I have been reading with interest the discussion about the upcoming 7.X gas engine for the 2020 SD trucks.

Besides fuel consumption the main complaint with gas engines is that peak torque is at a much higher rpm than a diesel. I previously owned a F150 with the 3.5L ecoboost engine and was greatly impressed by the low end torque and wonder why a turbo gas motor is not in the works for the SD truck line.

The argument that I hear is that an SD truck is designed for continuous heavy duty useage and the F150 for occasional towing and that an ecoboost engine would suffer from heat damage and have turbo reliability problems. Perhaps this is true but the 6.7 PSD engine is turbocharged and develops tremendous heat when boosting.

Why not a turbo gas motor for the Super Duty line? Perhaps a 5.0L ecoboost? The 3.5L has been in use long enough now for Ford to find its weaknesses and develop solutions.

 

I'd rather see a hybrid for the added torque.

 

weigh the short block of a 6.7 and a 6.2.. and there is your turbo answer...

thickness of the crankshaft.. the block, the heads....
compression for the 6.2 gas is 9.8 to 1
compression for the 6.7 diesel is 17.0 to 1...
and the reason a diesel is a $9,000 upgrade...

it make the 6.2L to handle a turbo and heavy duty.. new block, new heads, new crankshaft.. bigger cooling system.
and then the EPA testing.....

History... look at GM that made a gas engine into a Diesel.. for production cars.. HISTORY.
read up on using turbo's in auto racing in the 1970'''''''s many an engine destroyed... turbo lag.... overheating... even with large cooling systems.

 

If the 6.2L engine just had enough forced air to compensate for altitude I'd be ecstatic! It gets a bit winded in the Rockies.

 

The 3.5 ecoboost isn't a heavy engine - an 8 cylinder version would be about 4.7 liter and probably over 500 ft lbs of torque.

 

Here's the det's on the new 7.3L engine from interview with Ford engineer.
He mentions that the long term concern for durability and heat dissipation are part of the reason they are not going with higher tech turbo choices. And let's not forget that a simple single-cam OHV n/a design is the least expensive to make. No twin turbos and all their plumbing, sensors, etc.

The goal is to make low end grunt; that takes cubes in n/a engines, or turbos. Since the ruled out turbos for multiple reasons, they are left with cubes.

Note that the 6.2L will soldier on as the base engine! It's not dead yet!

 

https://www.torquecars.com/tuning/remote-turbo-kits.php

 

if you go over 500 horsepower... and or 500 foot pounds of torque.. you better be using STRONG Parts...
heavy cast iron... or forged steel...

I have built several drag race car engines over them numbers.. iron can shatter like glass.
aluminum cracks and bends..

and we are "Talking" about usable power , working hard for years... Super Duty.

 

totally agree.

 

a tail pipe turbo... as posted above..

try walking at 12,000 feet.. I have...

 

Yea at roughly 3% power loss at each 1000 feet it adds up quickly. This was part of the reason I left the 6.2L. Even with the 4.30's I just couldn't take it.

 

history.... forced induction.... Aircraft...

while forced induction has made major leaps... cost and dependability is still work in process...
turbocharging,, bearings.. cooling..
supercharging..... wiper seals and drive systems.

inlet air coolers and piping (intercooler)
limited cool air inlet into front of vehicle...
engine water cooling system
Air conditioning condenser
power steering fluid cooler
auto transmission fluid cooler
turbocharger post boost air cooler.
oil cooler for turbocharger
and the cool air to RUN the engine.

then the STUFF for mandated EPA parts needed.

 

Torque is ultimately related to cylinder pressure X bore^2 X stroke. Bore^2 x stroke is displacement.

Turbo's can double the cylinder pressure and high cylinder pressure mean more wear/heat. Ford was clearly shooting for durability, ease of service, with sustained output somewhere between the 6.2 gas and 6.7 diesel. The key is sustained output.....if you're gonna be into the boost all the time then you're better off with a bigger NA motor which is the decision they made.

 

I sort of agree and sort of don't.
OTR diesel engines are turbo boosted, but they soldier on for hundreds of thousands of miles. This is because they are heavily built and run reasonable (not excessive) boost levels. There are plenty of gasoline engines that are extremely hardy and last a long time. Those that last the longest typically have lower power levels, and don't need heavy duty parts because they are not hauling heavy loads. (4.9L I-6, 3.0 Vulcan v-6, 4.6L 2v, etc). My point is that just because something is or is not boosted, does not always assure some result of longevity. Heavily boosted engines with marginal components are a disaster waiting to happen; that I would agree with.

The key to engine longevity is making the entire system robust enough to survive it's designed intent of use. If they have created the new 7.3L engine with the right parts, material composition and design, the engine will be a great success. From what I saw, it seems to be awesome. The only thing I could not find myself excited about is the cam phaser on the back of the engine; how do you get to that if it goes bad? Pull the engine???? (ala my 3.5L Duratech water pump buried inside the cam chain cover ......)

 

I am sure Ford did not re-invent the wheel here..

like the 6.2L.. progression to the future...
some past lessons need to be remembered and not reused...

its still better then a un-named car... to replace a $18.00 water pump. entire engine/transaxle most be dropped from under the body...

the current F series to service turbo parts on the diesel .. body is lifted. to work on it..