Under boost the A/F ratio is much richer than 14.7, I don't know what is is for the 2.7 & 3.5 turbos, but in my Mustang with a Saleen SC its about 11.5 under 7-8 lbs boost. The difference is under boost an engine requires more fuel than a similar one thats naturally aspirated.

 

I would rather just rebuild and STS turbo my little 4.6L. Will perform and sound so much better. Not sure how I am going to come up with the money necessary to do it, but I just cannot bring myself to spend the kind of money Ford wants for their trucks, now. That and I think mine looks better than the new ones anyway. Though nothing looks better than a '79, imo. I really wish I could get to work on this Bronco of mine.

 

Just bought a 2015 F 150 Supercrew with 5 litre 4x4 , this truck gets noticeably better fuel mileage than my 2010 Ranger 4x4 .

Quick rundown as a recent buyer of the 2015 F 150 - the 2.7 litre ecoboost mimics the v8 , is a peppy engine, and would not be placed in this 700 lb weight loss truck if it could not perform, believe about 325 hp , the 3.5 liter ecoboost is 365 hp , my 5 litre is 387 hp before K&N , fuel mileage varies, the 2.7 would get the best in the city with it`s start/stop at a light technology-

test driving all 3 , decided upon the v8 , because, I`m old school. All these engines are tried and true, purchase per your own requirements.

That said, If the torque was there , would it be able to tow? No doubt it would , after all it is a Ford! So yes, I would test drive first

 

My all time favorite body styles include the 66,79, 80-86, 97-03, 09-14. Not sure which is THE favorite, maybe the 09-14. I like the 15, but not sure if it deserves to be at the top style wise. Still getting used to it.

Way off subject, but if you didn't know any better, could you line up a like new row of 88-15 GM trucks, and with certainty say which was the current model year? IMO, Ford has a far more modern looking truck.

 

Sorta but not quite. If a 3.5 engine is running 15PSI roughly twice as much air is going into the cylinders. All this extra air will require fuel to burn otherwise the engine will be way too lean. That means you will in effect be feeding a 7.0L engine. The FI engine can also use fuel to cool the cylinder temps to avoid detonation. Now the upside with a turbo is that under light throttle the wastegates can be opened and the engine can act like a NA engine to save fuel.

 

I understand that. At sea level the PSIA is 14.7, so 15 PSIG is a little over twice as much, but pretty close. My S197 4.6L Mustang @ 7.5 lbs boost (500+HP) burns more fuel (under boost) than a 5.0L Coyote Mustang @ 412HP naturally aspirated. I am a little surprised the 3.5L is running 15 lbs boost and as you mentioned equivalent to a 7.0L engine. And its only putting out 365HP while the naturally aspirated 5.0L is putting out 385HP.

 

The factory tune on the EB leaves a lot on the table. From what I remember it spikes to 11 PSI and tapers off to 9 or so. Your also not looking at the torque. The EB makes more torque at 1700 RPM than the 5.0 makes at peak.

 

Not to get off subject, but I'm not a turbo guy, I'm used to my twin screw SC which at full throttle, provides full boost for the duration. Just curious how a turbo spikes & tapers off?

Yeah, I see they are rated at 420 ft/lbs max torque @ 2500 rpm for the 3.5L and 387 ft/lbs max torque @ 3850 rpm for the 5.0L. Which is about 8.5% more max torque for the 3.5L.

 

As Jeremy Clarkson would say, "A turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster."

But in reality, the still expanding exhaust gasses are used to spin a turbine. This in turn is connected to another turbine via a shaft that compresses fresh air which is ducted into the intake manifold. On the EB as are all modern turbo engines, there is a computer controlled wastegate that allows for air to bypass the hot side compressor and go straight out the exhaust manifold. By limiting the exhaust flow the pressure in the intake manifold is controlled. That's a simple way of looking at things but it gets the concept across. So by spiking at 11 PSI the ECM lets the turbo make 11 PSI but then the wastegate control circuit kicks in and modulates the boost back to 9ish.

Oh the other hand your supercharger is spun by a belt attached to the crankshaft. If the engine is running you are making boost directly proportional to the engine's speed. However, they don't have a wastegate so at light throttle conditions you're making boost that's not really needed.

That's where the EB gets its economy. When driven easily it can act like a 3.5L V6. When you stand on the skinny pedal it can make the power of a much larger engine. The catch is you can't do both at the same time.

Now look at the torque curves. The EB is making 400+ Ft-Lb from ~1600 RPM to well over 5000RPM.

Remember, Horsepower = (torque x speed)/5252 in theory an engine could make 1 Ft-Lb but still have 1000Hp as long as it spins fast enough.

To get a better idea of what the 3.5 is actually capable of look at the upcoming Ford GT. It will have the same basic engine but well over 600Hp.

 

The Ford GT has more of the numbers I'd expect from such a setup. What's the boost level for them? I guess Ford thinks its too much power for F-150s, or maybe they have longevity concerns?

Boost is directly proportional to an engines speed on centrifugals but not on twin screws. On the twin screw it provides full boost from around 2000 rpm on up. That's whats nice about them, as soon as you want the power, its there.

 

You can't run 600 HP in the F150, give it a tow rating of 12000 lbs, and expect the engine to last, the tranny to hold up, and the frame to not twist apart.

The 600HP number is for a 2k lb race-ready car that will have a specially built platform and transmission. It ain't no F150!

The engine going into the GT is also the next gen 3.5 EB as well and will feature a dual injection system (port and direct).

 

Ford has a habit of detuning the F150 version of a motor that is also used in a car. It makes it easier to just bump the performance, should GM or Dodge surpass them even the slightest in performance. Make some tweaks to the tune, and bam right back on top. These new ecoboosts have quite a bit of potential that is left untapped. Also, too much performance might eat into Super Duty sales.

 

I've driven the 2.7 and it was impressive, it's the future for sure.

 

Has anyone dynoed the actual power output of the 2.7? Every source I've read states that they think Ford is sandbagging on the numbers. The acceleration is almost identical to 3.5 EB.

 

I would agree from what I have seen. Some are posting 300+HP and 325+TQ AT THE WHEELS!