Ecoboost engine question

8iron wrote:
Which is why Ford detuned the Superduty version of the 6.2 for durability. Speaks to duty cycles expected from the f250/350 vs the lighter duty f150.

I hear ya--makes sense. Not that I believe everything I see, read or watch, but if one believes only a fraction of Ford's promotional video for the 3.5 Ecoboost, it's still very impressive. Honestly, I can't imagine how a "super-duty duty-cycle" could surpass that kind of abuse. Again, I'm not saying this video is any more than outstanding marketing, but I'm sure it's one of the major reasons why the 3.5 Ecoboost has been such a kick-ass success for Ford.

Krusty wrote:

otrfun wrote:

goducks10 wrote:

otrfun wrote:

goducks10 wrote:
My guess is that the 3.5 is maxed out with the 11,300lb tow rating in an F150. Add the extra weight of the F250/350 and the 3.5 would have a hard time reaching the 15,000+lb tow rating offered with the 6.2. It works fine in it's own element.

The 3.5 Ecoboost has 15 lbs. more torque than the 6.2, not to mention the 6.2 develops max torque at a relatively high 4500 RPM vs. the 3.5 Ecoboosts's much lower, diesel-like, 2500 rpm. I would think the limiting factor (ref tow capacity) for the 3.5 Ecoboost F150 is the 1/2 ton drivetrain and suspension.

Concerns about the 3.5 Ecoboost duty-cycle and fuel economy aside, I believe the 3.5 Ecoboost's torque characteristics would provide much better realworld performance (to include towing) than a 6.2 in a F250/350 chassis. Torque does all the work. The 3.5 Ecoboost has more and at a much lower RPM than the 6.2.

IMO the 3.5 is maxed out for stress in the F150. Do you really think the 3.5 in a 7-800+lb heavier truck can pull a 15,700lb 5th wheel? Even in the HD F150 it's still 11,300lb max towing. And the HD F150 has payloads equal to the F250 in certain configs. So with your way of thinking the HD F150 3.5 should be able to tow 13,000lbs with the 3.5. Why didn't Ford up the tow rating in the HD F150? Just because it has more torque at lower rpms doesn't mean it's internals are up to heavier towing. Why would Ford waste their engineering money on building a 6.2 for their HD trucks if the 3.5 was up to the task.

In the context of this debate, I think you have to compare these two engines in the context of them using the same chassis and drivetrain. No, the F150 3.5 Ecoboost cannot tow 13,000 lbs. Why? Because the F150's 1/2 ton drivetrain and suspension won't support it, not because of the engine.

Would a 6.2 mounted in an F150 chassis support more tow weight? If you say, yes, than how and why? The 6.2 puts out less torque than the 3.5 Ecoboost. Torque tows trailers, not HP.

The 3.5 Ecoboost engine is designed to put out 420 ft. lb. of torque. The 6.2 is designed to put out 405 ft. lbs. of torque. IMO, torque is torque. Is 1 ft. lb. of higher displacement V8 torque somehow "better" than 1 ft. lb. of turbo-charged, V6 torque? If so, can you explain how and why?

The fact the 3.5 Ecoboost has more torque than the 6.2 is not even the real clincher. The real clincher is the fact the torque on the 3.5 Ecoboost is output at nearly half the RPM's of the 6.2. In the realworld this makes the 3.5 Ecoboost much more useful and desirable from a drivability perspective. This is why diesels are so, so addictive. This is also why the Ecoboost has been such a run-away success for Ford. The 3.5 Ecoboost does one heckuva fine job of emulating a diesel engine's torque curve.

For what its worth, the 6.2L in the F150 puts out 434 ft/lbs of torque

Which is why Ford detuned the Superduty version of the 6.2 for durability. Speaks to duty cycles expected from the f250/350 vs the lighter duty f150.

Krusty wrote:
For what its worth, the 6.2L in the F150 puts out 434 ft/lbs of torque

The 6.2 used in the Ford Super Duty's only produce 405 ft. lbs. of torque.

Nonetheless, it's interesting to note that the F150 3.5 Ecoboost has a slightly higher tow capacity than the F150 6.2 in most configurations.

otrfun wrote:

goducks10 wrote:

otrfun wrote:

goducks10 wrote:
My guess is that the 3.5 is maxed out with the 11,300lb tow rating in an F150. Add the extra weight of the F250/350 and the 3.5 would have a hard time reaching the 15,000+lb tow rating offered with the 6.2. It works fine in it's own element.

The 3.5 Ecoboost has 15 lbs. more torque than the 6.2, not to mention the 6.2 develops max torque at a relatively high 4500 RPM vs. the 3.5 Ecoboosts's much lower, diesel-like, 2500 rpm. I would think the limiting factor (ref tow capacity) for the 3.5 Ecoboost F150 is the 1/2 ton drivetrain and suspension.

Concerns about the 3.5 Ecoboost duty-cycle and fuel economy aside, I believe the 3.5 Ecoboost's torque characteristics would provide much better realworld performance (to include towing) than a 6.2 in a F250/350 chassis. Torque does all the work. The 3.5 Ecoboost has more and at a much lower RPM than the 6.2.

IMO the 3.5 is maxed out for stress in the F150. Do you really think the 3.5 in a 7-800+lb heavier truck can pull a 15,700lb 5th wheel? Even in the HD F150 it's still 11,300lb max towing. And the HD F150 has payloads equal to the F250 in certain configs. So with your way of thinking the HD F150 3.5 should be able to tow 13,000lbs with the 3.5. Why didn't Ford up the tow rating in the HD F150? Just because it has more torque at lower rpms doesn't mean it's internals are up to heavier towing. Why would Ford waste their engineering money on building a 6.2 for their HD trucks if the 3.5 was up to the task.

In the context of this debate, I think you have to compare these two engines in the context of them using the same chassis and drivetrain. No, the F150 3.5 Ecoboost cannot tow 13,000 lbs. Why? Because the F150's 1/2 ton drivetrain and suspension won't support it, not because of the engine.

Would a 6.2 mounted in an F150 chassis support more tow weight? If you say, yes, than how and why? The 6.2 puts out less torque than the 3.5 Ecoboost. Torque tows trailers, not HP.

The 3.5 Ecoboost engine is designed to put out 420 ft. lb. of torque. The 6.2 is designed to put out 405 ft. lbs. of torque. IMO, torque is torque. Is 1 ft. lb. of higher displacement V8 torque somehow "better" than 1 ft. lb. of turbo-charged, V6 torque? If so, can you explain how and why?

The fact the 3.5 Ecoboost has more torque than the 6.2 is not even the real clincher. The real clincher is the fact the torque on the 3.5 Ecoboost is output at nearly half the RPM's of the 6.2. In the realworld this makes the 3.5 Ecoboost much more useful and desirable from a drivability perspective. This is why diesels are so, so addictive. This is also why the Ecoboost has been such a run-away success for Ford. The 3.5 Ecoboost does one heckuva fine job of emulating a diesel engine's torque curve.

For what its worth, the 6.2L in the F150 puts out 434 ft/lbs of torque

Real HD trucks ("18 wheelers") use girly 6-cylinder engines LOL

goducks10 wrote:
It just boils down to the fact that real men drive HD trucks and no real man wants a 6cy motor in his manly truck:)

Hey, I have a 6-cylinder in my HD :P. And I think many RAM/Dodge owners consider themselves real men :B (Unless you're a hard died-in-wool GM or Ford fan LOL).

It just boils down to the fact that real men drive HD trucks and no real man wants a 6cy motor in his manly truck:)

I like to think of the IC engine as a air pump-a 3.5 becomes a 7.0 if you force twice as much air in ,add the calories of gasoline ,burn completely = work at crank.

elemental chemistry

The whole reason for the turbos on the Ecoboost engine are to fool a small displacement engine into thinking it is a large displacement engine. Same for turbo diesels.

The Ecoboost's low speed efficiency comes from its small displacement not its turbos.

You can never defy the laws of nature. Fuel energy is converted to heat. Heat is converted to horsepower. How an engine does this specifies how fuel efficient it will be. At low horsepower demand situations a small displacement engine will be more efficient because fuel is not needed merely to rotate large engine parts. In low horsepower demand situations a large displacement engine loses efficiency because energy is needed just to move it's more, and larger parts.

In high horse power demand situations all of the above no longer applies because both engines are working at capacity. In low horsepower demand situations the small displacement engine will focus a smaller percentage of the fuel burned on actually turning the engine parts. In the high horsepower demand situation a greater percentage of the work the engine is doing goes to the actual work being performed.

There is no free lunch. At the end of the day a certain level of fuel will still be needed to move a heavy brick through the air while its tires are trying to resist rolling. This is constant no matter what is under the hood.

Turtle n Peeps wrote:

Wes Tausend wrote:
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On the other hand, I believe that a turboed engine is slightly more efficient than a NA (normally aspirated) motor for the same hp and/or equivalent displacement. The reasoning is that the end exhaust is slightly cooler on the turbo, meaning it derives more power (more is used to do work) out of the same fuel that must be equally burned to provide identical propulsion of a pair of trucks. One of the pair is assumed to be turboed, the other NA in this imaginary test.
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You would be incorrect. BSFC is quite a bit higher with a supercharged engine.

Hi, Turtle,

We've had this discussion before although I always welcome your posts and comments. I know you've had a lot of experience with race engines.

I believe you, and your author are out of context about this type turbo application. You will note that the sole reason given by your source to the contrary is the air/fuel mix must be rich to prevent detonation.

QUOTE:
"Well, we can get a range of BSFCs for engines. For example, in our last post I used 0.65 as a safe number for a turbocharged engine. Most turbo’d engines run between 0.6 and 0.65 BSFC while supercharged cars have a BSFC between 0.55 and 0.6, and naturally aspirated engines use only 0.45 to 0.5 Lbs/Hp*Hr. These are only approximations, but you can clearly see the difference between naturally aspirated engines and turbocharged engines. Turbocharged engines usually require more fuel to keep detonation at bay due to the increased temperature and pressure of the intake air".

I think the BSFC efficiency is worthy of further debate in the overall 3.5L EB design. Like I said, I'd like to try it. From what I've read here, there are some indications that the towing efficiency is up to 1 mpg better using a turbo rather than larger NA displacement in this case.

That the turbo air/fuel mix must be rich to prevent detonation certainly usually true of non-intercooled carburation or indirect gasoline fuel injection. However, even in these cases, water/alcohol injection can be used to almost entirely mitigate the detonation and both rich mix and water/alcohol are only used best during high boost. The water/alcohol can also be used in turboed diesel engines to reduce exhaust gas temps. During racing, alternate EGT cooling can also be achieved by cold nitrous or, I believe, generous overfueling.

The one thing that is a game changer for Ford is the use of direct injection (DI), and under-piston oil spray cooling along with good intercooling. The combustion air/fuel mix can be run closer to stoic 14.7:1 because under conditions of high boost, the injection(s) can be delayed to any point beyond TDC (after top dead center). The pure air mix cannot detonate early, or pre-ignite, without the fuel being added. EGR can also be added before fuel, further reducing combustion temps. After TDC, the chance of detonation is less of a serious problem. This is nearly the sole reason DI is used in high tune diesel engines also.

None of this gasoline technology was commonly available to your author (good article by the way) on turboed race engines when he wrote the piece. In addition, he is basically just parroting earlier "safe" tech understandings without offering much on, what would be considered, exotic modification for efficiency. Ford has done something different here. Never before has any manufacturer actually combined all the previous knowledge into actual production, certainly not the last great turbo app OEM offering, the stupendous 3.8L Buick Grand National.

One of the reasons straight supercharging can be more efficient than a turbo is that the boost level, therefore the "planned" fuel curve, is well predetermined. Turbos are less predictable at any given RPM and only a very fast control system could possibly adjust parameters quick enough to prevent detonation. Fords computer is that good, it's a new game.

Which brings us finally to the question of whether a cooler downtube exhaust gas has really raised efficiency. The exhaust gas is hotter before it enters the turbo (even if we have to best wrap it with insulation ala Corvair). There is no doubt that more heat has been subtracted from the combustion process. But has it actually turned more heat into better torque propulsion? Or has the precious heat escaped by radiation from an extremely hot turbo feed, or intercooler loss? I don't really know. If the additional subtracted heat has been used to reduce intake pumping losses, then yes, the engine has used the fuel more efficiently to achieve the improved end torque we are looking for.

I think my Excursion might roll at low 3.5L boost cheaper than the V-10 internal losses at moderate highway speeds. I wouldn't expect a lot of difference. But just maybe. That is really the crux of this thread.

Wes
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