Hi guys,
New member here. Been dreaming about owning a bus since a kid (not that long ago! at 24, wonder if I'm the youngest bus owner here? 8)). Origionally planned on saving up for 10 years or so and get a 90's Prevost with hopefully a S60 engine, but came across this deal that I couldn't refuse, and can afford right now.
So I got myself a 1964 Prevost, which no one can figure out the model, with a 6V71 and Spicer (I think) 5 spd manual. To my surprise, I have 4 valve heads and N70 injectors, so I'm estimating my hp at 240. It's a 35' highway coach, and for the age, just about perfect inside out, and drivetrain wise.
So, now, the problem. For the past twenty years the bus had an electric cooling system. I've read just about every thread regarding this topic, and realize there has been some pretty heated discussion regarding the inability of electric fans to cool a bus. And I believe most of what has been said. I'm a Mechanical Engineer, and my last job at Daimler was fuel cell design. Fuel cells would make typical 2 stroke heatloads look like a lawn mower ;D (we're talking 50+% heat rejection here!)
I think this bus got lucky because 1, it's a 6V71 with relatively lower heat rejection, 2, it's got a manual transmission, and 3, it has big tanks and a big rad mister! So somehow, this bus made through 20 annual summer trips from British Columbia to Mexico (through Arizona).
But the radiator now needs a replacement, as the fins have rotted. It's on the small side as far as buses go - about 24" x 24" and 3" thick. It's currently cooled by 4 fans off old VW Bugs mounted on a custom made shroud. I realize it's no match for the engine driven OEM fan. But, the chances of finding a engine driven fan that fits my bus is slim to none, so unfortunately, I have no choice but to stick with electric. However, I do want to improve on the old setup.
What I'm guessing is that electric fans can blow a lot of CFM, but without the hp to back it up, they can't do so WHILE maintaining useful static pressure. Couple that to the thick radiator used on coaches, and you can smell (literally!) disaster. So here are two of my plans so far:
1) use two heavy duty pickup radiators. Typical measurement is 17" by 33" each, so a total of over 1000 sqin surface area. Flex-a-lite makes a "heavy duty" cooling fan and shroud system, consisting of dual 15" fans. In total, I'd have 4 15" fans (better than 4 10" fans now), but blowing through much less restriction, as the radiator is only 1.4" thick. The radiators will be connected in parallel to maintain higher water flow.
Problem: the Flex-a-lite fans are $550 for each rad, and from searching old posts, I realize their engineers don't even test their fans! So I feel getting ripped off paying $1100 for some fancy plastic work!
2) Get the rad re-cored to origional standard, and use a engine driven fan blade. The bus has dual alternators, I will change one so that it's full fielded, and therefore generate roughly 120V DC at full engine RPM. This is a cheap trick to get huge horsepower out of a ordinary alternator. With my 100amp model, I have the potential to generate 12kw, or 16hp! This will allow me to power universal motors found on power tools. I'm thinking of two 15 amp motors off a circular saw, which are geared for 5800 rpm.
Two such motors will produce 4 horsepower peak, and drive a fan enough for 95% of conditions.
I'll stop before this turns into a novel. What are everyone's opinion on this?
Thanks in advance.
Roy
Roy, did you buy the one that was listed on Maritime RV that is a nice looking bus if you did
good luck
I'm not familiar with that bus but I can offer a couple of thoughts for your consideration.
It sounds like the cooling system was woefully inadequate, thus the large misting system thus ultimately the most likely reason the radiators are in such bad shape.
Misters are a band-aid, not a solution.
Universal motors are not designed for continuous service, and will not survive very long.
I would strongly suggest a mechanical or hydraulic engine driven fan for cooling and using a full size heavy truck or bus radiator.
Welcome, nice way of describing your plans, well understood. I would go with option # 2. I believe when one starts modifying with such things as rads you may very well run into a restriction issue. Sure others will chime in.
Grant
Quote from: luvrbus on June 01, 2010, 07:22:36 PM
Roy, did you buy the one that was listed on Maritime RV that is a nice looking bus if you did
good luck
I haven't seen that ad, but I highly doubt it's the same bus.
Bought it from a local guy here in BC, Canada. Got it for $10k, which compared to the stick and staples trailers I was looking at, seems like a steal (so far, hope no surprises will pop up!).
Quote from: Len Silva on June 01, 2010, 07:33:26 PM
I'm not familiar with that bus but I can offer a couple of thoughts for your consideration.
It sounds like the cooling system was woefully inadequate, thus the large misting system thus ultimately the most likely reason the radiators are in such bad shape.
Misters are a band-aid, not a solution.
Universal motors are not designed for continuous service, and will not survive very long.
I would strongly suggest a mechanical or hydraulic engine driven fan for cooling and using a full size heavy truck or bus radiator.
I agree about the inadequacy, which is why I'm surprised it made it this long.
Thanks for warning me about the universal motor duty cycle thing. This is one of the things I'm afraid of. Although, most mountain grades in my area at no more than a 5 - 10 minute climb, which seems to be within limits of commercial strength power tools (heavy duty Makita grinders, etc.) When cruising at lower rpm, the fans would be effectively under-volted as the alternator is not putting out the full 120V.
If this ends up not working, anyone know of any reasonably priced DC motor solutions?
I'm thinking of driving a fan like this:
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.flex-a-lite.com%2Fcatalogs%2Fgraphics%2F00000002%2F4600.gif&hash=2892c6f418f1acae6391f3106c2745dd7b693402)
http://www.flex-a-lite.com/catalogs/merchant.mv?Screen=CTGY&Store_Code=heavyduty&Category_Code=4600series (http://www.flex-a-lite.com/catalogs/merchant.mv?Screen=CTGY&Store_Code=heavyduty&Category_Code=4600series)
Roy the one on the add looks gray and blue with a mask on the front with a nice front bumper on the front they were asking 12,000 for it.
I can not get the link to work for you maybe some of the smart guys can bring it up lol.
good luck
Quote from: luvrbus on June 01, 2010, 08:08:00 PM
Roy the one on the add looks gray and blue with a mask on the front with a nice front bumper on the front they were asking 12,000 for it.
I can not get the link to work for you maybe some of the smart guys can bring it up lol.
good luck
That's definitely not the one, but I think I might have seen that one as well. IIRC, it does look somewhat similar to mine.
My bus is natural color (stainless with aluminum window panels), and the trims are painted red. I'll take some pictures once I've got it all polished up.
Some old service receipts list the model as H340, but I've googled around and found no such thing. Some Canadian only coach perhaps?
Roy - a '64 H340 would be a 'rare' bird indeed - thanks for paying attention in school -
"What I'm guessing is that electric fans can blow a lot of CFM, but without the hp to back it up, they can't do so WHILE maintaining useful static pressure. Couple that to the thick radiator used on coaches, and you can smell (literally!) disaster"
Couldn't have said it better myself - Good Luck with your coach - Sounds like your first post-graduate experiment
Welcome to our wild and crazy world !!
I am in the process of removing my A/C condenser which uses a hydraulic fan, which I will no longer need, if the deal gets done.
It cools a 36" X 36" X 6" condenser, so I imagine it might be helpful in your application.
If you are unable to get the situation resolved with the radiators and fans, let me know and we may be able to work out a deal for the fan.
I also have the two condensers that are just collecting dust !!
Keith
PCC
Roy,
Lots of buses have large DC motors that ran both the evaporator & condenser fans. The venerable DN50 alternator that was original equipment has a plenty of power to drive the motors. Some bus nuts here have removed the original equipment setup & installed other options. You should be able to pick up the discarded components & fabricate what you need.
As a side note, you may want to look at the specs before you use an AC condenser for a radiator. Those are two different applications. The condenser was designed to convert a gas to a liquid by removing heat. The other just removes heat from water.
YMMV,
TOM
As far as model call prevost car with serial number or I just saw site that has prevost listed by serial number and tells to whom they were sold and spec. Hydraulic fans can be easily driven by a belt operated auto power steering pump.one large fan blade easier to put shroud around and control air flow.unlimited blade configur around...Just a thought. need pictures.....possible a prestiage (sp)model...need pictured of rad area...being a engineer you can apreciate the KISS principle it does well in our hobby especially when trying to get part on the road...Welcome and fyi there is no age requirements..we are all crazy Bus Nuts
My instinct would be to use an engine driven fan, either belt or hydraulic, since the power levels can be pretty high. I'm not sure if letting an alternator run at high voltage is a long-term reliable thing to do, if you are going to pull 16hp out of it you have to put more than that into it, and they just aren't designed for that loading. I also don't know how to figure the hp load to accomplish the air flow, but at a guess and looking at some charts put out by Caterpillar on their engines, you might need 20 hp. I use a rule of thumb of 1,000 watts for 1 HP output of electric motor, so 20,000 watts? That's a lot of electricity, but it's not a lot of mechanical power.
I also have this idea that an alternator may be power limited, in other words it can be designed for 100 amps at 12 volts for 1,200 watts, or 50 amps at 24 volts, or 10 amps at 120 volts. Certainly the literature on alternators that come in various voltages implies that sort of relationship.
Brian
I was NOT suggesting using an A/C condenser as a radiator, but the hydraulic fan might serve your purpose.
The condensers are available, but they are for A/C, not cooling an engine.
Sorry about being confusing.
Keith
Could a unused ac condensor be used to supplement cooling??have wondered???or heater core????
Pay attention to what is done by the manufacturers - that is usually the most reliable & cost effective solution.
If you must use electric fans, you must have the performance curve before you'll know if it will work. My experience with Flex a lite fans was sufficient enough that I won't ever spend a dime in that direction.
It takes HP to move air & if the factory setups use over 20 HP, you will too - else you will overheat . . . .
My suggestion/ advice is to stick with as big a radiator as you can fit in there & either belt or hydraulic drive the fan. (Get familiar with the heavy duty vehicle wrecking yards & you may find one that will fit nicely. Lots of ideas to drive the fan too. . . .)
Then you can watch the road & not the temp gauge. :D
Enjoy the ride!
Quote from: robertglines1 on June 02, 2010, 10:15:32 AM
Could a unused ac condensor be used to supplement cooling??have wondered???or heater core????
Short answer = yes
Longer answer = efficiency & heat rejection rate will depend on coolant flow rate, air flow, cross section, fin count, tube diameter, material, etc.
There is a reason that Flex-a-light does not make a heavy duty electric fan, only medium duty truck fans.
Quote from: PCC on June 01, 2010, 10:22:38 PM
Welcome to our wild and crazy world !!
I am in the process of removing my A/C condenser which uses a hydraulic fan, which I will no longer need, if the deal gets done.
It cools a 36" X 36" X 6" condenser, so I imagine it might be helpful in your application.
If you are unable to get the situation resolved with the radiators and fans, let me know and we may be able to work out a deal for the fan.
I also have the two condensers that are just collecting dust !!
Keith
PCC
Quote from: oldmansax on June 02, 2010, 04:42:35 AM
Roy,
Lots of buses have large DC motors that ran both the evaporator & condenser fans. The venerable DN50 alternator that was original equipment has a plenty of power to drive the motors. Some bus nuts here have removed the original equipment setup & installed other options. You should be able to pick up the discarded components & fabricate what you need.
TOM
Thanks for the info on condenser fans Keith and Tom.
This does seem like a good option, though I'm sure a lot of custom fabrication is required to fit my specific radiator. A new alternator at 24V would be necessary as well if the fan is electric. If an electric setup is used, I'd probably go high voltage, as even at 24V, it's hard to power a reasonable sized motor. A 300am 24V alternator would be cost prohibitive for me at this point as well.
Quote from: robertglines1 on June 02, 2010, 05:04:04 AM
As far as model call prevost car with serial number or I just saw site that has prevost listed by serial number and tells to whom they were sold and spec. Hydraulic fans can be easily driven by a belt operated auto power steering pump.one large fan blade easier to put shroud around and control air flow.unlimited blade configur around...Just a thought. need pictures.....possible a prestiage (sp)model...need pictured of rad area...being a engineer you can apreciate the KISS principle it does well in our hobby especially when trying to get part on the road...Welcome and fyi there is no age requirements..we are all crazy Bus Nuts
I'll probably call Prevost one day and find out exact what my model is called. Chances are there were only a handful ever made, but I do know that I can still get some parts from Prevost.
A lot of people have suggested hydraulic for me at this point, and I'm definitely keeping that open as an option. I'm a little concerened about the high-loss transmission of hydraulic power, as the 6V71 is definitely not overpowering for the coach! The bus has no power steering (will save me on gym membership), so I'll need a full hydraulic system.
Are hydraulic fans only on-off? If so I'd go with a 2 speed clutch.
Quote from: bevans6 on June 02, 2010, 05:11:44 AM
My instinct would be to use an engine driven fan, either belt or hydraulic, since the power levels can be pretty high. I'm not sure if letting an alternator run at high voltage is a long-term reliable thing to do, if you are going to pull 16hp out of it you have to put more than that into it, and they just aren't designed for that loading. I also don't know how to figure the hp load to accomplish the air flow, but at a guess and looking at some charts put out by Caterpillar on their engines, you might need 20 hp. I use a rule of thumb of 1,000 watts for 1 HP output of electric motor, so 20,000 watts? That's a lot of electricity, but it's not a lot of mechanical power.
I also have this idea that an alternator may be power limited, in other words it can be designed for 100 amps at 12 volts for 1,200 watts, or 50 amps at 24 volts, or 10 amps at 120 volts. Certainly the literature on alternators that come in various voltages implies that sort of relationship.
Brian
You bring up a good point Brian. I'm not to worried about the alternator itself, but chances are, the belts and pulleys were not designed to transmit more than 5 hp.
I'm no an expert on alternators, but have done my share of research. From what I know, as long as the diodes can handle the higher voltage, the alternator itself is of low concern. The heat generated in a conductor is determined by current (amperage) only, and not power. A wire conducting 600V at 25 amps will have the same heat generation as 12V and 25 amps. Alternator windings are also the same as motor windings, so reasonable voltage (120v) should be no problem.
At 120V, a 5 hp motor (the highest I'd go for) would only consume 35 amp or so. The alternator internals would be working a lot LESS than at 12V full capacity. However, the mechanical components would be working as if producing 350 amps!
Thanks for all the replies guys. I'll quickly breif on what I think of the power issue.
Upon research, I found the following regarding the hp consumption and CFM for a typical Class 8 truck:
http://www.drivetrainindustries.com/kitmas2sp.pdf (http://www.drivetrainindustries.com/kitmas2sp.pdf)
Take a look on the chart on page 2. In summary, for the fan, it takes:
- 1 hp to induce 3300 cfm flow over the rad fins
- 2 hp to induce 10,000 cfm
- 70 hp to induce 30,000 cfm !!!
Like most fluid work, the relationship of power vs speed is to the 3rd power!
From this, we can conclude that the 20 - 40 hp the OEM fan consumes falls in the ultra-inefficient region, akin to 70hp on a truck. OEMs have to design at this level to pass durability testing at maximum duty cycle - full throttle hill clim in 100 degree weather.
As a private owner, I don't have to follow such strict requirements. The current fans on my bus probably represent the very first step on that curve - 1 hp and 3300 cfm. I'd like to improve this to atleast the 2 hp/10,000cfm level, which would be a vast improvement over current. Anthing over this is a bonus for me, but by no means am I trying to cover the 100% percentile operating conditions of a stock fan.
Keep the suggestions coming guys, they're of great help to me. So far, I think the hydraulic and condenser fan / motor is the best best solution. The hard part would be the custom fabrication, and tailoring the rad and shroud to such a fan setup. I'll probably have to find such a fan first before going to a rad shop.
Thanks again everyone.
Removed
Found this website that describes the many factors involved in a successful cooling system.
http://www.arrowheadradiator.com/14_rules_for_improving_engine_cooling_system_capability_in_high-performance_automobiles.htm (http://www.arrowheadradiator.com/14_rules_for_improving_engine_cooling_system_capability_in_high-performance_automobiles.htm)
Kenny
Quote from: Kenny on June 02, 2010, 07:32:01 PM
Found this website that describes the many factors involved in a successful cooling system.
http://www.arrowheadradiator.com/14_rules_for_improving_engine_cooling_system_capability_in_high-performance_automobiles.htm (http://www.arrowheadradiator.com/14_rules_for_improving_engine_cooling_system_capability_in_high-performance_automobiles.htm)
Kenny
Kenny, I have read that article, and it's the exact reason why I though of putting two F150 radiators, at 1.42" thick and 1200 in^2, instead of my current radiator, at 3" thick and 600 in^2.
With electric fans, the current fins are too dense and reaching the point of diminishing returns. Following the logic in that article, using two thinner F150 radiators in parallel should increase both the coolant flow within the radiator cores, as well as the effective CFM and active fin area. My concern is the uncertainty of automotive radiators in a bus, and the fabrication involved in fitting a fan and shroud to such a setup.
Quote from: Now Just Dallas on June 02, 2010, 05:09:48 PM
Something wrong with those numbers.
I think I wuld do some more research if I were you. That company is trying to sell you something and I would take their graph with a box of salt(s).
According to that, I should be able to use 2 fans and at 4HP supply 20K CFM.
And then there is the problem of their RPM figures.
To be honest I'm not believing the numbers 100% either, and I will keep on researching for sure, but I think it does illustrate an important point.
95% of te driving can probably accomplished by a much lower powered fan, but to design to the 100 percentile, you'll need a very powerful fan. This is the same reason why a typical family sedan requires 8 - 9 hp at 55 mph, but most are equipped with 250+ hp.
I believe the catch is that, while you can use 2 fans to produce 20,000 cfm, it will be much less effective than a single fan at 20,000 cfm because the single fan would be producing much higher pressure (and therefore consuming much more power).
I've already realized that electric can never fully replace an engine driven fan; I am simply trying to cover more driving situations than the previous owner did. If I can find a suitable hydraulic unit, I will definitely put on a 2 speed clutch to preserve the limited power of my 6 cylinder.
Quote from: RoyJ on June 02, 2010, 03:42:49 PM
Are hydraulic fans only on-off? If so I'd go with a 2 speed clutch.
Nope, they are (or can be) two-speed. At 190 degrees my fan goes to full speed, and drops to half speed at 180 degrees. A solenoid flow-restrictor is triggered by a coolant temperature switch, and is fail-safe so if the switch or solenoid fail the fan will run at full speed. Simple and very effective.
I'm thinking of replacing my original 6-blade fan with a newer multi-blade fan, more like those on newer OTR buses. If I can pull more air through my radiator I may not need to have it recored instead, and a fan is cheaper than a new radiator. Other folk here have had success with this approach, so I may give it a try.
John
When moving a compressible fluid (like air), power is required to 1) create the pressure differential, 2) actually move a volume, 3) overcome the efficiency losses.
Actually moving the air takes the most power, so the manufacturers use shutters to reduce air flow -OR- they use a variable speed fan.
Also you will want to seal between the fan & the radiator to ensure all that air you are paying to move goes thru the radiator.
BTW, the engine is providing power to move the air - be it to drive an alt or hyd pump or v-belts, so don't casually discount the stock method.
It is damn difficult to get reliable & satisfactory cooling with electric fans on heavy vehicles. It can be done, but it ain't easy or cheap.
There are reasons the factory did it the way they did - If it was simple & cheap to do it otherwise, they would!
I've had things in the past with marginal cooling systems - that is an inconvenience I'd rather not deal with again - it always cost more to do it over & over than it would have to do it right the first time.
Good luck with your project.
Quote from: kyle4501 on June 02, 2010, 09:06:49 PM
Actually moving the air takes the most power, so the manufacturers use shutters to reduce air flow -OR- they use a variable speed fan.
Also you will want to seal between the fan & the radiator to ensure all that air you are paying to move goes thru the radiator.
BTW, the engine is providing power to move the air - be it to drive an alt or hyd pump or v-belts, so don't casually discount the stock method.
It is damn difficult to get reliable & satisfactory cooling with electric fans on heavy vehicles. It can be done, but it ain't easy or cheap.
There are reasons the factory did it the way they did - If it was simple & cheap to do it otherwise, they would!
Thanks Kyle, good points for me to consider.
I hear you about the seal between the fan shroud and radiator. In an ideal situation, if the fan is freely turning in vacuum, then it's consuming no power. Unfortunately though, my bus does not have shutters.
If I owned the bus since day one, I would have NEVER changed the cooling system. But now that the parts are all gone, and with such a rare coach, any attempt to rebuild to factory spec would involve tons of custom fabrication.
A little off topic, but the only reason an electric system can have less parasitic power loss is because of the battery. It acts as a power storage / buffer. On an uphill climb, the alternator can support only 25% of fan power, and the twin 8D batteries provide the rest. Once the hill is over, the batteries can slowly recharge.
Quote from: Iceni John on June 02, 2010, 08:36:23 PM
Quote from: RoyJ on June 02, 2010, 03:42:49 PM
Are hydraulic fans only on-off? If so I'd go with a 2 speed clutch.
Nope, they are (or can be) two-speed. At 190 degrees my fan goes to full speed, and drops to half speed at 180 degrees. A solenoid flow-restrictor is triggered by a coolant temperature switch, and is fail-safe so if the switch or solenoid fail the fan will run at full speed. Simple and very effective.
I'm thinking of replacing my original 6-blade fan with a newer multi-blade fan, more like those on newer OTR buses. If I can pull more air through my radiator I may not need to have it recored instead, and a fan is cheaper than a new radiator. Other folk here have had success with this approach, so I may give it a try.
John
Yeah I just did some browsing on the web, and realized that hydraulic can get really fancy indeed.
By varying or reversion the displacement of the pump and / or motor, they have systems that can be continuous variable in speed, stop all together, and even reverse the fan for debris cleaning! The challenge is for me to locate a cheap hydraulic system at a bus yard / auction (which I don't know of any in my area).
New fan blades are probably a good idea also. With computer fluid simulation and 50 years of fluid research, I'm sure they've come up with more efficient ones than the 60's.
Consider a pulley setup if it is possible. look at a later prevost where a pulley and belt drive a shaft to a miter box that turns a fan. If you get a thermo fan clutch on the Fan you save horses big time and if you can source some scrap for the miter box this is a simple reliable system....less fancy bet gets it done...remember KIS there are lot's of other things to work on on your bus....(I'm guessing?) here are a couple of pics a of a mid 70's prevost miter box
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi392.photobucket.com%2Falbums%2Fpp3%2Fzubzub_photos%2Fprevost%2520scrap%2520and%25204104%2520interior%2FIMG_0145.jpg&hash=b7d0474aebc183a038bfbb957aee3b29a3a36913)
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi392.photobucket.com%2Falbums%2Fpp3%2Fzubzub_photos%2Fprevost%2520scrap%2520and%25204104%2520interior%2FIMG_0143.jpg&hash=d07d4d2d6c2e22c137b39c9497f669f21adae40d)
That does look a bit like my engine bay. The problem is, I don't have that "outer part" on the bottom main pulley. It ends where the multi-vbelt part stops, and then it's the back bumper. I also have this vertical bar that would get in the way.
This makes no sense at all, how could the factory have fitted any mechanical fan to such a setup? If hydraulic, where was the pump driven off of? I'm guessing the engine may have been swapped in. If I use a hydraulic setup, I'd have to put the pump where that alternator is in that pic.
I'll get some pics posted up soon. Does anyone know if this board has a photo uploading section?
Removed
On my Gillig the PS and fan-drive (and the wheelchair-lift I took out) are from the same pump, in a single loop configuration.
You can do a hydraulic drive from the accessory ports on your block - from my memory there are two (one at the end of each cam shaft). You need a pump and a motor (or two pump/motors), a reservoir, pressure relief valve right after the pump (bypassing to the reservoir - some pumps come with this built-in), and a control valve at the absolute minimum.
You can do an el-cheepo 2-speed control by getting a solenoid valve that has a restrictor fitting in it. For best safety, you should set it up so that the fan will get max-flow with the pump spinning and no power to the solenoid (bypass closed), and let restricted fluid bypass the fan motor only when the solenoid is powered (bypass open) - this way if the solenoid fails or the circuit supplying it fails, the fan will at least be able to cool the engine completely, you'll just have more "hunting" with the thermostats (relatively fail-safe design).
You can fancy it up with a variable-flow control valve (http://stores.daltonhydraulic.com/-strse-858/Flow-Control-Valve-w-fdsh-/Detail.bok) to change the speed of the motor using the same principal - they make electronic ones if you are good with that stuff, you can whip up a control circuit that uses the return temperature of the coolant to the block as a speed control stimulus (not the kind we pay for later with taxes).
Any hydraulic shop should have the parts to do this.
-Tim
The bus has no power steering, so the hydraulic loop would have to be totally new.
I think for a $10k bus, doing a brand new, custom hydraulic loop would be a little cost prohibitive for me at this point. If I go hydraulic, I'd have to wait for a good salvage unit to show up. The engine does have lots of leftover pullies, so I'm sure I'll find a place for the pump.
I did a little maintenance on my band-aid solution to make sure the bus can atleast get around safely. Took apart all the fans and motors, cleaned out the dirty bearings/bushings with solvent, and lubed with fresh grease / machine oil. Also sanded and repainted the shroud, and put in new double foam seals. To my surprise, the fans pull much harder than before. Don't know how many amps they pull, but the 6 gauge wire was warm at the terminals. The wind generated would pull the rad access door shut from 6" away.
By no means am I giving up in finding a new solution, but it does show the PO put in a some effort to design it as well as he could. They're certainly better than those flex-a-lite stuff.
here is a thought. If this bus has worked the way it's set up and has pulled grades etc...has an operating engine temp gauge that you can watch from the cock pit....why change it? I know everyone says it can't be done but apparently the PO did it. And it has worked for 20 years, so why change it?
Quote from: zubzub on June 03, 2010, 09:19:15 PM
here is a thought. If this bus has worked the way it's set up and has pulled grades etc...has an operating engine temp gauge that you can watch from the cock pit....why change it? I know everyone says it can't be done but apparently the PO did it. And it has worked for 20 years, so why change it?
My origional reason is the radiator's need of replacement, and I have to decide whether or not to stay the same size. If I upsize the radiator (which I realized I can't, no space), then I'd have to get a new fan setup anyway, so might as well start planning for a proper replacement.
So far, I don't have any personal experience driving the bus yet, so I have no idea how well the setup works. I can only relate to what the PO told me (and he admits to relying on the mister on hot days). I'll make sure to do a lot of hot weather hill climb test before the maiden trip.
Forgot to mention earlier, with a miter box you wouldn't need the extra pulley just run a serpentine belt. Re the mister s et al, the naysayers will say, look it ruined the rad etc...but the yea sayers will say how much are you really going to use this, and it's not like the rads are going to rot right away. If you find a transit scrap yard they have some nice smaller rads, and the cool thing about transits is that they are maintained while in service so a retired scrapper can have some nice new rads etc on it.
We have a 6V71 with hyd fan drive off a Carpenter/Thomas transit 6v. It was/is a Webster unit. webster harder to get parts now but we replaced the drive motor with a webster copy. Robert said the hardest part of the repower was the cooling system! Nimco in NJ will have take outs and as Zub says get to a transit yard for ideas. Wonder what the stock engine was in your rig if they repowered with a 6V? Ours originally had a 4-71. good luck
Electric fans for radiators have been discussed extensively. If they are so good, don't you think OEM's would have been using them since they are easier to set up then a direct drive or a hydraulic drive and they take less horsepower drag? On big rigs, they had a setup that had 6-8 fans (depending on the radiator shape) and didn't work on a front radiator! Trying to get an electric motor that will pull like a 32" 8 bladed fan (the equivalent of 30hp) just won't happen. 30hp with a 24v electric motor would have to draw about 950 amps! With our side intake radiators, the only way to go is with either a direct drive or hydraulic motor setup. We've had too many members try electric and by now have realized that using an electric motor for the radiator is like banging your head against the wall because it feels so good. Good Luck, TomC
Quote from: zubzub on June 03, 2010, 09:19:15 PM
here is a thought. If this bus has worked the way it's set up and has pulled grades etc...has an operating engine temp gauge that you can watch from the cock pit....why change it? I know everyone says it can't be done but apparently the PO did it. And it has worked for 20 years, so why change it?
That's just it, it didn't work - hence the need for misters. How many commercial vehicles come with a mister system? Misters are a great bandaid to temporarily increase the cooling system capacity, but, misters are not a permanent solution.
The engine isn't always the limiting factor in HP available to move your bus - heat rejection abilities of the radiator can limit things too.
A properly sized radiator won't care what moves the air, as long as it gets enough air moving across it. The smaller the radiator, the more air required = more fan HP.
Sure electric motors can do it & use the batteries to buffer the peak power required from the main engine - BUT - the electric fan will HAVE TO move the required air to keep the temps in line during peak demand. That means the elec motor MUST be capable of that level of horsepower (which is in excess of 20 HP).
SO, for the time being, "Run what 'ya brung" & see how it is. Your useage may be puttering around flat, cool areas & your system will work just fine as is. OR, you may find you need to cover distances quickly (due to limited vacation time) & the hills must be climbed (which creates more heat to be rejected) which mandates more cooling.
Only you can determine what your real needs are.
I know Mark (Boomer) is reading this and having a good laugh he is all over Mexico , Northwest and the Southwest using his electric fan setup on a 45 ft 102 wide Eagle never once have I heard of overheating on his bus
good luck
Yeah, but he isn't using low hp elec fans either, is he?
Not all electric fans are equal. The fans he used are not anything like the typical automotive radiator fans.
Another thing, If I recall, he spent a bit of time developing the total system. Quite a bit of work in the fan shrouds too.
Yep he did do it right Kyle but some of these guys say it won't work period with electric fans that is point I am trying to get across it will work if done right
good luck
Clifford,
Good to see at least we're still on the same page. ;D
Quote from: TomC on June 04, 2010, 07:13:56 AM
Electric fans for radiators have been discussed extensively. If they are so good, don't you think OEM's would have been using them since they are easier to set up then a direct drive or a hydraulic drive and they take less horsepower drag? On big rigs, they had a setup that had 6-8 fans (depending on the radiator shape) and didn't work on a front radiator! Trying to get an electric motor that will pull like a 32" 8 bladed fan (the equivalent of 30hp) just won't happen. 30hp with a 24v electric motor would have to draw about 950 amps! With our side intake radiators, the only way to go is with either a direct drive or hydraulic motor setup. We've had too many members try electric and by now have realized that using an electric motor for the radiator is like banging your head against the wall because it feels so good. Good Luck, TomC
Tom, (and other anti-electric folks)
I have read just about all the old posts regarding electric fans (including some pretty heated ones with Twodoggs), and I hear you loud and clear. But please understand I'm in a difference situation: I'm not trying to take out the factory system and playing smart. I DO NOT HAVE A FACTORY SYSTEM TO START WITH! The engine and bay seems to have been altered, and I have a super-rare bus, which makes a engine driven fan almost impossible.
Hydraulics, as I'm quickly learning, is not cheap. I'd have to mount the pump on the passenger side, and use long hoses to reach the radiator. Even then, I'd have to play with altering pumps/motors, unless I find a 24" or smaller fan, unlikely on a transit.
Electric is simply one of the more viable options at this point. I'm not stuck on it, and I'm not saying it's superior, and I am not trying to argue, but electric is a possibility for me. If I do go electric, then no, I will not slap on some $35 Ebay fan.
Now, regarding the electric hp issue:
Important for us all to realize that cooling fan is not a "either you have the hp or you don't" thing. Any fluid (air) operates on a curve - flow, restriction, power, efficiency, heat conduction, etc.
I've looked at a lot of fan curves in the last couple days, and they all somewhat mirror what I've posted in that PDF - it takes a lot of hp to cover the max flow situation. As you increase flow over a set of fins, restriction goes up to the squared. Since power is a multiplication of flow and restriction, it goes up to the 3rd power.
You can get half the flow, and retain a huge amount of drivability, at only 1/8 the power. The problems with most "electric fans" on the web, is that they're most like 1/100 the power of a diesel engine fan. If I go electric, it will be the 1/8 to 1/4 power region, with a high voltage alternator setup. It will be an improvement over the current system, and though inadequate, has carried the PO across North America for 20+ years.
Regarding misters. I'll admit I'm not a big fan of them, and they do feel like a bandaid. However, after thinking about it, I don't think they are bad for the radiator at all. Think about driving in the rain with a front radiator. And doesn't matter where you live, the rain is guaranteed to be worse quality than potable water.
Quote from: kyle4501 on June 04, 2010, 07:52:28 AM
The engine isn't always the limiting factor in HP available to move your bus - heat rejection abilities of the radiator can limit things too.
Sure electric motors can do it & use the batteries to buffer the peak power required from the main engine - BUT - the electric fan will HAVE TO move the required air to keep the temps in line during peak demand. That means the elec motor MUST be capable of that level of horsepower (which is in excess of 20 HP).
The hp limit is an interesting matter. If you have a 2.5hp fan, you might be limited to 200hp on a 250hp engine. Put on a 20hp fan, you'll be effectively limited to 230hp, but get 250hp level fuel mileage. What's the sweet spot? Back when I worked in fuel cell, this troubled a LOT of engineers. Go too far on cooling a PEM fuel cell, and it's almost always diminishing returns.
About the stock fan hp. I can't speak for buses due to my lack of experience, but as an OTR trucker, I can say that OEM fans (at 70hp) are almost always over-designed, for that one day you might haul a 100ton coal train in a tropical rain forest.
Even grossing over 80k in the rockies, on 8% grades, the fan is never in constant-on mode. They do make for great engine brakes on the way down though!
Quote from: luvrbus on June 04, 2010, 09:00:53 AM
Yep he did do it right Kyle but some of these guys say it won't work period with electric fans that is point I am trying to get across it will work if done right
good luck
This is my point exactly, the OP has a bus that has had an electric system with misters that has worked for 20 years.....does this mean it doesn't work? No....it works (apparently) with misters....now this may not be the way many of us want to go, but it's hauled itself back and forth from Canada to mexico via Arizona, so for the use it has had the system works. Misters are considered a crutch well I guess this bus uses crutches but it still gets there. The main thing I am trying to say is, buddy has a new bus, he's working it out...I know how quickly the little/medium projects pile up and before you know it the bus hasn't hit the road in 2 yrs...so I was suggesting maybe keep what you have 'til you find a good solution, in the mean time a new rad will keep you on the road.
Quote from: zubzub on June 04, 2010, 04:21:05 PM
so I was suggesting maybe keep what you have 'til you find a good solution, in the mean time a new rad will keep you on the road.
Thanks, that's exactly my plan.
I'll get a new rad build to current size, so atleast I can use the fans the way they are for now. If I build the rad for a new fan, then I'm stuck till the new system can be put in.
zubzub, great minds think alike ;D
Quote from: kyle4501 on June 04, 2010, 07:52:28 AM
. . . .SO, for the time being, "Run what 'ya brung" & see how it is. . . . .
Nice to see someone looking at his situation from all sides to determine the best direction to throw cash. ;D :o 8)