Ideas to increase F350 MPG (DIY Cyl Deact?)

[Frank Lee]

A supercharger on a 460 isn't going to help economy.

[kerryp]

[QUOTE=Poodwaddle;520523]My understanding is that a supercharger allows a manufacturer to use a smaller engine (squeeze adequate HP from smaller engine) and thus improve MPG.

Another option is to make the gearing taller.

The cost/benefit is not even close. Superchargers are NOT cheap, plus swapping differentials....

[RCB]

Originally Posted by oil pan 4

A supercharger is not going to increase fuel economy on a gasoline engine.

Man, not to be a naysayer, but yes it does in most cases. It's been well documented. They've been used extensively in the RV aftermarket for years for just that reason. Have a 100ft lbs more off idle has proven results. Essentially you are artificially increasing compression.

Just like building an engine, selecting a supercharger is all about what you want. Roots style blowers are perfect for trucks and usually add fuel efficiency. Again, not dramatic, but at 7mpg, a bump of 2 would be huge.

The downside is you'd really need to run premium.

As far as the cost/benefit... if you are buying used, and install it yourself your return on invest might be relatively short depending on miles per year. If you wanted to buy new, have it installed and drive it 1000 miles per year, yeah it'd be a horrible investment.

[rmay635703]

Originally Posted by RCB

Man, not to be a naysayer, but yes it does in most cases. It's been well documented. They've been used extensively in the RV aftermarket for years for just that reason. Have a 100ft lbs more off idle has proven results. Essentially you are artificially increasing compression.

Just like building an engine, selecting a supercharger is all about what you want. Roots style blowers are perfect for trucks and usually add fuel efficiency. Again, not dramatic, but at 7mpg, a bump of 2 would be huge

For his circumstance this sounds like bad advice.

If he had a 2 liter engine and was already turbo'd with a load maybe, but that isn't the circumstance

[RCB]

Don't believe me, like I said it's pretty well documented for RVs and towing trucks. While the improvement isn't staggering, you're still talking about over a 10% increase in fuel efficiency. You loose some at none moving idle, but under motion you instantly pick up over 20% energy efficiency (or better) and then start thinning out your gains at the high end as fuel demands increase.

I think all of this is moot however as he hasn't been back on in a month.

[ChillyBear]

Yeah it's moot. But 460's are so torque focused, that anything over 3,500rpm is kinda irrelevant.

I still think an ecu from an egr equipped model (and the egr system) would be a nice way to improve cruising mpg. A lot of fords before 1997ish had lean-on-cruise or "mpg" which work very well with tons of egr flow and a 17:1+ AFR. Very dirty, but smooth and efficient. Plus, ford's with kidney shaped heads always seem to not lose mpg with load. That's why crown vic's get good mpg for some reason, or why 460 owners claim to not lose mpg with a trailer, or why old escorts get 28 mpg at 90 mph.

Not to mention that ford had a habit of making their cars (up to 1997) run "inappropriately lean" while accelerating faster than 3.3mph/sec or going over 58 mph

I don't even know what I'm ranting for..... Oh yeah, old Ford's rule!

[mwilliamshs]

Originally Posted by ChillyBear

Yeah it's moot. But 460's are so torque focused, that anything over 3,500rpm is kinda irrelevant.

I still think an ecu from an egr equipped model (and the egr system) would be a nice way to improve cruising mpg. A lot of fords before 1997ish had lean-on-cruise or "mpg" which work very well with tons of egr flow and a 17:1+ AFR. Very dirty, but smooth and efficient. Plus, ford's with kidney shaped heads always seem to not lose mpg with load. That's why crown vic's get good mpg for some reason, or why 460 owners claim to not lose mpg with a trailer, or why old escorts get 28 mpg at 90 mph.

Not to mention that ford had a habit of making their cars (up to 1997) run "inappropriately lean" while accelerating faster than 3.3mph/sec or going over 58 mph

I don't even know what I'm ranting for..... Oh yeah, old Ford's rule!

Can you support these claims? I'm an old ford fan myself.

[ChillyBear]

Unfortunately, they are mostly old pdf's that do no belong to me. Google works like escort enleanment EPA reprimanded or inappropriate enleanment. You will find some hits. The real trouble started around 91-93, when ethyl and the EPA were going back and forth over the additive DDT, and boy did the escort's do some suspicious stuff when independent researchers were taking sniffer tests! All fords for that matter.

Here's some
:http://www2.epa.gov/sites/production...rdmotor-cd.pdf

There's a lot on this subject, but like I said, most are pdf's, but are all on google.
Enleanment is the best keyword.

I experimented with egr mods, and changing my can timing etc, all on a stock ecu. Had lost of interesting results not really worth piecing together. Mostly got either exceptional or terrible mpg. And check engine lights.

The best conclusion I had, was that my 1.9 escort is A-ok with 10+% ethanol. I actually set my mpg record with a bone stock escort (no power steering+44psi tires) and I ran approximately 18-22% ethanol. Blended 87 octane with 10% ethanol+e85. Hardly any side effects, made it faster too. Sorry for being so vague, it was a year ago when I was spending hours a day, and my conclusion was to recommend a custom ecu.

[cosmick]

I have a 91 F350 dually with the 460, and even with the optional 4.10:1 axle, mph loaded is not the same as empty. It has an MSD 6A ignition that made no measurable improvement, a cam which did, and the 460 has never h ad any heads that didnt have excessive cross sectional area in the intake ports near the intake manifold. Experimenting with epoxy is about the best hope for getting a 460 to rival a peanut- port 454.
Mine has the E4OD, and has seen 14 MPG empty. One spike to 15, never repeated, yet. I bet the 3.55:1 gears would help, not sure lowering would prove worthwhile, but since mine has the early Sterling 10.25 axle rather than the Dana 80, a 3.08:1 gear is a real possibility.
There is a 3.23 for the D80, but the 3.31 is far cheaper.
If you have a non-dually, a D71 from a late 80s 2wd Cummins offers a 3.07 gear, you would have to swap the entire axle assembly, but it is stronger than the 3.08:1 10.25" Sterling.

[cosmick]

Oh, and a turbo would be a good move if i go to 3.55s, but not if i go to 3.08s, and it has nothing to do with gear strength.