Bingo give that man a cigar. I could not agree more. Once you install a good high stall converter. Gears are not as important, the converter will put you instantly into the power band where your engine is making good power when you go WOT.

 

Understood on the converter. BUT I think I read a post where Subfloor admitted that without the gears he could see the possibilty of a slushy feel on the street. Correct me if I'm wrong Sub.

Haljensen Thanks for the link to the calculator! Is there a formula to calculate how it affects drive ratio?

I know that the 17 is a bit narrower giving up traction to the 18s but I dont think Im at that power level. Though they are narrower by .5 to the stocks the R compound should be stickier than what I got now.. I think.

 

To join the chorus, once you have a high stall, the gains from gears are small. 3.15s should be enough to get the OP into the 11s since he is stock stall.

I don't see a conflict here.
His point was that 18" provides more sidewall and flexibility than a 19" tire and you can get an R-compound tire that will have good handling aspects and substantially improve straight line performance. If all you want is straight line, I doubt he'd argue about using 17" and getting some serious wrinkle capability with an even larger sidewall.

FWIW on the F-body, my experience is similar to yours. Nitto DRs on 16" worked better than guys with 17" rims despite the 17" rims having a wider footprint. Sidewall flex trumps size.

 

If I'm at 12.1 in the qtr now w/Invos .. In your opinions how "into" the 11s do you think gears and say 18' DR will get me? (stock stall A6)

And thanks again to all who have taken the time to write.

 

A converter overlaps gears in the function of getting you to a higher rpm faster where you make more HP. A car with a higher stall gets to a higher rpm faster as does steeper gears because of this overlap. If you arent getting a converter then steeper gears will make have a much greater effect since the converter wont get you to the higher rpm faster and it would be the gears only that do this for you. A mix of the two wold likely feel best as far as loosness of the converter and the steep gear pull. Guys with 3200 stalls say it doesnt feel loose but its not like stock having driven a few with both gears and converter. I believe Subfloor's position about the effectiveness of gears being lower as the stall gets bigger.

As far as the higher MPH car, thats not true.

If two cars with the same power run at the drag track or on the street from a dig, the car with the lower ET is always in front. On the street you dont roll your window down and ask the other driver what his speedo says.

Car 1: 10.8 1/4 mile with a 128 trap speed
Car 2: 11.8 with a 138 traps speed-I've seen this

At the drag track or on the street, the car with the faster ET will always be in front and will appear to both cars to have won the race. You lose on the street too when the other car is ahead of you not by what your speedo says.

Now on a 50-150 roll, the thing that makes the nigher MPH car slower is eliminated and it has nothing to do with gears. In fact, the higher MPG car will always be in front because he has traction.

The gears make you wind faster and lowers your 60' and thats why they get you a faster MPH but it wont overcome having more HP.

The lesson learned here is to match the tire to the power and application. Dont run runflats with 3.42's, 3200 stall and 10psi s/c kits.

Good luck with the mods.

 

A true statesman; giving hope to the Honda crowd.


I know its just a typo.

 

SgtRod; Haven't seen a calculator online for how gear ratio or tire size changes affect performance.

To calculate gear ratio differences is simple math; original gear ratio minus new gear ratio = Difference. The difference divided by original ratio = % of difference.

ie. 3.42 to 3.15 = 0.27
0.27 divided by 3.42 = 7.9% difference (rounded)
Doesn't mean there is a 7.9% performance difference, just a ratio difference.

Same with tire size;

ie. 26.85" stock to 25.66" 17' drag = 1.19" difference
1.19 divided by 26.85 = 4.4% difference (rounded)
Same disclaimer; doesn't mean a 4.4% performance difference, just a diameter difference.

So many possible combinations of tire and gear that it would take me HOURS to calculate. Tire from a short 16" to a tall 20" and ratios from a 2.56 stock A6 to a 4.56 available aftermarket.

Then try to calculate the difference between stall convertors, peak torque/peak HP, under the curve usable TQ/HP, etc and you have a lifetime job.

 

Thanks Spin, I knew that ET means you win at the track/dig so by the street I meant on a roll 50-1xx. After racing at the track, a dig on the block isn't as fun. I know your an advocate of gears. So my question is from a 50 roll, will a 315 geared car beat a 256 (equal hp)geared car to 150mph? Considerably or by a bumper?

All scenarios are hypathetical and in no way agree with street racing.

 

No way Budy! I just thought that there might be an existing chart that could be used. You never know with computers now a days.

Yeah, my brain hurt just reading this last part.

 

I’m running OEM C5 Z06 fronts but the thing you need to know about repros is that they’re typically a lot heavier than stock rims. Between the lightweight rims and the Hoosiers it’s amazing how light my setup actually is.

 

Yes, that is correct as the general rule of thumb is that in order to maintain decent drivability you should change your gear ratio as you change your stall speed.

With that said however, I put a Yank SS3600 in my buddy's car while it still only had 2.56 gears and we were both very surprised at how well it still drove and it wasn't until you put your foot into it that you even knew it had a converter.