Shifting at 3100rpms?

AllanB · Jun 24, 2012

Just something that has made me curious for quite sometime. Why does the 6.4 shift out at about 1000rpms less than the 6.0 ? Don't get into a bunch of talk about camshafts. That isn't the answer I am looking for. What I am wondering is, what is the deal that International would build it to shift around 3100rpms and not higher? No problems with it, just curious. Might be a dumb question, so don't drag out the bash hammer on me.

09stroker · Jun 24, 2012

I would think cause the 6.4 makes decent power early with it's compounds.

AllanB · Jun 24, 2012

Yeah I thought about it being at its peak power at that point. But still had to ask as I am not sure that would be the answer. This is where the camshaft discussion will start lol.

AllanB · Jun 25, 2012

One last time, just to see if anyone else has any answers on this.

6.4psd916 · Jun 25, 2012

I know on my dyno runs, power falls off fast over about 3500rpms

Sequential6.4L · Jun 25, 2012

Im sure it just has to do with where the horsepower an torque are at, 6.0 is a peakier motor.. shifts up higher so when the rpm drops with the shift it doesnt fall out of the peak of the power curve.

AllanB · Jun 25, 2012

Sequential6.4L said:
Im sure it just has to do with where the horsepower an torque are at, 6.0 is a peakier motor.. shifts up higher so when the rpm drops with the shift it doesnt fall out of the peak of the power curve.

So what you are saying basically is, every motor design has a peak hp range somewhere in the rpm range and Navistar just installed specific tuning and trans to shift out at that rpm range?
I understood that the 6.0 and 6.4 were very different in rpm/hp shifting range. That was my question is why are they so different. What makes them make that peak power at such a different range? Not trying to drive ya crazy. I see a lot of names at the bottom of this page that I know these guys could answer this question. There are enough guys out there that have gone from a 6.0 to a 6.4 that I am sure are wondering the same thing. Hope curiousity doesn't kill the cat here lol.

Erikclaw · Jun 25, 2012

Here's my guess. Head flow, cam profile-duration etc, compression, valve size, fuel rail pressures, injectors. One is a common rail the 6.0 isn't. All this is what makes up power bands.

AllanB · Jun 25, 2012

That is more along the lines I was looking for. Thanks for the answers guys. I have noticed since I bought my 6.4 that it doesn't have the most aggressive sound. Hauls ass, just doesn't sound like it. I figured the fueling, compounds and camshaft had a lot to do with it. Just wasn't sure about what all it tool to make the peak power/rpm range.

AllanB · Jun 25, 2012

Now this 6.4 sounds pretty damn aggressive
http://www.youtube.com/watch?v=B4JXbhSvF-U

GROSSpolluter · Jun 25, 2012

Dude I think that thing was turning more rpms than a street bike LOL

blk350on20s · Jun 26, 2012

Jeremey(lubeowner) built that truck. Things awesome

Breaking Habits · Jun 26, 2012

Your lack of aggressive sound is also in that you have a second turbocharger calming the sound of your motor. Single Turbo 6.4 VS Single Turbo 6.0, both with non vgts, you'll know which one is more rowdy

Dustball8504 · Jun 26, 2012

Single turbo 6.4s sound nasty. So do non vgt 6.0s!

AllanB · Jun 26, 2012

blk350on20s said:
Jeremey(lubeowner) built that truck. Things awesome

:thumbup: to Jeremy, that thing sounds Badass. And I am sure it is.

Jared @ River City Diesel said:
Your lack of aggressive sound is also in that you have a second turbocharger calming the sound of your motor. Single Turbo 6.4 VS Single Turbo 6.0, both with non vgts, you'll know which one is more rowdy

You might have a point.
http://www.youtube.com/watch?v=dJPMarjTWNw&feature=related

Breaking Habits · Jun 26, 2012

AllanB said:
:thumbup: to Jeremy, that thing sounds Badass. And I am sure it is.

You might have a point.
http://www.youtube.com/watch?v=dJPMarjTWNw&feature=related

Precisely. A turbocharger acts as a resonator of sorts. Ever hear a straight piped triple turbo truck? calm sounding. only if they are in stages of course.

VGT's also do quite a big for calming out a lot of harshness and replacing it with a hairdryer sound.

Gotta love it.