I noticed for the first time yesterday - my tach has no redline; noted when pulling up hill, at 3500 RPMs.
I'm not asking what's max torque/hp, but engines max before destruction (if not electronically limited).

2002 F250, V10.

 

My 08's tach I believe goes to 6k without a redline indication (red marks). Would assume past that range would be self destruction time.


People seem to say running it at 4000-4500rpms is not an issue. I've been at those rpms pulling heavy loads up a hill but try not to be there too often otherwise.

 

I'm pretty sure the RPM limiter will kick in when you reach the actual redline. Most modern vehicles have a rev-limiter, so the old marked redline on the tach is useless.

 

The only thing I've ever consistently hit the rev limiter on was a 2004 Suzuki GSXR-600. All my buddies had 750's or 1000's and I had to crank that sucker up to 10,000-12,000 rpms to get moving. Ha.

Can't imagine hitting the rev limiter on my truck.

 

I did that math a while back and determined that the redline on the V10 is ~5200rpm.

I probably need to dig up my paperwork (or just work it all out again) to be sure I have that number right.

 

I never noticed it missing; now I can't believe that they didn't mark it. Good thing I drive like a grandpa and stay out of it.

So at what point does the rev limiter cut in?

 

I've wondered the same thing but with an automatic transmission behind my 06 v10 I very much doubt that the rev limiter could be activated unless you locked it in A low gear.
The max I have ever seen my 3v v10 turn was very close to 5000rpm pulling 14 tons of hay going up a short but very steep grade I had to see what the v10 could do. Only did that once but boy did it pull!

 

My 09 has a rev limiter, I've only hit it a couple times I've raced a buddy here leaving work. I thought it was either 5500 or 6000 but its been a couple years. I know it will go over 5000 ok.

 

I don't know what I did with my original paperwork, but here's how I figured my ~5200rpm number.

The physics behind a redline has to do with the mass that's flying around inside the engine. Rev it too high, and bad things start to happen.

The metric I've most often seen referenced when determining a redline is "feet per minute", which is the total distance an individual piston travels as it's going up and down.

The feet per minute maximum for a typical street engine is 3500-4000. A "modified" race-oriented street engine is somewhere in the 4000-4500 realm. And a full on race engine is 5000, maybe a bit more.

(Someone's going to ask where I got these numbers I'm sure. I don't specifically recall, but they do stick in my mind.)

For the 6.8L V10, I used a 3700 feet per minute figure.

3700 feet per minute = 44,400 inches per minute
V10 stroke ==> 4.125 inches
1 revolution = 1 up stroke + 1 down stroke = 8.25 inches

44,400 inches per minute / 8.25 inches per revolution = 5381 revolutions per minute

I have no problems letting my engine go to 5000rpm. I've been at that point, though I try not to do it too often. I won't let it go beyond that, though.

 

Maybe I misunderstood your math, but I can tell you with all certainty a V10 will reach 6,000 rpms. I don't recommend it, but mine has done it a couple times for giggles. Also not sure where you get the "modified street engine" and "full on race engine" figures from but my flat-tappet cam mild 302 in my '68 Mustang will pull to 6,000 with ease and the roller cam motor (stock) in my old '88 Mustang would easily hit 6,800. I didn't even need to break out my calculator for that

 

What's the stroke in the two engines you refer to?

 

I have my rev limiter set to 5,300 RPM and it shifts at wide open throttle at 5,000 RPM, this happens many times a day when i'm driving.

 

For gas mileage I try and keep mine at/below 2,000. I'm pretty good at that (flat-lander country) unless I'm pulling my camper; there I strive for under 3,000 RPMs.

Those noted 3,500 RPMs (pulling w/cruise control engaged) just sounded angry to my ears.

 

The destruction RPM is above what the PCM will allow the engine to run. There is a rev limiter that will turn off the injectors at the set point. No, I don't know the specific RPM for a 2002 V10.

 

There's an easy way to find out. The limit is set at a still-safe RPM, so put the pedal to the metal and see where it stops.