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‘13 Challenger SRT 6M
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Discussion Starter #1
How come the tach in my 392 starts the "redline" at 6200 rpm but in all the specs I read about this motor it says it has a 6400 rpm redline? Which is it?


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6600 when you tune it... stock is 6400.
 

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I've only just got past the 500 mile break in, but when I got on it the other day it seemed to be shifting at 6,000 when I had it in drive. I put it in sport mode and shifted myself and I think I got 6,200 out of it. I kind of expected it to hold gear until 6,200 when in drive.
 

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I've only just got past the 500 mile break in, but when I got on it the other day it seemed to be shifting at 6,000 when I had it in drive. I put it in sport mode and shifted myself and I think I got 6,200 out of it. I kind of expected it to hold gear until 6,200 when in drive.
It may with more miles / adaptives in it. 1st to 2nd shifts a little earlier than 2nd to 3rd Mine shifts in sport mode "D" at 6400 but that is with the shift points raised and rev limiter set to 6600.
 

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rev limiter is the same as far as I know. 6400 RPM unless raised with a tuner/tune.
 

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Discussion Starter #7
I understand all of this. But my question is why does the gauge show one limit and the performance data shows another? It's not a big deal, it's just an inconsistency I don't understand and wish too.


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perhaps the slight delay from motor to display. I would assume the tach is behind the motor by a number of hundredths of a sec ( exactly how many I don't know) You press the gas the motor reacts, the tach then reacts to the motor. If the tach reads 6000 the motor is probably a little higher as your still on the gas. Maybe the do it to keep you from going over accidently. This is just a guess, I know about as much as you, just trying to put some logic into it..lol.
 
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I understand all of this. But my question is why does the gauge show one limit and the performance data shows another? It's not a big deal, it's just an inconsistency I don't understand and wish too.


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Maybe the 6200 is where the autos shift stock... I've never logged a stock tune run to see where it shifts but it probably is a couple hundred less than red line which would be 6200.
 
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perhaps the slight delay from motor to display. I would assume the tach is behind the motor by a number of hundredths of a sec ( exactly how many I don't know) You press the gas the motor reacts, the tach then reacts to the motor. If the tach reads 6000 the motor is probably a little higher as your still on the gas. Maybe the do it to keep you from going over accidently. This is just a guess, I know about as much as you, just trying to put some logic into it..lol.
Whenever I am racing I always keep the pedal to the floor and make sure I see the tach hit 6k, then I shift as fast as I can knowing I'm close to the redline/cutoff(because I do agree that the analog gauge has to lag the actual number slightly) but I have never hit it or noticed a fuel cut off.
 

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Discussion Starter #14
Possible... Not just Edmonds though. I know sometimes the fuel cut off and rpm limiter get posted depending on the source... I have a 200rpm gap between limiter and fuel cut. That's why I asked.


Edit. Like this...
http://www.edmunds.com/jeep/grand-cherokee/2012/road-test-specs1.html
Fuel cutoff listed as 6400, rev limiter 6200.
I checked out that link. Interesting I never saw something like that. Why do you think they do that? Just wondering.


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Hopefully someone with more knowledge can chime in. I just know my car had a 6000rom limiter and 6200 fuel cut stock (I noticed the rev limiter was listed as 6k in most places and 6200 in others)... When I raised it the new numbers were 6600 rev and 6800 fuel cut. Has something to do with over rev and should be kept a few hundred rpm apart but exactly how it comes together I don't know.
 

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I did some reading on the HP Tuners software and I think I have it sort of figured out.


Rev limiter = Fuel Cutoff
This is to prevent engine damage, newer vehicles can also close the throttle plate.

Shift points / listed as rev limiter (observed per edmunds) accounts for the delay in shifting to prevent the engine from reaching the fuel cutoff.

I'll keep reading in case I screwed that up but that's what I've gathered so far.
 
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