'03 3.0 2WD exhaust, improving efficiency while maintaining reasonable noise.

[pentode]

Look into 5R44 torque converter clutch solenoid and coast clutch solenoid In case you’re having issues with either.

I don’t want to state the obvious but torque converters are designed to impart the maximum torque in one (forward) direction so they’re extremely inefficient in the other direction.

I would say with this particular transmission if you’re feeling engine braking it’s because the converter is locked up but I’m waiting for someone to tell me I’m wrong because I’m here to learn.

 

[franklin2]

If I wasn't looking for a project I'd agree with you completely, but this is the research stage.

At highway speeds this truck is actually running within it's power band since I'm in 4.10 gearing. By turning off overdrive I can keep the engine turning in its sweet spot of 2750-3250 RPM this range and above has the leanest section in the fuel curve with stock tunes, and it can breathe freely. Aside from gains in general combustion efficiency, the only improvement would be from on throttle coasting downhill/uphill sections where I need to balance throttle input with speed. The less resistance in the engine from backpressure means less throttle/air/gas on those downhill sections.

Likewise when moving uphill less speed being scrubbed from engine resistance at the same throttle position means I can coast in throttle up hill longer, both super important for long distance fuel economy.

Since I don't typically need engine, or exhaust braking in my use case it's a fair trade off and I think I'll see some efficiency gains by decreasing backpressure just enough.

Is it relatively flat where you live? I would get rid of the 4.10 gears and go with the lowest numbered gear they offered. I do not think you need max efficiency from the engine which would be the most power output for the amount of fuel going in. Thing is, that is way more power than you need at cruising speed.

When researching an electric vehicle, of course it will vary a little bit, but it's generally known that a vehicle needs around 10 hp to maintain 55mph. So you want your truck to barely need any throttle to maintain speed. I have never had one, but have heard the 3.0 does have some use able torque down low.

I am sure you have driven many modern vehicles from the factory. You can tell all the OEM's do it now. When in drive they have engine, whatever engine it is, barely loping along. Any sort of maneuvers by the operator require the transmission to downshift. Thus why they went to the 5, 6, 8, and 10 speed transmissions. They are not doing it because they want to or the car buyers wants the mpg, the government is making them do it.

 

[don4331]

I’m familiar with exhaust braking - Jake brakes etc. I’ve just never heard of issues with exhaust restrictions in a street car causing excessive engine braking barring extreme damage.

Exhaust brakes aka Jake brakes work on diesels because there isn't any restriction on the intake. Therefore after few revs, there is sufficient air to build pressure for the engine to fight against which slows it down.

Exhaust brakes don't work on gas engines (at least not very well) because when the throttle is closed, there isn't any significant amount of air flowing to build pressure to work against.

Unfortunately, <15 psi vaccum with a gas engine doesn't work near as good as >100psi pressure which a diesel may build in slowing you down.

The Rangers have a lock up torque convertor so they get good fuel economy. If they didn't, the slow engine rpms in OD would result in the torque convertor 'slipping'. On other hand, Ford did set the lock up to disengage when you release the throttle (so, engine could rev a little when you resumed acceleration and and accelerate smartly).

 

[franklin2]

On other hand, Ford did set the lock up to disengage when you release the throttle (so, engine could rev a little when you resumed acceleration and and accelerate smartly).

Doesn't that help with coasting also? One of the main differences between tow haul and normal it seems in the larger trucks.

 

[bhgl]

Look into 5R44 torque converter clutch solenoid and coast clutch solenoid In case you’re having issues with either.

I don’t want to state the obvious but torque converters are designed to impart the maximum torque in one (forward) direction so they’re extremely inefficient in the other direction.

I would say with this particular transmission if you’re feeling engine braking it’s because the converter is locked up but I’m waiting for someone to tell me I’m wrong because I’m here to learn.

I'll definitely look into it since you mentioned it, regardless I still think I'd see some fuel economy benefit from a free-er flowing exhaust.

The other part of the equation is that a lot of the coasting is done in gear and on throttle specifically for ascents and descents, where I'm trying to make the most out of gravity assistance, or trying to get as much power from the engine to the ground at a given throttle input

 

[bhgl]

Is it relatively flat where you live? I would get rid of the 4.10 gears and go with the lowest numbered gear they offered. I do not think you need max efficiency from the engine which would be the most power output for the amount of fuel going in. Thing is, that is way more power than you need at cruising speed.

When researching an electric vehicle, of course it will vary a little bit, but it's generally known that a vehicle needs around 10 hp to maintain 55mph. So you want your truck to barely need any throttle to maintain speed. I have never had one, but have heard the 3.0 does have some use able torque down low.

I am sure you have driven many modern vehicles from the factory. You can tell all the OEM's do it now. When in drive they have engine, whatever engine it is, barely loping along. Any sort of maneuvers by the operator require the transmission to downshift. Thus why they went to the 5, 6, 8, and 10 speed transmissions. They are not doing it because they want to or the car buyers wants the mpg, the government is making them do it.

So on the main build thread, as well as a different post this has been discussed and with the help of the forum we came to some interesting conclusions about engine RPM, and axle ratios on this truck in particular.

I do in fact live in a hilly place, but the main reason I'm not prioritizing installing a lower gear axle is one, cost and time, and two:

This engine is overall built to be inefficient but stupid reliable from Ford, with very low compression and tuned to run super rich particularly at the low end. It's fuel curve finally starts to lean out around 2750, where the truck is in its power band. At first I assumed, as is typically the case that lower RPM = less fuel, and that is somewhat still the case here.

After some fuel economy runs where I kept the engine as low RPM possible over a 400 KM journey, and on then drove the truck with O/D turned off at lower speeds, and driving faster to keep the truck in the "sweet spot" of 2750-3300 RPM, out of the two runs, the faster, higher RPM run yielded better fuel economy results by a noticeable margin.

I could most likely see some benefit by dropping in a tune, or at most 3.73 gears but to go with a lower ratio some more work needs to be done, and a tune needs to be applied. Then I could be in that situation of trying to basically keep my truck at just above idle in final drive for a slower but efficient highway cruising speed, as I used to with my other vehicles.

On the extra speed gears, I will say as someone who hyper miles having extra gearing even though it's typically just more ratios in between what would otherwise be the same 1st and final drive, is actually pretty useful for fuel economy in mixed driving, or carry a load.

I know we all hate CVTs, but genuinely the quick drive I took in a new Prius Prime with it's hybrid and CVT transmission made me really appreciate them as the engine was always in the most efficient place for the task, whether that was coasting or accelerating.

 

[bhgl]

Exhaust brakes aka Jake brakes work on diesels because there isn't any restriction on the intake. Therefore after few revs, there is sufficient air to build pressure for the engine to fight against which slows it down.

Exhaust brakes don't work on gas engines (at least not very well) because when the throttle is closed, there isn't any significant amount of air flowing to build pressure to work against.

Unfortunately, <15 psi vaccum with a gas engine doesn't work near as good as >100psi pressure which a diesel may build in slowing you down.

The Rangers have a lock up torque convertor so they get good fuel economy. If they didn't, the slow engine rpms in OD would result in the torque convertor 'slipping'. On other hand, Ford did set the lock up to disengage when you release the throttle (so, engine could rev a little when you resumed acceleration and and accelerate smartly).

Absolutely, there's a reason why proper exhaust brakes aren't found on standard vehicles, even gas powered trucks. Diesel's do better on engine braking thanks to their higher compression ratios too, this truck is barely squishing air at a 9:1 ratio isn't moving the same volumes out the back as a 3.0 diesel would.

Regardless, backpressure and vacuum still are a factor in petrol powered vehicles and can affect efficiency if they're out of spec, or not tuned for the use case.

In my case, I do a lot of "on-throttle coasting" which isn't really coasting, but effectively I'm holding a limited throttle range on ascents and descents to gain or hold speed. In those the convertor is fully locked as throttle is being applied, but gravity is tipping the scales one way or the other in terms of the speed of the vehicle.

If I can give the engine less resistance from backpressure at the same fuel/air volumes, it should in theory slow down less on uphills, and gain more speed on downhills at the same throttle input. At least I think anyways.

I'm talking marginal increases to efficiency here, but so far marginal increases have totaled up to a 20%+ increase of EPA estimate, and still a 15%+ increase over the truck in its original form, so marginal gains do add up.

 

[bhgl]

Doesn't that help with coasting also? One of the main differences between tow haul and normal it seems in the larger trucks.

It most certainly does, I think the more modern full size vehicles have electronic locking torque convertors.

In my use case, if I'm looking to purely coast I'll typically put the truck in neutral for that period of speed reduction, or downhills if they're long enough, which is above and beyond more efficient than leaving it in gear regardless of the torque convertor.

 

[pentode]

I've never heard of anyone hypermiling a Ranger before - you've set yourself quite a challenge
Seriously though, given how bad the mileage is on the 3.0 I have tried various things over the years to see if I could coax a bit more fuel efficiency out of mine and I've only found 2 things that made a noticeable difference: driving with a really light foot and leaving it parked in the driveway.
You said it yourself, it's a durable engine but not built for efficiency. After I did all the basics and didn't see much improvement (2-3mpg), I reached the conclusion that there weren't any meaningful mods I could do that wouldn't pay for a fair amount of gasoline. At the cost of a custom exhaust with new cats etc, I would think you'd have to cover a lot of ground to save enough on fuel to pay for it.
Having said all that, I'm still very interested to see what you learn. I'm certain there are many people on here who would love to see a breakdown of how to get that 20% extra fuel economy. I certainly would!

 

[pentode]

It most certainly does, I think the more modern full size vehicles have electronic locking torque convertors.

I know I'm going into full pedantic mode here, but I think it's right to say that your 5R44E is fully electronic, computer controlled, across the board, torque converter and everything else.
I'm only mentioning this as it sounds like you're thinking about all the details and in this case I would guess transmission operation is going to be a (big) factor.

 

[Blmpkn]

The cost/benefit ratio is probably in the dumper IMO but.. going to a true dual exhaust with an H-pipe would certainly improve flow as well as give you a bump in torque which would/should increase fuel efficiency.

 

[pentode]

The cost/benefit ratio is probably in the dumper IMO but.. going to a true dual exhaust with an H-pipe would certainly improve flow as well as give you a bump in torque which would/should increase fuel efficiency.

I know that's 100% true- my wallet just isn't thick enough to try that experiment.
If I ever say anything that sounds discouraging, it comes from my cheapness. Just say "I'm rich" and that'll shut me up.

edit: frankly I'd love to see the dyno testing on that. Maybe jump from 150hp to 155? 160? I'm not being facetious... I'd genuinely be curious.

 

[franklin2]

The cost/benefit ratio is probably in the dumper IMO but.. going to a true dual exhaust with an H-pipe would certainly improve flow as well as give you a bump in torque which would/should increase fuel efficiency.

I am thinking if was simple as a dual exhaust system to get a few more mpg and horsepower, Ford would have done it already. Anything to show up GM and their little trucks.

 

[pentode]

I am thinking if was simple as a dual exhaust system to get a few more mpg and horsepower, Ford would have done it already. Anything to show up GM and their little trucks.

I'm certain Ford calculates everything down to the penny and I'm not sure in the 2000s they would have spent an extra fifty bucks per truck to gain 2mpg. Not saying you're wrong, I'm saying they're cheap (like me). I just don't think this engine moves enough air to worry about. As the OP said, it's actually a pretty good sized exhaust for a 3 liter 150hp engine.

 

[bhgl]

I'm certain Ford calculates everything down to the penny and I'm not sure in the 2000s they would have spent an extra fifty bucks per truck to gain 2mpg. Not saying you're wrong, I'm saying they're cheap (like me). I just don't think this engine moves enough air to worry about. As the OP said, it's actually a pretty good sized exhaust for a 3 liter 150hp engine.

When these trucks were built, the price of gas, and efficiency in general wasn't the biggest concern so the cost to build each truck and profit from was a bigger concern.

For example, I installed an electric fan to replace my truck's stock clutch fan. This fan and shroud came directly from a 2.3L Ranger, that basically only ran when the truck's AC was on. By installing on my 3L with only basic modification necessary, and by installing a temperature sensor and relay (because the stock 4 litre and 3 litre rangers didn't have any of them) I saw my biggest boost in fuel economy.

So why didn't Ford just do this from the beginning? Probably just cost, the MPG didn't matter as much and the extra wiring, relays, sensors, higher amp alternators, plus the electric fan itself wasn't worth the benefit of slightly better fuel economy.

Ford sold this 3L engine at the same time it sold a 4 Litre that had nearly the same fuel economy, but significantly more power up until 2008/9, why? Because it was cheap to build and sell.