Making them highway friendly........

[jimburke77502]

You have a bus. Taking any one of the inline 6's,(because let's face it, everyone has their own favorite) coupled to an Allison 545AT (with the future ability to upgrade to a 643), what's the 1st thing you do to make it more "highway" friendly? By that I mean getting better milage, not having the thing screaming like a porn queen in her best film yet, and keeping it with in the comfort zone of RPM's and a speed of no more than 65. I only say 65 because the old 55 is now 65. That and that's the most you want or need to push these things anyway. I'm curious to see what kind of responses I'll get.

[o1marc]

I would start with a quality transmission cooler to try and keep that 545 alive for any period of time. Rear gear and trans swap will be great for fuel improvement and highway travel. I constantly want to and need to travel at over 70mph, absolutely nothing unsafe about it.

[jimburke77502]

By no means am I saying it's unsafe traveling over 65. But let's face it, most of the time you're on vacation. Unless you're the Grizwalds, there's rarely need for it.

[EastCoastCB]

Originally Posted by jimburke77502

You have a bus. Taking any one of the inline 6's,(because let's face it, everyone has their own favorite) coupled to an Allison 545AT (with the future ability to upgrade to a 643), what's the 1st thing you do to make it more "highway" friendly? By that I mean getting better milage, not having the thing screaming like a porn queen in her best film yet, and keeping it with in the comfort zone of RPM's and a speed of no more than 65. I only say 65 because the old 55 is now 65. That and that's the most you want or need to push these things anyway. I'm curious to see what kind of responses I'll get.

Gearing. Buses are almost always geared for stop and go driving. Swap in some highway capable gearing for better mpg's and less rpm's.
As Marc pointed out- a cooler can help.
I've got a 545 with 3.42 in the rear and my bus is great. If/when the 545 goes I'll upgrade.

[PNW_Steve]

To start with.... I would be looking for a bus already equipped with the drivetrane that you want.

I wanted an 8.3 Cummins and a MD-3060. It took me 18 months to successfully buy one at auction.

I paid $3450 for it and it is in great shape.

If I had bought a similar bus with a 5.9 and AT-545 for a bargain. Say $2000. What would I spend swapping engine and transmission? Probably $6k to $15k depending on how well I shopped the parts and how much of the work I was able to do myself.

Well equipped buses are a bargain when you take your time and wait for them.

Good luck.

[Sehnsucht]

I agree with all but personally am in the same camp as PNW_Steve. It's much easier to just buy what powertrain you want straight away than piecemeal it but plan to pay a little more for it. In the end though i think you spend less and save your sanity.

[jimburke77502]

I don't think some are getting the point her. It's the bus with the aforementioned drivetrain that you have. I fully understand waiting for the right one to come along, totally understandable. Let's throw another variable in here. Let's say that you're undecided on whether or not you want to go automatic or stick. Finding a stick bus, you're gonna be waiting a long while. I'm quite sure there's someone here that's retro fitted a stick into a bus. I'm quite sure finding the right donor vehicle for all the right parts is easier. Anyone who's done this care to chime in? What trans did you decide to go with? Any major hurdles that you faced doing the swap? I only ask because it is a viable option. A side note here. The bus was at a price you couldn't pass up. So the changes are more affordable.

[alpine44]

As already suggested, change the gear ratio of the rear axle. Keep in mind that the MT643 does not have OD either. You are just adding a locking torque converter.

The advantage of truck/bus differentials is that ring, pinion, and bearings are mounted and pre-adjusted in what is called the carrier. That's what you unbolt from the axle after pulling out the half-shafts.

Search the local truck salvage yard for a compatible carrier with a numerically lower ratio. You can use the rpm calculators on one of the off-road sites to determine the most suitable ratio.

Once you found the right carrier, check the health of the bearings and the adjustment on the bench and then install it in your axle. Driveshaft should fit without modifications.

That is a cheap and straight forward upgrade to make a bus more highway friendly.

Don't forget the transmission cooler and quality transmission fluid (I had good results with TranSynd) since the longer axle ratio will cause more converter slip in the AT545.

[Booyah45828]

Originally Posted by jimburke77502

You have a bus. Taking any one of the inline 6's,(because let's face it, everyone has their own favorite) coupled to an Allison 545AT (with the future ability to upgrade to a 643), what's the 1st thing you do to make it more "highway" friendly? By that I mean getting better milage, not having the thing screaming like a porn queen in her best film yet, and keeping it with in the comfort zone of RPM's and a speed of no more than 65. I only say 65 because the old 55 is now 65. That and that's the most you want or need to push these things anyway. I'm curious to see what kind of responses I'll get.

First thing I'm doing is checking the tires. If it's an older bus using split rims, I'm upgrading those to one piece wheels and a taller tire in the process. I'm doing that more for safety and commonality of parts, but that upgrade to a taller tire could be considered making it more "highway friendly".

The next upgrade depends on which of the following I can find first.

The first option that I would be interested in doing is swapping rear gear sets. Follow that with the mt643 or at1545 swap and you're in business for a highway cruiser.

However, the option I would prefer to do is to swap the at545 with an md3060 taken out of a wreck or salvage yard. Reason I specify where the md3060 is taken from is because you'll also need the shifter, computers, wiring harness, and other related bits that will get super expensive to source separately.

The md3060 will give you a double OD, so no need to change rear gear sets, but I think I could find the first option easier then the second.

But, at the end of the day, it's easier and cheaper to buy a bus already set up and ready to go for highway speeds. If highway speeds is one of your big issues, fight the urge to spring on the first bus you see and wait for the right one. Search far and wide for it, and don't be afraid to bid more then a normal bus for it. That is something that I cannot stress enough to prospective owners.

[Sleddgracer]

Originally Posted by jimburke77502

I don't think some are getting the point her. It's the bus with the aforementioned drivetrain that you have. I fully understand waiting for the right one to come along, totally understandable. Let's throw another variable in here. Let's say that you're undecided on whether or not you want to go automatic or stick. Finding a stick bus, you're gonna be waiting a long while. I'm quite sure there's someone here that's retro fitted a stick into a bus. I'm quite sure finding the right donor vehicle for all the right parts is easier. Anyone who's done this care to chime in? What trans did you decide to go with? Any major hurdles that you faced doing the swap? I only ask because it is a viable option. A side note here. The bus was at a price you couldn't pass up. So the changes are more affordable.

standard transmissions are quite common behind a number of different motors in Canada - check out kIjIjI, especially the 3 western provinces

[magnakansas]

I'll talk about what I did and why.

bus - rounded butt, no roof air or hatches or decks. Why? Trailing side shape for aerodynamic. I know it is not a lot. I also know that, .5% here, 1% there, adds up and does make a difference.

Future modifications include under tray and air dam up front and belly pan along the body, along with tighter fitting fender liners. Yes quite a bit of work for diminishing returns.

I know that at 65mph, my intended cruise speed, I can reduce turbulent air flow under the bus. I might be able to reduce some of the turbulent air flow on the side of the bus. The front? Not a lot that I am seeing, need to do "yarn testing" to find the messy air flow and see what I can do about cleaning it up.

Rear end gearing--- I am aiming to put the engine at lowest engine rpm on flat level ground, with out bringing the engine to a "lugging" condtion.
3.73 rear gears, 245/70-19.5 tires... calculated engine rpm at 65 mph is 1875 rpm. I am changing from 225/70 19.5 and old rear gears were 4.88

engine -- funny thing here is, with diesels, the fuel you burn is the power. So if you burn 100,000 btu per mile with a 5.9 or burn 100,000 btu per mile with a 8.3, or 100,000 btu per mile with a 10.0..... mileage does not seem to vary a bunch with engine size. I have a smaller engine because it fits the engine bay easier. I started with no engine or transmission in my bus.
I have hopped up my bus engine, more fuel, bigger turbo charger, changes to the engine to take more turbo pressure, The only thing I think would increase mileage though, might be more turbo, and advance injection timing. I have not done testing yet on best fuel economy vs power I want going up hills.

future project... That big honkin cooling fan, Really want to convert that to one of the newer electric clutch jobs. Also in the future is moving power steering to an electric pump power steering, and link to speed, more speed = less pump pressure. Dont need power assist at 65 mph. Want all I can get in a parking lot.

side view cameras and itty bitty mirrors. -- that might change as time goes on. If I have problems with not being able to see well enough, or the police have a problem with my electronic mirrors.

Radial tires in stead of bias ply. -- Also running pressure of tires according to weight they carry, so much less than maximum pressure listed on the side wall. Tread pattern, those blocky treads pump more air, I have what would be called "shitty for the off road" tires. I could well see my self stuck on wet grass on a mild incline. But better highway mileage.

Six speed manual transmission -- mostly because less moving parts, usually mean less to go wrong. but, I like the gear spread and has .73 overdrive. First gear is low enough to get me moving from a stop on a hill. Dual disc clutch to take the extra torque the engine can put out if I am feeding all the fuel it can take.. extreme case around 700ft/lb to 800 ft/lbs estimated.

But with the way automatics are usually built, I think the manual will absorb less power operate.

with out the under tray stuff, fender liners, small mirrors, fan clutch, or electric steering pumps... This kind of bus gets 12 mpg all the time on the road. in town less..... but paying attention and such, when I get more miles on it, I expect to see 14 to 17 mpg at 65 miles an hour...... I think I might be able to get 18 to 19 when I call it "done".

This is a game for me. Something I devote my free time because it is fun for me to see how far I can take it.

1954 ford Wayne body, sitting on 2005 ford 450 chassis, cummins 5.9 12 valve engine, with NV 5600 six speed transmission, 3.73 rear end gears, steel rims, 245/70-R19.5 michelin hiway ribs. Steel wheels. Big job F700 front fenders. The front axle is as wide as the rear axle. The outer dimension of the tires is about 4" wider than the 1954 chassis. expected total weight with hooligans 12,000 lbs

william



Type of transmission and rear end oil .. synthetics ... much thinner viscosity wise = less drag.

[Sleddgracer]

Originally Posted by magnakansas

I'll talk about what I did and why.

bus - rounded butt, no roof air or hatches or decks. Why? Trailing side shape for aerodynamic. I know it is not a lot. I also know that, .5% here, 1% there, adds up and does make a difference.

Future modifications include under tray and air dam up front and belly pan along the body, along with tighter fitting fender liners. Yes quite a bit of work for diminishing returns.

I know that at 65mph, my intended cruise speed, I can reduce turbulent air flow under the bus. I might be able to reduce some of the turbulent air flow on the side of the bus. The front? Not a lot that I am seeing, need to do "yarn testing" to find the messy air flow and see what I can do about cleaning it up.

Rear end gearing--- I am aiming to put the engine at lowest engine rpm on flat level ground, with out bringing the engine to a "lugging" condtion.
3.73 rear gears, 245/70-19.5 tires... calculated engine rpm at 65 mph is 1875 rpm. I am changing from 225/70 19.5 and old rear gears were 4.88

engine -- funny thing here is, with diesels, the fuel you burn is the power. So if you burn 100,000 btu per mile with a 5.9 or burn 100,000 btu per mile with a 8.3, or 100,000 btu per mile with a 10.0..... mileage does not seem to vary a bunch with engine size. I have a smaller engine because it fits the engine bay easier. I started with no engine or transmission in my bus.
I have hopped up my bus engine, more fuel, bigger turbo charger, changes to the engine to take more turbo pressure, The only thing I think would increase mileage though, might be more turbo, and advance injection timing. I have not done testing yet on best fuel economy vs power I want going up hills.

future project... That big honkin cooling fan, Really want to convert that to one of the newer electric clutch jobs. Also in the future is moving power steering to an electric pump power steering, and link to speed, more speed = less pump pressure. Dont need power assist at 65 mph. Want all I can get in a parking lot.

side view cameras and itty bitty mirrors. -- that might change as time goes on. If I have problems with not being able to see well enough, or the police have a problem with my electronic mirrors.

Radial tires in stead of bias ply. -- Also running pressure of tires according to weight they carry, so much less than maximum pressure listed on the side wall. Tread pattern, those blocky treads pump more air, I have what would be called "shitty for the off road" tires. I could well see my self stuck on wet grass on a mild incline. But better highway mileage.

Six speed manual transmission -- mostly because less moving parts, usually mean less to go wrong. but, I like the gear spread and has .73 overdrive. First gear is low enough to get me moving from a stop on a hill. Dual disc clutch to take the extra torque the engine can put out if I am feeding all the fuel it can take.. extreme case around 700ft/lb to 800 ft/lbs estimated.

But with the way automatics are usually built, I think the manual will absorb less power operate.

with out the under tray stuff, fender liners, small mirrors, fan clutch, or electric steering pumps... This kind of bus gets 12 mpg all the time on the road. in town less..... but paying attention and such, when I get more miles on it, I expect to see 14 to 17 mpg at 65 miles an hour...... I think I might be able to get 18 to 19 when I call it "done".

This is a game for me. Something I devote my free time because it is fun for me to see how far I can take it.

1954 ford Wayne body, sitting on 2005 ford 450 chassis, cummins 5.9 12 valve engine, with NV 5600 six speed transmission, 3.73 rear end gears, steel rims, 245/70-R19.5 michelin hiway ribs. Steel wheels. Big job F700 front fenders. The front axle is as wide as the rear axle. The outer dimension of the tires is about 4" wider than the 1954 chassis. expected total weight with hooligans 12,000 lbs

william



Type of transmission and rear end oil .. synthetics ... much thinner viscosity wise = less drag.

do you have pictures of the body changes? - I plan on using some of the same ideas when it comes time

[jimburke77502]

magnakansas, you have some great info there along with some very good ideas for aerodynamic design mods. I'm thinking along the same lines. I'll have my work cut out for me due to a 30+inch increase in height that I'm designing into what ever I build.(trying to keep it as close to 13 feet as I can, knowing that many coach designers are now doing the max of 13'6")Milage..... Well let's just say that i have a 28 foot step van with the cummins 3.9 and a 542 trans. Depending on wind, whether I'm running my usual full load of tools or pushing my max, I get 12-15 per gallon. Aerodynamic it ain't. I personally love the cummins. I contemplated doing the bus buy with no engine and trans and doing an 8.3 mechanical with a 6-10 speed. An m-10,11?? Why?? Because it's the challenge that makes it fun!! The same attitude I'm taking with the conversion design I'm doing.

[Sehnsucht]

Speaking of increasing fuel economy, I remember reading about this kid ...

https://americanprofile.com/articles...-bus-retrofit/

Who basically added a roof bump to the front of the school bus roof to alter the airflow and improve fuel economy. I don't profess to understand all the dynamics of aerodynamics but apparently this works along the same lines as the front bump upper deck on a Boeing 747 in that it actually creates a low pressure zone behind itself to reduce drag for a positive net effect. Might be worth a look and perhaps utilizing the rooftop space inside for a roof air unit without the traditional bozy shape drag effect.

[o1marc]

Originally Posted by Sehnsucht

Speaking of increasing fuel economy, I remember reading about this kid ...

https://americanprofile.com/articles...-bus-retrofit/

Who basically added a roof bump to the front of the school bus roof to alter the airflow and improve fuel economy. I don't profess to understand all the dynamics of aerodynamics but apparently this works along the same lines as the front bump upper deck on a Boeing 747 in that it actually creates a low pressure zone behind itself to reduce drag for a positive net effect. Might be worth a look and perhaps utilizing the rooftop space inside for a roof air unit without the traditional bozy shape drag effect.

$30 for a 20% increase in mileage, where do I buy one? For $30 I wouldn't even attempt to make my own for less. avoiding working with fiberglass is worth $30 to me.

[jimburke77502]

Funny that you mention that. That's exactly what I plan on doing to the bus I build. Only mine will slop back the entire length of the bus. I got the idea from the old style teardrop camper trailers.

[o1marc]

Originally Posted by jimburke77502

Funny that you mention that. That's exactly what I plan on doing to the bus I build. Only mine will slop back the entire length of the bus. I got the idea from the old style teardrop camper trailers.

I'm actually considering it now. I can use a 4 x 8 sheet of plastic supported by plywood spars shaped in the wing pattern, couple of end caps and it's in like Flint. It would be nice to have it on by the end of the month, have a 2000 mile round trip planned and would give me an accurate idea of fuel savings. In the story the 20% turned into 10-20%. I'd be happy to get 10mpg on the freeway.

[magnakansas]

There are many school busses that have that Bump at the front top of the roof. I think there maybe something to do with viscous flow and skin drag happening there... That would be a yarn test thing. One thing that is done is to get the air flow to join back up at the tail end... so you "trip" the air flow in front of the tail end.. so that as it trying to smooth back out, it is past the back end and joins up sooner... what it boils down to ... the dirty turbulent cone at the tail of the bus is shorter. You see some of the big rigs with those flap lookin things at the back of the box? that is to promote smoother air flow and a smaller cone of turbulent air at the rear of the box.. less turbulence = less drag.

Look at the roof line of the mazda 5, the honda insight, prius, dodge magnum station wagon things.... they all have the same thing in common.. the roof line tapers down the farther back it goes.... Most modern cars and vans probably do. It all goes back to getting the air flow to smooth back up behind the vehicle. Some cars have a pan at the rear that curve up, like the rounded end of my bus curves down... the rear lower valence, if shaped well, also helps air to come back together behind the vehicle.

blunt front is not too bad... tapered tails are the thing... look at the shape of beluga whale butt flat front with a tapered tail, sperm whale, big bulky flat front with tapered tail.

The magic angle for low speed aerodynamics is 7 degrees, bend more than that and the mass of the air cannot usually follow. bend seven, go a little bend seven go a little bend seven go a little...... There are ways to help this along , trip strips, turbulators, slats, surface finnish .... the trailing side of a rotating golf ball has less turbulence because of the dimples, surface finnish is the dimples.

From my personal experience with roadgoing automobiles, 35 mph seems to be a transition point of useful air flow management. But I know drag makes a difference at lower speeds. go ride a bicycle in a 15 mph head wind and then turn around and go with a 15 mph tail wind..... pretty big difference after pedaling for a couple of hours....

a flat nose bus vs dog nose bus at 30 to 40 feet is not going to be much different at all, the length helps to mitigate the ugly of the flat nose.

a short bus, 25 feet with flat nose vs dog nose..... you could see measurable differences. I dont know for sure. never checked. I am pretty sure a 1970 chevelle sedan probably has more drag than a 1970 chevlle station wagon. The length helps to change drag coefficient for the better. Flat nose shorties are worse in terms of drag than long ones.

william

[magnakansas]

to get the benefit of slope and space... you may only have to slope part of the rear.... again the deal is to reduce that turbulent ball of air trailing the bus... cardboard, plywood, duct tape. might be enough to allow yarn testing to see air flow and decide how much to do. Then cut metal... or fiberglass or what ever.....

william

[Native]

Originally Posted by o1marc

I'm actually considering it now. I can use a 4 x 8 sheet of plastic supported by plywood spars shaped in the wing pattern, couple of end caps and it's in like Flint. It would be nice to have it on by the end of the month, have a 2000 mile round trip planned and would give me an accurate idea of fuel savings. In the story the 20% turned into 10-20%. I'd be happy to get 10mpg on the freeway.

Let us know how it works out (and pictures, of course).


I have been following the GreenShields project for a few years now. They still do not have a product we can buy. Darn it!