Post Your Street Tyred 1/4 Mile Time!

[Peppy_t92]

How you stage makes a difference.. Shallow or deep, idk about 4mph though

[Saski]

The MPH was picked up by manually shifting the auto rather than leaving it in sports performance mode. Manual shift ensures that it stays in 3rd gear as you cross the line meaning its using peak power/torque whereas in performance auto it was shifting to 4th before the finish line which slows down the time and kills the 4 speed auto box.

[BenDoCo]

Calder 13/6/2014

12.06 @ 119.43mph

1.95 60'

275/35/18 Toyo Proxes T1 (with 1/4 tread left) @ 32 psi

FG G6ET

[22470]

On 21/5/14 I ran my standard (and untuned) 2009 FG XR6 Turbo Auto at WSID and I got the following two best timeslips. The car was shallow staged on both occasions, so there was some rollout.

1) Launching in second gear, 12.731 sec quarter, 60 feet 2.026, a bit over 2000 rpm stall up, 4.85 seconds to 100 kph.

2) Launching in first gear (in Drive), 12.509 quarter, 60 feet 1.934, 1800 - 1900 rpm stall up, 4.62 seconds to 100 kph.

No apparent wheelspin, new Goodyear Eagle Directional F1 tyres, 38 psi, full sized spare and tools in the boot, 92 kg driver, total load in the car the equivalent to just over half a tank,18 to 19 degrees, 70% plus humidity.

I used my GPS based Racelogic Performance Box during the runs and it recorded the following 400 metre and acceleration data (without dragstrip rollout).

Run 1, second gear launch, 2000 rpm plus stall...............Run 2, 1st gear launch in drive.1800 - 1900 rpm stall.

Speed.......Time.........Metres.............................................Speed.......Time..........Metres

0................0................0....................................................0................0...............0

20..............0.85...........2.40...............................................20..............0.84..........2.25

40..............1.64...........9.01...............................................40..............1.61..........8.65

60..............2.61...........22.54.............................................60..............2.37..........19.37

80..............3.70...........43.78.............................................80..............3.43..........40.07

100............4.85...........72.51.............................................100............4.62..........69.68

120............6.40...........120.46...........................................120............6.19..........117.92

140............8.19...........184.87...........................................140............8.07..........185.94

160...........10.24...........270.74..........................................160...........10.13..........272.14

180...........12.96...........399.41..........................................179.39......12.84..........400 Metres

180.04......12.97...........400 metres...................................12.509 sec Dragstrip timeslip for this run

12.731 Dragstrip timeslip for this run

Note how effective the higher 2000 rpm plus stall up was in run 1. Even though the car was in the much higher second gear both times to 40 were almost identical.

Previously on a better surface with a heavier load at high altitude, I have used the 2000 plus rpm stall up technique with a first gear launch and the car was exactly 2 tenths faster to 20 than it was in Run 2 (ie. the 12.509 quarter run).

The Racelogic software makes it possible for me to apply that fast high altitude launch data to the runs that I did at the Dragstrip. So I've been able to accurately calculate how fast Run 2 would be with the best high altitude launch data applied. As you can see below it would reduce the 400 metre time by nearly 2 tenths. It shows that the car certainly has the power to go at least that fast at WSID, but I don't know about the grip. Perhaps a set of ET Radials would make it possible.

0...............0

20.............0.64 seconds at 1.97 metres achieved in the earlier high altitude test vs 0.84 sec at 2.25 metres in run 2 above.

40.............1.41

60.............2.17

80.............3.23

100...........4.42

120...........5.99

140...........7.87

160...........9.93

179.44.....12.65 sec 400 Metre time with no rollout.

Edited 19/06/14 03:52 PM by 22470

[22470]

How you stage makes a difference.. Shallow or deep, idk about 4mph though

Yes it would make a difference, but I was thinking that the difference would have to be very small, because even with maximum possible rollout you've only ran about 15 or 16 inches further than 1320 feet (ie.if your car has a Falcon sized wheel) when you pass through the 1/4 mile end beam. and the car won't accelerate much in that small extra distance.

To check that out I've used the Racelogic software (see my last post on my cars performance at WSID) to compare it's Run 2 speed at 1320 feet, with it's speed at 1321.3 feet (15.6 inches later) and it only picked up 0.06 kph in that distance.

Interestingly on my last run of the night I opted to just check the cars performance over the last part of third gear, so I launched it slowly in second and then changed early into third. The result was that it hit the rev limiter in third about 3 metres before the start of the 66 foot end speed measurement trap. When I collected the timing slip after the run I was totally confused by the end speed. It was 179.22 kph and that's about right on 4 kph faster than the car can possibly go in third gear.

The mystery remained till I found out that apparently the beams at Dragstrips (after the early 60 foot point) are set at around 5 inches above the track and it appears obvious to me that the as the front of the car dropped from hitting the rev limiter, it caused the 66 foot speed trap beam to be broken by the spoiler under the car instead of the front wheels, and final the end beam would have been broken by the front bumper bar as the nose dropped even lower from the engine braking. The car would have travelled around 1.5 feet less than 66 feet, but the timing system would have calculated the speed assuming that my car had really covered the full 66 feet. That would put the speed up by practically 4 kph.

Actually from crunching the numbers, I can see that I could get even around a 4 mile per hour (too high) discrepancy if the car tripped the 66 foot beam with the wheels and then tripped the final beam with the front bumper.

I guess Dragstrip timing systems are very accurate in measuring the time between beams, but you won't get a totally accurate time slip if the wrong parts of the car break the beams.

[rednose]

Down to 11.0 @ 135 MPH

305 30 19 Invos

[sct911]

11.016@133.78 mph (with 3rd-4th shift playing up)
60 ft 1.912
FG XR6T
470 rwkw
Achilles 2233 245/40/18 street tyres

[BenDoCo]

Sweeeeet.. Did anyone video this ^^^

[sct911]

yep pretty sure there is, but I'm not sure how to contact him, he does all the videos and photos for CMS , matty webber and joe might be able to get a hold of the video

[rednose]

Danny jetsix was videoing today, pretty sure he got both our 11.0 runs