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Author
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Topic: Please explain this timeslip
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 11-22-2003 02:10 AM
   
How can these 2 e.t. slips be so different and yet both cars had almost identical 60' times and mph.  Mine: His:
1.96 1.99
5.11 5.62
7.88 8.49
90mph-->89mph
10.28 11.06
12.28 13.01
112mph-->111mph ------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank, rods and girdle, TFS alum. heads, Stealth 8020 intake, Xtreme 274 Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
11.86 @ 116 mph (7.62 @ 93 mph)daily driver!
DanH [This message has been edited by bluestreek (edited 11-22-2003).]
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denny
Journeyman Posts: 80
From: Northfield NH USA
Registered: Jul 2000
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posted 11-22-2003 09:46 AM
he to have missed 2nd gear I would think would be the only explaination. Do you know the car in question is it normally a little faster than you? stick will generally have a slow 60 ft but make some up on the other end that would explain the slower 60 but the better mph If he missed a gear he probably lost 2-3 mph too. Thats my guess for what its worth------------------
D French
67 427 Fairlane(A/SA) 73 Mustang 351c
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 11-22-2003 12:08 PM
We both usually run similar e.t.s.. He runs a 5 spd 5.0. On that race I hit a .520 light and he had a .720 btw.OK here's another ?? At what point on the track and what method is used to figure mph at an NHRA track. I glanced at my tach as my win light came up last night and it showed 5800 rpms. With 3.50 gears and 25.5" tires, that should put my mph a lot higher than 112. Could that mean that my tach is reading way too high or the rear gear is lower than I thought? I just feel like there's something strange about the mph readings on my timeslips. I release the throttle as soon as I see the win light come on. Is that OK? ------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank, rods and girdle, TFS alum. heads, Stealth 8020 intake, Xtreme 274 Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
11.86 @ 116 mph (7.62 @ 93 mph)daily driver!
DanH
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mustangboy
Gearhead Posts: 1098
From: Ont, Canada
Registered: Mar 2002
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posted 11-22-2003 12:32 PM
I think your mph is averaged over the last 100 ft or so just before and a little after the line (I'm sure someone will correct me on the exact measurements).I read this while using one of those G-tech units that measures your 1/4 mile times,0-60 etc etc.The G-tech is pretty accurate with the ET but the mph usually reads high because it doesn't average out your speed it simply gives your speed at exactly the 1/4 mile.I believe if you "run it out the backdoor" your mph may go up a little.------------------
1968 mustang j-code sprint.13.69@101 306cu.in, stock ported heads,weiand exellerator,650 holley DP,hedman hedders,comp 292 Magnum cam,4-speed,8 inch 4.11 detroit locker http://mustangsandmore.50megs.com/MembersPics/mustangboy.html [This message has been edited by mustangboy (edited 11-22-2003).]
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Tea'sGrabber
Gearhead Posts: 276
From: Seattle, Wash.
Registered: Feb 2003
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posted 11-22-2003 01:29 PM
Gears,Tire height,Tuning,Shift points....etc. Looks like yours pulls harder on the top end and his fell on it's face!------------------
Todd 71 Mav Grabber All orig 306 cu.in. Cast Iron heads. Carillo Rods.Best et. 10.71 @ 124 thru the mufflers.
http://mustangsandmore.50megs.com/MembersPics/TeasGrabber.html
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kid vishus
Gearhead Posts: 6405
From: middle of NC
Registered: Oct 2000
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posted 11-22-2003 04:46 PM
I've always been under the impression mph is averaged over the last 60' of the track. Some old timing systems used to figure it past the finish line, but I don't think many of those are still in use.
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Dubz
Gearhead Posts: 1890
From: Manitoba Canada
Registered: Oct 2002
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posted 11-22-2003 05:53 PM
next time, keep her pinned for another 60 feet after the win light and see if your mph changesall i can think of
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 11-22-2003 06:26 PM
I'll have to wait till next season! 
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steve'66
Gearhead Posts: 9489
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 11-22-2003 07:02 PM
Rob's right,It's the average speed through the last 60'. Lifting right after the finish line will not affect the trap speed.  Dan, your freind lost the 3/4 second et before the 1/8mi mark. Like he's missed a shift, roasted the tires on the 1-2 shift or granny shifted that thing.  SteveW
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 11-22-2003 10:56 PM
quote:
Originally posted by steve'66:
Rob's right,Dan, your freind lost the 3/4 second et before the 1/8mi mark. Like he's missed a shift, roasted the tires on the 1-2 shift or granny shifted that thing. SteveW
Or maybe he hit the button a little too late. But I still don't understand why my rpms were so high for only 112 mph.
------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank, rods and girdle, TFS alum. heads, Stealth 8020 intake, Xtreme 268 Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
11.86 @ 116 mph (7.62 @ 93 mph)daily driver!
DanH
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Tbird
Gearhead Posts: 298
From: USA
Registered: May 2003
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posted 11-24-2003 08:53 AM
But I still don't understand why my rpms were so high for only 112 mph. As mentioned before....it is an average of the speed over a distance not at one instance. You may have only been at 4800 or 5000 rpm at the beginning of the 60ft mph light and then at 5800 at the end of the 60ft used for mph.
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