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#1
08-02-2008, 01:43 PM
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1/8 vs 1/4 MPH
OK.....I have been looking at my timeslips......1/8 vs 1/4.....I noticed that in the 1/8 mile with good traction, I can muster 92-93 MPH.......in the quarter I can only get to 110-111.....seems a little light in the 1/4....
the question?.........is this because of a fuel deficiency?....poor aerodynamics?......heavy car?......other mismatched components?..... or does this seem about normal? this is a full bodied, full weight, street\strip\show car....
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71 GTO, 463, KRE 295 cfm heads ported by SD Performance, RPM intake, Qjet, Dougs Headers, Comp cams HR 246/252 ...11 to 1 , 3.55 cogs, 3985lbs.....day three- 11.04 at 120mph ....1.53 60', 6.98 1/8 mile |
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#2
08-02-2008, 01:47 PM
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Gross HP, my combo is very similar I can muster a best mph of 110.8.
Time for more ponies. John |
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#3
08-02-2008, 01:57 PM
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I was running around 89, never hit 90 mph in the 1/8 and would run 110-111 in the 1/4. My buddy runs 92 and 114 in a lighter car but still an aerodynamic nightmare. It does sound a little off, how is the fuel delivery?
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#4
08-02-2008, 02:27 PM
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Sounds about rite to me without doing the math.
You can go to wallace calc site,they have a calc to convert it and say what it should be.
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9.81 at 139.89mph 3400lbs Butler 468,11.3:1 comp,N/A,PUMP 93 OCT GAS! 370cfm butler eheads port matched victor 1095 king demon 4.30gear,th400 MICKEY THOMPSON DRAG RADIAL tire  
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#5
08-02-2008, 02:28 PM
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Quote:
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9.81 at 139.89mph 3400lbs Butler 468,11.3:1 comp,N/A,PUMP 93 OCT GAS! 370cfm butler eheads port matched victor 1095 king demon 4.30gear,th400 MICKEY THOMPSON DRAG RADIAL tire
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#6
08-02-2008, 03:00 PM
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My 1/8 mph is typically 89.4
john |
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#7
08-02-2008, 05:01 PM
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17 to 20 [or so] increase in MPH for the second half of the strip is a the general rule of thumb.
Later, Jim
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65 Catalina sedan. Allen Thomas Performance 495. KRE Heads at 310cfm ported by SD Performance, ProSystems Dominator carb on ported Victor intake, P-Dude custom grind hydraulic roller, MSD ignition, 3.50 Moser/Ford rear. F-Glass front bumper by son Rob, rear by the old man and joint effort for trunk lid. 3950# w/driver. Best of 9.5761/139 on 175 shot, 6.01 /114 in 1/8. |
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#8
08-02-2008, 05:07 PM
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Mines around 25 mph difference 1/8 to 1/4.
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Mark 1970 Lemans Convertible,462,6x-4, 234/242 cam.3.42 posi.12.55@109,4100 lbs...SOLD.... 1968 Firebird , 467 , KRE d-ports ,stock type suspension,3100lbs (1.30 60')(6.08 1/8)(113.43)different runs 9.59 @140.71 on E85 all motor 8.97@148.63 on 150 shot |
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#9
08-02-2008, 05:15 PM
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Agree with 17 to 20mph post is pretty common, but what is your torque converter efficiency?
http://www.tciauto.com/Products/Tech...alculators.asp I doubt the cars getting fatter as you get through 3rd but I'd look at your fueling up top and making sure your car isn't preigniting or detonating due to load or running hot.
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69 GTO Convertible, 4000lbs 462ci, 606tq/569hp - 93 oct at 34 deg (207psi) 11.7:1, KRE H Ports, Lunati HR 282/290 w Johnson Lifters & 1.65 Scorp, E30, EFI, Holley HP + Dual Sync, 12-1 Crank Trig, 120lb Inj & 1000cfm TB, Torker II EFI Int & Rails, PTC 10" 0 Stat, Ricks SS Gas Tank, Magna 4303, Aerom EFI Reg, Aero Front & Wilwood Rear Disc Brakes, Dougs 1 7/8" Headers & Borla Pro XS 3" Muffs, Alum Rad & Dual Fans, 12:1 Box, UMI Control Arms & Viking Berz Fr + Rear CO Shocks, Hella UP28 Vac Pump |
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#10
08-02-2008, 05:58 PM
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I'm pushing a box that weighs a little under 2700 lbs. My 1/8 mph is 132 and my 1/4 is 165, racing gas, all motor. I think that the difference between 1/8 and 1/4 mph depends on the amount of power that your engine is making. Mine is making about 1120 at the flywheel, and about 935 at the rear, and with the 5" stroke, gobs of torque.
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Bill 64 GTO, tube chassis w/606" IA tall deck, PG & a pro geared Fab 9". 2750 lbs. 8.2550@164.17-1/4, 5.2901@131.97-1/8, 1.1981-60-ft. 8/10/08 
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#11
08-02-2008, 06:41 PM
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torque converter slip or inadequate fuel delivery
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69 GTO 11:66@114.17 all balls no bottle 406 d-port iron heads 3700lbs all steel |
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#12
08-02-2008, 06:47 PM
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I gain around 25-27 MPH on the back half. It really has a lot to do with effective gear ratio, converter characteristics, and the amount of power you are making. Can't compare apples to oranges.
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Darin '64 Bonneville Wagon (sold) 69 Lemans-All motor (sold) 9.81 @ 136.39MPH |
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#13
08-02-2008, 07:02 PM
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24.18 mph here
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  Nothing is impossible if you break it down into possibilities. It's all a matter of "Want to". |
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#14
08-02-2008, 08:23 PM
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Typical formula is:
1/8 mile mph X 1.23 = 1/4 mile mph |
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#15
08-02-2008, 08:29 PM
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Mike
Maybe your car is just slow ...... Mine runs around 82-83 and 102-103... so that 20mph thing works for me...
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Darby 74 Grandville 2Dr 455 c.i 4550# 2011 1.60 60 ft,7.33@94.55-11.502@117.74  2017, 74 firebird -3600 lbs (all bests) 1.33 60 ft, 6.314@108.39 9.950@134.32 M/T 275/60 ET SS Drag Radial 2023,(Pontiac 505) 1.27 60 ft, 5.97@112.86, 9.48@139.31.... 275/60 Radial Pro's |
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#16
08-02-2008, 09:14 PM
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Quote:
1/8 mile X 1.55 = 1/4 mile here's a conversion chart http://www.mopowerstyle.com/index.php?pid=6 Last edited by 360Rocket; 08-02-2008 at 09:19 PM. |
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#17
08-02-2008, 10:31 PM
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hummm.84 mph in 1/8 106 in 1/4 100 shot 91.05 1/8 111.84 1/4 ?
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1978 ,t/a 3660# 455 2010 / 1/8 7.86 1/4 12.40 @ 109,19 http://www.youtube.com/watch?v=6PaHbLnszS0 http://www.youtube.com/watch?v=XMxhM...eature=related 12.01@109 http://www.youtube.com/watch?v=MC-dganA2jQ 100 shot 11.78. A,ll new head cam combo 96 ported bye Mike Chell!! Comp cam yes the 284 XE. Firsthand outing of the street 7.69 1/8 12.15 109.47 hot and humid.not hooking. 1.73 60. |
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#18
08-02-2008, 10:41 PM
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25mph for me!
PHILLYGOAT
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PHILLYGOAT 1965 GTO/ OEM Block, Crank & D-ports(all slightly modified of course)/ 3550lbs/ Full Exhaust/ Foot Braking 1.41 60ft 6.45@104.97mph 10.25@127.12mph(Pontiac Heaven)  More Details on GOAT http://www.pontiaczone.com/forum/vbpicgallery.php?do=view&g=379 GTO Burnout http://www.youtube.com/watch?v=nZqdcH0Ltc4 |
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#19
08-02-2008, 10:45 PM
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Quote:
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#20
08-02-2008, 11:13 PM
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It all depends on the car combo. My vega with the dport 408 was 14 difference, but that isn't the whole story as I was out of rpm 400 feet before the line in the 1/4. With a taller 4.30 or 4.10 gear, I believe putting my top mph about 50 feet from the line would have posted higher mph and a quicker e.t.
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