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Old 10-23-2007, 03:55 PM   #1 (permalink)
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1/8 mile vs 1/4 mile ET

I've seen all the online calculators out there and have heard the numbers used to figure out 1/4 mile times using known 1/8 mile runs but would like to hear some true life experiances. My car, a 289 powered '65 Falcon (2,850 lbs) with me in it ran a best to date 1/8th mile of 8.82 @ 85 MPH with a 1.84 60 ft. This run was on a 90+ degree day out here in So Cal at a track in Parris, CA. I'm not sure about the elevation but would guess it to be under 1000'. I do expect a slighter quicker 60 ft now since I've gone wider on the rear tires without adding height (295/50-15's) so traction will not be an issue next time. Ya, I know I overdid it but I like the look.

What kind of 1/4 mile times should I expect to see? I've heard everything from low 14's to high 13's but am wondering what people with a similar weight car running these times are seeing.

Thanks,

John

PS: If it matters the car has 3.50 gears with a C4 trans.
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Old 10-23-2007, 04:12 PM   #2 (permalink)
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Re: 1/8 mile vs 1/4 mile ET

Should be about 13.7 to 13.9 or so in the 1/4.
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Old 10-23-2007, 05:01 PM   #3 (permalink)
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Re: 1/8 mile vs 1/4 mile ET

65Falcon: 1/8 mile ET X 1.57 will give a close approximation of 1/4 mile ET. So your 8.82 x 1.57 = 13.85 which seems about right.

Perris Drag Strip isn't known for running quick times. Bring your Falcon out to Irwindale and it might run 8.50's and for sure will 60 foot better.
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Old 10-23-2007, 06:29 PM   #4 (permalink)
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Re: 1/8 mile vs 1/4 mile ET

My old 302 4 speed combo ran pretty much exactly the same ets as you in the 1/8th(8.80s) and it ran pretty consistant 13.70s-13.80s in the 1/4...The strange part is that I was only running 2.0 60 fts compared to your 1.84s and my mph was only 80 mph compared to your 85 mph..So you are leaving quicker than me and going 5 mph faster yet we are running the same et..
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Old 10-23-2007, 06:57 PM   #5 (permalink)
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Re: 1/8 mile vs 1/4 mile ET

Interesting! I never knew that there was a numeric figure to use.

5.89 x 1.57 = 9.24

Thanks!!
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Old 10-23-2007, 07:50 PM   #6 (permalink)
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Re: 1/8 mile vs 1/4 mile ET

Funny you should mention Parris. Last year my son Steve was teaching his son ( 18 years old ) to drive with a little 1965 box Nova, Well anyway, the car was MUCH faster than we expected. With a mild 383 Chevy ( 539 HP )it would go 6.55 at 108.85, with a 1.30 60 foot time. I almost didnt believe their clocks. They ran there about 6 or 7 times, and it was consistent from week to week, The shutoff area was very short for a car that fast, and we finnally stopped goiong there because of that, but it was fun while it lasted.
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Old 10-24-2007, 05:22 AM   #7 (permalink)
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Re: 1/8 mile vs 1/4 mile ET

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Originally Posted by frdnut View Post
My old 302 4 speed combo ran pretty much exactly the same ets as you in the 1/8th(8.80s) and it ran pretty consistant 13.70s-13.80s in the 1/4...The strange part is that I was only running 2.0 60 fts compared to your 1.84s and my mph was only 80 mph compared to your 85 mph..So you are leaving quicker than me and going 5 mph faster yet we are running the same et..

I would echo frdnuts comment, I ran a 8.97 1/8 @80mph and same run hit 13.83 in the 1/4 @100.9 on only a 2.2 60 that run. With your 85mph 1/8
and 1.84 60 i would think your 1/8 would be faster. I too have a 289, car w/ me in it at the track weights 2990. Given an average 20mph increase from 1/8 to 1/4 your looking at 105ish mph that's good for low 13's or high 12's on a great 60'. But again something looks off w/ your 1/8 time given the mph..
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Old 10-24-2007, 07:00 AM   #8 (permalink)
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Re: 1/8 mile vs 1/4 mile ET

Agree - 85 MPH should be more like 8.40s. Here's that TQ vs HP thing from the other thread. For reference, the Mustang @ 3150 lbs runs 87 MPH, but with a 1.75 60' and an ET of 7.85ish.
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Old 10-24-2007, 08:18 AM   #9 (permalink)
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Re: 1/8 mile vs 1/4 mile ET

A local Malibu runs 7.90's@85. I too wonder why the 1/8 times are so high. My car runs 8.30's at 94 with high 1.80 60', but my 3.08 gear is to blame for lack of ET.
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Old 10-24-2007, 03:14 PM   #10 (permalink)
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Re: 1/8 mile vs 1/4 mile ET

My mistake. When I made that run it wasn't at Parris it was during the Show and Go event last year at the California Speedways old track on the south side of the oval. We were only allowed to run 1/8th mile since there were so many people without racing experiance there. Anyway, I was running on smaller 225/60-15's so I couldn't leave real hard. I'm hoping that with the bigger tires I can run all out from the get go.

John
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Old 10-24-2007, 03:30 PM   #11 (permalink)
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Re: 1/8 mile vs 1/4 mile ET

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Old 10-24-2007, 05:13 PM   #12 (permalink)
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Re: 1/8 mile vs 1/4 mile ET

That calculator uses the same formula of 1/8 ET x 1.57 = 1/4 ET that I posted earlier. Interesting.

Seems like the 1/8 mile MPH times posted here are all over the place though and 85MPH with an ET of 8.85 seems high.

Here's some 1/8 numbers from my "fleet" run at Irwindale:

Morris: 6.82/99.9MPH 1.44 60ft

Falcon: 7.30/94.1MPH 1.61 60ft

Datsun: 7.72/86.3MPH 1.63 60ft

The Datsun is still getting dialed in but the MPH seems low.
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Old 10-25-2007, 04:50 PM   #13 (permalink)
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Re: 1/8 mile vs 1/4 mile ET

Heres a couple of mine

1.73 1/8 = 8.14 @ 83 /// 1/4 = 12.88 @ 103.2

1.75 1/8 = 8.18 @ 82.8 /// 1/4 = 12.94 @ 102.5
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Old 01-16-2010, 05:28 PM   #14 (permalink)
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Re: 1/8 mile vs 1/4 mile ET

Mine weighs 2708.

60' time was a 1.96 1/8 mile 8.96 @ 77.21 1/4 mile 14.11 @ 94.27

There doesnt seem to be a foolproof way of converting 1/8th mile to 1/4 mile et's IMO.

Later,

Doug
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Old 01-18-2010, 08:35 AM   #15 (permalink)
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Re: 1/8 mile vs 1/4 mile ET

Try this

Drag Guess

An old buddy of mine, Steve Lothridge, has been working on this.

Try it out. Steve would like feedback on how it differs from your actual results, and he will tweak the formulas when he gets enough feedback.

I helped Steve with the data he used initially. We looked at NHRA records, and MOST of the cars had a 1/8 to 1/4 ratios that varied between 1.55 and 1.61. Baiscally, some cars launch soft and finish hard, others launch hard then taper off, and the rest fall in the middle.

Lee
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Last edited by L n L; 01-18-2010 at 08:43 AM.
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