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E90 M3 (Sedan) | E92 M3 (Coupe) | E93 M3 (Convertible) (2008-2013) {Engine: S65 - Max Hp: 414 hp (420 hp Euro) at 8,300 rpm / 295 lb/ft at 3,900 rpm}


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Old Thu, Apr-14-2011, 07:08:26 AM   #11
k1ndafast
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Default Re: Mystery solved: Does shift speed affect 1/4 mile trap speed?

I would say your times are what they should be for a stock M3 running on the street. The somewhat high average ET in both modes can be explained by the 60fts which are a little slow probably due to grip issues. The trap is good, your car is definitely healthy.

But to stay on topic - Your conclusion is spot on. The longer it takes one to shift gears, the longer it will take him to finish the 1/4 (higher ET), and also the less distance he will have to keep fully accelerating thus resulting in a lesser Trap Speed. Very simple.
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Old Sat, Apr-16-2011, 03:44:43 AM   #12
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Default Re: Mystery solved: Does shift speed affect 1/4 mile trap speed?

Video of the runs:

http://www.youtube.com/watch?v=MAXGBr4ioeA
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Old Mon, Apr-18-2011, 04:20:27 PM   #13
NETO
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Default Re: Mystery solved: Does shift speed affect 1/4 mile trap speed?

great read, thanks!

btw, did you try doing any runs with LC?
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Old Mon, Apr-18-2011, 08:19:28 PM   #14
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Default Re: Mystery solved: Does shift speed affect 1/4 mile trap speed?

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great read, thanks!

btw, did you try doing any runs with LC?
I didn't use launch control. It was always "mash the pedal and go."
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Old Tue, Apr-19-2011, 01:14:32 AM   #15
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Default Re: Mystery solved: Does shift speed affect 1/4 mile trap speed?

dude thats way overkill for a really simple idea.. say you accelerate full throttle first gear, you misshift into 2nd and instead go to fourth...you then wait a second or two, then put it in second gear and go at it again full throttle, you obviously have been coasting for the last few meters before you reengaged the gear, or were luggin along for a brief second in 4th..., how could shift speed not effect the trap ? it wastes precious linear space down the track where the engine was not engaged. the car continues to roll forwar even though your not engaged in gear, thereby losing precious space to accelerate. not trying to knock any of your hard effort, just seems to be an amazingly basic concept.
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Old Tue, Apr-19-2011, 02:03:51 AM   #16
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Default Re: Mystery solved: Does shift speed affect 1/4 mile trap speed?

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dude thats way overkill for a really simple idea.. say you accelerate full throttle first gear, you misshift into 2nd and instead go to fourth...you then wait a second or two, then put it in second gear and go at it again full throttle, you obviously have been coasting for the last few meters before you reengaged the gear, or were luggin along for a brief second in 4th..., how could shift speed not effect the trap ? it wastes precious linear space down the track where the engine was not engaged. the car continues to roll forwar even though your not engaged in gear, thereby losing precious space to accelerate. not trying to knock any of your hard effort, just seems to be an amazingly basic concept.
Remember, I was trying to prove it to Sticky...a guy who has fought over this tooth and nail and said that trap speed is solely determined by horsepower and not affected by shift speed. He and I have flamed about this topic on a few occasions...and since he's the self-proclaimed expert of all things drag racing (who also is consistently proven wrong in everything he says), I had no choice but to break it down into the most overkill test to make the results so obvious that he'd look like even more of a retard if he tried to continue saying that it doesn't make a difference.

That's all...but it was a fun test.
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Old Tue, Apr-19-2011, 04:20:41 AM   #17
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Default Re: Mystery solved: Does shift speed affect 1/4 mile trap speed?

theres no question it effects the trap speed if you really mess up like taking 3 seconds to shift of going into the wrong gear.

maybe my memory serves me wrong, but I think sticky was saying it doesnt effect it that much.

Do you have the link to thread it was discussed in?
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Old Tue, Apr-19-2011, 07:06:48 AM   #18
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Default Re: Mystery solved: Does shift speed affect 1/4 mile trap speed?

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theres no question it effects the trap speed if you really mess up like taking 3 seconds to shift of going into the wrong gear.

maybe my memory serves me wrong, but I think sticky was saying it doesnt effect it that much.

Do you have the link to thread it was discussed in?
I pretty vividly recall Sticky saying shift speed wouldn't affect trap speed at all. Sticky said trap speed was solely determined by horsepower, and I vividly recall telling him him how absurd that was. We argued this exact point many times...so it's pretty hard to forget it. This article is more about getting to the truth and answering a lingering question to satisfy my own curiosity -- and letting others benefit from the research -- than it is about proving Sticky wrong. Proving Sticky wrong isn't ever very difficult. So for that reason, I won't go looking for the past posts, nor going through my private emails I had with him on the topic. Somebody else can do the research if they want.

But look at the results here Sammy. 120 milliseconds (a tiny bit under 1/8 of a second) made as much as a 1.97 MPH difference. I would call that quite a significant difference in trap speed for such a small amount of shift speed. 120 milliseconds was only 9.2/10000ths of the total ET, yet in the worst case, it accounted for 173.5/10000ths of the total trap speed. That's a 19x larger affect on trap speed than reduction in ET. That's a pretty huge output (19x) given such a small input. If you take those numbers, and extend them to a supercharged 130MPH 1/4 mile, then that same 120 milliseconds reduction would have accounted for a 2.26 MPH difference. Again, that's pretty significant in my books -- especially when it's the difference between 130 MPH, and 132.26 MPH -- which is a new E9x M3 trap speed record.
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Old Tue, Apr-19-2011, 08:53:28 AM   #19
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Default Re: Mystery solved: Does shift speed affect 1/4 mile trap speed?

There's no doubt to me your test showed that shift speed effects the trap speed. Even at such a small difference in shift speed. Pretty cool test and a good idea to just use a dct and switch shift modes for the test.


I do remember the thread a bit, and I remember there being logic to his reasoning.
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Old Tue, Apr-19-2011, 04:44:38 PM   #20
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Default Re: Mystery solved: Does shift speed affect 1/4 mile trap speed?

I think Sticky got part of it right. Trap speed is more indicative of horsepower than ET, which depends partially on traction and number of shifts and shift speeds.

I can see how super fast and harsh shifts break traction and result in wheelspin on a car with enough power to break traction (like a 600 rwhp supercharged E9xM3), resulting in slower ETs. Drag racers with manual trans and high power cars slip the clutch off the line and feather in the throttle rather than drop the clutch and sit there and spin. The test by the OP may not be 100% applicable to the same car but with 75% more horsepower.
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Discussing Mystery solved: Does shift speed affect 1/4 mile trap speed? in the E90 M3 (Sedan) | E92 M3 (Coupe) | E93 M3 (Convertible) (2008-2013) Forum - {Engine: S65 - Max Hp: 414 hp (420 hp Euro) at 8,300 rpm / 295 lb/ft at 3,900 rpm} at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)