Hey group, I have a question. I have a 1988 E350 bus that has an old and tired 460 EFI engine in it. It is killing me in gas, getting about 6MPG. The GVW is rated at 11,000lbs, with actual weight in its current configuration at 9470lbs with the driver in it. The bus no longer carries the 21 passengers that it was designed to carry. I was wondering if I have any options when replacing the motor. Should I stay with another 460CI motor, which, apparently, hardly ever gets more than about 12mpg, or can I downsize the big block to a 429 or even move to small block for better fuel economy? I use this bus to travel and teach science to students, and I fund the program myself on my retirement income, so "money is not an problem" solutions will not work. Any ideas?

Thanks

 

I'm sorry to say I don't think there's much you can do.
You're driving a barn around.

Destroking the 460 won't change mileage and might hurt torque.
Besides, there are no externally balanced 429 cranks...

351m/400's are smaller still and should bolt to the tranny, but were also never offered as a fuel injected engine. (lots to swap in order to get them to run) and depending where you are registered might prove difficult/impossible to drive legally.

Your best option from a mpg perspective would be to trade it in for a diesel.

 

Trading it in for a diesel is not really an option either. I have a ton of time and money in this body converting it for the purpose of outreach, so trading to another vehicle will involve thousands of dollars and alot of time to build again what I already have in this bus. You can see a bit more of what I have done at astronomyoutreach dot org and what this bus looks like and the work already done.
Are there any mods that can be done to get better fuel mileage out of a 460 EFI engine, or is 12mpg the best I can possibly get?

 

There is no magic bullet.
Given the weight, aerodynamics, final gearing and transmission losses of your chosen vehicle I'd think you're doing pretty darn good at 12.
(heck, I'm happy to see 12 highway in my pickup, and I have overdrive, half the aerodynamic drag and only weigh around 6500)

A smaller engine would be working harder and mileage would be the same but it would wear out quicker because it would be WFO all the time.

With a Banks exhaust (expensive) and a better torque converter you might see some gains.
Driving it at it's torque peak would help. Have you considered installing a vacuum gauge?

 

I don't get 12MPG now. I get 6MPG now. I have heard that 12 is the most I can expect from that size motor. I have talked to a custom motor rebuilder about it, and they said they could rebuild my motor for my uses and for max mileage, but I want to make sure I don't have any other options before I go through the hassle of pulling that motor. I would hate to find out I had other options after I put another 460 in it.

 

I get 6 sometimes too.

I am saying that I think 12MPG would be VERY good for the vehicle you have.
But the engine needs to be healthy and you need to drive it conservatively.
Forum member Mark Kovalsky used to work for Ford in their drivetrain division and could help you with a TC better suited to your needs.
Perhaps you ought to PM him for his advice. ?

A better exhaust would help you optimize engine performance.

Here are some links to C6 mileage threads;
https://www.ford-trucks.com/forums/1...e-and-mpg.html
https://www.ford-trucks.com/forums/7...converter.html
C6 Torque Converter Slippage and MPG - 460 Ford Forum

Edit to add; You could use an E40D transmission with a stand alone shift controller like a Baumann. But that's a LOT of expense that could buy you many, many gallons of gas before it paid off the difference in highway mileage the overdrive could gain. (and it wouldn't gain anything around town if it couldn't get into overdrive)

 

It's not a matter of what mileage the engine gets, but what the Bus is capable of getting. Huge weight, horrible aerodynamics, I suspect maybe 8-9 MPG is much as you could expect to ever get.

Any engine of that era that would bolt up to your transmission will not really get you any better mileage.

 

That would make sense, but this bus is more aerodynamic than most, and I know of other similar sized, less aerodynamic buses with diesel engines getting 16MPG, so it can't be all aerodynamics. More recent V10's are getting 12 to 14 MPG, and that is carrying passengers. I am sure aerodynamics play a part in it, but I would imagine that the 460 was selected to be able to propel the bus down the road safely with 21 passengers on it, which is a load of 3150 pounds (avg.) which it does not now have to carry. Also, since I took out all of the metal and seats, the bus weighs 1500lbs less than it did before empty. Now that the bus is almost 2.5 tons less weight in actual weight and load rated weight, is the 460 really necessary? Of course, switching it to another motor would be a pain as far as the EFI and computer goes.

 

The 460 Was chosen not because it was adequate, but because it was the biggest gas motor Ford had available at the time. You have a 9500 pound bus with a 225HP Engine. That's marginal at best. Any smaller engine around that era would have less power and significantly less torque.

An overdrive transmission would probably get you close to 9-11 MPG.

The Diesel bus can get 16 MPG simply because it's a Diesel. They are far more efficient. The V10s are a much more modern engine, and 12-13 MPG sounds reasonable out of one.

 

I'm with the above posters on this - you can definitely upgrade the motor (plenty of info on that out there, sky's the limit as to how much $ you want to put into a motor), but you're going to be doing incredibly well if you can break into double-digit mileage, if at all. And consider this - going from 6 mpg to 9 mpg is a 50% increase in fuel economy (not saying that it is possible, but that is a HUGE difference that is not easy to do in most cases).

The only real option to significantly increase the fuel economy is to put a diesel engine in - there is a reason why they are used in trucks and busses!

It's pretty darn hard to break the laws of physics . . .

 

rv cam, overdrive trans, look into your rear end gear ratio, will all be ways of improving.........

Or you can buy one of those tornado things for the air cleaner. lol....