Upgrades for milage

[chris mc bride]

Not my big thing but got to wondering what can be done to get better mileage. Gas cost little more than did in 1969.Something like 10 to 12 times. Plus seems like could be fun thread.

Already installing 4 spd auto with od. Lower truck with small air damn should help with drag. Some sheet metal work under hood behind grille reducing or redirecting air might help .Plus look cool. Lot freer flowing exhaust should help except when making it heard. Someone else's right foot be good too. When can get EFI good boost I am told. Electric fan and better pulley ratios.


So anyone have good suggestions. While tearing it down to bare bones might as well do something to gain more than power and cool points.

[weq92f]

.

I've put a lot of thought into this over the years as I've driven a bunch more than the average...spent a lot of time behind the wheel contemplating a large variety of things including this topic. Lots of folk believe that setting the cruise (old trucks usually don't have this but...keep going) to a reasonable speed and sticking to it will save fuel. While that may be true where the travel path is flat, it's more than likely going to cost fuel over time. Some systems are better than others but my experience tells me that it is very inefficient.

Example (extreme):
Cruise set to 65 approach an incline/hill vehicle slows so cruise increases throttle and continues to do so in a chase to get back to 65. Vehicle reaches crest of incline/hill at 69 to 72 MPH and pulls throttle 100% off in another chase to get back to 65. Vehicle coasts down opposite side of incline/hill while throttle is still cut (and brake applied if equipped BMW) until speed goes below 65 at which point the vehicle is climbing the next incline/hill and quickly falls way below 65 before throttle increases enough to smoothly maintain speed and so downshift in a hurry to get back to 65...

This oscillation, the speed up => slow down cycle is a mileage killer. I've ridden with people who couldn't keep their foot steady on the pedal at all. They constantly speed up and then slow down, then speed up again and slow down all in small increments...I can feel it but it's subtle. Again this kills mileage.

If I want to drive for mileage, which is what I'm suggesting with this post to you, I do the exact opposite of the above. No cruise, just me thinking what I'm doing with the throttle, looking ahead and planning my moves for efficiency. Sometimes this means by the time I reach the crest of the hill, I'm going 10 to 15 MPH slower than my target speed. By the time I coast all the way to the bottom of the other side I'm going maybe 15MPH faster than my target speed ready to carry that into the next incline or milk it on a flat as far as possible.

This is preservation of momentum and is something you can start doing today, free of charge. However, be aware that others following you are not likely to understand your motive and think you're an idiot.

Hey, vehicle manufacturers, write some intelligent code into your cruise control systems and program it for fuel efficiency, incorporating the concept of preservation of momentum and allow the user to adjust sensitivity as follows:

turtle (allows large speed variations around target speed: best MPG)
normal (normal: optimized for comfort: avg MPG)
hare (strict adherence to target speed: just stay on target: MPG don't matter)

-Kevin

[72c20customcamper]

I get 15-16 mpg with my 68 . 250 sm465 and a 4.11 rear thought it was a 4.57 till I opened it up . Caveat I have to drive under 50 . Really not important to me to get a few extra out of my 72 it’s consistently around 13 mpg 350/tb350 4.11 . My 85 with 350/700r4 and 3.23 gears nets me a whopping 2 mpg better than the 72 . While it would be nice but the cost to do so far out ways the benefit .

But fuel injection overdrive and a real tall rear will most likely give the most gain.

[LS short box]

The trouble with the 68-72 C10's they have the aero of a brick. No way to change that.
As said an OD trans and gears will help. FI versus carb? If your carb is well tuned to your engine combo I can't see changing to FI. And that's coming from a died in the wool LS guy.
My 68 C10 with a LS6/T56 combo and 4.10 gears would knock down about 19-20 mpg at 60 mph. Around town 15-16 mpg? I didn't really care because I only drove it about 3000? miles a year. The LS6 tune was spot on.

[Rust_never_sleeps]

6cyl with a manual box+OD and a Rochester Dualjet would be a pretty good start

[jabborabbo]

Keep in mind that in 1967 regular cost $0.33/gallon…cumulative inflation raises that price to $3.19/gallon in 2025…. Jus’ sayin’….

[MARKDTN]

EFI and OD transmission is a great way to increase mileage, however the payback is very long. If you need an engine and/or transmission already, that can defray some of that cost.

I would think lowering and an air dam might help, but you soon will look like an import tuner car if you are not careful.

Can't speak to any actual testing for regular automotive (but I thought Mythbusters looked at this?), but I can tell you in an 18wheeler cruise is a huge way to improve mileage so much so that some big fleets will only allow you to say 60 mph with the pedal but will allow you to bump up to 70 in cruise.

[Mike80D]

Take the back roads, keep your foot out of it, and enjoy the view
That's all the tricks I can come up with.

[weq92f]

Originally Posted by MARKDTN

EFI and OD transmission is a great way to increase mileage, however the payback is very long. If you need an engine and/or transmission already, that can defray some of that cost.

I would think lowering and an air dam might help, but you soon will look like an import tuner car if you are not careful.

Can't speak to any actual testing for regular automotive (but I thought Mythbusters looked at this?), but I can tell you in an 18wheeler cruise is a huge way to improve mileage so much so that some big fleets will only allow you to say 60 mph with the pedal but will allow you to bump up to 70 in cruise.

.

I understand, based on some article I read about a trucker not liking cruise, the industry promotes the use of cruise control because it's designed for efficiency and safety. The author spoke of how frustrating using cruise is because of its tendency to back off automatically under certain circumstances and stay backed off for extended periods. Then the ramp up is also very slow to respond. A scenario painted was cruising along, someone passes and when they come back over into the right lane after pass, the cruise is triggered and backs off way too much and for too long.

-Kevin

[Steeveedee]

Driving behind a semi will reduce wind drag. I remember something about MythBusters getting mileage data, but don't recall the details. I personally would hesitate to do it, given the amount off trash that gets picked up and tossed out behind those trucks.

[weq92f]

Originally Posted by Steeveedee

Driving behind a semi will reduce wind drag. I remember something about MythBusters getting mileage data, but don't recall the details. I personally would hesitate to do it, given the amount off trash that gets picked up and tossed out behind those trucks.

.

When I was a youngster driving my '68 stepper, I regularly did this. I can say for certain that many truck drivers do not like it. Had one slowly start going off the road to the right slightly and I of course stayed behind him until he ran over a big piece of road debris intentionally so that I would hit it. It missed me or I missed it but whatever.

Also burned up a powerglide while doing this one day. Who knows whether that tranny was getting ready to start slipping already or the fluid got way too hot with so little airflow. After that, I wised up and stopped doing it.

-Kevin

[jumpsoffrock]

I have a stock '56 Ford with I6, 3OTT, and fairly deep 3.92 gears.
60 is 3000rpm, 50 is 2500rpm.

If I cruise 60 on a long hwy roadtrip I get 15-16 maybe.
I have gotten 20-21 going steady 50mph.
Huge difference in my opinion.

I think the key is keeping RPM's low as possible.

IMO this is the true power of diesels, I don't think they naturally burn less fuel, or that one drop of diesel produces more energy than one equal drop of gas. I really thing the super power of diesel vehicles is that they can naturally operate at a fairly low RPM. Not rare to find a diesel 1 ton truck that can cruise empty or lightly loaded at 1100rpm at 65mph

That's insane.

[Steeveedee]

Originally Posted by weq92f

.

When I was a youngster driving my '68 stepper, I regularly did this. I can say for certain that many truck drivers do not like it. Had one slowly start going off the road to the right slightly and I of course stayed behind him until he ran over a big piece of road debris intentionally so that I would hit it. It missed me or I missed it but whatever.

Also burned up a powerglide while doing this one day. Who knows whether that tranny was getting ready to start slipping already or the fluid got way too hot with so little airflow. After that, I wised up and stopped doing it.

-Kevin

Not directly behind, but back about 80 feet or so. I forget the magic distance. My sons watched the show, and I did not.

[weq92f]

Originally Posted by Steeveedee

Not directly behind, but back about 80 feet or so. I forget the magic distance. My sons watched the show, and I did not.

.

Found it. Indeed I remember this episode with particular interest in what a big rig blow out could potentially do to a person/motorcycle/car right next to it!

The tailgating for fuel economy starts at 29:26 in the video below. They found the sweet spot at 20 feet where they observed a 27% increase in MPG.

Big Rig myths:
https://youtu.be/VabClSuOi_8?si=RuvL7f-WgBHJVD1f

-Kevin

[Steeveedee]

Originally Posted by weq92f

.

Found it. Indeed I remember this episode with particular interest in what a big rig blow out could potentially do to a person/motorcycle/car right next to it!

The tailgating for fuel economy starts at 29:26 in the video below. They found the sweet spot at 20 feet where they observed a 27% increase in MPG.

Big Rig myths:
https://youtu.be/VabClSuOi_8?si=RuvL7f-WgBHJVD1f

-Kevin

Pretty cool! I watched the whole thing. I don't usually watch this stuff, as for me it's too much hyperbole. But then my work was pretty cut and dried. We designed things with appropriate materials and tech, and delivered them. Your defense dollars were well spent, when I had anything to say about it.

[Accelo]

A lot of good suggestions given.
Over drive is one of the easiest methods to increase mileage.
I still haven't figured out exactly why the OEM's kept such low differential ratios for so long.
30% mileage improvements are not unusual. The modern transmissions have lock up torque converters incorporated into them for another couple percent improvement.

Reducing the tire / wheel weight is an under rated improvement.

It is technically possible for a driver to get better mileage than cruise control. The issue is our attention span, our thoughts wonder and then cruise beats most drivers.

Driving slower is very effective at increasing mileage. Air resistance increases at the square of our speed. Twice as fast 2x2 or four time the air resistance and three times the speed is 3x3 or 9 times the air resistance. The only reason we do not typically notice is the internal combustion engine inefficiency.

raising the engine compression ratio is another efficiency improvement
Good luck om your quest

[Rust_never_sleeps]

If you plan to drive 20' behind a semi trailer, please mount a dash cam and post your encounters with the underrun bar ;-)

[Steeveedee]

Originally Posted by Rust_never_sleeps

If you plan to drive 20' behind a semi trailer, please mount a dash cam and post your encounters with the underrun bar ;-)

Like the sign on the back of lifted trucks-
"If you can't stop, smile as you go under!"

[connorm]

I track the mileage in my 1970 GMC C2500 with a 307 4 speed and 4:10 in a Dana 60. I got 14 mpg once doing 65 for pretty much a full tank of gas. 65 mph is about 2600-2700 rpm and once you get past about 2900 rpm you can just about watch the gas gauge move. From what I have seen lower rpms does raise gas mileage as long as you are not lugging around the engine. Driving around town I prefer to have too high of rpm compared to too little.

As far as improvements, I have really thrown around the idea of an overdrive in my truck. Something like an a883 overdrive from a squarebody seems like a nice upgrade while still keeping the character of an old truck. To me the feeling of driving an old truck is most important, and trying to make it practical for everyday use is a side affect.

[MS66]

Originally Posted by Mike80D

Take the back roads, keep your foot out of it, and enjoy the view
That's all the tricks I can come up with.

That's a good one, it's my system to a Tee! Two lane blacktop, scenic backroads, 35-55mph. Grinning, enjoying the truck and never in a hurry. Truck will consistently get over 20 mpg if you can stay out of stop and go traffic.
Keeping everything properly tuned is top priority for fuel efficiency. ANY extra pedal input kills it. I don't necessarily feather foot my truck, but I also don't play around with the pedal unnecessarily. YMMV

[tim_mc]

Upgrading from a TH350 to a late version 700R4 did the trick for me. Now if I could just keep my foot out of it. It's sometimes tough to resist dropping it into passing gear on the interstate and opening up the headers. Hopefully you'll enjoy your 4 speed and notice an improvement in both mileage and performance. Here's an old thread on a cheap air dam mod, which I think looks good on the lowered '72 shown:
http://67-72chevytrucks.com/vboard/s...d.php?t=423059

[chris mc bride]

Originally Posted by Accelo

A lot of good suggestions given.
Over drive is one of the easiest methods to increase mileage.
I still haven't figured out exactly why the OEM's kept such low differential ratios for so long.
30% mileage improvements are not unusual. The modern transmissions have lock up torque converters incorporated into them for another couple percent improvement.


It is technically possible for a driver to get better mileage than cruise control. The issue is our attention span, our thoughts wonder and then cruise beats most drivers.

Driving slower is very effective at increasing mileage. Air resistance increases at the square of our speed. Twice as fast 2x2 or four time the air resistance and three times the speed is 3x3 or 9 times the air resistance. The only reason we do not typically notice is the internal combustion engine inefficiency.

raising the engine compression ratio is another efficiency improvement
Good luck om your quest

So have od trans going in. Plan is tio raise compression 1.5 i think or 10:1 final, Found some aluminum rally wheels got to be lot lighter. Doing few things to reduce under hood air like reducing gill opening which may or may not help can see both sides there. Air damn under front I know helps. Smaller mirrors while minor is a gain.

As drag racer tuner I know little bits here and there add up to real world gains. When come to weight we rule the world in cutting it. Hell I drill holes in the holes to get the air out.

I agree CC would help most. Me I just find myself laying foot on it and going faster not paying atention since CC is on. Backroads idea is good for those who can do slow for me it means open this thing up and let'er eat. That why need to get better mileage when do behave to help pay for the show my butt stuff. Heck too much money ion exhuast to not let it sing.LOL

[Steeveedee]

^ A long time ago I did the math for when aluminum wheels would pay me back in fuel savings when I had my Corolla. It was something like 200k miles. That calculation did not consider the extra turbulence from the aluminum wheel spokes. A full wheel cover would be better, imo. I ran over a chunk of concrete and trashed one of the stock wheels. I was irritated enough at $50 for a used wheel. An aluminum wheel would have been even more money. Just something to think about.

[ullose272]

find a donor 5.3/4l60e. tune and headers.

[chris mc bride]

Originally Posted by jabborabbo

Keep in mind that in 1967 regular cost $0.33/gallon…cumulative inflation raises that price to $3.19/gallon in 2025…. Jus’ sayin’….

Heck use to 45 per gallon for notro in race car and use 6 gal. per 1.4 miles. Do the math.Can fill tank few times on on 1/5 mile shot. Just fun side line fact.