[MVF4Rrider]

Originally Posted by swamp2

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.

Sigh

How frustrating when trying to educate the masses. You clearly don't understand the concept of multiplied torque, as you cite "% additional HP" as an actual variable. You probably think the same car at 3,000 rpm in 2nd gear is putting down the same torque to the pavement as the same car at 3,000 rpms in 4th gear. Why not, right? It's the same rpm and therefore the torque would be equal.

Do you understand that a one-step change in FD equals an 8% increase in total torque across the entire rev counter (every single rpm) in each and every gear? Can you not realize how much additional power that is, and that it would cause the car to reach terminal velocity in each gear quicker as the revs build quicker. You think this additional multiplied torque (essentially - total torque) increase has a negative affect on performance? This is not a radical example requiring dozens of gears as you say. It is a moderate increase that makes a real acceleration change, not a perceived one. It makes the power band more usable in both normal driving situations and in spirited driving. In every day, the 8% increase in torque means you can use less rpms per gear to yield the same rate of acceleration you enjoy. Or when you opt to put your foot in it the throttle response is more crisp and acceleration is quicker. It is IMPOSSIBLE to have more applied torque (at a mere 8%) and for acceleration in a given gear to be less, or even equal. That doesn’t mean I’m ignoring gear changes and that affect on real driving. I can assure you no variable escapes me, whether I write to it or not. My argument applies to only the affects of a single-step rear end gear change and does not speak to any other type modding, including engine mods. Only a novice wouldn’t be able to use that extra grunt to their advantage. People here want more torque. This is a sure way to deliver it without any adverse affects (although a very slight decrease in fuel economy at cruise in top gear due to a small increase in rpm, which proves the gear change has a power affect). In fact, both Dinan and AC Schnitzer state unequivocally it’s the best bang for the buck mod and makes the most pronounced improvement in acceleration in consideration to drivability (keeps the torque curve as is), yet you argue against and offer inane remarks such as “no such thing as a free lunch.” Dinan and AC Schnitzer must be idiots I suppose? I guess they didn’t read your referenced thread either. Not to mention, you think a few % HP increase will produce more tangible results than FD change? Do you realize what you are saying? First, that % change you speak of isn’t consistent across the rev counter and second, it would have to be a hell of a lot more than a few % to equal an 8% increase in total torque to the ground. How much more HP would the car need to shave a half-second 0-62? That’s what you’re up against. And no one is saying you can’t do both. But total torque is what affects acceleration the most, and gearing is the best way to get it without making a peaky power band which is not necessarily a good thing. IMO, BMW M cars are geared a tad too tall. I understand why, which is predominantly biased toward fuel economy and to limit stress to the drive train. Nothing wrong with that. In fact, actual automotive enthusiasts are a minority of owners worldwide (especially in the US). I wonder why?