7.3 "Godzilla" V8

[MJC62]

Awhile ago on here there was a long discussion about the new Ford 7.3 L V8.

I am wondering if anyone here has bought a new MH with the 7.3 that previously had the 6.8 V10 and can give us a users comparison of V10 versus V8.
The engine has been in service for a bit over a production year and I have an interest in what those who have had both think of the new V8.

We are kicking around getting another MH in the same basic configuration as our ACE 27.2 but on a heavier chassis Jayco builds basically the same coach, a 27A, on an 18000 lb chassis.

[16ACE27]

Originally Posted by MJC62

Awhile ago on here there was a long discussion about the new Ford 7.3 L V8.

I am wondering if anyone here has bought a new MH with the 7.3 that previously had the 6.8 V10 and can give us a users comparison of V10 versus V8.
The engine has been in service for a bit over a production year and I have an interest in what those who have had both think of the new V8.

We are kicking around getting another MH in the same basic configuration as our ACE 27.2 but on a heavier chassis Jayco builds basically the same coach, a 27A, on an 18000 lb chassis.

You think 2000 lbs will make much difference?

[Pete'sMH]

Originally Posted by 16ACE27

You think 2000 lbs will make much difference?

I do. It almost certainly will give you a higher OCCC which is something I always appreciate.

[DavidEM]

This may not be relevant but I picked up a new 2021 Axis 24.1 in January. It has the 7.3 V8 on an E350 chassis not the F53 chassis that I think the OP is considering. And I don't have any experience with the 6.8 V10 to compare against.

But I do like the new engine very much. Smooth just like a V8 should be. Also the suspension drives better than Axis owners report their older V10 based chassis does. I don't plan to do any suspension mods, just maybe an alignment to make sure the caster is +5 deg.

And there are reports including a video comparing the new V8 F53 with the older V10 F53 that indicate better acceleration and ride for the new engine and chassis.

David

[EA37TS]

Originally Posted by Pete'sMH

I do. It almost certainly will give you a higher OCCC which is something I always appreciate.

Not always. Often times the bigger chassis is needed because of the additional weight of materials in construction. The end result is often a minimal difference in OCCC and in some instances a lower OCCC.

[16ACE27]

Originally Posted by EA37TS

Not always. Often times the bigger chassis is needed because of the additional weight of materials in construction. The end result is often a minimal difference in OCCC and in some instances a lower OCCC.

Zactly! Unfortunately you have to go see the MH to get the OCCC since manufacturers aren't prone to publish it.

[Bob Denman]

I get the impression that the V-8 is tuned for more low-end torque. It'll be a much better engine for RV usage; than the V-10 "screamer".

[16ACE27]

Originally Posted by Bob Denman

I get the impression that the V-8 is tuned for more low-end torque. It'll be a much better engine for RV usage; than the V-10 "screamer".

The thing is, the maximum torque on the V10 "screamer" is at 3200 rpm. But the stock transmission tuning (at least in the 5 speed) jumps right past that on a downshift, to third gear (screaming RPMs).

[Bob Denman]

The six speeds were a huge improvement, and matched-up much better to the V-10's power output.

[MJC62]

Originally Posted by 16ACE27

You think 2000 lbs will make much difference?

Won't know that for certain till one of the sales Goobers at a couple dealers I have contacted reply to my request for the OCCC on the 27A. It is a simple question but I don't think the sales people 1, no what the OCCC is (I even spelled it out) and 2, where to locate the information. For the life of me I don't know why finding that bit of information from the manufacturer is that hard to come by. Been all over different brands web sites and nobody wants to publish even an approximate.
If and its a big if we decide on getting another coach the OCCC would have to be substantially higher than the 1233 lbs in our 27.2, at least double.

I still would like to hear from previous owners of the V10 who now own the V8 and hear their thoughts on the new motor. I would think it has to be a big improvement or why would Ford go to all the trouble to re-tool?

And thank you David EM for your thoughts on your V8. I have seen the videos comparing a V10 MH to a V8 mock up MH, still nothing like hearing from an end users experiences out on the roads with both.

[Chance]

Originally Posted by 16ACE27

The thing is, the maximum torque on the V10 "screamer" is at 3200 rpm. But the stock transmission tuning (at least in the 5 speed) jumps right past that on a downshift, to third gear (screaming RPMs).

I would expect that if I pushed down hard on the “GO” pedal, that software will select whatever subsequent engine speed will yield most power, not torque at the crankshaft. More power at engine means more torque at wheels because of the lower gearing, which is what I’d want.

When I don't want high RPMs out of V10 (which is normally the case), I downshift 5-speed manually out of OD to Drive and use less throttle to avoid an additional downshift to 3rd.

You’re correct that going from OD to 3rd on 5-speed more than doubles RPMs, and if there is one thing I dislike about my V10s is noise and vibration at higher RPMs.

If I’m honest, the V10 isn’t quiet at low RPMs either, particularly when cold. Neighbor across street has an E-350 work van and it often wakes me when he goes off to work in AM. It’s a lot louder at idle than all other vehicles on street, except for my V10 which is worse due to high mileage.

[Bob Denman]

Technically: that's not quite true...
The torque and horsepower curves will often take different paths.
Torque peaks are often tuned to be about a thousand RPM less than the horsepower peak.
Theoretically: if you always upshifted at your horsepower peak RPM; you would want the upshift to drop your RPM back to the torque peak.

[Chance]

Originally Posted by Bob Denman

Technically: that's not quite true...
The torque and horsepower curves will often take different paths.
Torque peaks are often tuned to be about a thousand RPM less than the horsepower peak.
Theoretically: if you always upshifted at your horsepower peak RPM; you would want the upshift to drop your RPM back to the torque peak.

Changing careers now from insurance to mechanical engineering?

[Bob Denman]

Common car sense...
If you happen to remember the Pontiac Trans Am SD455: They set it up so that redline upshifts (at the hp peak): landed you right on top of the torque peak in the next gear.
It made that car brutally fast!

[bherron1]

Have run the V10 and 7.3 V8 the V8 seems to make good power down low in the RPM range and I think its tuned at 350 HP in my class C E350 but the Torque rating is still close to the 430 HP 7.3 in my F250 Torque is better on a push rod motor. Im thinking the V10 was a OHC engine The 7.3 can be tuned to 430 HP but she would suck some gas in a big motor home.

[The_Breeze]

Originally Posted by Bob Denman

Common car sense...
If you happen to remember the Pontiac Trans Am SD455: They set it up so that redline upshifts (at the hp peak): landed you right on top of the torque peak in the next gear.
It made that car brutally fast!

Gears helped too (tranny and rear). The one strong point about auto's (back then) was you NEVER missed a gear unless you manually shifted and accidently slipped her into 'N'. The extra weight was a real 'drag' too (pun intended).

Now...find the right shift points in a consistent manner with a 4-speed, grabbing second and third along the way, and you were a boulevard bruiser That was also back in the days when candy canes were made of black rubber on a cool summer's night

[Bob Denman]

They shipped those cars with 3.42 cogs in the rear diff...

[Bill Johnson]

Originally Posted by MJC62

Awhile ago on here there was a long discussion about the new Ford 7.3 L V8.

I am wondering if anyone here has bought a new MH with the 7.3 that previously had the 6.8 V10 and can give us a users comparison of V10 versus V8.
The engine has been in service for a bit over a production year and I have an interest in what those who have had both think of the new V8.

We are kicking around getting another MH in the same basic configuration as our ACE 27.2 but on a heavier chassis Jayco builds basically the same coach, a 27A, on an 18000 lb chassis.

I had a Jayco class C with a GVWR of 14,500 with the V10 and now have a Thor 33.1 with V8 and a GVWR of 20,500 the V10 was quicker but there is a big difference in weight so it's not a fair comparison. Go test drive both engines in motorhomes that weigh approximately the same amount

[Chance]

The main reason for having “certified” engine power ratings is that they can be easily compared. The 2-valve V10 was 305 HP and 420 lb-ft (E-350 and E-450) and the latest 3-valve V10 was 320 HP and 460 lb-ft (F-53).

The new V8 is rated 350 HP and 468 lb-ft in heavy-duty truck and motorhome applications, which exceeds the V10.

The only exception is the new V8 with “Economy” tune which is rated lower than previous V10, but I have yet to see a single RV manufacturer select that “Economy” option.

[RVGUY45]

Originally Posted by Bob Denman

I get the impression that the V-8 is tuned for more low-end torque. It'll be a much better engine for RV usage; than the V-10 "screamer".

I have a V10 in a 30 ft class C towing a Honda Civic on a dolly and it never screams, just purrs happily along the highways of Canada