so....but I told ya so
so many women,so little time |
mark (65.40.225.193)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 1:35 am: | |
So the "8 blade belt driven fan" has a little help from the electric fans...?
mark
75 gillig 636D |
ralph7 (208.148.72.150)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 8:02 am: | |
Mark the 8 blade fan is a car fan , is a help when the bus is sitting ideling. It moves cool air from bottom left rear to under bottom front of engine past bottom 1/3 of radiator. They do not have a generator [noise maker] either, they do boondock at car flee markets an other times too. 7 solar pannels an 2 8d battery's for house. |
Terrance A.Haag (Mrbus) (152.163.252.163)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 9:16 am: | |
As I understand this, they replaced one tried and true method of moving air through the radiator with eight (8) electric fans and a converted fan from a Ford being driven by a belt from the crank, and my question is WHY?
Gus Haag |
two dogs (67.30.23.5)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 10:15 am: | |
to take them 30 horses and put 'em to pullin' the rig....(or pushin') |
Stan (216.95.238.99)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 10:15 am: | |
I don't understand the purpose of the Ford fan either.If the electric fans cool the engine at 60 MPH what is the belt driven fan for? When a 8V71 is at idle you can't get it warm enough to even open the rad shutters. |
Richard Bowyer (Drivingmisslazy) (24.196.191.70)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 10:57 am: | |
I believe that if it takes thirty hp to cool the engine, then the hp requirements will be the same, regardless of the technique used, whether belt driven, hydraulic or electric. And this hp has to all come from the same source, the engine.
If using electric fans, then more hp would be required due to the inherent ineffeciencies in the alternator supplying the power to the electric fans.
Richard |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 1:00 pm: | |
Hey Richard--You're using Physics again, you're actually going to force some folks to think.
I think converting HP to Electricity, back to HP, is one of the least efficient ways to transmit power, until you get to huge power transmission loads (Dieselectric).
I'm planning to keep my Hydraulic-driven fan in place and add a couple of pancake fans on the outside of the rad, controlled by thermostat.
Gary |
Derek (24.66.241.23)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 1:03 pm: | |
Richard: You've hit it on the nose. Energy can't be created or detroyed, only converted.. Which is a very inefficient process... So you take that 30HP, move it to the alternator, and send it to the fans.. You don't gain anything, and stand to lose something. |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 1:40 pm: | |
On the other hand-- (Devil's Advocate)
The HP draw is saved to the battery, so the load is stored and released over time.
So really are the electric fans really robbing the 30HP? Probably not, but then you might argue that they're not they're not moving enough air...
I think though, that you might see a difference when pulling a hill, but then you'd be loading the engine recharging the batt at other times.
Gary |
Richard Bowyer (Drivingmisslazy) (24.196.191.70)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 5:20 pm: | |
I would assume that 30 hp is 30 hp, regardless of how it is obtained. In most cases the batteries are at or close to full charge, so there is no place to store additional energy in the batteries. They are already full. The full 30 hp is coming from the engine, thru the alternator, directly all the time. And this hp is needed regardless of whether you are going down hill or uphill.
BTW, this is not physics in my case as I have no background in that subject, just good common horse sense. LOL
Richard |
ggypsy (66.21.166.70)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 8:13 pm: | |
hmm but take a portable air compressor...1 1/2hp electric motor will run it...change it to gas and all of a sudden it takes 5hp....any industrial application and elect. and gas differ the same....which is more efficent???? just thinking...GG |
Don KS/TX (66.82.9.47)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 8:42 pm: | |
Not so fast there Ralph, I met that SAME GUY
I think, and spoke with him too, a year or so ago. If you did, you recall that he kept adding fans and more fans, and when it did not work, he added the crank drive fan, and STILL has to keep his foot out of the throttle to keep it from boiling. His evaluation to me was, that it did not work. Sorry Two Dogs, my personal principals say I have to tell it like it is. |
two dogs (67.30.23.14)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 9:06 pm: | |
no problem...that's the neat thing...everybody gets to build it like he wants |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 9:21 pm: | |
ggypsy--
That's because electric horsepower and Internal combustion horsepower have no connection with each other.
for Electric- 1hp=1KW
for Internal Combustion- 1HP = ((lb/ft torque)X RPM/5252)
The two have little connection.
Gary |
ggypsy (66.21.166.70)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 10:03 pm: | |
yes I KNOW...but other people keep equating them as the same.....they are not...plus thanks to NASA modern low voltage motors are nearly 5 times more efficient than just two years ago....at least your awake
Gary... gg |
Don KS/TX (66.82.9.39)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 10:52 pm: | |
So you guys with the calculators, tell us something.
Somewhere in a reputable place I read about dyno tests of an 8V71, with and then again without the fan. Dyno showed it was somewhere in the 30-40 hp that the fan drew at fast cruise rpm. Assuming that is true, then how big an electric motor is it going to take (in electric HP rating?) Does Graingers sell a radiator fan with that horsepower? |
BrianMCI96A3 (65.41.249.117)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 03, 2003 - 11:32 pm: | |
I think it might be possible to replace the squirrel cages and miter box of an MCI coach and exchange them with comparable CFM squirrel cages meant for an evaporative cooler, belt driven with relatively smallish DC motors...maybe even using a rheostat driven by throttle position. The down side of this is the bearings would assuredly need to be replaced with sturdier units, and the 50 thou. question would be: how well would it stand up to road use? ALSO, it might be possible to utilize the passanger cabin AC blower motor and it's squirrel cages... Well it's something to think about, but I think I'll stick with my miter box set-up it looks like it was replaced at some point in the near past so it should last a while yet.
Brian |
Scott Whitney (66.82.9.25)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 04, 2003 - 8:35 pm: | |
Google sez:
1 horsepower = 0.745699872 kiloWatts
But I have no idea what kind of horsepower it is talking about. I always thought a horsepower was a horsepower. Guess that is as incorrect as me assuming gauge was gauge. . .?
So how many other units exist that are context dependant?
Scott |
two dogs (67.30.23.56)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 04, 2003 - 10:38 pm: | |
maybe lots of people don't know about evapperative coolers...simple squirrel cage fan...with pillow block bearings 1/2 h.p. =4000cfm...enough to knock ya' over when you walk by it ...1"pillow block bearing 10.00 (need two)
brian and ggypsy are getting close..also...if you are makeing air,(air comp.) usualy 5 elec h.p. make about 11, but it takes a 10 h.p. gas to make the same scfm....THAT FORMULA ...elec just does a better job..no need to argue about it, h.p. doesn't cool....... cfm cools |
Tom Caffrey (Pvcces) (65.74.64.199)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 04, 2003 - 11:10 pm: | |
Hey, you guys, the 746 watts is the correct energy equivilant of one horsepower. The Electric motors are rated for continuous duty, but the gas engines aren't.
Most gas engines are way overrated for continuous duty because they are not suitable for that use. If you need to run an engine at rated power for any length of time, and make it reliable, you use a diesel.
The nearest examples I can think of that is an exception is small airplane engines and race car engines. I believe that it is common to run them at 50% in air taxi service. Race car engines don't usually have a long service life and they take pains to avoid preigniton.
I imagine that some of you do some flying and would know how the cruise gph would compare to the full power gph. In autos, I don't know of a case where 80 mph fuel consumption runs over 1/3 of full power consumption.
For what it's worth.
Tom Caffrey PD4106-2576
Suncatcher |
Don KS/TX (66.82.9.34)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 05, 2003 - 9:35 am: | |
Good post Tom, as a pilot and A&P myself I like to use such examples. Lets see now, it takes 250 hp to turn my airplane "fan", so how much weight in batteries would it take if I converted to an electric airplane? Too much for me, but we MAY be on to why you don't see a whole lot of electric planes flying around these days, reckon? |
Sam Sperbeck (206.230.105.248)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 05, 2003 - 9:48 am: | |
Hi two dogs,
Was that a typo in your post "1/2 h.p. =4000cfm"?
Thanks, Sam Sperbeck
La Crescent, MN |
Scott Whitney (66.82.9.26)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 05, 2003 - 12:13 pm: | |
OK, so . . .Are we saying now that a horsepower IS a horsepower, i.e. 745 watts, no matter what is producing it? (certainly seems more logical than the gauge hullaballoo) But the HP descrepnancy is in the ratings of the device producing it? In other words, electric motors are rated far more conservatively than are gas motors, but a horsepower is still a horspower regardless?
So, if we put a 5 hp electric motor and a 5 hp Briggs and Stratton on the roof of a building, put the same size spool on each, wrapped a steel cable around and attached a 10 Lb weight at the end of each line, the electric motor would beat the Briggs pulling the load to the roof everytime?
What if the electic motor had to get it's electric power from an appropriately sized gas generator (and all its inherent inefficiencies). Which device could pull the load to the roof the most times on one gallon of gas. . .?
Scott |
two dogs (67.30.23.65)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 05, 2003 - 12:56 pm: | |
sam...don't think so...unless it should have been c.f.m. instead of cfm |
Tom Caffrey (Pvcces) (65.74.64.199)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 05, 2003 - 7:37 pm: | |
If you would like to make a comparison, how about this? Our 4 kw Onan is 55 cubic inches in the engine. Now, there are a good many gas engines that are rated for over 1 hp to the cubic inch. But the Onan has to be able to deliver 6 hp continuously without running over 1800 RPM.
To do that, they hang a big enough engine on the generator that it does not have to run hot to do it's job. The compression ratio is only 5.5 to 1, so they're not taking any chances of preignition, either.
Instead, they get their reliability out of our wallets by reducing the fuel economy and increasing the machine cost and weight. This is where I think the Hondas and a few other makers have a lot better products.
For what it's worth.
Tom Caffrey PD4106-2576
Suncatcher |
Johnny (67.241.224.143)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 05, 2003 - 9:48 pm: | |
Zoiks--that engine is only a little smaller than the 1 litre mill in a Geo Metro! 55ci for only 6HP...yikes.
It seems to me it would be more efficient to spin a smaller engine faster, & gear down the genhead to 1800. |
Tom Caffrey (Pvcces) (65.74.64.199)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, October 06, 2003 - 8:20 pm: | |
The Japanese do it with a smaller engine, but they don't have to run over 1800 RPM, AFAIK. And if you think about it, there's really no reason that they have to.
The hp per cu. in. that I mentioned can be achieved at 3600 RPM easily enough, so 1/2 hp. per cu. in. at 1800 should not be any problem. That means that the work can be done by an engine half the size of our Onan, no sweat.
The higher power can be accomplished with better pistons and valves, as long as the cooling is adequate.
For what it's worth.
Tom Caffrey PD4106-2576
Suncatcher |