I was trying to keep it simple. es the longer stroke has faster piston speed in the bore, but overall the combination of long stroke vs short stroke crankshafts there will be more miles put on the pistons with the short stroke since your having to spin it faster to move the same volume of air as a long stroke....i was trying to keep it simple for the herd to grasp the concept.

Obviously you need to read more V10 towing threads, bragging about holding the engine at 4000-4500 rpm when towing hills is "normal", "that's what they like" I've got this picture of my V10 junker and the mechanic that swapped engines for me telling me of all the mod motors that they change engines in with broken valves that this was not a fluke deal, it's common amoungst them....just what i was told, and since he's a master tech/certified in a real life dealership i tend to believe what he has to say.

Oh, before the goons start trying to throw "the inside of your engine was dirty, you dont take care of your stuff" the valve cover was taken off while still in the truck, and just set outside once they pulled it and the neighbors cottonwood tree was spewing crap that stuck to it, but the way the V10 lovers are, it'll prolly still be my fault the valve broke

 

Where I work (police) we have 60-100 Ford Vics. They are not babied, trust me. And I talk to our mechanice all the time. The modular motors have no trouble bouncing off the limiter. And they do.
The odd one has trouble but I haven't seen an engine failure in years. But the cars are only kept for about 60-80K.
But I do not spin my V10 at 4500. If I go up a hill at 3500 at 80kmh thats fast enough for me.
My old 460's never went that fast anyway.

 

That's interesting, because we can go back years here in the V10 forum, or the 4.6/5.4 forum, and there are no (hardly, almost none, etc) reports of broken valves.

Spit plugs? Plenty.

 

This debate about low RPM torque vs high RPM power is confusing me. Conventinal wisdom as I have heard it, was that an "over square" motor - one with bore larger than the stroke is a high RPM motor and an "under square" motor - with the stroke bigger than the bore is a low RPM torquer.

Now the 460 has a bore and stroke of 4.36X3.85. Decidely over square. The V10 has a bore and stroke of 3.55X4.16. Definatly under square.

Why is the 460 considered a low RPM torque motor and the V10 cast as the high RPM motor?

 

hmm? Interesting point.

I would venture to say the cam and heads of these motors play a big role in its high or low rpm abilities and characteristics.

 

https://www.ford-trucks.com/forums/5...ve-spring.html

I guess I've never understood entirely why one would need to rev this engine much past 3250rpm. Isn't that where peak torque would have been? If so, I don't consider that revving the snot out of the engine. My old 300cid I6 w/ Mazda 5spd manual, produced all of its torque long before 2200rpm and there was nothing to be gained from going much beyond that. It saw 3000rpm shifts aplenty though and it lasted well after the 267,000 miles when I sold it.

I love my engine/trans combo for what I bought it for. I will say that when loaded up to a GCVW of 11,820lbs I thought there could've been more grunt while hitting the switchbacks in the mountains of the Finger Lakes in NY. Don't get me wrong, I had a blast driving the truck up there, just thought maybe there could've been more ooomph from the motor.

And on the issue of revving this motor. I read many an article in a few of the truck magazines back when this motor (6.8L) was being developed and the concern from some engineers was putting a high revving motor in a truck. I know I was hit on this before about an overhead cam engine not being any different than a pushrod engine. As I thought I remembered it from those articles, that an overhead cam engine produces its torque and HP at a higher rpm than a pushrod engine. And perhaps my confusion lay with the short stroke/long stroke/piston speed stuff. But the bottom line is this. One which I firmly believe. Hi rpms, whether an engine is designed for it or not, will make more heat quicker than a similar engine spinning slower given the same speed of the vehicle driven. I believe it is this higher, prolonged heat to the internals that may, over time have a detrimental affect on any one component.

Again, having said all that, I do like my motor. It's unique, it more than suits my needs, I'll always want more power from what I'm driving no matter what. And I won't be spinning this thing into the stratosphere to get where I'm going. About the only real thing I've absolutely hated about my engine though is the (what I consider to be) excessive oil consumption.

I enjoy my V10 powered truck, I'm a supporter of the V10 through thick and thin. I've owned it and towed with it for 62,000 miles so I'm educated on its capabilities, it limitations, its pros and it cons.

Enjoy,
RustyFuryIII

 

The point of revving the motor higher is so you can stay in a lower tranny gear - putting more torque to the ground.

The V10 has a very flat torque curve. The 2-valve develops 80% of it's peak torque at only 1000RPM, at least according to the torque curve in the Ford brochure. Not sure what a 2-valve PI-head V10 actually does on a dyno.

It's also missing 45 cubes compared to a 460.

Also, the big difference between OHC and pushrods is, you can make the ramps on the cam much more radical, because you're not pushing a big lifter, AND pushrod around, as well as use a smaller valve spring because you don't have the inertia of the lifter and pushrod to counteract. Overall, less power lost through big valve springs and heavy lifter/pushrod.

But this has been gone over again and again and again until we're all blue in the face

 

Hi Krewat,

"The point of revving the motor higher is so you can stay in a lower tranny gear - putting more torque to the ground."

I get that, the revving thing, and that's why I love my 6spd manual, I get to select the gear! Guess I should've been more specific though. Some have mentioned revving this motor up around 4500rpm. That's up there as far as I'm concerned, I would have thought the 3 valve V10 had reached peak torque around 3250rpm, and the need to go higher was moot; I thought it (the torque) fell off from there.

"Also, the big difference between OHC and pushrods is, you can make the ramps on the cam much more radical, because you're not pushing a big lifter, AND pushrod around, as well as use a smaller valve spring because you don't have the inertia of the lifter and pushrod to counteract. Overall, less power lost through big valve springs and heavy lifter/pushrod."

Cool, not something I was educated on. Although I had always been led to understand that a typical OHC engine is a higher reving engine vs a pushrod engine. Just never fully understood the reason why it could or would. If that info has been around on this site for awhile, I apologize, I haven't read every post when these debates come up.

Do the cams in our 6.8L OHC V10s utilize a cam shaft with a slightly more radical cam lobe or ramp?

Enjoy,
RustyFuryIII

 

Yes, it falls off, but how much? There's still plenty of usable torque way up past the peak. You don't just sit at the peak torque all day, you need to rev the engine both lower than the peak, and higher than the peak.

If you're putting out 80% of the peak torque, at lets say, 4800RPM, which is probably within the ballpark given a 3-valve, and you're holding a lower gear that puts that much more torque to the ground as the next gear, then, it's a win.

Let's say the next gear would bring it down to the peak of 3250RPM.

So, the next gear is 67% of the torque to the ground. That's a drop of 33%. If you only lose 20% of the peak torque at 4800RPM, holding that higher gear will give you more torque to the ground than it would to shift up and drop the RPMs (and engine torque) to whatever it is as 3250RPM.


That's just something generally known about overhead-cam engines. It amounts to a little more rotating weight because of two cams, but the cams themselves don't have to be as heavy because they aren't fighting all the extra inertia of a pushrod valvetrain.


Can't really say, but I believe all the Ford modulars do have "better" open and close ramps than a pushrod motor would.

And even if not, there is a lot more wasted energy pushing around a lifter and pushrod and heavier valve spring.

 

I have a P71 vic that sees the rev limiter daily and a V10 E350 that tows 12-18K all the time. I have never had a problem.

 

Sorry, but the V10 has a longer stroke than the 460 and even the rods are same (actually V10 minutely larger), only the bore is smaller because there is 2 more pistons and less cubes overall.

Again the V10 does not have a smaller stroke.

The V10 makes a really high percentage of power down low too. It just has a wider powerband than a stock 460.


Thats one he11 of an opinion and far from FACT. I spent the last year looking for a SD and I can say it was a FACT that there were fewer V10 engines out there than any other choice. Why? Well I asked my dealer actually... what he said was that folks thought the V10 was a gas hog compared to the V8. Which it is but the difference between the 8 and 10 often isnt much especially when hauling. Most folks that are really working the truck as you say, tend to go diesel and it seems the dealers push that way too, so you'll see a lot more diesels on the lot that V10. True the dealers have having poorer sales than ever right now, but that isnt anything to do with the V10 inparticular except for those that think they will get better mpg with the 5.4 or 6.4.

And for you soccer dad anology, well its true more folks are driving trucks lately (well at least up until a few years ago when gas hit $5) but those folks are mainly driving F150s. The few that drive SD's that dont really need the towing power are typically getting 5.4's at least around here... Its true ford is making the truck more cadillac like now-a-days, but they are also larger, heavier, more powerfull, and more capable, then ever, period. Persoally I'm not into the cushy trucks myself either... you wont find much fancy stuff in my 09 XL, just one of the toughest trucks for has ever made.

 

I have towed the same loads on the same hills with both a 4bbl 460 and a 2v V10, and the v10 wins hands down.

 

I towed our 7,000lb 24' TT over the 6% hills on I-10 in between Junction and San Antonio recently. Kept the motor around 3,000 - 3250 rpm and rolled up the hills at 65mph. Quiet and smooth - DW and the DD's didn't even notice any engine noise. Pulling uphill at 65mph in an 80mph zone with people overtaking at 85mph gives me more driving comfort than going up at 55mph with my foot nearly on the floor in the old truck. I love this 3v motor.

-V

 

so was the old truck you are comparing to a 2V V10 or a 460?
were in Texas is the speed limit 80? I have never seen it higher than 70 and thought that was as high as it got.

 

A little bit West of San Antonio,it jumps up to 80 on the interstate. There's nothing out there.......
JL