Why does a 6.9 sound different than a 7.3?

[Ironman03R]

Having never owned a 6.9 until now, I've never really been around them but I've noticed on the ones that I have heard that the sound different when they run, Kinda a higher pich w/o the loud rattle. Having 7.3's around me most of my life it seems they have a lower tone and more noticable rattle.
I'm not talking about exhaust, but the sound of the engine while your standing infront of it. Last night I had 2 7.3's runnin one turbo one NA and the 6.9 turbo, the 7.3's sound identical(one 91 one 94)
Does the comp ratio make that much difference or are the 6.9's timed different? Or is the timing just retarded on every 6.9 I've ever heard run?

 

[92F350CC]

Might be the valve/rocker differences.

 

[Russ]

I would think it would be different timing. The sound of the engine can change a lot just by adjusting the timing.

 

[hesutton]

I would think it would be different timing. The sound of the engine can change a lot just by adjusting the timing.

Bingo! That can make a big difference. Just think about how different the your 7.3 sounds with the cold start advance on vs. with it off.

Heath

 

[6 Nebraska IDIs]

Really there are allot of things that could possibly make it sound different. Say like what's already been mentioned, rocker arms (valve train is one of the noisiest parts of an engine), timing, compression ratio, injector rattle, differenced in rotating assemblies (such as the 6.9 uses smaller wrist pins in the pistons), and flywheel (Most 7.3's run the Valeo dual mass flywheel which is noisy in its own way, and 6.9's used solid mass flywheels).
My personal experience with them is that I can always tell when a 6.9 resides under the hood, or a 7.3 without even looking at it. Why I dont know, I just can. Personally I think the 6.9s are "friendlier" sounding than the 7.3's. We just finished installing a 6.9 into my moms 94 factory turbo truck, timed it at the same spot the 7.3 was at, has the DMF on it just like the 7.3, and I can still tell by the sound its a 6.9. Like I said, I honestly dont know why, I just can.

 

[Agnem]

I have both, and they sound the same. But then I timed them both. There isn't really enough of a difference for them to sound different. If there is a difference, it is in the slight retraction of the injector from the pre-cup on the 7.3, or perhaps the accessory arrangement, belts, etc.

 

[FordGuy100]

I've noticed that to....I can tell there is a difference when idling between a 6.9 and a 7.3.

....And its obvious that 6.9's sound better....

 

[Ironman03R]

I guess I'm not the only one that has noticed it then. Like I said until now I've never owned a running one!
Does the 7.3 rev higher? Seems this engine dont wind out like the 94, but it smokes about 2x as much, and I'm maxed out on fuel in the 94.

 

[Diesel JD]

I've thought the 6.9s had a tinnier sound. I always assumed it was the rocker arms, maybe its not. Timing should be the same.

 

[82F100SWB]

Stock, the 7.3 pump does have a higher governor setting. I believe around 3700 or so, I know that's what my 6.9 would turn when it still had a working tach, and it has a pump built for a 91 7.3, and a few others I've been around run the same rpm... I never actually ran my 6.9 with a 6.9 pump...