Believe it or not I was actually considering 4.10 a while back... then I rode in a C5 with 4.10s behind an A4 and a Magnaflow exhaust. At 75mph I felt like my head was in a tuba. That is when I came to the conclusion that 4.10s on a 928 with a 4L60E swap would be downright crazy.

There is a part of me that wants to make this a Saturday-night special at the Sonoma drags (err that would actually be a Wednesday night special now that I look at the schedule). Of course I would get laid to waste by LS swaps out there, but it would still be fun.

It is a restomod afterall.

 

ok variant analysis:
yes, in each gear, you are correct but you are not taking into account the losses you would have post shift.

after C5 box shifts, you have a 35% loss of torque to the wheels for a proportional period of time
then at the next shift, you have a 32% loss of torque for a proportional period of time. its a trade off... cat and mouse .... besides the launch, you need to look at this. look at the optimal speed ranges for YOU ... see if that coincides with the new gear ratios or not. on the track , its easy. plug in the HP available, speeds desired for all straights and you do some quick averaging and get the optimal gear box set of ratios.

Most people, like Jim, seem to discount the FULL picture. its a series of trade offs with gearing. the easiest way to see this is mapping out the thrust curves, were you can see them clearly OR, just do what i did and multiply this out and see what you got. keep in mind at the higher speeds, those trade offs are much more critical, as the application of hp becomes more speed dependent to optimize.

so, in the end, at say , terminal velocity, both cars with different ratios should just as quick as one another. (pick a terminal speed that doesn't favor one or the other) this is why, there was not much difference between even 0-60 tests of the S4 with the different gear box variations 0-60 in itself will have to favor one or the other, but usually , it doesnt and if it does, the differences are very small

 

Given the almost universal measures of performance are 0-60MPH or 0-100 MPH or 1/4 mile time....that is what people are interested in. Racing from 50 to 100 ?? Who really cares ?

 

if you start thinking of the gear box as a HP optimizaer rather than a power gainer, you will make the right choise for your goals.

the reason there is so much confusion, is that there are two factors. the numerica ratio numbers that folks get so excited about "hey, i have 4:11 gears!" and the fact that the end ratio is made up of another number that no one talks about, and the result is the final ratio.

I remmber racing my C5 corvette buddy for a number of years and one time he changed his ratios from a 3.73 to the 3.90.. he then asked me what my rear end was and i said..... "oh, its 2.2". his jaw dropped... it didnt make any sense how we could drag down the straights and almost matching shift points.
I explained the concepts and he was good! his change did help him by the way.... because it optimized his RPM to the most HP down the longest straight.
what really gave me problems , was when he put the cams in it and started making 390rwhp and i only had 320...... that was tough to overcome, but we were always very close.

 

knowledge is king.... just because we use the Imperial measuring system, does it matter if its an inch or a cm? the analogy is that we need some baselines and the smart guys take all into account. weight, aero, power, 4x4, etc.
no one buys cars strictly by a 0-60 number.
people do race on the streets or compare their cars where they are most optimal. and by the way, 0-100 is good enough because most of the cars dont have drag radials and are drivin by magazine drivers. So, in the end, it washes out the advantages of the high reduction rear ends and the result is a general idea of how good the package runs for the majority of the speed ranges.
1/4mile, 0-100, near the same for 300-400hp cars.... they dont change much with different gear ratio packages jim, due to the tradeoffs that i mention.
i think our own cars have the same 1/4 mile time with a 2.2 vs a 2.64.... heck,i think its the same for 0-60 or 0-100Km/h too.... why is that??

gears dont develop power, they only optimize over any speed range.

 

Gears multiply, or divide, torque, which is force, which is what makes the car accelerate. F=ma. God, and Newton, said so.