08 C6 shift RPM's to high?

BAIN · 07-09-2009, 01:52 PM

I did a couple of logs from the stock tune and the new "tranny tune". It looks like the torque management and the drop in timing (it would pull 13-20* of timing on the shifts) has been fixed with the new tune

One thing I did notice in the logs of the stock and tuned is that the shift rpm was higher than I expected. I didn't touch the shiftpoints from stock tune so I checked the shift rpm on the stock tune and noticed it was calling for 6400 rpm on the 1-2, 2-3 and 6300 rpm on 3-4, 4-5. Is it supposed to be that high?

WhiteLightning_ · 07-09-2009, 02:00 PM

i shift at 6700-6800.. if you take a look at your dyno in a stock cammed ls3. i peak at 416 rwhp and by 6800 im down to 400ish rwhp.. but if i shift at 6400 i drop down to 330ish rwhp in the next gear. Hold it to 6800 and then shifting im higher in my HP and TQ band. i tested his just playing around on the road and the difference relative to shifting at 6400ish was drastic for just a few hundred rpm.

BAIN · 07-09-2009, 02:12 PM

Are these motors designed to rev to 6800 without having issues with valve springs and rod bolts stock? I know the LS1's are not. What rpm did your hp peak?

WhiteLightning_ · 07-09-2009, 02:23 PM

peaked around 5800.. and slowly tapered off to 400ish by 6600/6700.
shifting at 6k would drop me from 414 rwhp to 325 rwhp.. shifting at 6700 drops me from 400 rwhp to 360/370 rwhp so the average power and TQ through the range is higher.
can they live at 6700 with stock valvesprings? i wouldnt be there every single day all the time.. but in normal spiritied driving i normally shift it well below 6k.. just driving around around time.. much lower then even that.

but for occasional jaunts.. sure..

pmj341 · 07-09-2009, 03:41 PM

the shifts are controlled by mph at wot, not rpm!!

thesubfloor · 07-09-2009, 05:20 PM

Quote:

Originally Posted by pmj341

the shifts are controlled by mph at wot, not rpm!!

Yep, unfortunately that's how it works which makes getting it properly dialed in somewhat frustrating at times.

BAIN · 07-09-2009, 07:48 PM

Quote:

Originally Posted by thesubfloor

Yep, unfortunately that's how it works which makes getting it properly dialed in somewhat frustrating at times.

So I should lower my mph until I get the shifts to occur at the rpm desired?

thesubfloor · 07-09-2009, 07:58 PM

Quote:

Originally Posted by BAIN

So I should lower my mph until I get the shifts to occur at the rpm desired?

Yes, but you also need to make sure you have the correct tire size and gear ratio in your tune first or else it won’t respond to MPH adjustments either.

As an example, last night at the track I wanted to lower my 2-3 shift by a few hundred RPM so I dropped the MPH value a bit but the shift point still didn’t change. What ended up causing that was because I was running a smaller drag radial but forgot the make the adjustment in my tune so even though I wanted it to shift at 53MPH it kept on shifting at 58MPH.

Once you do get those values entered correctly the car will shift based on MPH adjustments.

Christopher