1/4 Mile Race HELP Needed Please (Gernby spitting shift point knowledge, use Normal)!
11-06-07 | 01:41 PM
#32
Lexus Champion
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I have done extensive data logging with my laptop connected to the car's CAN bus that shows that the shift points are higher with ECT-PWR. It is also evident (in my car at least) when I switch to ECT-PWR after lots of miles with it turned off, the ECU will wait a little too long to initiate the shift from 1st to 2nd, and it will actually hit the rev limitter for about 1/2 a second. After doing that a couple times, it figures out it needs to initiate the shift sooner. It never does this in normal mode.
It wouldn't surprise me if 10% wheel spin would be optimum, but my tires seem to do 0% or 100%. Maybe if I had true "drag radials" instead of regular R compounds...
It wouldn't surprise me if 10% wheel spin would be optimum, but my tires seem to do 0% or 100%. Maybe if I had true "drag radials" instead of regular R compounds...
11-07-07 | 08:34 PM
#36
Pole Position
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Well, after reading the R&T I have always launched the same way. However, if I was at a track where I did a burnout and there was a lot of rubber down at the launch you could probably do a 2k launch w/no traction control because you would hook up better. Maybe it would help with 275 rears too? Anyway on the street you don't have the burnout or the extra rubber so maybe its best to launch R&T style. Plus, many worthy opponents may not be able to launch with a clutch and little wheelspin, especially with larger power engines.
11-07-07 | 08:41 PM
#37
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At WOT it doesn't matter weather the PWR ECT is on or off but it does help if you are playing on the street.
You will get your best launch if the trac control is off and the tires hook up. Any time the traction control kicks in you are losing time. The sooner you get into the power curve (above 3500 rpm) the better your times.
Get as much weight out of the vehicle as possible. Empty the trunk, try to have less then 1/4 tank of gas, etc.
Keep the trans in full auto, if you are running from the dig (from a stop). Don't use the paddle unless you are running from a roll. From a roll you want the PWR ECT on and use the manual trans option to keep the engine in the power curve for the start. Use the lowest gear that will keep you in the power curve and still leave enough time to up-shift. As soon as you go WOT, from a roll, you should select 4/5 gear and let the trans auto up-shift (this will produce the fastest shifts and allow you to concentrate on driving). You can bounce the speed limiter in 5th gear, so selecting 6th is not necessary. If you are only running a 1/4 mile, 4th gear is fine.
Brake launching can help sometimes. I don’t see any better launches doing it so why put extra stress on the drive-train.
High air pressure in the front tires and lower pressure in the rear, works best. You want to lower the rear air pressure until you get the least wheel spin. Sometimes you don’t need to lower it at all.
Keep all your your windows up.
Many races are won and lost in the first 60 feet so practice your launch!
Koz
You will get your best launch if the trac control is off and the tires hook up. Any time the traction control kicks in you are losing time. The sooner you get into the power curve (above 3500 rpm) the better your times.
Get as much weight out of the vehicle as possible. Empty the trunk, try to have less then 1/4 tank of gas, etc.
Keep the trans in full auto, if you are running from the dig (from a stop). Don't use the paddle unless you are running from a roll. From a roll you want the PWR ECT on and use the manual trans option to keep the engine in the power curve for the start. Use the lowest gear that will keep you in the power curve and still leave enough time to up-shift. As soon as you go WOT, from a roll, you should select 4/5 gear and let the trans auto up-shift (this will produce the fastest shifts and allow you to concentrate on driving). You can bounce the speed limiter in 5th gear, so selecting 6th is not necessary. If you are only running a 1/4 mile, 4th gear is fine.
Brake launching can help sometimes. I don’t see any better launches doing it so why put extra stress on the drive-train.
High air pressure in the front tires and lower pressure in the rear, works best. You want to lower the rear air pressure until you get the least wheel spin. Sometimes you don’t need to lower it at all.
Keep all your your windows up.
Many races are won and lost in the first 60 feet so practice your launch!
Koz
Your best run most times if the first, or when your engine is coolest.
11-08-07 | 11:43 AM
#38
Lexus Champion
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Are you guys ready for a real shocker?! It turns out that the shift points are different for each ECT mode (Snow, Normal, and PWR) when in automatic mode. However, to my extreme surprise, the mode that shifts at the highest RPM is Normal! Peak RPM in Snow mode is 6260. For Normal mode it shifts as high as 6625, and PWR mode it shift as high as 6510. It also seems to shift at a lower RPM in 1st gear than in 2nd gear for all 3 modes.
Here is the chart below, the blue line is ECT-PWR, pink line is ECT-Normal, and yellow is ECT-Snow. Ignore the relative rate of accelleration between the lines. The 3 snap shots weren't done on the same piece of road or same direction of road. One might have been on a slight incline while the other might have been on a slight decline...
Here is the chart below, the blue line is ECT-PWR, pink line is ECT-Normal, and yellow is ECT-Snow. Ignore the relative rate of accelleration between the lines. The 3 snap shots weren't done on the same piece of road or same direction of road. One might have been on a slight incline while the other might have been on a slight decline...
11-08-07 | 11:55 AM
#39
Lexus Champion
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BTW, the rev limiter doesn't kick in until over 6700 RPMs, so there would be some benefit to using the paddles if you got it perfect, especially in 1st gear where it only hits 6388 in PWR mode, and 6544 in Normal mode. Basically, I was shifting 322 RPMs early in 1st gear, and 190 RPMs early in 2nd and 3rd gear when I did my 13.094! That alone might put some of us in the 12's!
11-08-07 | 12:21 PM
#40
11 Second Club
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BTW, the rev limiter doesn't kick in until over 6700 RPMs, so there would be some benefit to using the paddles if you got it perfect, especially in 1st gear where it only hits 6388 in PWR mode, and 6544 in Normal mode. Basically, I was shifting 322 RPMs early in 1st gear, and 190 RPMs early in 2nd and 3rd gear when I did my 13.094! That alone might put some of us in the 12's!
Maybe Lexus should have named ECT PWR something else.
11-08-07 | 12:28 PM
#42
11 Second Club
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Read my first post here.
Paddles won't help 99% of us drivers in the quarter mile because it's damn near impossible getting it to shift at just the right point without hitting the rev limiter.
11-08-07 | 12:59 PM
#44
11 Second Club
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