Quote:
Originally Posted by MVF4Rrider
Well, you’re entitled to disagree but in this case you’re taking into consideration things outside of the real world, which is outside the context of this discussion. BTW, I meant to say quicker, not faster. Back on point: rear diff gear changes (shorter gearing) affect every gear at every rpm by the same exact % increase in multiplied torque to the pavement. Therefore it will make the car “quicker” in any gear and at any rpm when simply opening the throttle to increase the rate of acceleration and speed. It also enables the engine to reach terminal speed quicker in each gear, which is an advantage. Now, when including constraints such as closed circuits, 0-60 times, ¼ mile times, etc. the gearing change could have adverse affects IF and only IF an additional gear change is required. But I don’t live in a world where that matters so I’ll take the constant % increase of multiplied torque and enjoy the quicker acceleration under every conceivable real world condition. Again, stepping up 1 gear ratio is not going to lend itself to adverse affects comparatively. Going too short on the final drive could. I don’t advocate radical gear changes.
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Sorry you are sorely mistaken here. Did you bother the read the extensive thread and debate I mentioned? It appears not. Please have a look
here. You are arguing that a diff change can and typically will make this modded car accelerate better under any conceivable real world situation than the stock car. Hmmm, this leads to a fairly obvious logical contradiction. Why not just run an infinite (or absolutely enormous FD ratio)? Seriously think about what a car would do if given a FD say 3 times as large as its existing one. Sure it will be producing enormous rear wheel torque and thrust but again there is no such thing as a free lunch. Will it out accelerate the unmodified car by 3 times across any meaningful range? How many gears would it need to reach a similar top speed (or even a similar high track or crusing speed)? How many gear changes would be involved and how often would they occur? This exact same reasoning along with the prior point I made will occur even with a slightly modified FD ratio, just to a lesser extent. You really need to think this problem through more carefully and holistically. You must compare the cars ACROSS shifts not in the very limited case of the results in one gear only. The acceleration difference between first and second gear is nearly 50% different in the M3 (less difference between successive gears of course). Do you claim that spending a half second or so (maybe more, maybe less depending on how large of a change to the FD ratio one made) would not impact in a very significant way any measure of acceleration where a 1-2 shift is involved?
I absolutely am not claiming that FD ratios are fully optimized in all sporty cars, I am also not claiming that some metrics can not be improved with FD modifications. I am not claiming that modding your FD won't make your call FEEL a bit faster. However, I am vehemently arguing, in the case of the M3 ,there is little to nothing to be gained in most real world acceleration metrics through a FD mod. The benefits of either 7 gears and DCT vs. 6 or even a few percent hp increase will trump what you would get from any reasonable FD mod.
Really, think very carefully about what a huge FD modification would mean. Also think carefully about an acceleration run involving multiple gears and the disadvantage of spending more time in gears offering less torque. There is no such thing as a free lunch here.