Ford’s New 7.3-L Engine — Your Predictions?

[Chance]

Looking at Coach House specs they list power and torque ratings for new E-450 that are different than any I have seen from Ford. For E-Series, F53, F59, and larger trucks, Ford has used the Dynamometer ratings which stop at 3,900 RPM, but we know the engine isn’t going to stop there, right?

Coach House ratings are just below that of Super Duty pickups, which makes them plausible, but where did they come from? My first thought was that it was a misprint, but it seems deliberate.

Maybe Ford is sharing information with RV manufacturers that they are not publishing. If 425 HP and 465 lb-ft are correct, that’s great news. Hope it is, but would like to see from other sources.

[Luke D]

Well when in doubt go backwards. The new V8 is a push rod engine. Yup back to the 60's. The fuel consumption of the V-10 finally doomed it. Ford Technically the design and block was already available. Remember the 7.3 Bravo, originally a Navistar family in Marine use. Then of course the 7.3 Diesel. Not opposed but find it hard to replace the V-10 Reliability. The RPM HP/Torque curve has been lowered to meet user demands. The real deal is the six speed transmission it's married to. Now remember a V-10 has a five speed. GM's and Dodges use of the Allison paved the way.
It will be interesting to see the real HP/Torque numbers of the V8 and hear MotorHome owners of the new combination speak.

Then again another issue for change as always is emissions. The V8 a cleaner burn.
In retro spec let's hope for the best and hope for the V-10 engine life.

[Chance]

Originally Posted by Luke D

Well when in doubt go backwards. The new V8 is a push rod engine. Yup back to the 60's. The fuel consumption of the V-10 finally doomed it. Ford Technically the design and block was already available. Remember the 7.3 Bravo, originally a Navistar family in Marine use. Then of course the 7.3 Diesel. Not opposed but find it hard to replace the V-10 Reliability. The RPM HP/Torque curve has been lowered to meet user demands. The real deal is the six speed transmission it's married to. Now remember a V-10 has a five speed. GM's and Dodges use of the Allison paved the way.
It will be interesting to see the real HP/Torque numbers of the V8 and hear MotorHome owners of the new combination speak.

Then again another issue for change as always is emissions. The V8 a cleaner burn.
In retro spec let's hope for the best and hope for the V-10 engine life.

There is nothing in common between old 7.3L diesel V8 and new 7.3L gas V8. They just happen to be of same displacement. That’s all. Ford may have used the 7.3L size in part for marketing association because the old 7.3L diesel (again totally different engine) had/has a great reputation.

Pushrod designs are not that old, and certainly not limited to the 60s. Chevy and RAM V8s remain of pushrod design, including that of new Corvette.

Overhead cam engines have the advantage of being able to rev to higher RPMs, but that seems pointless for truck engines designed to operate at lower RPMs. Another advantage is that if designed with dual overhead cams, it becomes easier to vary intake and exhaust valve timing independently of each other, but that wasn’t the case with the V10 anyway.

The V10 was derived from the 4.6L Modular V8, which has a very small 100 mm bore spacing. Ford stroked that engine to 5.4L V8, then added two more cylinders to make the 6.8L V10. Its a horrible design compromise I’m certain they did to keep development cost down.

The question I’d ask is this: If the V10 is so great, why didn’t Ford just add heads with a similar design as the 5.0L Coyote V8? They both share Modular design so it couldn’t have been that difficult. The point is that it would have been a bad idea on so many levels because the old V10 is a rough engine by design, doesn’t do well at high RPMs due to inherent lack of balance, and would have been physically much larger than the new 7.3L gas V8.

I’m glad Ford finally invested in a new truck-specific gas engine. Only time will tell if reliability is better than that of V10. For now we’ll have to settle for it being a much simpler engine and built for much tougher heavy-duty applications.

[16ACE27]

Originally Posted by Luke D

The real deal is the six speed transmission it's married to. Now remember a V-10 has a five speed. GM's and Dodges use of the Allison paved the way.

The V-10 has had a 6 speed transmission for several years. The "real deal" is the marriage to the 10 speed transmission. So far that's only in the consumer trucks area but hopefully it will make its way to the stripped MH chassis in a year or two.

[Chance]

The E-Series will also have the same 6-speed for now, but I’d bet the 10-speed will find it’s way into Cutaways in time.


So far I’m only disappointed the van’s doghouse wasn’t made smaller to increase foot room, particularly on passenger side. Since V8 is narrower than V10, I hoped Ford would revise the doghouse, but it appears the same.

[Luke D]

Quote: "we built a map where an engine can run stoichiometric air fuel without a bunch of spark retard. It is critical for an engine to operate at peak power with optimal air fuel ratio. From here we worked backwards. "we built a map that let us to torque per liter value and power per liter valve. Knowing that, boxed us to 7.3 liters.
Ford Push rod design with our Company since the early 50's was our model. the Mercury Bravo 7.3 Marine engine a blueprint for block , piston, rod and valve design.
So a little over 445 cubic inch engine was brought back to life with todays upper bells and whistles.New fuel delivery design and valve design that produces lower RPM HP and Torque. It was the best solution for the over 14,000lb segment. Lower RPM of course better fuel mileage.
I totally respect Chance's Post but wanted to show where my thoughts came from. I was following up on a requested opinion. AS a note the Motor Coach has a six speed automatic married to it on the F53 chassis. the multi speed will be used on the super duty F series. The new combo is already been produced and sold in Class A motor homes, maybe others as a retired ASME mechanic and mechanical engineer I have feelers out for that answer.
The other issue reliability. Ford published reports, as well as Consumer reports have a very high dependability rating for the V-10 Triton. FORD states the engine life design was for a quarter of a million miles.
My hope remains the same , that the new 7.3 exceeds all expectations.

[Chance]

A few 2021 Thor Class A motorhomes, both F-53 and Stripped E-Series, are being advertised with the new 2021 Ford Chassis. Thor hasn’t updated their website yet, which still shows 2020 motorhomes with discontinued V10.

I’m glad to see Thor seem to be switching to 2021 chassis and motorhome model year at same time (at least on these Ford units).


https://www.rvusa.com/2021-thor-moto...lass-a-2719273


https://www.rvusa.com/2021-thor-moto...lass-a-2698148

[Chance]

Since this is the technical section, and so many of us are bored stiff having to stay in place, I thought we could discuss what happens to fuel economy when engines are too small, too large, or just about the right size for the job at hand.

I’m aware most people only care about how much we spend on fuel/gas, but a few of us may be interested on how we get to that point in greater detail.

A few unscientific fuel-economy data points are starting to roll in for the new Ford 7.3L V8, and results comparing to other engines of different sizes are not completely unexpected. However, in my opinion it helps to consider results in proper context.

As a starting point for discussion, it’s interesting to see what happened when TFLT pulled the same trailer at 70 MPH with three pickups ranging from RAM/Jeep 3.6L V6 up to Ford 7.3L V8. And to make it more interesting, a Chevy 5.3L V8 is right in the middle of engine displacement.

Jeep with 3.6L V6
285 HP and 260 lb-ft torque
8-speed with 4.10 gears
11.108 gallons
5.9 MPG

Chevy with 5.3L V8
355 HP and 383 lb-ft torque
10-speed with 3.23 gears
8.033 gallons
8.2 MPG

Ford with 7.3L V8
430 HP and 475 lb-ft
10-speed with 3.55 gears
8.534 gallons
7.7 MPG

Please keep in mind that there’s not a lot of accuracy here since measuring 1/2 a gallon of fuel difference with a normal gas-pump fill-up is not exact. Still, it shows a trend that could be predicted.

For what it’s worth, none of the trucks pulled the trailer in top gear, so differences in final axle ratio is secondary (plays a role but is not critical). Overall ratio and engine RPMs was affected mostly by engine size and associated capability.

Anyone surprised with MPG results? Thoughts?

[Metalman]

I don't know what to make of the differences in fuel economy between those vehicles, but I wonder how a 454 with a three speed transmission would fair. I had one in a 33 foot class A and it rarely got more or less than 10 MPG.

[Luke D]

Not surprising Chance. My friend Robert and wife Deb purchased Thor 30.2, 2020 with the new Ford 7.3 and trans. After 1433 miles he is getting at best 7.4 mpg. I told him maybe it will get better. He insisted he never drove over 67 mph. Again I reminded him give it time. He’s not towing a car an only him and Deb are traveling. Now with the stay at home he’ll have to wait as the rest of us.
My 2015 Thor ACE 30.1 has 43000 on it. V10 5 sos. I never get under 9.5 mpg. I’m not towing either. So who knows.
Hope all is well and safe With you and family.

[Judge]

My 2018 Outlaw 29H with V10 was 7 - 8 MPG at best around 65mph without towing.

My 2020 Magnitude with 6.7 PowerStroke is getting 9 - 11 towing.

[Luke D]

Originally Posted by Judge

My 2018 Outlaw 29H with V10 was 7 - 8 MPG at best around 65mph without towing.

My 2020 Magnitude with 6.7 PowerStroke is getting 9 - 11 towing.

Well diesel not surprised. A lot of people tell me the 2017 thru 2020 V10 gets 7 or 8 mpg. Not sure what changed. Just happy with what my 30.1 ACE does. I was hoping for more lol. Welcome to Class A motor home. I'm sure if I tow it will drop by 1.5 or 2. I would prefer a deisel pusher but $$$$$$.
Now that we can't go anywhere, covid19, of course gas below $1.50. I did fill up though.
Be safe. Hope all is well

[Pete'sMH]

I’ll certainly be interested in real world reports. Not to be demeaning to anyone but my mileage always seems to be rather less than everyone else reports here so I may be just a bit skeptical when I start seeing performance and mpg reports on the new engine. The power and torque ratings are very similar to the older engine and the transmission is the same though perhaps the gear ratios are different (?). I’m very happy with the V10/6speed combination even at 7 mpg on a good day.

[Luke D]

Hi Pete, good post. Skepticism is a must when talking about Motorhome gas mileage. My V10 Thor only has a five speed trans. Then again it's a 2015. Guess my mpg is lucky but the computer and my wallet like it. Went cross country in 2015. Fleetwood bounder 34' . It had a GM 526 V8. It got 10 at times and in the mountains 7.5 to 8. No computer on board just my calculations. I'm sure not super accurate. Lol the trip with our three grandkids, thier mom and dad was like the Griswald vacation. My intro to RV life. I enjoy it. Wish this virus would soon be over. I doubt it but stay healthy and safe.

[Chance]

Originally Posted by Luke D

Not surprising Chance. My friend Robert and wife Deb purchased Thor 30.2, 2020 with the new Ford 7.3 and trans. After 1433 miles he is getting at best 7.4 mpg. I told him maybe it will get better. He insisted he never drove over 67 mph. Again I reminded him give it time. He’s not towing a car an only him and Deb are traveling. Now with the stay at home he’ll have to wait as the rest of us.
My 2015 Thor ACE 30.1 has 43000 on it. V10 5 sos. I never get under 9.5 mpg. I’m not towing either. So who knows.
Hope all is well and safe With you and family.

I’m a little bit of a skeptic myself, and I’d have to question your friend’s claim. Thor specs show the 2020 Ace 30.2 as having the old 6.8L V10, not the new V8.

I’ve been looking at motorhome ads with the new 7.3L V8 and have seen a few Model Year 2021 listings but none in stock yet. I’m sure they are close though.

Anyway, without physical confirmation that it’s a 2021 Ford F-53 chassis with new 7.3L V8, I’d assume it’s an old V10.


P.S. — In large Class A motorhomes I expect the new V8 to be a little more fuel efficient than the outgoing V10. I could be wrong though.

[Luke D]

Sorry Chance Robert's is a 2021. Got at Lazy days Tampa, Fl. MSRP $141 something. 30.2 and is a V8 I've been in it. Haven't ridden in it just looked it over. He ordered it specifically for the new design. Deb told me they paid a lot less than the 141 but no number was given. I was thinking 2020 lol. Geez RVs
Way ahead. Shoot they got it end of February or early March. Went to Tennessee and back to St. Mary Florida.
Lazy Days has 3 , 2021 Outlaws arriving this week. So no more V8 waiting but all orders units. So they say
Just got sent a copy of iRV2 in new V8 gas mpg. News not so good. Check it out, I've sent to Robert.

[Chance]

Originally Posted by Luke D

Sorry Chance Robert's is a 2021. Got at Lazy days Tampa, Fl. MSRP $141 something. 30.2 and is a V8 I've been in it. Haven't ridden in it just looked it over. He ordered it specifically for the new design. Deb told me they paid a lot less than the 141 but no number was given. I was thinking 2020 lol. Geez RVs
Way ahead. Shoot they got it end of February or early March. Went to Tennessee and back to St. Mary Florida.
Lazy Days has 3 , 2021 Outlaws arriving this week. So no more V8 waiting but all orders units. So they say
Just got sent a copy of iRV2 in new V8 gas mpg. News not so good. Check it out, I've sent to Robert.

I could not find any new objective information there worth reading. What I could find was based on TheFastLaneTruck guys’ short test, and it compared to Chevy 6.6L V8, both in pickup trucks, and on different days when wind was different. From that forum members started comparing to V10.

It’s natural and expected that present owners of V10 will be more critical of new V8 in order to make their engine seem better by comparison. I’m on my second V10, and it has over 200,000 miles, but I welcome new things when they are actually better. I like my V10 just fine, but think it’s possible (probable) the new V8 can be much better. Or not. I just want to see objective data under controlled conditions.

If you have a link to discussion of motorhomes with new Ford 7.3L V8, please post; I’d like to read it. I may have missed the thread you are referring to.

[Chance]

Here’s a short video of a new Class A with new V8 and updated chassis. They show dash at beginning of video.

He mentions towards end that their motorhomes won’t reach dealers for a couple of months.


https://youtu.be/XycNM91whtk

[Luke D]

Originally Posted by Chance

I could not find any new objective information there worth reading. What I could find was based on TheFastLaneTruck guys’ short test, and it compared to Chevy 6.6L V8, both in pickup trucks, and on different days when wind was different. From that forum members started comparing to V10.



It’s natural and expected that present owners of V10 will be more critical of new V8 in order to make their engine seem better by comparison. I’m on my second V10, and it has over 200,000 miles, but I welcome new things when they are actually better. I like my V10 just fine, but think it’s possible (probable) the new V8 can be much better. Or not. I just want to see objective data under controlled conditions.



If you have a link to discussion of motorhomes with new Ford 7.3L V8, please post; I’d like to read it. I may have missed the thread you are referring to.

I concur Chance, The IRV2 doesn't really give us much to go on. In truth I should be in the market by fall. If we ever get off this stay at home I plan on driving Robert's. I'm excited more about the new F53 chassis and new transmission. I really feel any mpg gain would be a welcomed but I don't expect it. The new V8 is a good thing for Ford. They own the Class A motorhome market. Not sure why GM and Mopar abandoned it. Most likely no product and no profit. You hit the nail on the head, people are Leary due to their success with the V-10. Time is the true test of reliability for most owners. Other than mpg I never hear bad things from owners on the V-10 . Ford knows their sh$!. In time I'm sure the new V8 will be the market favorite. I did like the look of the 22.5 tires on Robert and Deb's btw. Be safe and healthy

[Chance]

Here’s another video that makes two important distinctions. One is that engine doghouse is smaller than previous motorhome with V10, and at end of video they take it out on road and claim that it’s significantly quieter.


https://youtu.be/YDWY2L_ke1w