| Author | Message | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 574 Registered: 10-2006 Posted From: 66.82.9.62 Rating: N/A |
Looking at the price of diesel vs the price of gasoline , I wonder if folks will begin to repower with gas engines. 1/10 the engine cost . lots less maint , far cheaper fuel, and no out of service complex procedures, NAPA everywhere with cheap parts! Since most sleek coaches will get 9mpg and the big bricks get 6 the actual power needed to cruise (figure 18hp/hr for diesel, 12hp/hr for todays gassers) it is within the cont' output for even a modern 350. 70mph/9mpg=7.7gph x 18 = 140 hp 70mph/6mpg=11,6gphx18=210hp Sure it wont become a swop for 200,000 OTR trucks or line haul coaches , but 10,000 mile a year Bus RV's might save big . Biggest problem I can see is hull climbing at speed , which might need another 100hp for the heavy feet folks , and the inability for modern E-gas to age over a month or so. ???? | ||
| Dan West (Utahclaimjumper)
Registered Member Username: Utahclaimjumper Post Number: 132 Registered: 1-2005 Posted From: 208.66.38.115 Rating: N/A |
The old 440 Dodges use to do well and then the 454 Chev. does a good job, now we have the 501 or 2 that pulls very well. But all in all I dont think we will be having cheap gas for long, the states are allready crying about no income so in the name of inviroment (of coarse)they will raise the gas taxes.>>>Dan (Utah in particular, the road builders have the politicos in there pockets) | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 306 Registered: 8-2004 Posted From: 69.143.52.250 Rating: N/A |
We've been a "totally" diesel household for 7 years (2 VW TDI's and one bus). I've watched all the price things. I'm pretty sure that a number of things are going to reduce the cost difference between diesel and gasoline in the near future. Europe is going to a lower sulphur reg that US fuel can't meet (meaning that US fuel won't be exported to Europe), most existing refineries are being converted to higher diesel-per-barrel-of-crude ratios, new refineries in Asia are being built for very high diesel ratios, and foreign diesel subsidies are under strain in the financial environment. Add to that that the crude "bubble" on speculation ended just as the home heating oil market began (and this year a lot of people left their tanks empty after last winter because of high oil prices) and diesel prices are artificially higher. I'd hate to see somebody spend $$$$ on a reengine in December and see diesel prices go below gasoline in April! | ||
| Wec4104 (Wec4104)
Registered Member Username: Wec4104 Post Number: 10 Registered: 7-2008 Posted From: 68.46.66.57 Rating: |
Just to pick some numbers to play with, let's assume a diesel coach that gets 8 mpg today is converted to a gas coach that ends up getting 6 mpg. As we have seen this year, fuel prices go up and down, but let's just use $2.00 for gas and $3.00 for diesel. Using the 10K/year RV style driving.. Diesel: 10,000 / 8 = 1250 gallons 1250 @ $3.00 = $3750 annual fuel cost Gas: 10,000 / 6 = 1667 gallons 1667 @ $2.00 = $3333 annual fuel cost So the net fuel savings is only $417/year, and on it's own merits, isn't worth the swap. The primary justification would have to come from the cost of the engine itself. It could only make sense if the repower was necessitated by a blown engine (not simply converting a working diesel coach to gas). To offset the lower cost of the gas engine, you would have to figure in the labor and parts to modify all the rest of the stuff to make a workable coach (transmission mating and drive ratios, cooling, alternator,etc.). There are a handful of guys on this board that could pull it all off, but the ones that are that resourceful probably wouldn't want to give up their diesels to downgrade to gas. | ||
| John Lacey (Junkman42)
Registered Member Username: Junkman42 Post Number: 60 Registered: 3-2007 Posted From: 66.82.162.21 Rating: |
Just curious, which automotive engine can produce the torque of even a tired 8v71? And then do so for 500,000 miles! I don't think so! I am ready FF, just blast away. John | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 36 Registered: 11-2008 Posted From: 74.13.197.18  Rating: N/A |
Finally! Something I know enough about to actually contribute. I had two big motorhomes, one 33' and one 36' and both had gasoline ('petrol' to you hinterlanders). One ran a 440, the other ran a 454. Both had the propane option too. Both sucked. The 440 did about 7 mpg and the 454 (on the 33 footer) did about 8 mpg. The 440 died at 36,000 miles and the 454 made just over 50,000 miles. Neither one could top a Colorado pass - maybe my old bus can't either, but it's way cooler and (except for that 80 lb. beast of a clutch) much more fun to drive. Personally, I'd never go back to gas in a heavy rig. The engines just can't handle that much load. Hey, it's why I got a bus! Nellie Wilson | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1405 Registered: 12-2000 Posted From: 76.68.123.169 Rating: N/A |
John, you've missed the point. What busnut needs an engine for 500 000 miles? The academic/economic theorizing is the point here, not to hurl disparaging comments. Need versus want versus cold hard total cost of ownership, before we die and the heirs sell it off as scrap metal... Have a little plausible fun with this, eh? happy coaching! buswarrior | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 167 Registered: 1-2007 Posted From: 208.81.157.90 Rating: N/A |
I have a gas bus. 1968 GMC Carpenter 35' college bus. Big ole GMC 478 cubic inch (I think) V6 T-drive. Weights a bit over 20K. 5 speed standard tranny, air brakes, spring suspension. It does OK pulling hills but it is no race car. On a good day it gets 5.5 MPG. On a bad day it gets 5.5 MPG. If we planned to keep it there would be a diesel in it's future. While it might do better with a more modern gas mill, if I was keeping it a modern 4 stroke diesel like a Cummins 5.9 would probably come close to doubling the MPG. As a side note, son replaced a 6.2 diesel in a little light short box PU with a stock fuel injected 454 and now gets 12-14 MPG instead of 20+ with the diesel. Of course when you have it you tend to use it and I notice him going through more tires these days.  Don 4107 | ||
| Keith Wood (Ft6)
Registered Member Username: Ft6 Post Number: 59 Registered: 8-2008 Posted From: 174.144.41.148 Rating: |
I think it's more than numbers. I have a car with a 350HP engine. I used to have a semi with a 365HP engine, and the engine alone weighs about what the whole car does. I wouldn't try to move 20,000 lbs with the car, though the truck and load routinely weighed close to the 80,000 lb limit. It's not just horsepower -- you don't use most of your horsepower most of the time. It's a matter of engine strength. That Diesel will move full loads, day in and day out, with minimal maintenance. The gas engine just won't do that for very long without finding ways to express its displeasure. | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1244 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
To get a gas engine that will run with most of the diesel versions, you are probably looking at more like 4 to 5 mile to the gallon unless it is computer controlled.Don't forget it will require a medium duty automatic trans or manual Roadranger or similar. Before you are done, all those savings are going to start to evaporate. Figure up those savings now. If you want a big gas job, you could detune a Chevrolet 672ci. | ||
| ED Hackenbruch (Shadowman)
Registered Member Username: Shadowman Post Number: 77 Registered: 11-2003 Posted From: 174.145.152.150 Rating: N/A |
Before i came across our bus i looked at a lot of ads for motorhomes that were gas powered. One of the things that i noticed was that a lot of them stated that they had a new rebuilt motor. They also only had anywhere from 30 to 70 thousand miles total on the rv.....got me to wondering why a gas engine did not last longer in rvs. How many gas engines do you see moving 80-120 thousand lbs of weight down the road? Now look at all of the semis hauling their loads day in and day out. At times gas is cheaper than diesel and at other times diesel is cheaper than gas........i am going to stay with my detroit. :>) | ||
| JamesB (56gmbusman)
Registered Member Username: 56gmbusman Post Number: 4 Registered: 8-2008 Posted From: 96.39.174.3 Rating: N/A |
a cool and realistic setup would be to utilize a Natural gas Cummins motor and convert it to Petrol. The low compression and spark plugs are there. Plus the heavy duty components that you will not find in any gas motor(except a Hall Scott) | ||
| John Lacey (Junkman42)
Registered Member Username: Junkman42 Post Number: 61 Registered: 3-2007 Posted From: 69.19.14.34 Rating: |
Buswarrior, I thought I got the point! The torque rise of a diesel engine under load is the biggest thing that makes a diesel the engine of choice for heavy work. As a collector of farm tractors I can tell You that a large two cylinder gas engine that is built for heavy loads is a fuel hog. Thought I was being constructive, no disparging thoughts intended. John | ||
| Jim Shepherd (Rv_safetyman)
Registered Member Username: Rv_safetyman Post Number: 272 Registered: 1-2004 Posted From: 67.142.130.21 Rating: |
Several years ago a drag racer (Darrell Gwynn) who was paralyzed in a racing accident, became a team owner. In part, he was sponsored by a MAJOR motorhome manufacturer. They built him a special handicapped motorhome. He would travel to some, but not all of the races in this rig. It was gas powered (can't remember which) and had an automatic transmission. He had several transmission failures and at least one engine failure. To be fair, the rig would pull a fairly large trailer. Towards the end, they carried a spare engine and transmission in the race support trailer. Obviously this was not public information, but I did some technical work with them and saw, firsthand, the engine and transmission in the trailer. Someone talked about HP. If you compare some 350 HP gas engine with a 350 truck diesel engine you will see that the torque is 3-4 times higher with the diesel (less with a two stroke). Torque is what gets you up the hill. I had my share of gas engines in large RVs and even at low mileage, there is no way that I would go back to a gas engine (and the generally terrible automatic transmission attached to them). Jim | ||
| Len Silva (Lsilva)
Registered Member Username: Lsilva Post Number: 184 Registered: 12-2000 Posted From: 71.99.25.84  Rating: N/A |
I've been a firm believer in diesels both for economy and longevity. I drive an old Dodge/Cummins with 400k plus and it still runs strong. However, I have been thinking about replacing my wife's car with a Jetta diesel and now I think Fred may have a point. If diesel is $1.00 more than gas and the car costs a $1000 more for the diesel engine, it might not pay off. I've got to do some more number crunching here but it's not a slam dunk. | ||
| David Dulmage (Daved)
Registered Member Username: Daved Post Number: 225 Registered: 12-2003 Posted From: 192.139.198.194 Rating: N/A |
One of the problems with RVs is the high under hood temperatures that occur with the typical configurations. However, I have had two gas powered RVs and both achieved over 80,000 miles by the time I sold them without any major problems. The last one was a 30' Winnebago with a 454 on a Chevy P-30 chassis. It was fast and a good hill climber, but gross weight was only about 16,000 lbs. I think the major problem with early engine failure also relates to a lack of understanding and inadequate preventative maintenance on the part of the owners (my personal opinion). I've had excellent experience with Dodge 488 cid v-10 gas engines. These provide about the same torque as a 6.2 litre Cummins diesel, but again gross combined vehicle weights have typically been 18,000 lbs or less. And nothing sounds quite the same as a Detroit Diesel. FWIW DaveD | ||
| Wec4104 (Wec4104)
Registered Member Username: Wec4104 Post Number: 11 Registered: 7-2008 Posted From: 68.46.66.57 Rating: N/A |
Len, as you probably already know, VW stopped making the Jetta TDI for a couple of years and is bringing out the redesigned model for '09. The latest issue of Car & Driver (Jan 09) has a one page write-up on it. It states; "...the feds are offering a $1300 income-tax-credit for Jetta TDI buyers in recognition of the diesel's advanced lean-burn technology." For the record, 1968cc turboed, intercooled 16V inline 4. 140 bhp, 236 lb-ft, 0-60 mph in 8.1, EPA city/highway of 29/40 mpg. | ||
| David Lower (Dave_l)
Registered Member Username: Dave_l Post Number: 100 Registered: 11-2007 Posted From: 67.58.201.10  Rating: N/A |
Western Flyer had large 6 cylinder gas engines in their bus's, but they used lots of gas I guess 60 years ago that did not mater. I think you have to ask your self is the cost of fuel realy that big a deal considering what you have invested in your coach. As far as useing a gas engine I dont think it would live long in a coach as heavy as mine. Just my 2 cents worth Dave L | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 576 Registered: 10-2006 Posted From: 66.82.9.57 Rating: N/A |
So far folks seem to be using old to ancient gas engines as a comparison to truck engines. The NEW gassers are computer assembled and with lots of upgrades (castings , metal selection and treatment. Weight might be the killer , our ancient 30ft Wanderlodge had a Ford Truck 390 (391?) that had a rebuild by a good enough shop that it was blueprinted and came with a build sheet. (Previous owner was a NASCAR guy moving up). Moves that 25,000 or so lbs just fine with an Allison and was in the 7 -8 mpg range. Today one would hope for 20% better . And remember a new truck engine if transplanted would have the polution stuff , which kills mileage by about 15% . Guess gas would be fine for any RV that could still climb hills with under 300hp. FF | ||
| Keith Wood (Ft6)
Registered Member Username: Ft6 Post Number: 61 Registered: 8-2008 Posted From: 68.26.32.251 Rating: N/A |
Fred, you have a point about "ancient" thinking, and this will delay acceptance of gas engines, even if they are up to the job, simply because all of the transportation companies are heavily invested in diesel fuel contracts, spare parts, etc. I think that hybrid diesel-electrics will be the logical next step, though. | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 594 Registered: 8-2006 Posted From: 74.33.35.55 Rating: N/A |
From what I have been reading 25% of the class 8 trucks will be LNG or CNG in the next 5 years,they are popular in CA now but what isn't good luck | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 168 Registered: 1-2007 Posted From: 208.81.157.90 Rating: N/A |
Another thing that hurts gasoline engine mileage these days is mandated gasohol with it's reduction in gas mileage. Not to mention how crappy engines run on it. Bah humbug! | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1246 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
Fred, since you brought this up, why don't you yank out that Detroit from your "sports car", put in a gas engine and show us how great it is going to be. Report back. Remember that the new diesels are also computer controlled and have had their mileage improved also. How many want to walk up to a 4104,4106, MCI, Eagle, etc., and listen to that great gas engine sound? Might as well buy an S&S. How about a gasoline leak in that rear compartment? | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 642 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
CNG popular in a class 8 truck? CNG=Compressed Natural Gas LNG=Liquefied Natural Gas As there is ABOUT 1100 BTU per cubic foot of natural gas, (methane) it will take almost 90 cubic feet of CNG to equal the BTUs available in a gallon of propane, and about 120 cubic feet to equal the BTU content of a gallon of diesel. Now you have to compress it and store it in a high pressure (2000 psi) cylinder. Heavy, and you don't get a lot of capacity in them. A local gas utility company put two essentially 5 foot tall oxygen cylinders in the beds of a dozen 1/2 ton pickups, and was able to get about 90 miles out of them between refills. The MTA refills a lot of their transits twice a day. NG must be refrigerated and kept well below Zero F, and kept under at least 2000 psi in order to liquify, so it isn't practical in a vehicle either. Methane won't ignite under combustion pressure, so the engine used is a diesel with the injection system removed, a "carburetor" added, and a spark plug in the injector hole. Don't know about mileage, because it has to be expressed in cubic feet per mile. G | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 577 Registered: 10-2006 Posted From: 66.82.9.99 Rating: N/A |
"Fred, since you brought this up, why don't you yank out that Detroit from your "sports car", put in a gas engine and show us how great it is going to be. Report back." Sorry , am in the midst of collecting parts to do a 50 swop into a flex. This is a bus nut MENTAL EXERCISE , although for diesel boat owners , that seldom do 100 hours a year it might pay . AS noted the biggest hassle in a bus camper might be the minute 1/2 life of E gas . FF | ||
| Len Silva (Lsilva)
Registered Member Username: Lsilva Post Number: 186 Registered: 12-2000 Posted From: 71.99.25.84 Rating: N/A |
Not too long ago, I drove the biggest U-Haul truck (26' I think), a GMC with a gas engine and auto. Have to say it had plenty of power and the fuel economy was not bad (don't remember the numbers but it was much better than I expected) (Message edited by lsilva on December 05, 2008) | ||
| Tom Christman (Tchristman)
Registered Member Username: Tchristman Post Number: 44 Registered: 1-2006 Posted From: 66.218.33.156 Rating: N/A |
The biggest gasoline engine I knew of was the Hall Scott 1000 cu in with 300hp. It was used in semi's and fire engines. They got 1-3 mpg weather they liked it or not. My first semi truck I drove was an international with a 478 cu in V-8. If I drove 50mph, I could squeeze 4mpg out of it. Diesels will always be the engine choice for big vehicles. While the fuel is more expensive, the efficiency of Diesels is second to none, and the longevity can't be beat (new engines having a B50 life of 1.2 million miles). When I was driving truck, my 400hp Caterpillar 3406B would burn maybe 2 quarts of oil between 12,000 mile oil changes. Always amazed me how an 893 cu in engine working so hard could just be lazing along. Good Luck, TomC | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 700 Registered: 7-2006 Posted From: 70.157.211.161  Rating: N/A |
My '79 MC9 (now gone), got a whopping 6 mpg, uphill, downhill, 10 mph or 80 mph. Both of our old rvs: a 33' winnie, and a 37' Georgie-Boy (both with GMC 454s), never got better than a whopping of 6mpg...... regardless. And they were very much lighter. My 1 ton 2002 Ford E350 7.3 powerstroke diesel is getting 15+ mpg in town (and with an after-market chip, should go to 20+ and greater, over-the-road). Any comparable gas engine would net around 8 mpg, regardless. In any vehicle as heavy as a bus, I wouldn't consider anything but a diesel engine. | ||
| Moe Hollow (Moehollow)
Registered Member Username: Moehollow Post Number: 84 Registered: 12-2007 Posted From: 71.102.20.26 Rating: N/A |
There are a lot of schoolies that run on gas. I would guess the schools maintain them well and get good use out of them. They, however, may represent the current max weight for efficient use of gas engines. It might be a go for something like my 5a or FF's 4106 if kept lean. There was a long article I remember reading that compared gas and diesel for motorhome use. Actually, I think that I got it from an FF post about 6 years ago. Gas did have a lot going for it, but I think the comparison did stick to standard motorhome weights and not buses. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 648 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Along the same lines as John's truck, I have a 75 W-200 Dodge (3/4Ton 4by) that had a 440 with 4.10 ratios for the first 20 years and 130,000 miles. I put a used utility bed on it off of an 82 Chevy, and welded up a ladder rack. On gas, and flat land, it would pass everything but a gas station. 8 mpg was absolute tops, as it is heavy. It got my second 5.9 Cummins conversion, the first being an '84 Ramcharger. I should have done it BEFORE the gasser quit! The conversion took a new tranny case, as the diesel torque converter is much bigger, and a brass governor weight to make it shift sooner, all the rest of the old 727 parts are the same. It went 56 mph to the differential shop with the 4.10s, and 68 mph back with 3.56s. I found out the hard way that you can only change a Dana 60 one ratio, the Ramcharger had a Mopar diff in the back, and it and the Dana 44 in the front were both agreeable to about anything. So, next for the truck was a used Gear Vendors' P30 Overdrive. Top speed is now about 85 at 2500 rpm. Mileage DOUBLED, mountain climbing performance improved greatly, it idles better, and doesn't stall when its cold any more either! That was 9 years ago, the used engine I bought turned out to be very well-used, 150,000 miles later, it got another engine, and this time I saw the wrecked donor truck, and its odometer! Gas price would have to go less than half the cost of diesel just to make the operating cost EQUAL, and I wouldn't change back then, because of the loss of performance. George | ||
| Gary Cole (Gecole)
Registered Member Username: Gecole Post Number: 1 Registered: 4-2008 Posted From: 216.99.210.120 Rating: N/A |
I think Fast Fred is on to something. When I was just a kid in the late 60's I drove a 1948 LJ Mack with a 707 cubic inch gas Mack engine hauling steel out of Houston,Tx. The old truck must have had close to a million miles on it when I started driving it. The original owner said it had been virtually trouble free its entire life having been majored one time and re-ringed another. It used a little oil at that time, maybe a quart every 800 miles, but it had a lot of miles on the last overhaul when I started driving it. The transmission had never had the top pulled. It averaged 4 mile per gallon every time I filled it. That was grossing 80,000 lbs one way and coming back empty pulling a float. It was geared at 64 mph and bumped the governor pretty much the whole time both ways. That truck was not slow. Today I'll bet someone could find a still in good condition engine and transmission like that for maybe what ever it took to haul it off. I'm pretty sure one of those old engines would still outlast the average bus body. But for a few spark plugs a lot of us could buy enough fuel to bus for free for the rest of our lives with the money we would save on a free engine and and an indestructible Mack duplex transmission. Engine sounded real good at 2100 rpm. Someone said Mack manufactured that engine into the late 70's for export use for primarily the firetruck market. Parts probably wouldn't be a problem. (Message edited by gecole on December 10, 2008) (Message edited by gecole on December 10, 2008) | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 656 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Hmmm, "A 1948 Mack with a million miles on it... and an engine manufactured for export into the late 70's, so parts shouldn't be a problem?" Well, by my math, that design is SIXTY YEARS OLD, (when gas was fifteen cents a gallon) and has been out of production for at least 30 years, right? IMNSHO, the chance of finding a rebuildable core sitting somewhere for the last 20 years, and the availability of factory replacement parts for an over 30 year old obsolete engine are very slim and none. There might just be a reason that Detroit, Cat and Cummins only make diesels. I know, there's also DT466 binders, and Isuzus too. G | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 594 Registered: 10-2006 Posted From: 69.19.14.42 Rating: N/A |
"There might just be a reason that Detroit, Cat and Cummins only make diesels. I know, there's also DT466 binders, and Isuzus too," Well for decades Diesel WAS cheaper than gas , and the service life on diesel (if maintained) is far longer, BUT for a MH that cranks 5000 or 10,000 miles a year the lower fuel and maint costs could add up to savings over the first 20 years? In the smaller sizes on boats the longevity of diesels is disapearing , as the converters (Yannmar and others) marinize high speed car (BMW) diesel engines. 3500rpm Cruise! FF | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 660 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
I'm having some trouble figuring out why Gary says "I think Fast Fred is onto something." At a station yesterday, regular was $1.67, diesel was $2.37. If Gary drove his 1948 Mack gas engine truck 1000 miles at 4 MPG, he would burn 250 gallons of gas. If the truck had a diesel, WHICH ONLY GOT 2 MPG BETTER, it would burn 167 gallons of diesel in the same 1000 miles. 250 gallons times $1.67 equals $417.50. 167 gallons times $2.37 equals $395.79. Its already been posted in this thread that a gas engine with the same horsepower as a diesel will only produce half the torque. Gas engine power and torque curves are published everywhere, and most gas engines will produce their maximum HP at 3600-4000 rpm. Obviously you won't get much out of a gasser at 1800-2100. So, anybody got a bunch of 5.95 pusher gears laying around that will fit in our diff housings??? Next, anybody have heating problems with their bus? Put in a gasser and reduce the mileage from 6 to 4 MPG, or in other words, INCREASE THE AMOUNT OF FUEL BURNED BY 33% in the same distance, and see what your temp is! I won't even go into the fact that a diesel runs cooler than a gasser because the gas engine has a throttle valve, and doesn't flow as much air thru it, so it doesn't dissipate as much heat out the exhaust... Next: The belt, miter-box, and hydraulic motor driven radiator and condenser fans that we all have, were designed to be driven by a 2100 RPM engine. WE DOUBLE THE RPM ON A SET OF 40 YEAR OLD BLADES? How many of them are going to fly apart? I'm afraid the answer would be several, but thats speculation on my part, and isn't as important as the next question. I'm pretty sure that doubling the speed of a fan more than doubles its horsepower requirement? I know, it would pull almost twice as much air thru the rad(s), so maybe it wouldn't cause a heating problem if it didn't throw off blades. Different size pulleys are available for those of us with belt driven fans, but what about the whole bunch of us with miter boxes? Straight out of Allison's HT740 specs: "Input speed range.....1900 - 2400 rpm." I haven't seen 4 auxiliary drives on the back of a V8 gasser either! Fred did say this was a mental exercise, but my attempt at turning some of my fat head into muscle has resulted in a headache... G (Message edited by George Mc6 on December 12, 2008) |
