| Author | Message | ||
| David Ljung Madison (Daveola)
Rating: N/A |
Does anyone know where I can find stats on the MCI air compressor? I'm trying to calculate what the CFM of the air is for running temporary tools and the like (not while driving!  So - does anyone either know the general CFM of the compressor, or else the size of the air tanks in cubic feet or gallons so that I can calculate my buses CFM? Thanks! | ||
| David Hartley (Drdave)
Rating: N/A |
If its the stock Bendix TU 700 series, It's 15.5 cu/ft/min @ 1280 rpm (engine speed). it is water cooled and uses engine oil system. Using the bus air system is a an expensive way to make air and not a good idea to idle the engine just to run tools. CFM is cubic feet per minute. Air system output cannot exceed the capacity of the compressor so tank capacity doesn't really enter into the calculation. The only factor would be how much air you can dump in a given time. | ||
| David Ljung Madison (Daveola)
Rating: N/A |
Expensive how? And why is it not a good idea to idle to run tools? If it's just a matter of fuel costs, then it's well worth it for the application I have in mind, but I'd rather not damage the compressor. And is it possible to swap out the TU-FLO 700 with a bigger compressor? | ||
| John Jewett (Jayjay)
Rating: N/A |
15.5CFM @120 PSI is more than many autobody shops have. That will run 2 DA sanders non-stop, or a big board file. More than enough to run a 1" impact wrench too, though you amy have to wait from time to time for it to catch up with the impact. I use my bus air for that and for smaller air tools as well, but mine is a 12.5 CFM. Occasional/emergemncy use should not be a problem. Cheers...JJ | ||
| RJ Long (Rjlong)
Rating: N/A |
It's not the compressor you're going to damage, it's the engine. Detroit two-strokes don't like prolonged idling without any load on them. They tend to slobber a lot, and you run the risk of loading up the rings in such a way that when you do need the power (like pulling a grade), the rings won't seal properly. Lots of blue smoke will be the result, mixed with complaints of "my bus is slow". . . IF the damage is severe enough, it's time for an overhaul, which runs about $10K. That's the expensive David was talking about. The OEM air compressor on the engine is an off-the-shelf Bendix unit. IIRC, there's also a TU-FLO 900 available, common on transit buses, as their air requirements are a little greater than an MCI's. Might be a better idea to simply pick up an electric air compressor that you power off the genset for your tool usage. Added benefit: You can air up the coach w/o having to fire up the Detroit before leaving the campsite! FWIW, RJ PD4106-2784 Fresno CA | ||
| John MC9 Rating: N/A |
I don't mean to argue, but every time I read about idling doing severe harm to a DD 2-banger, it reminds me of my driving days. On charters, we were instructed to run the engine to keep the bus warm while we waited for our passengers during the winter, and during the the summer for keeping the bus cool for the same reason. Engines were running from the time they left the barn, until their return. Never an engine failure that I can remember. (I usually drove the same bus every day, just as the other drivers.. But we did use the fast idle when we idled it). On line runs, where the bus sits for periods of time at each end, or during the many stops, it's never shut down... We sat in stop and go traffic for hours damn near every day on the L.I.E., B.Q.E., and Cross Bronx.. where's the difference between that, and running some air tools for a few hours? I can understand the problem of a slow idle, with oil buildup, etc, but at fast idle, what difference should it make? Although I understand the concern to make note of the possibility, is it really a matter to be worried about? These are used buses. Can any of us undo it's past, by not doing what's already been done? | ||
| sylverstone (Sylverstone_pd4501864)
Rating: N/A |
being the owner of a wwII smokescreen machine, (my bus smokes *a lot*) i'll tell ya, it's *very* nice to be able to build air before you fire it up. i'm going to be basically rolling my own auxillary "stuff" thing... i.e. small diesel engine, with a generator head, an alternator, and an air compressor. you know, fire the little bugger up, air the bus up, (running the block heater if i choose, topping the batteries if i choose) then i'll shut it off, fire up the big diesel, release the brakes, and go. anyone you don't upset with the smoke a 2 stroke diesel produces when cold, is one less person to complain about you. | ||
| David Ljung Madison (Daveola)
Rating: N/A |
It's not always more expensive to use bus air for tools. Consider needing to run a *big* pump for 5 minutes every few weeks. I can get an air powered pump that does the job I need and requires 15-20 CFM at 80+ PSI for about $200, OR I can buy an electric pump for $1000 or more. I'll keep my bus idling for a few minutes for that kind of savings. Finding an electric air compressor at 15+ CFM would also be many hundreds as well, so that doesn't really work either. And it's one more tool on a crowded bus. So - am I wrong in thinking that using the bus at idle would be such a big mistake? Heck, I see big diesels sitting at idle for far longer than that. Or am I missing some other problem with straining the air system? | ||
| David Ljung Madison (Daveola)
Rating: N/A |
Oh - and the reason I wanted to know the tank capacity was because I can use that to calculate the CFM based on how long it takes the compressor to fill the tanks. Interesting article at: http://truetex.com/aircompressors.htm | ||
| FAST FRED Rating: N/A |
On charters, we were instructed to run the engine to keep the bus warm while we waited for our passengers during the winter, and during the the summer for keeping the bus cool for the same reason. ON CHARTERS , the cost of an early rebuild was built into the charter PRICE. Some folks get 200,000 miles after an inframe , some get 300,000. Ideling , non use care , oil selection , and driving style (cruise at 1800 or 2200+?) all make a difference. FAST FRED | ||
| Doug Dickinson (Dougd470)
Rating: N/A |
Let's also look at REASONABLE as a part of this discussion. Bus companies got about 250K between rebuilds (industry average for DD 2 cycle in the 80s). They ran buses most of the time - driven to failure usually - and idled the engines a LOT. Also, trucking companies did similar with drivers idling all night and then running all day. Their engines lasted a little longer than in bus service - about 300 - 400K. In an IDEAL situation, Fred is absolutely correct - you only run the coach when you need to - no extra idle to run things and the engine is going to last a good bit longer - maybe as much as 30% longer with perfect maintenance - perfect operation, etc. I have yet to see a perfect world! If someone runs the coach for a couple of hundred hours more than absolutely necessary - that is not going to create a noticable effect on longivity. If you run it THOUSANDS of hours - you bet there will be an impact. Some things that are more important to longivity are oil changes, oil type, operating temperature, and how you drive. THOSE are the things that make big differences. I air up my coach before I move it around people so that I don't smoke them out in cold weather or bother them with long idle noise. I also used the air system for taking out the interior with air tools - probably reduced the life of the engine by a tenth of a percent - whoopie! Figure out how to measure THAT. If you take the "reasonable" approach to the issue, the impact of using the engine air system to power tools - somewhat - there isn't much impact to the overall life. If you are going to use it for a full time shop air supply - you are certainly going to see a reduction in life. Now let me wrap this up a little - this also assumes you are not running the engine at substantially below the coperating temperature (or above at all) and you have good oil pressure yada yada yada. You can abuse an engine in all kinds of ways. I doubt that any of us are going to have a fresh engine in our coach and will run it to rebuild time - maybe a couple - but mostly doubtful. If you need to limp along on a sick engine, then even a little abuse may put it over the edge. You have to look at your situation and see what makes sense. I doubt I will drive this engine 200K in my lifetime. Some of us look at sage advice, like "it is not good to idle the engine for long periods" into something that reads like "never idle your engine for long periods because you will kill it in no time". Those are not equal statements! Figure out what makes a difference for you. My $0.02 worth Doug St Louis MC9 | ||
| John MC9 Rating: N/A |
Freddie - When one considers that 100,000 miles equates to $250,000+ in fuel, are you seriously telling me I should be worried about the reduction of engine life from 400,000 miles to 350,000 miles? A. I can't afford to go the 100,000 this year (or the next 100). B. I likely won't be around to see the odometer roll to 350,000. | ||
| Jim Stewart (H3jim)
Rating: N/A |
John, check your math. I hope we get more than 1 MPG with these things. about $50,000 in fuel | ||
| John MC9 Rating: N/A |
Yeah Jim.. I saw that whopper after I hit the send.. That's what I get for yakkin' on the phone and trying to type at the same time.. Probably closer to 5 mpg average over that amount of miles, bringing it closer to $50,000 for 100,000 miles. Not out of the question, but my bank account would suffer if it took less than a whole bunch of years to rack 'em up. Multiply that cost of fuel by 3 or 4 times for the amount of miles the engine should last....? I'm more concerned with the cost of fuel to idle my bus at fast idle, than "damage" caused by fast idling it. Doug summed it up best. | ||
| Dale Waller (Happycampersrus)
Rating: N/A |
Fast idle and a block heater to keep the engine temp up while using the compressed air. I would have to agree with Doug. I doubt you could even measure the impact on the life of the engine for no more than you are planning to use it for. The saw mills around here are rough on their portable engines and with proper maintenance thay last for years. | ||
| David Hartley (Drdave)
Rating: N/A |
If it was only an impact on the engine from extended idling I would have said that. There are other things to consider besides the direct impact on the engine systems. Air suspension, electrical system, batteries, noise, smoke, fumes, coolant operating temperatures and all that other stuff thats attached. You also have hydraulic oil circulating in the steering and transmission. I know that it doesn't matter in the grand scheme of things and probably would not affect most of us that have decent engines. It's them "Fringe Dwellers" you have to worry about around here. Neighbors complaining about the noise and smoke, wrong oil in the engines, poor compression and oil staining the ground for miles around... Ya Know??? | ||
| John Jewett (Jayjay)
Rating: N/A |
My multiple neighbors, regular, obnoxious backyard barbecues, and their rug rats loud boom boxes and stereos are far more smoke/noise pollution than my occasional use of the bus air will ever be! Plus I don't do it at midnight either. The guy burning leaves in his side yard fits into this as well. Like Dougd470 said, "it's a matter of perspective." | ||
| FAST FRED Rating: N/A |
"Now let me wrap this up a little - this also assumes you are not running the engine at substantially below the coperating temperature." Which does happen with an ideling DD ,seldome will the water get near even 140 just ideling, although the idea of fast idle AND a 1500w block heater and blocked radiator might do it. FAST FRED | ||
| Buswarrior (Buswarrior)
Rating: N/A |
Hello Daveola. I think the recurring "anti-idle" discussions amongst busnuts are academic at best, and irrelevent to our situation at worst. I will be so bold to say there is no boogey man hiding in your idling DD. Install the big airline connectors in the coach air system and go for it! Your coach engine and air compressor will have to be run for quite some time (days/weeks/months/years) before the cost of doing so will pay for the big shop compressor that one would need to do the same work. Why would a busnut, who, by nature, usually is a value seeking person, resist using their engine and whopper of a good air compressor to use to run air tools, and instead, spend the money duplicating the set-up by buying a big shop compressor that is rarely used to its full capacity? Why spend air compressor money to delay by a questionable time frame a rebuild that I'll never need in my lifetime? Philisophically, does it make sence with the rest of our goals? happy coaching! buswarrior | ||
| David Hartley (Drdave)
Rating: N/A |
Gorsh Batman... It's not that I wouldn't do it, I have, Its not that its really bad, Its probably not that bad. For the sake of "some" unmentionable people that visit the boards if you say sure go ahead and use your bus as an air compressor and they do it and either get hurt or damage something and they did it simply because everyone said it was OK then who will no doubt get flamed over it? My only safety worry was to tell someone it is OK to use the bus air that they be very careful. If someone is using the bus air to jack the bus up or work underneath it or around it with the engine running I feel that this would not be a good situation. STUFF HAPPENS... There was another thread about this some time back and its very similar in nature to the one about using ether for things that it was not intended to be used for. Lifelong words of wisdom. I know, Been there done that in my more stupid days. Never work around a running engine with hand tools that can get dropped into the belts, fans or pulleys. Never string cords or air hoses across a running engine where they can get caught up in moving parts. Never get under any portion of any vehicle that is supported on jacks only and especially one that is running. Have lots of blocking materials to block tires and up under chassis support points if you do have to go under. Yeah' its like reaching through the belts on an MCI with the engine running to tweak the throttle and yakking with someone standing there watching, Long sleeves and moving belts are not compatable. For that matter skin and moving belts are not compatable. Oh well.. I tried but everyone thinks differently. | ||
| John MC9 Rating: N/A |
It's unfortunate, but there are a ton of things that only can be done to an engine while it's running. Is there's a way to properly set the idle speed, or governor, with the engine off? The issue is safety, and we can't make any work duty safer by simply telling people to avoid doing the work duty. But advising an individual to block and chock, not wear loose clothing, wear safety glasses, have someone within hearing range, having a cell phone handy, etc., etc., is 100% better. As safe as most of us try to be, accidents happen. |