Why large displacement v8 for SuperDuty

[SilverFusion2010]

Ok so I just spent a little time nerding out on Wikipedia.

Two V8s

5.0L Coyote:
395HP @5750 and 400lb-ft torque @4000

6.2L

385hp @5750 and 430 lb-ft @3800

These are very similar outputs given the difference in displacement. Why are the large displacement V8s lingering on in the heavy duty truck classes?

 

[skyactiv]

Long term reliability is my guess.

 

[SubieRubyRoo]

Where's your data that there is any service time/reliability difference between the two engines? Just asking, since we are a board of data-seekers...

 

[Snagglefoot]

Does anyone have the cam specs and CR for the two engines. I’m thinking the 6.4 has a milder cam and lower cylinder pressure.

 

[SilverFusion2010]

Second thought, the 3.5L ecoboost v6 is making 375hp @5000 and 470lb-ft from 2250-3500 rpm. Seems like that could easily do the job as well.

As far as service data I have no idea, that’s why I’m asking the questions

Edit

The 5L is 12:1 (increased this year with the addition of dual direct and port injection)

The 6.2L is 9.8:1

 

[skyactiv]

Originally Posted By: SubieRubyRoo
Where's your data that there is any service time/reliability difference between the two engines? Just asking, since we are a board of data-seekers...


Paging BCcardinal

 

[MParr]

A visit to Ford’s website lists 2 engines for the F-250 Super Duty. The standard engine is the 6.2L gas and the optional engine is the 6.7L Powerstroke diesel. They are made for towing and hauling. The 5.0L Coyote is a F-150 engine option. The 3.5L Ecoboost is also a F-150 engine.

 

[Eric2018]

Maybe extra weight of larger engine helps balance weight of truck.

 

[02SE]

The powertrain engineers understand power curves and duty cycles.

 

[spk2000]

I was just over at the KTP plant that makes the Super Duty trucks. The current gas engine is 6.2L and they are bumping it to 7.2L in the 2020 model. Mostly for more pulling / towing power since that is what these trucks do well. Fuel economy are not a strength. Usually 12mpg on hwy. Good F150 can nearly double that unless you really need the additional power of the super duty. Many say unless all you do is tow you should opt for gas now due to lower maintenance. The gas motors have very good towing performance. Pretty tired as I walked over 5 miles in that plant today.

 

[clinebarger]

Torque Curve.....No replacement for displacement on N/A engines!

 

[gathermewool]

Originally Posted By: 02SE
The powertrain engineers understand power curves and duty cycles.


Originally Posted By: clinebarger
Torque Curve.....No replacement for displacement on N/A engines!


+1

Neither the max HP nor Tq number shows the complete picture. The larger-displacement engine may have more area under the curve BEFORE 5750RPM, meaning more usable power without having to rev to peak.

Max HP and Tq, as well as 0-60MPH times to some extent, are used merely for marketing purposes!

 

[bdcardinal]

The 6.2 is extremely reliable. We literally don't see them for anything except maintenance. When the 6.2L was available in the Raptor up until 2014 that was the truck to get.

Now the 5.0 Coyote is the engine to get in the F-150 is you want to avoid turbos.

Something to keep in mind, the 6.2 has 2 plugs per cylinder. One up top under the coil like where the 2V and 3V mod motors had them and then a wire going down to where a plug would have been on a pushrod engine. People for some reason miss that and freak out when they see 16 plugs billed out.

Also there is supposedly a new actual large displacement, 7.0L, V8 being run around and tested to be used in Super Duty trucks in the 2020 range.

 

[BrocLuno]

Yup, it's all about starting torque and getting the payload up to the operating range. The mini-turbo motor will not do much just off idle. The big engine will move you at 1,200 RPM

It's also about heat density. Some of the smaller engines are getting really high heat density numbers under load. Fine as long as everything is good and nothing pops. But if you spring a coolant leak, it's goinna be shrapnel before you can get off the road. The big engine may get hurt, but not nearly as bad ...

 

[SilverFusion2010]

With the eco boost making 470 lb-ft from 2250-3500 and most of that in up to redline I think it could pull just as well as the 6.2L. I’d love to see a side by side test.

 

[Camprunner]

Years ago my father and I were looking to buy a new Ford box truck for his business and the engine options were the 351 or the 460 V8 both had similar power when we drove them. My father decided to go down to the local Ryder truck rental and talk to the service guys and they all said get the big block 460 V8 it will hold up much better over time and millage the 351 is a great motor but it is just stressed out when you have the full load on your truck and just won't hold up like the big block.

 

[Imp4]

Originally Posted By: SubieRubyRoo
Where's your data that there is any service time/reliability difference between the two engines? Just asking, since we are a board of data-seekers...

The great thing about data is that when gathered correctly and analyzed appropriately it will always give you the right answer.
The challenge is that it is often times a different answer than you were expecting.

Hopefully we are a board of truth seekers based on sound data gathering and analysis, not just data seekers....
(As a side note, this is what companies do in capitalist societies, because that's where the money is.)

 

[09_GXP]

2 reasons from my time in the industry:
#1: Different emissions and fuel economy standards for super duty chassis.
#2: Heavy duty transmissions have different bolt patterns than "passenger" duty. Need the engine to match up which influences torque converter or flywheel size.

 

[Carbon12]

Originally Posted By: SilverFusion2010
With the eco boost making 470 lb-ft from 2250-3500 and most of that in up to redline I think it could pull just as well as the 6.2L. I’d love to see a side by side test.


I bet the ecoboost would do just fine in a Super Duty and would be more than adequate for most people, but then they wouldn't sell as many over priced diesels. ;-)

 

[Johnny2Bad]

You need to compare a dyno chart of the torque output of each engine. I think you will find the Big Block has more torque over a wider range, and probably hefty at low RPM. Ideal for towing and other heavy loads, which is what a Super Duty is built for, so either go for torque or get a lighter truck.

For example, apparently the 6.2 outputs 80% of peak torque value at 1500~2000 RPM. Also the axle ratio options differ when you choose either engine.

" ... over-priced diesels. ..."

Diesels cost what they cost. Gasoline engines are cheap to manufacture, that's why the auto industry in North America had to be dragged, screaming and kicking, into offering Diesels in the first place. High Cost does not equal Over Priced. Poor Value equals Over Priced. Some people choose gasoline engines because they feel they offer the best value, and others choose Diesel engines because they believe a Diesel offers the best value. Horses for Courses.