2.3 ECO, MPG with Lift/Tires

[The Pope]

Ok.... I don't care which engine Ford puts in it as long as I can accelerate (after already on the assent) up any of Interstate Roads as they wind their way through the mountains with a trailer in tow that's loaded to the Max GVW & Tow Rate (hopefully 5k lbs.).

Yea, yea, yea,,,, geared properly even the smallest engine could do this... but my 77 F250 w/460, C6(3 speed transmission), 3:07 gears with 30" tires, 7700GVW can do it.

Torque.....
If I've got to spin the engine to ove 6000 RPM to get it, it's not going to be the engine that "I" want.

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[Stampede.Offroad]

...Torque.....
If I've got to spin the engine to ove 6000 RPM to get it, it's not going to be the engine that "I" want.

That's one of the things that has held me back from the Wrangler. Most people consider the 3.6 to be happy revving really high to get things done, but that sounds wrong to me. We'll see if the 3.0L V6 diesel strikes a better balance soon.

It will be interesting to see how Ford tunes the engines that make it into the Bronco. No doubt there will be a couple Ecoboosts, but all the ones I've driven have felt jumpy/snappy in power delivery -- lack of torque at 'low' RPM isn't a problem, but smooth delivery is That might be fun unladen on a nice flat street surface while the driver is pretending they're a race car driver, but it isn't appealing on technical terrain, or slippery road surfaces.

 

[Jalisurr]

That's one of the things that has held me back from the Wrangler. Most people consider the 3.6 to be happy revving really high to get things done, but that sounds wrong to me. We'll see if the 3.0L V6 diesel strikes a better balance soon.

It will be interesting to see how Ford tunes the engines that make it into the Bronco. No doubt there will be a couple Ecoboosts, but all the ones I've driven have felt jumpy/snappy in power delivery -- lack of torque at 'low' RPM isn't a problem, but smooth delivery is That might be fun unladen on a nice flat street surface while the driver is pretending they're a race car driver, but it isn't appealing on technical terrain, or slippery road surfaces.

Out of curiosity, have you driven one with it in 'snow/slippery' mode and still had the same issue? I haven't driven any modern fords so I'm curious how much of a difference the driving mode makes in this respect.

 

[OX1]

BSFC is anecdotal in this discussion. There countless other factors that come into play to determine real world platform performance vs another. I'm my personal experience and commercial fleet the larger displacements are all averaging better MPG. Logged and validated over 100's of thousands of miles.

Ford agrees, hence the new 7.3 NA, when they can get that power and torque from a 3.5.

And we haven't even touched on octane yet. Ford doesn't de-rate torque for most ECO's anymore
with 87, but there is no free lunch. The ECO's use higher engine speeds and higher boost to get the
same torque on 87, then add in the smaller engine that needs even more of both of these or
switching up to a higher octane to maintain power, so what is the real overall MP$, not just MPG.

"Figure 41 shows the ignition timing for both fuels for the UDDS, the Highway and the US06 cycles. At higher absolute engine loads the spark timing for the 93 AKI fuel is more advanced enabling the engine to operate closer to the maximum brake torque combustion conditions. For the lower octane fuel the spark ignition timing is retarded at these higher loads to prevent engine knocking from occurring. The vertical axis in these figures is absolute engine load as reported by the powertrain controller that is different than mechanical torque output from the engine. Overall the lower octane fuel resulted in higher engine speeds and higher boost levels to compensate for the lower mechanical torque."

See page 56............

https://www.nhtsa.gov/sites/nhtsa.dot.gov/files/documents/812520.pdf

 

[Jalisurr]

Look as gas-powered economy cars. They generally use very small 4 cylinders with the bare minimum power necessary to provide "adequate" performance. That is because a smaller, less powerful engine will always be operating with a more fully open throttle, thus providing better BSFC.

You obviously have a lot of knowledge in this so I appreciate the info here. I was under the impression (as I think many of us were) that the little 4 cyl economy cars tended to only get significantly better mileage in the city, where they are spending a lot of time coasting or idling in traffic and not needing as much power.

Obviously this is anecdotal as you say, but my partner has a Toyota MR2, and I have a Corvette Z06 with the 7.0L LS7. Her car gets far FAR better fuel economy around town, but on the open highway travelling the same 80ish mph speed (and we've done highway trips together a few times), my corvette gets better gas mileage, I've seen up to 27-28mpg on legs with minimal elevation change. That to me supports that larger engines can be at least as efficient as the small ones under more load (with the extra benefit to me made up by the presumably better aero of the vette).

 

[Jalisurr]

A gasoline engine hits peak BSFC with the throttle wide open. When the throttle is only partially open, the engine is working against a vacuum which reduces efficiency. That is why you get better fuel economy in higher gears despite needing more throttle to maintain speed.

This has me super curious because it didn't jive with what I understood about engine efficiency. So I actually managed to dig up a BSFC chart for the 2.7L ecoboost - source: https://www.epa.gov/vehicle-and-fuel-emissions-testing/combining-data-complete-engine-alpha-maps

As we can see, the peak efficiency looks like it happens at only about 50% of peak torque (far from WOT), and between 1600 and 4200 rpm. If the 2.3 has a similar map, anything where the 2.7 can be operating in its happy place but the 2.3 is up higher where it's less efficient, the 2.7 will get better fuel economy.

 

[Jalisurr]

The difference here is that the Ecoboost is turbo charged (no vacuum losses at higher engine loads, as the intake is well above atmospheric pressure), and at higher loads they probably have a highly enrichened fuel mixture biased for power rater than efficiency and to stave off detonation at higher cylinder pressures.

I suppose I should have qualified my statement with mentioning that it applies only to NA engines. Still, I appreciate some data being posted; now if you could just find a similar chart for the 2.3L.

EPA doesn't have one for the 2.3 unfortunately. They do have the 1.6 ecoboost as another data point for a 4cyl turbo Ford engine, it shows a similar shape, and the peak BSFC is actually better on the 2.7 than here:

 

[Jalisurr]

The difference here is that the Ecoboost is turbo charged (no vacuum losses at higher engine loads, as the intake is well above atmospheric pressure), and at higher loads they probably have a highly enrichened fuel mixture biased for power rater than efficiency and to stave off detonation at higher cylinder pressures.

I suppose I should have qualified my statement with mentioning that it applies only to NA engines. Still, I appreciate some data being posted; now if you could just find a similar chart for the 2.3L.

I also pulled this one out, which is the 4.3L chevy engine, a N/A V6. It shows a similar shape to the turbo ones, even with cylinder deactivation disabled, with peak efficiency a fair ways away from peak torque. Why is that?

 

[Stampede.Offroad]

Out of curiosity, have you driven one with it in 'snow/slippery' mode and still had the same issue? I haven't driven any modern fords so I'm curious how much of a difference the driving mode makes in this respect.

No, but there are a couple fleet vehicles I'll probably tinker with in the near future now that the roads are all iced over.

 

[BroncoBuyer]

There must have been an issue with the 4.0L for a discrepancy that large, or the driving conditions were not as equal as you believe them to be.

We chalked it up to big ass heavy suv underpowered with 6 cyl versus HO V8.
Heavy ass suv took more pedal to create the same acceleration and therefore used more fuel to create the same performance.

 

[BroncoBuyer]

Fuel economy is not the reason Ford is putting the 7.3L in its 80+LB. GVWR trucks, durability is.

Im willing to bet the 7.3 big block is more efficient and gets better mpg than the 6.8 ever did. As a matter of fact, my 8.1 liter big block in my 3/4 ton gmc gets better mileage than the 6.8 ford as I’ve had both. The V10 F250 wanted to rev to produce torque, the 8.1 vortec likes to hang real low in the rpm range for optimal torque and therefore both require totally different throttle applications.

now that I think about it, it might even come down to how a particular engine encourages a person to drive it..

 

[jamanrr]

Im willing to bet the 7.3 big block is more efficient and gets better mpg than the 6.8 ever did. As a matter of fact, my 8.1 liter big block in my 3/4 ton gmc gets better mileage than the 6.8 ford as I’ve had both. The V10 F250 wanted to rev to produce torque, the 8.1 vortec likes to hang real low in the rpm range for optimal torque and therefore both require totally different throttle applications.

now that I think about it, it might even come down to how a particular engine encourages a person to drive it..

My old 6.2 liter when I would stay in it's normal range would return 14 mpg, the big super duties with big blocks probably don't rate mpg as I believe certain size trucks are exempt. I know a few people with the v10s and they get like 8 mpgs if that. The large diesels are the ones that can return the best mpgs then the smaller 3 liter diesels tend to get the best especially with the ram and f150.

 

[OX1]

Fuel economy is not the reason Ford is putting the 7.3L in its 8,500+LB. GVWR trucks, durability is. Why do you think the gas engines are de-rated in 3/4 + ton applications compared to the 1/2 tons, and diesels are de-rated in medium duty applications?

Probably more durable over the 6.8 or 6.2 maybe, but I'm comparing MP$ to Fords current top ECO that puts out comparable HP/torque.
It will be way more economical, especially counting in fuel grade, vs the top tier 3.5 ECO's.

Ford could have maybe gone to a 4.4 ECO (or even a 5.0 with lower boost), unless we are now saying the ECO's are not as durable
as the larger NA engines. which is exactly the opposite many on this board have been stating for a long time now . Not me, in the very
harsh environments I would want to run a new bronco in (on 87 or worse octane), but I was taking all of "yous" word for it.

 

[OX1]

You are full of it with the 8.1L vs. 6.8L. I have operated both, and they have very similar power delivery and fuel mileage. Power depends a bit on year, but the best years for pickup applications, the 6.8L was rated at 362 HP @ 4,750 RPM & 457 lb-ft @ 3,250 RPM while the 8.1L was rated 340 HP @ 4,200 RPM & 455 lb-ft @ 3,200 RPM. The both have broad torque curves and peak at almost the exact same point, the V10 just carries the power a bit further than the 8.1L. The 2012+ medium duty 6.8L were rated at 460 lb-ft @ 3,000RPM for what its worth.

8.1 has 50 ft-lb advantage @ 1000 RPM, so as you like to say, similar power delivery is your perception only.
Significant if you want to keep RPM's in the lower range, under higher load for better mileage.

 

[OX1]

You have power curves for the 8.1L and the 6.8L starting at or below 1,000RPM? I would be interested in seeing those if you wouldn't mind sharing. Is that comparison with a 2 valve 6.8L or 3 valve? My statements were made in regards to the 3 valve version.

Frankly, I wouldn't be that surprised by a 50FtLb advantage at 1,000RPM given the nearly 100 ci advantage the Chevy engine has, but 1,000RPM isn't really part of the operating range on the street. The 4L85 won't hold 1,000RPM and neither will the 4R100 or 5R110 in the Ford.



The Ecoboost engines are certainly built stout, but the high cylinder pressures necessary to get that kind of power in such small displacemnts takes its toll on bearings. You probably wouldn't necessarily have a catastrophic failure using an Ecoboost in a heavier duty application, but the engince would certainly wear out more quickly than a larger displacement naturally aspirated engine of similar output. Many of the people on here just lap up the marketing hype.

There is a reason Ford came out with the 7.3L for 3/4+ton trucks instead of putting a 3.5L Ecoboost or turbo 5.0L in them.

This is the same reason class 8 trucks run much larger engines even though you can build a 5.9L ISB with more horsepower and torque than the engines most of these trucks are running. Bigger is better in terms of durability.

Work computer restarted, links are gone, but wasn't that hard to find. It was factory type ratings, gross output. 8.1 was 400 ft-lbs, 6.8 was 350. Each started @ 1000, not below, but if you start @ 6-700, and get 50 ft-lbs more by 1000, chances are off idle is also much stronger.

Not all high load applications are steady state highway, plenty of stop and go with big trailers locally, which means you run though that idle to 2000 RPM over and over, allowing less overall RPM and many times better mileage due to that (because of better low end torque without needing very rich A/F).

I'm not arguing durability was not one of the factors, but equally important is being able to run 14.5ish:1 @ 70 % load, virtually forever on 87 octane, even with 10.5:1 compression (this is my guess, not something I found published, but is not far off in stock ford NA tunes I've messed with, like the stock coyote tune).

EDIT, found one of them..................

http://www.duramaxhub.com/gas/gm-8.1-vortec-l18.html

And uncorked just a bit for marine was this. Still 400 ft-lbs @ 1000 (maybe 390).
I specially ordered this in a 24' boat in 2001. Not a perf hull, but pulls up skiers with
even 10 people on board. Crazy torque....... (also helps I have a $2600 twin pitch prop
that switches from either 17 or 23).

http://aerostarmarine.aerostaraircraft.com/ppp.html

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