We may need to mark this day down in the history books as it's probably the first time I've ever publically agreed with you on something - I love my 3.42s and would never consider getting rid of them even if somebody were to offer up empirical evidence I could actually run faster in the quarter mile using a different gearset. The purpose of my post was simply to set people's expectations accordingly, in that particular swap doesn't really affect the car's bottom line performance numbers all that much.

I've also spoken to Spin a few times on the phone about my car and I can take credit that if he ever decides to buy an A6 it'll be because of what I've done with mine. (Spin, if you happen to read this and I've misquoted you in any way please feel free to set the record straight. )

I do however disagree (see, I knew the good times wouldn't last) with what you said regarding my results being not applicable. While it's true that different cars will certainly yield different results, I was providing a benchmark to illustrate the difference on the same car in the same conditions in the same application.

If I only saw a difference of slightly over a tenth in the quarter mile with my setup, the average person can use that to reasonably conclude the type of gains they'd likely see in relation to their power level. As an example, a twin turbo setup might see as much as two tenths at the track whereas somebody with a lightly modded LS2 or LS3 might see slightly under a tenth. It was just to establish a frame of reference, that's all.

 

Thank you.

Realize that if every customer was a quarter mile/dyno guy, I would have to evaluate each case differently. (and I think SPIN would also AGREE)
that the best foundation for just about ANY application - including RACING is a lower than stock Diff ratio.

Not unlike a converter, it permits you to operate at a higher rpm and stay in your "power window" better.

I'm sure we'll both agree, just about ANY Vette with gears will be more fun on the street than without them. Most guys that made the switch
to a lower ratio, would NEVER switch back.

Chuck CoW

 

Actually, in a Wot situation, the rear gear has no effect on the.operating rpm range of the engine. The rpm drop between shifts is consistent no matter what ratio is in the differential. That's determined by the ratios in the transmission.

 

How much the RPMs drop between shifts is actually dictated by the stall speed of the converter and is called "shift extension".

 

My car felt totally anemic with 2.56s compared to 3.42s and here's another piece of info you might find useful:

Based on those same set of scans I was able to calculate the difference in 0-60MPH times which a lot of people out there can relate to.

With the 2.56s the average 0-60 time was 2.906 seconds and with the 3.42s it 2.594. This data was obtained by looking at the average across several different scans, all with a good clean launch.

 

My point is the rear differential ratio has no effect on this.

 

Hey Chuck, you may have noticed the 'lil factoid I posted earlier about the ZR1's mufflers necking the 3" pipe down to 2 1/2" at the inlet, and that just got me wondering about something you might know or could easily find out. Do you know if there are any other such "irregularities" on say a GS Vert/Auto/Heritage Pkg (looking at an '11 w/out F55, so I'm still scratchin' m'head 'bout THAT gal)? Or for that matter, ANY of the other '10-'11 models choked up like that? Actually, now that I think of it, I've also been looking at a relatively cheap, low mi '09 ZO6, & I wonder if that one suffers from the same ***-phixia as the ZR1? I will be changing the gears on whatever C6 I end up with though, too.

Best regards,
...z

 

Well, for instance.... If you have ANY C6Z or NPP system you'll notice that even if it's got a full 3" system from front to back, the pipe is swedged down to 2.5" going into the mufflers...

All of them are like that.
Chuck CoW