87 octane fuel requirement

[Snakebitten]

I would not risk putting e85 in an ecoboost. The 5.0 LOVES it, but in the EB, that's taking an unnecessary risk IMO.

Depends on what you mean by "putting E85"

You should NOT attempt to run an untuned 3.5 Ecoboost on E85. I agree.

But that's not what I described above

Sponsored

 

[My 2ND Ford]

I would not risk putting e85 in an ecoboost. The 5.0 LOVES it, but in the EB, that's taking an unnecessary risk IMO.

Only the 5.0 is flex fuel enabled. E85 In a vehicle that is not designed and engineered for it is asking for trouble. The o rings and fuel lines are not designed to handle it and they will deteriorate .

 

[My 2ND Ford]

While I'm not entirely sure, I believe the o rings and fuel lines are the same as the 5.0. Why would they be different material?

I suspect the reason the turbo trucks are not flex fuel capable, is that the stock injectors can not flow enough of it. If I am correct, then the truck would run lean, and detonate.

In the past, materials were different to accommodate the flex fuel. At least this was my understanding.

 

[JExpedition07]

While I'm not entirely sure, I believe the o rings and fuel lines are the same as the 5.0. Why would they be different material?

I suspect the reason the turbo trucks are not flex fuel capable, is that the stock injectors can not flow enough of it. If I am correct, then the truck would run lean, and detonate.

Bingo, injectors and fuel pump. 5.0L has a high volume fuel pump, this is required to get the needed flow when running ethanol. I admittedly do not know how the high pressure direct fuel injection is run in the 5.0, I’d assume there is both a low pressure fuel pump in the tank (likely the variable unit), and then a high pressure direct injector pump off the camshafts? This would service both portions of the PFDI injection. Now I have extra reading to do, just great .

 

[Snakebitten]

Yes, the current model flex fuel vehicle has E85 fuel flow components and necessary engine management to accommodate it.
But the E15 rated modern vehicle isn't the no-ethanol vehicle of the past.

A 3.5 Ecoboost isn't going to be injured with a tank of 3 or 4% of ethanol beyond its E15 design.

 

[JExpedition07]

Here is an article on the PFDI dual fuel delivery system on the 5.0. Looks like there is an in-tank pump that services the port injectors and a high pressure 3,000 psi camshaft driven pump to service the direct injectors. These mixing tables are GREAT INFO!

https://www.enginelabs.com/engine-tech/efi/how-does-dual-fuel-work-on-a-gen-3-coyote/

 

[Snakebitten]

True, but I was answering a very specific ethanol mix question, and the great debate erupted! ?

Which I fully expected and kinda enjoy the banter.

 

[JExpedition07]

Ok, You guys got me into geek mode. I looked up the fuel pumps for the 5.0 vs. the 3.5. Both for the 2023 version.

Same part # given the same wheelbase, same tank. And surprisingly a damn good price too!!

The high pressure direct injection pumps are different though. Perhaps E-85 is interacting more with the high pressure side with the 5.0.

 

[Samson16]

I like to think I feed it gourmet quality fuel

Meow ?

 

[JExpedition07]

Good catch!

Which leads me to another question I've been pondering.

In my 5.0, there seems to be a 2 stroke like power "hit" around 3,000rpm. I've been wondering why. Could this be where the direct injection system kicks in? or is it more related to a cam timing event? Just curious.

Not trying to derail here.

After looking at those mixing tables on the article I posted on the previous page…that’s a dynamic question. The mixing depends on load, coolant temp, and rpm all at once. I’d be guessing. I’d say it’s a combination of the fuel delivery and Ti-VCT system though . If you are towing or under hard acceleration it seems the 5.0 goes to 90% direct injection with very little input from the port injectors, but at low loads the port injectors make up a large portion of the mixing.

 

[Eskram]

98% speculation, but I believe injectors may be the limiting factor for the 3.5 and mixtures > E30.

Nothing to back it up with, but I assume the 3.5 ingests more air at full boost than the 5.0 at high RPM's, leaving the fueling side as the weak point for it.

 

[Eskram]

Hmmm.... 5.0 litres at 7,000 rpm is a shit ton of air.... But I agree about the injectors making the difference. And the high pressure pump as @JExpedition07 discovered.

Again, nothing to back it up with, but 3.5l sucking in 20psi is a considerable amount of air as well. If the rest of the fueling system is the same, that leaves injector capacity and tuning as the difference. There are some Ecoboost tunes that will flirt with E30, but that seems to be the limit without fuel and injector upgrades.

Someone smarter than me will chime in, I'm sure. ?

 

[JExpedition07]

Interesting topic! I have no idea, and it’s hard to get a baseline with the CFM readings available as the 2021+ 5.0L is much different than people realize from the 18-20 version. The intake manifold and throttle body were both upsized (from 80 to 87 mm), as with the new 6,800 rpm redline the old plumbing from the 13th gen F-150 wasn’t cutting the mustard. I would love to know what the current F-150 version flows, because our intake manifolds are HUGE compared to the 3rd gen motors, it’s like a ported manifold from the factory but with tons more meat to port all over again . They are quite different. Still amazing to me that Ford was able to bring the torque up down lower in the revs simultaneously with the top end add. Talk about covering all your bases.

 

[Eskram]

I'm pretty sure the Coyote injectors are bigger, but again.... I'm not claiming to be the smartest guy here either.

What I'm thinking...
5.0/8cylinders=0.625 cubic liters per cylinder. Multiply that by 12-1 compression= 7.5 cubic litres per stroke, per cylinder. x8.

3.5/6 cylinders=0.58333333 cubic liters per cylinder. Multiplied by the 10-1 ratio= 5.83 cubic L/stroke. x6.

I could be totally wrong, but stock for stock, I think the 5.0 flows more air. Remember, pressure and volume are 2 different things.

I work with hydraulic systems and can factually state that once a system is full, it takes very little volume to increase pressure drastically.

ETA: I don't think the compression ratios are really that relevant to the discussion, but it was fun to do the math. Lol. Still looking at 5.0 vs. 3.5.

I'm several beers in, and some wacky tabaccy, so take that into account... ?

Air and fluid compress way differently. Turbos/superchargers exist for a reason - they make more torque given the same engine size + additional fuel to account for the increased airflow.

A SC'd 5.0 makes drastically more power than NA, because of more air. And fuel, of course.

 

[Samson16]

Makes sense. Of course I'm referring to being at WOT when noticing the "event" Lol... I need to check out that info, and study it.

We can run tests and see if you get any closer to my tailgate after 3000 rpm or do I just continue to walk away. ?

Sponsored