Gear ratios...
#331
Drifting
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^Holy crap you have a lot to say... no work?
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#332
Rennlist Member
#334
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Anyone know approximately what a limited slip + 3rd + 4th + install run? I'm pricing it out but need some reference points.
#335
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All the above is for the GT4 and others with flat HP curves up top (or gears that are close enough to keep RPM in the max HP range) ... an older GT3 cup car with a peak HP at redline, can benefit more by optimizing shift points on the track. however, in a straight line, redline shifts and average RPM operation near redline, assure max acceleration overall
Perhaps your broad point in all this is "it all comes out in the wash and is highly track dependent so don't worry about it". Otherwise, it seems like your arguments could be taken to an extreme where we only had one gear - sixth.
I'm sincerely not trying to be snarky, just trying to understand this better. Thanks.
#336
Drifting
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I confess I'm a bit lost by all of this. I understand that gearing does not change how much power an engine makes, but it does change how much rear wheel torque is available, doesn't it? So it seems to me that if you drive a track at 80 mph and that is middle of third gear in the rpm range, there would be benefit to having a slightly lower 3rd gear that, at the same 80mph, results in a slightly higher RPM. With that, it seems that you would have more acceleration out of an 80 mph corner with the lower 3rd gear because you're starting your exit higher up in the rev range where the motor is making more power. Is this correct?
Perhaps your broad point in all this is "it all comes out in the wash and is highly track dependent so don't worry about it". Otherwise, it seems like your arguments could be taken to an extreme where we only had one gear - sixth.
I'm sincerely not trying to be snarky, just trying to understand this better. Thanks.
Perhaps your broad point in all this is "it all comes out in the wash and is highly track dependent so don't worry about it". Otherwise, it seems like your arguments could be taken to an extreme where we only had one gear - sixth.
I'm sincerely not trying to be snarky, just trying to understand this better. Thanks.
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#337
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The only downside of lower gearing (assuming it's not limiting your top speed) is that you might have to shift more often or at a inopportune time on a particular track.
For example, at TWS going into turn 5 (old 997), I was bouncing off my rev limiter for about 80 feet because it was a wash to shift to 4th and then back to 3rd. If I was running the OEM 19" wheels with 5% longer gearing over the 18" wheels I typically used, it would address that opportunity and remove about 2 tenths a lap. PDK would have fixed this....![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
At COTA, in the GT4 - you have to be in 4th to get through T18 without running out of revs, but you don't want to be shifting while going through 16-18 laterally loaded. I find that 4th is too tall to accelerate to take advantage of the grip that appears as you enter 18, so my exit speeds out of 18 are limited to my entry speeds into 16...when I get a ton of understeer and lose the line. If 4th was little lower, I think I'd find some time there, not to mention being able to carry 4th through 19 as well.
I think you could optimize gearing for a particular track to reduce inopportune shifts and to maximize the area under the time-HP curve (maximizing energy produced/consumed).
For example, at TWS going into turn 5 (old 997), I was bouncing off my rev limiter for about 80 feet because it was a wash to shift to 4th and then back to 3rd. If I was running the OEM 19" wheels with 5% longer gearing over the 18" wheels I typically used, it would address that opportunity and remove about 2 tenths a lap. PDK would have fixed this....
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
At COTA, in the GT4 - you have to be in 4th to get through T18 without running out of revs, but you don't want to be shifting while going through 16-18 laterally loaded. I find that 4th is too tall to accelerate to take advantage of the grip that appears as you enter 18, so my exit speeds out of 18 are limited to my entry speeds into 16...when I get a ton of understeer and lose the line. If 4th was little lower, I think I'd find some time there, not to mention being able to carry 4th through 19 as well.
I think you could optimize gearing for a particular track to reduce inopportune shifts and to maximize the area under the time-HP curve (maximizing energy produced/consumed).
#338
#339
Nordschleife Master
#340
Rennlist Member
#343
Drifting
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At COTA, in the GT4 - you have to be in 4th to get through T18 without running out of revs, but you don't want to be shifting while going through 16-18 laterally loaded. I find that 4th is too tall to accelerate to take advantage of the grip that appears as you enter 18, so my exit speeds out of 18 are limited to my entry speeds into 16...when I get a ton of understeer and lose the line. If 4th was little lower, I think I'd find some time there, not to mention being able to carry 4th through 19 as well.
#344
Drifting
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Here you go:
#345