The New 6.8L V8 Thread

[1970TorinoGT]

On 10/1/2022 at 8:58 AM, ESP08 said:

I always suspected Ford used a belt to drive the oil pump on Gen 4s to help reduce harmonics of the chain drive.    
Harmonics are what tended to shatter oil pump gears and crack timing crank sprockets on high power Coyotes.   
 

The billet parts never addressed the root cause, only used a softer material that is less prone to cracking.   

 

My conspiracy theory is that they moved the oil pump to the pan so it will prime faster and get rid of the startup VVT chatter that Gen1-3 Coyotes are (in)famous for. 

 

My understanding is that only vehicles which had their RPM limiter increased generally saw OPG failures.

[blksn8k2]

On 10/1/2022 at 5:22 PM, jpd80 said:

Yes, 3.74” stroke as blksn8k2 said in his post. The 6.8 would seem to cure  a lot of perceived mistakes with the Boss 6,2.

 

The 2V mods generally had smaller ports and valves which promoted more low end torque but tended to run out of horsepower. 

Conversely, the 6.2 was give large intake ports which tends to make the engine a bit “hollow” down low where heavy duty trucks would be looking for more torque when starting heavy loads. I can’t find a torque chart for the 6.2 but my research points to it being 95% of the GM 6.6 V8, so maybe the extra 10% capacity of the 6.8 has enough torque to be a winning combination…

 

We need to be careful not to over complicate the reasons why one engine will produce more low rpm torque than another of similar displacement. Again, go back to the old 427 and 428 FE big blocks. They were essentially the same displacement yet the 428 produced more torque at lower rpms than the 427. If you compare the street version of the 427, which was the medium riser, to a 428 CJ you will see that they essentially used the same cylinder heads, intake manifold and carb. Other than the camshaft profiles the biggest differences between the two were bore diameter and crankshaft stroke. I know that might be an oversimplification because the racing versions of the 427 did have a bunch of other parts that allowed them to achieve and survive much higher rpms. But back to the basics: The 427 used a 4.23" bore and a 3.78" stroke. The 428 used a 4.13" bore and a 3.98" stroke. The biggest reason why the 428 could produce more low rpm torque was because it had the mechanical advantage of the longer crankshaft stroke. It's like comparing a 3" long screwdriver to a 30" long crow bar. You can move a lot more mass with the longer lever arm of the crow bar with a lot less effort. It's the same thing with a 4-stroke engine. When the piston is on it's downward power stroke the longer the "arm" of the crankshaft the easier it is to turn the crankshaft so it takes less effort to create more twisting force, or torque,  at slower speeds. The 427, on the other hand, could achieve the same rpm at a much quicker rate and could take better advantage of more air and fuel to achieve higher rpms because the shorter lever arm (stroke) of it's crankshaft could make the crankshaft turn at a faster rate in less time. It just took more effort at slower engine speeds which meant that it couldn't produce as much torque at those slower speeds. Now, you can certainly do a lot of things with induction systems, camshaft designs, ignition and valve timing, exhaust systems, etc. but you still need that basic mechanical advantage of the longer lever arm.

 

How does all that apply to the 6.8? I'm betting it will be a little snappier than the 7.3 and be damned impressive with a set of 3.73 or 4.10 gears. Just don't expect it to pull as heavy loads without a little more effort, or in this case, a little more rpms.

 

 

[jpd80]

32 minutes ago, blksn8k2 said:

 

We need to be careful not to over complicate the reasons why one engine will produce more low rpm torque than another of similar displacement. Again, go back to the old 427 and 428 FE big blocks. They were essentially the same displacement yet the 428 produced more torque at lower rpms than the 427. If you compare the street version of the 427, which was the medium riser, to a 428 CJ you will see that they essentially used the same cylinder heads, intake manifold and carb. Other than the camshaft profiles the biggest differences between the two were bore diameter and crankshaft stroke. I know that might be an oversimplification because the racing versions of the 427 did have a bunch of other parts that allowed them to achieve and survive much higher rpms. But back to the basics: The 427 used a 4.23" bore and a 3.78" stroke. The 428 used a 4.13" bore and a 3.98" stroke. The biggest reason why the 428 could produce more low rpm torque was because it had the mechanical advantage of the longer crankshaft stroke. It's like comparing a 3" long screwdriver to a 30" long crow bar. You can move a lot more mass with the longer lever arm of the crow bar with a lot less effort. It's the same thing with a 4-stroke engine. When the piston is on it's downward power stroke the longer the "arm" of the crankshaft the easier it is to turn the crankshaft so it takes less effort to create more twisting force, or torque,  at slower speeds. The 427, on the other hand, could achieve the same rpm at a much quicker rate and could take better advantage of more air and fuel to achieve higher rpms because the shorter lever arm (stroke) of it's crankshaft could make the crankshaft turn at a faster rate in less time. It just took more effort at slower engine speeds which meant that it couldn't produce as much torque at those slower speeds. Now, you can certainly do a lot of things with induction systems, camshaft designs, ignition and valve timing, exhaust systems, etc. but you still need that basic mechanical advantage of the longer lever arm.

 

How does all that apply to the 6.8? I'm betting it will be a little snappier than the 7.3 and be damned impressive with a set of 3.73 or 4.10 gears. Just don't expect it to pull as heavy loads without a little more effort, or in this case, a little more rpms.

Sewer ports on 6.2 didn’t help low end torque but adding 10% capacity on basically a better design is worth every penny.

 

The 7.3 is also getting an increase in power and torque, presumably to keep justification for the $1,700 up charge, so it will impress too….

[ESP08]

11 hours ago, blksn8k2 said:

 

We need to be careful not to over complicate the reasons why one engine will produce more low rpm torque than another of similar displacement. Again, go back to the old 427 and 428 FE big blocks. They were essentially the same displacement yet the 428 produced more torque at lower rpms than the 427. If you compare the street version of the 427, which was the medium riser, to a 428 CJ you will see that they essentially used the same cylinder heads, intake manifold and carb. Other than the camshaft profiles the biggest differences between the two were bore diameter and crankshaft stroke. I know that might be an oversimplification because the racing versions of the 427 did have a bunch of other parts that allowed them to achieve and survive much higher rpms. But back to the basics: The 427 used a 4.23" bore and a 3.78" stroke. The 428 used a 4.13" bore and a 3.98" stroke. The biggest reason why the 428 could produce more low rpm torque was because it had the mechanical advantage of the longer crankshaft stroke. It's like comparing a 3" long screwdriver to a 30" long crow bar. You can move a lot more mass with the longer lever arm of the crow bar with a lot less effort. It's the same thing with a 4-stroke engine. When the piston is on it's downward power stroke the longer the "arm" of the crankshaft the easier it is to turn the crankshaft so it takes less effort to create more twisting force, or torque,  at slower speeds. The 427, on the other hand, could achieve the same rpm at a much quicker rate and could take better advantage of more air and fuel to achieve higher rpms because the shorter lever arm (stroke) of it's crankshaft could make the crankshaft turn at a faster rate in less time. It just took more effort at slower engine speeds which meant that it couldn't produce as much torque at those slower speeds. Now, you can certainly do a lot of things with induction systems, camshaft designs, ignition and valve timing, exhaust systems, etc. but you still need that basic mechanical advantage of the longer lever arm.

 

How does all that apply to the 6.8? I'm betting it will be a little snappier than the 7.3 and be damned impressive with a set of 3.73 or 4.10 gears. Just don't expect it to pull as heavy loads without a little more effort, or in this case, a little more rpms.

 

The mechanical advantage provided by a longer stroke length is a distant secondary factor determining the RPM an engine combination develops its power/torque.   

IMO, the mechanical advantage highlighted in the 427/428 comparison will be closer to the statistical noise end of the spectrum than a root variable for any measurable difference in power-band.  

 

If the 6.8 retains the 7.3's heads/cam/intake package it will obviously be a higher RPM combination -- not because it's now more over-square or has less mechanical leverage thanks to its 0.296" stroke reduction -- but because the same top end is feeding less total displacement.   

 

I've built and dyno'd many engines and played with bore/stroke combinations a lot personally.   

 

If anyone doubts me maybe you'll take Richard Holdener's word on the topic -- a guy who has dyno'd (and has data for) hundreds of engine combinations.   

This isn't "appeal to authority" so don't take it as that,  just a very educated opinion:  

 

 

 

Regarding the 427/428 comparison - having no hands-on experience with the FE -  I'd wager their differences extend beyond bore/stroke.   

Do you have access to cylinder head intake port cross section, intake valve diameter, cylinder head flow, camshaft duration (w/OE intake centerline), and intake manifold runner length/cross section for both engines?      

 

I'll bet we find virtually all of the 427's more rev happy nature in those differences.  

Edited October 4, 2022 by ESP08

[edselford]

Very interesting discussion on 427 vs 428 FE offerings.

For the most part what. is reviewed is accurate!

However, in the mid 1960’s Ford needed to come up with a competitive V8 for full sized cars because the 390 V8 was not competitive with the 396/427 Chevy or the other offerings . Also, the base 428 ford offered in 1966 was not much stronger than the 390.  Chevy did offer the 427 in full sized cars at lower hp levels (385hp)

Ford had nothing but the high performance 427 which could not be purchased with an automatic or power steering!

In 1968, ford offered a 427 FE side oiler block, hydraulic lifter engine for a short period of time rated at 390 hp.  It utilized a 600 cfm Holley carb and it was offered only with a heavy Duty C6 automatic.

The vehicle was almost as fast as the 428 cobra jet. 
I think the cobra jet utilized at 750 cfm Holly.

Except for the different blocks bores/strokes, and carburetors, the engines were almost identical .

The big difference was ford’s manufacturing costs because of the 4.63” bore centers of the FE family, the 427 was very expensive to make. The 428 could be made without the high scrap rate of the 427 block machining process and on the same machining line as the 352 & 390 .

The 427 was machined on a special machine, one at a time.

 

edselford

[ESP08]

Did a little fishing here, from what I see the 427 Medium Riser and High Riser heads had 2.19” intake and 1.73” exhaust valves.

The 428 heads were apparently "similar" to the medium risers (I'm assuming similar in regards to port volume?) but with smaller 2.09” intake and 1.66” exhaust valves. 

The 428 apparently also used a shorter duration hydraulic cam borrowed from the 390 GT.  

 

 

It's hard to find much real info about the intake manifolds, from photo it "looks" like the 427 High Riser than larger cross section runners.   

 

 

 

[jpd80]

19 hours ago, edselford said:

Very interesting discussion on 427 vs 428 FE offerings.

For the most part what. is reviewed is accurate!

However, in the mid 1960’s Ford needed to come up with a competitive V8 for full sized cars because the 390 V8 was not competitive with the 396/427 Chevy or the other offerings . Also, the base 428 ford offered in 1966 was not much stronger than the 390.  Chevy did offer the 427 in full sized cars at lower hp levels (385hp)

Ford had nothing but the high performance 427 which could not be purchased with an automatic or power steering!

In 1968, ford offered a 427 FE side oiler block, hydraulic lifter engine for a short period of time rated at 390 hp.  It utilized a 600 cfm Holley carb and it was offered only with a heavy Duty C6 automatic.

The vehicle was almost as fast as the 428 cobra jet. 
I think the cobra jet utilized at 750 cfm Holly.

Except for the different blocks bores/strokes, and carburetors, the engines were almost identical .

The big difference was ford’s manufacturing costs because of the 4.63” bore centers of the FE family, the 427 was very expensive to make. The 428 could be made without the high scrap rate of the 427 block machining process and on the same machining line as the 352 & 390 .

The 427 was machined on a special machine, one at a time.

 

edselford

Interesting to tie back into the modern 6.8 with 4.22” x 3.68” versus 427 with 4.23” x 3.78”

Valve sizes are 2.17 (intake) and 1.66-inches on the exhaust, they sit at an 8.8-degree angle and are canted at 1.8 degrees - that’s gotta be a massive improvement in flow over the FE wedge heads.
 

I marvel at the casting  improvements made from the late 1950s to late 1960s that permitted larger pistons to be used in FE and SBF but also understandable perfectly why the MEL was replaced by 385 Lima engine and the common 4.9” bore spacing. I wonder, had Ford continued to develop the 385 with alloy heads, roller cam and VCT, maybe a lot of unnecessary engine development could have been avoided..

Edited October 5, 2022 by jpd80

[Captainp4]

10 hours ago, jpd80 said:

Interesting to tie back into the modern 6.8 with 4.22” x 3.68” versus 427 with 4.23” x 3.78”

Valve sizes are 2.17 (intake) and 1.66-inches on the exhaust, they sit at an 8.8-degree angle and are canted at 1.8 degrees - that’s gotta be a massive improvement in flow over the FE wedge heads.
 

I marvel at the casting  improvements made from the late 1950s to late 1960s that permitted larger pistons to be used in FE and SBF but also understandable perfectly why the MEL was replaced by 385 Lima engine and the common 4.9” bore spacing. I wonder, had Ford continued to develop the 385 with alloy heads, roller cam and VCT, maybe a lot of unnecessary engine development could have been avoided..

7-800 very street friendly hp on pump gas all under 6k rpm is easily done with the heads/intakes/cams/stroker kits available in the 385 series these days. Obviously ignoring all the things needed for nvh/emissions/longevity/etc a factory engine needs, but a modern version of it from the factory would probably do everything the godzilla does. The block tends to find it's limit around 1k hp n/a though, don't think anyone has pushed the godzilla hard enough to find the limit of the block yet.

 

[30 OTT 6]

Third shift at Windsor Annex Engine Plant announced for 6.8L V8 launch in January 2023.

[jpd80]

On 10/4/2022 at 9:03 PM, ESP08 said:

 

The mechanical advantage provided by a longer stroke length is a distant secondary factor determining the RPM an engine combination develops its power/torque.   

IMO, the mechanical advantage highlighted in the 427/428 comparison will be closer to the statistical noise end of the spectrum than a root variable for any measurable difference in power-band.  

 

If the 6.8 retains the 7.3's heads/cam/intake package it will obviously be a higher RPM combination -- not because it's now more over-square or has less mechanical leverage thanks to its 0.296" stroke reduction -- but because the same top end is feeding less total displacement.   

OK, your thoughts on the design differences between the outgoing 6.2 (OHC 2V with VCT) and the new 6.8 (8.8 degree wedge 1.8 degree cantered valves and VCT). The question here is whether the new 6.8 simply meets or exceeds the power and torque of the 6.2, logic suggests othat the power and torque will probably fall between the Boss 6.2 and the GM 6.6’s numbers…

Also,

None of these engines 6.2, 6.8 or 7.3 has a “short stroke” in comparison to the earlier small blocks like 283, 289 or 302. 

 

 

 

Quote

I've built and dyno'd many engines and played with bore/stroke combinations a lot personally.   

 

If anyone doubts me maybe you'll take Richard Holdener's word on the topic -- a guy who has dyno'd (and has data for) hundreds of engine combinations.   

This isn't "appeal to authority" so don't take it as that,  just a very educated opinion:  

 

 

Regarding the 427/428 comparison - having no hands-on experience with the FE -  I'd wager their differences extend beyond bore/stroke.   

Do you have access to cylinder head intake port cross section, intake valve diameter, cylinder head flow, camshaft duration (w/OE intake centerline), and intake manifold runner length/cross section for both engines?      

 

I'll bet we find virtually all of the 427's more rev happy nature in those differences.  

427/428 were evolutions of the earlier 390/ 410 engines from early 60s when castings needed to be thicker, I think they were always struggling against the 409 and later BBC 396/427/454, that would be due to superior head design, yes?

Something I’ve noticed over the years is that newer engines in the 383, 393, 402, 408, 410 capacity tend to (not always) make a lot more torque per cubic inch than engines below or above. There must be a sound reason for this where heads, cam, intake and exhaust are optimal in a near 4” bore….

 

 

Random thought, perhaps a separate thread to discuss:

David Vizard pushes his design software and 128 rule for camshaft selection, claiming up to 1.4 lb per cubic inch is possible by getting optimal LCA and valve overlap for the intended rpm range. I stared at this for ages until I realised that he was talking same overlap as OTS cams but shorter IVC and EVO timing points (raising dynamic compression?)

LCA = 128 - (CID/8/inlet valve dia x 0.91) 302 ~110, 350~108

Of course, limiting factor with tighter LCA is idle quality, the bigger the cam, the more the idle get really snotty and higher rpm needed to stabilise..what I’m interested in is tightening the LCA from 114 to 110/108 but reducing the duration to maintain the same overlap.

https://www.whichcar.com.au/features/holden-308-sig-erson-tq20-tq30-street-strip-cam-combo

edit,

Said a different way, these tighter LCA cams are smaller duration cams with more overlap….needs good heads to really work. have you noticed any similarities in torque improvement like this in all the engine builds and dyno tests or does the theory break down in real world?

Edited October 7, 2022 by jpd80

[2005Explorer]

I don't really see the point in wasting development dollars on anything ICE with everything going EV in the next few years, but it is an improvement as a base engine in the Super Duty. I suppose with the 7.3 V8 already engineered this didn't cost them much.

[jpd80]

2 hours ago, 2005Explorer said:

I don't really see the point in wasting development dollars on anything ICE with everything going EV in the next few years, but it is an improvement as a base engine in the Super Duty. I suppose with the 7.3 V8 already engineered this didn't cost them much.

Correct, this allows closing down the 6.2 at Romeo plant and increasing product at the Windsor 7.3 plant,

in overall terms, the 6.8 is money for jam in F250/350 XL and XLT, allowing  7.3 to stay a premium option.

Ford is now saying that everything won’t go EV in the next few years, I take this as Super Duty buyers….

[Bob Rosadini]

8 hours ago, jpd80 said:

Correct, this allows closing down the 6.2 at Romeo plant and increasing product at the Windsor 7.3 plant,

in overall terms, the 6.8 is money for jam in F250/350 XL and XLT, allowing  7.3 to stay a premium option.

Ford is now saying that everything won’t go EV in the next few years, I take this as Super Duty buyers….

Yes...I believe Farley has publicly stated ...."except HD trucks"... or words to  that effect.

I also think more people are beginning to  ask...."but  where does the electricity come from"?????  Usually followed by a discussion on materials used in battery construction.

As always, no such thing as a free lunch.

[SoonerLS]

13 hours ago, jpd80 said:

Ford is now saying that everything won’t go EV in the next few years, I take this as Super Duty buyers….

I think it’ll be a lot longer than 12 years before the pickup fleets are all electric because I’ve driven through west Texas. Out there, everywhere is at least 90 miles from anywhere else. 

[jpd80]

4 hours ago, SoonerLS said:

I think it’ll be a lot longer than 12 years before the pickup fleets are all electric because I’ve driven through west Texas. Out there, everywhere is at least 90 miles from anywhere else. 

And thinking about this, a smaller diesel is hard to justify in Super Duty but what about a 6.8/7.3 hybrid?

Now that may be worth something to those buyers.

Most of the infrastructure is sort of in place, just adding things drive motor to gearbox and a small battery inside the frame rails…..

Edited October 9, 2022 by jpd80

[jpd80]

9 hours ago, Bob Rosadini said:

Yes...I believe Farley has publicly stated ...."except HD trucks"... or words to  that effect.

I also think more people are beginning to  ask...."but  where does the electricity come from"?????  Usually followed by a discussion on materials used in battery construction.

As always, no such thing as a free lunch.

Absolutely and eventually I suspect that the high cost of lithium will force a change of materials to something like grapheme which will make lithium ion batteries look like lead acid. 
 

I think swap-n- go batteries for large vehicles is the way to win larger trucks but still lots of questions 

[SoonerLS]

5 hours ago, jpd80 said:

And thinking about this, a smaller diesel is hard to justify in Super Duty but what about a 6.8/7.3 hybrid?

Now that may be worth something to those buyers.

Most of the infrastructure is sort of in place, just adding things drive motor to gearbox and a small battery inside the frame rails…..

I still think that's the way to completely electrify the F-Series and the commercial vehicles. The Lightning is, no doubt, a smash hit, but it's a niche product because of the lack of infrastructure to support it in the F-Series's biggest markets, and I don't see that changing anytime soon. If you're in one of the metro areas, a BEV might be able to git 'er done, but if you need to haul a load or tow a trailer all over hell's half acre, pure electrics won't tote the mail. A 6.8 PowerBoost might be just the ticket, though...

Edited October 10, 2022 by SoonerLS

[edselford]

I never thought ford would go down to .307” between finished bores in a cast iron block!

Probably, 60 years of casting technology refinements and seimezed  block bores did the trick.

Ford removed weight going from 462 MEL to the 385 460 but actually gave up low end torque because the 462 heads flowed better than the 385 heads to about 4800 rpm.

I think until charging times are like ten minutes, for a full recharge, we will have IC power for vast majority of pickup truck buyers.

Also, when federal and state governments see their tax revenues get slashed because of electrics, we will see some type of transportation surcharge(tax) imposed to make up the shortfall and the cost benefit of EV will drastically change.

Imagine if we some day have to ration electricity for EV vehicles because coal produces net positive CO2 and natural gas is too expensive?

I see this as a 20 year process not 5 years!

 

edselford

[Chrisgb]

1 hour ago, edselford said:

10 hours ago, SoonerLS said:

I still think that's the way to completely electrify the F-Series and the commercial vehicles. The Lightning is, no doubt, a smash hit, but it's a niche product because of the lack of infrastructure to support it in the F-Series's biggest markets, and I don't see that changing anytime soon. If you're in one of the metro areas, a BEV might be able to git 'er done, but if you need to haul a load or tow a trailer all over hell's half acre, pure electrics won't tote the mail. A 6.8 PowerBoost might be just the ticket, though...

Potential downside being, adding more weight and complexity versus marginal gain in usability. But it may work using the BEV component and cylinder deactivation in highway/light load situations.

 

[Captainp4]

6 hours ago, edselford said:

I never thought ford would go down to .307” between finished bores in a cast iron block!

Probably, 60 years of casting technology refinements and seimezed  block bores did the trick.

Ford removed weight going from 462 MEL to the 385 460 but actually gave up low end torque because the 462 heads flowed better than the 385 heads to about 4800 rpm.

I think until charging times are like ten minutes, for a full recharge, we will have IC power for vast majority of pickup truck buyers.

Also, when federal and state governments see their tax revenues get slashed because of electrics, we will see some type of transportation surcharge(tax) imposed to make up the shortfall and the cost benefit of EV will drastically change.

Imagine if we some day have to ration electricity for EV vehicles because coal produces net positive CO2 and natural gas is too expensive?

I see this as a 20 year process not 5 years!

 

edselford

I'll admit I don't know much about the MEL besides there's very few aftermarket parts for them. I have a 430 in my 64 continental, but that thing is a giant turd compared to any 460 I've owned, even stock ones. Thinking about dropping a godzilla in it's place one of these days. Not that power matters much in a car like that cause it doesn't turn, but efi and more than 14mpg plus a little more power would be cool.

[jpd80]

So it doesn’t sound like super Duty is getting hybrids anytime soon, so probably the 6.8 for now and a bump in 7.3 torque and Hp. 
 

if the economy is looking sad next year, I think Ford will tighten its spending and do the least required to keep sales coming. 

[ESP08]

2023 SD numbers revealed:  

 

6.8 - 405 HP / 445 LB-FT

7.3 - 430 HP / 485 LB-FT

 

6.7 PSD - 475 / 1050 LB-FT

6.7 PSD HO - 500 / 1200 LB-FT 

[Bob Rosadini]

2 hours ago, ESP08 said:

2023 SD numbers revealed:  

 

6.8 - 405 HP / 445 LB-FT

7.3 - 430 HP / 485 LB-FT

 

6.7 PSD - 475 / 1050 LB-FT

6.7 PSD HO - 500 / 1200 LB-FT 

Well this has been an impressive thread in terms of the knowledge shown by so  many.

So as always appreciate the education.  How  about an education on these  numbers.

 

Assuming these are dyno numbers let's say we are talking about an F-350-one with a 6.8 and one with a 6.7.  My  first  thought is the PS version has all sorts of engine controls so those torque numbers do not get to the rear wheels  on start up. 

 

If they do, that means everything in the 6.7 drive line is TWICE the rating of the 6.8's components.?  I don't think they  are...so what is the point-other than bragging rights of 1000 lb ft of torque in a 13,000 GCW "one ton"?

[7Mary3]

The H.O. diesel's numbers are impressive.

 

The 6.8L seems to be a complete waste of time.  Less than 10% less H.P. and torque, and I will be willing to wager about the same fuel economy as the 7.3L.

[silvrsvt]

44 minutes ago, 7Mary3 said:

The 6.8L seems to be a complete waste of time.  Less than 10% less H.P. and torque, and I will be willing to wager about the same fuel economy as the 7.3L.

 

It is replacing the 6.2L in the lineup-more HP and more likely better MPG and cheaper to build since its shared with the 6.8L