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Old 07-05-2009, 05:23 PM   #1
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When to shift

I don't really push my car that hard, but sometimes I do feel like it. This may be the dumbest question asked on the forum yet, BUT...what is the max point where you can shift so that the computer doesn't determine that you have overrevved (from PST2) and what is the max point that you should rev up to. I always thought that you were never supposed to go in the red, but is it ok to go just a little bit like this guy?:

http://www.youtube.com/watch?v=anpaciUu6xY

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Old 07-05-2009, 06:37 PM   #2
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Here's the deal. Your variocam kicks in at 4200 rpm and ideally, you want to keep above this level for maximum performance in a hard acceleration situation.

The HP and torque drop off dramatically after 6200 rpm in my car and it redlines at 6500 rpm, so there's no reason for me to go above the 6000 line as it just puts additional wear and tear on the motor without any additional benefit and risks a computer reaction. (I've no idea what size motor you have so I don't know where the power falls off on your motor, but it will be shown in your manual or other forum members can tell you the specs on your motor size.)

I took my car out Friday morning and headed to the country. I took it up to 6000 rpm in first through fourth a number of times. Blows out all the carbon and the motor actually seems to like it.

Some forum members will tell you going to 6k all the time will prematurely wear out your motor, and while they're right, why did you buy the car?

If you bought it to drive hard and enjoy the way I drive my car, get busy rowing through the gears when you take it out, and shift up at 6k or so and enjoy the glorious intake and exhaust sounds of a flat six.

I gotta say thought that I do not wind it up to 6k on every shift all the time. When I'm driving around town I shift at 3500 to 4000 to save on fuel and not wear out the motor for no good reason. But when I take it out for a drive in the country, the shift points change dramatically.

Hope this helps!

BTW, I'm willing to bet money that 550 special edition was fitted with a tiptronic and he was letting the computer shift for him. It was too smooth and each upshift only brought the rpms down to 6000 on the nose. That's not easy to do with flat out driving with a stick.
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Last edited by RandallNeighbour; 07-05-2009 at 06:46 PM.
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Old 07-05-2009, 06:39 PM   #3
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As far as p*ssing off the PST, I dunno. I'm planning on keeping my Box til it's not got all that much value in the resale market anyway, to the point I don't really care. I do fairly regularly hit the redline (the sound is intoxicating, liberating, MUSIC to my ears! ), occasionally going into the red. Got about 45K on the odometer, so far so good.

Many people on this forum tend to push RPMs on a fairly regular basis, and they typically sound like people who know Porsches well.

PM "Paul", a regular on 986forum, with this question. He seems to be pretty knowledgeable and definitely has got opinions on such issues. I think you'll be interested in what he has to say on the matter.
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Old 07-05-2009, 07:05 PM   #4
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Thanks for the response. BTW, I have a 2000 S model. My redline starts at 7 (same as in vid) so just normal driving I'll go up to 5 or 6, but when I want to accelerate hard, i'll go to upper 6. I think I don't shift optimally because when I get into next gear, I drop around 2-3k rpms. Should I be shifting faster than that?

Last edited by Viper5; 07-05-2009 at 07:07 PM.
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Old 07-05-2009, 08:25 PM   #5
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I auto-x my 2004 Boxster (non-S) and was curious about what is the best RPM to launch and shift at. I experimented with launching at 3000, 4000 and 5000 rpm, and with shifting at 6000, 6500 and 7000 rpm. I used a MaxQdata system and did it on a runway we use for auto-x, always starting in the same area, going in the same direction and letting the tires cool between runs. The tires were Bridgestone RE-01R and the only mod to the car is a home made cat back exhaust. I re-tested the different launch RPM at the end of the test to ensure that the conditions were the same. Sorry for not listing the other shift data but I deleted all the data except for the launch at 5000, shift at 7000 rpm ones because that was easily the quickest. Launching at 5000 rpm, shifting at 6000 rpm resulted in 6.1 seconds, shifting at 6500 was 5.7 seconds. Here's the data to 60 mph when shifting at 7000 rpm(before it hits the rev limiter at 7200 rpm) but I have the whole chart to 1/4 mile-note that 0-60 mph is 5.5 seconds:
Time------g--- MPH-- ft
0.000 +0.65 4.04 0.0
0.050 +0.58 5.27 0.4
0.100 +0.54 6.28 0.9
0.150 +0.53 7.06 1.4
0.200 +0.54 7.69 1.9
0.250 +0.55 8.28 2.6
0.300 +0.55 8.86 3.2
0.350 +0.55 9.40 3.9
0.400 +0.57 9.89 4.6
0.450 +0.58 10.37 5.4
0.500 +0.58 10.90 6.2
0.550 +0.58 11.50 7.0
0.600 +0.59 12.14 7.9
0.650 +0.60 12.79 8.9
0.700 +0.62 13.44 9.8
0.750 +0.60 14.47 10.9
0.800 +0.60 15.91 12.1
0.850 +0.63 17.54 13.4
0.900 +0.67 18.79 14.7
0.950 +0.69 19.83 16.2
1.000 +0.69 20.90 17.7
1.050 +0.65 22.09 19.4
1.100 +0.57 23.11 21.0
1.150 +0.51 23.95 22.8
1.200 +0.45 24.69 24.6
1.250 +0.42 25.36 26.5
1.300 +0.43 25.94 28.4
1.350 +0.47 26.45 30.3
1.400 +0.49 26.91 32.3
1.450 +0.49 27.38 34.3
1.500 +0.48 27.87 36.4
1.550 +0.46 28.38 38.4
1.600 +0.45 28.89 40.6
1.650 +0.48 29.38 42.7
1.700 +0.51 29.87 44.9
1.750 +0.54 30.35 47.1
1.800 +0.56 30.82 49.4
1.850 +0.54 31.32 51.7
1.900 +0.52 31.86 54.0
1.950 +0.49 32.52 56.4
2.000 +0.48 33.24 58.9
2.050 +0.46 33.98 61.4
2.100 +0.46 34.62 63.9
2.150 +0.46 35.17 66.5
2.200 +0.47 35.68 69.1
2.250 +0.48 36.18 71.8
2.300 +0.48 36.69 74.4
2.350 +0.48 37.19 77.2
2.400 +0.47 37.68 79.9
2.450 +0.49 38.16 82.7
2.500 +0.50 38.66 85.6
2.550 +0.51 39.11 88.4
2.600 +0.54 39.52 91.3
2.650 +0.53 39.93 94.3
2.700 +0.53 40.40 97.2
2.750 +0.50 40.89 100.2
2.800 +0.47 41.32 103.2
2.850 +0.44 41.71 106.3
2.900 +0.44 42.14 109.4
2.950 +0.44 42.55 112.5
3.000 +0.43 42.90 115.7
3.050 +0.41 43.22 118.9
3.100 +0.39 43.59 122.0
3.150 +0.36 44.02 125.3
3.200 +0.29 44.35 128.5
3.250 +0.23 44.58 131.8
3.300 +0.17 44.76 135.1
3.350 +0.08 44.95 138.4
3.400 +0.10 45.10 141.7
3.450 +0.18 45.16 145.0
3.500 +0.28 45.23 148.3
3.550 +0.42 45.41 151.7
3.600 +0.54 45.75 155.0
3.650 +0.58 46.22 158.4
3.700 +0.58 46.77 161.8
3.750 +0.52 47.35 165.3
3.800 +0.45 47.93 168.8
3.850 +0.38 48.50 172.4
3.900 +0.35 49.03 176.0
3.950 +0.35 49.43 179.6
4.000 +0.36 49.71 183.3
4.050 +0.36 49.93 186.9
4.100 +0.36 50.21 190.6
4.150 +0.38 50.52 194.3
4.200 +0.38 50.83 198.1
4.250 +0.38 51.12 201.8
4.300 +0.37 51.46 205.6
4.350 +0.37 51.82 209.4
4.400 +0.37 52.18 213.2
4.450 +0.37 52.52 217.1
4.500 +0.35 52.88 221.0
4.550 +0.34 53.25 224.9
4.600 +0.34 53.60 228.8
4.650 +0.35 53.93 232.7
4.700 +0.37 54.27 236.7
4.750 +0.38 54.62 240.7
4.800 +0.38 54.96 244.8
4.850 +0.38 55.31 248.9
4.900 +0.38 55.69 252.9
4.950 +0.36 56.08 257.1
5.000 +0.34 56.44 261.2
5.050 +0.34 56.77 265.4
5.100 +0.33 57.12 269.5
5.150 +0.32 57.47 273.8
5.200 +0.33 57.82 278.0
5.250 +0.34 58.15 282.3
5.300 +0.35 58.50 286.5
5.350 +0.38 58.86 290.9
5.400 +0.37 59.23 295.2
5.450 +0.38 59.62 299.6
5.500 +0.38 60.01 304.0

Last edited by loosecannon; 07-06-2009 at 06:47 AM.
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Old 07-05-2009, 08:40 PM   #6
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Thats pretty good considering it's rated at 6.2sec
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Old 07-05-2009, 09:19 PM   #7
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Doesn't the PST record any rev in the redline?
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Old 07-06-2009, 06:51 AM   #8
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Quote:
Originally Posted by Viper5
Thats pretty good considering it's rated at 6.2sec
Yeh, Porsche definitely underrates it's stuff. On street tires the car pulls .69 G on the launch, which is outstanding but yesterday when running Hoosier A6's, it pulled .8 G.
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Old 07-06-2009, 07:19 AM   #9
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We've covered this in detail before and it always brings out many opinions. In actuality, the shift point for best acceleration is dictated by which gear/RPM provides the most torque to the wheels at a given road speed. It's a bit more complicated than looking at the power or torque curves (sorry Randal ) You have to look at the torque curve, the gear ratios, and the road speed.

For most high performance cars, the manufacturer will choose gear ratios that take full advantage of the rev range. So almost always, high performance cars will give the best acceleration if the car is run to redline. The numbers prove this out on the Boxster and also agree with what loosecannon has found.

I wouldn't worry much about stage 1 over-revs by hitting the fuel cut-off at redline, that's not damaging to the engine. It's the miss-shift that runs the engine beyond red line that you should and Porsche does care about.

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