1320 Method?
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 9,916
Likes: 38
From: South Carolina
St. Jude Donor '03 & '05
1320 Method?
"From another Forum...."I learned this a few years ago and thought you guys might find it interesting and enlightening. It is a numerical method that evaluates how efficiently you are putting your power (measured by trap speed) to the track (measured by ET). I’ll call it the 1320 method. Here’s what you do.
Take your naturally aspirated ET and multiply it by your trap speed.
Examples:
13.2 X 105.0 = 1386
12.3 X 107.5 = 1333
12.1 X 109.0 = 1319
11.9 X 110.0 = 1309
Now compare the result to 1320. The closer your result is to 1320, the more efficiently you are putting the power to the ground. The car running 13.2@105 needs more traction or suspension work. The car running 11.9@110 has ample (too much) suspension/traction work. It is rare to see people under 1320 naturally aspirated. 1340 is a more realistic number for hard running Car.
Where does your setup stand?"
Ever heard of this and its validity? Steve
Take your naturally aspirated ET and multiply it by your trap speed.
Examples:
13.2 X 105.0 = 1386
12.3 X 107.5 = 1333
12.1 X 109.0 = 1319
11.9 X 110.0 = 1309
Now compare the result to 1320. The closer your result is to 1320, the more efficiently you are putting the power to the ground. The car running 13.2@105 needs more traction or suspension work. The car running 11.9@110 has ample (too much) suspension/traction work. It is rare to see people under 1320 naturally aspirated. 1340 is a more realistic number for hard running Car.
Where does your setup stand?"
Ever heard of this and its validity? Steve
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
10.15sec x 131.0 MPH = 1329.65
The way I have heard it explained is: If the number is over 1320 then you have traction problems. If your under 1320 then you have good traction, but the car is dying on the top end.
If your real close to 1320 then the car is working like its suppose to. Looking at mine above, I would have to say it is a pretty good indicator, especially when comparing my car to Hooked Ups. Nearly the same motor size/configuration, but he has a solid rear and better 60' times. 1.2X 60' time to my mid 1.3s, but our MPH is nearly the same and sometimes I do hit over 133 depending on weather. The above times were from my last runs in 2000ft DA.
9.89 x 133 =1315
The way I have heard it explained is: If the number is over 1320 then you have traction problems. If your under 1320 then you have good traction, but the car is dying on the top end.
If your real close to 1320 then the car is working like its suppose to. Looking at mine above, I would have to say it is a pretty good indicator, especially when comparing my car to Hooked Ups. Nearly the same motor size/configuration, but he has a solid rear and better 60' times. 1.2X 60' time to my mid 1.3s, but our MPH is nearly the same and sometimes I do hit over 133 depending on weather. The above times were from my last runs in 2000ft DA.
9.89 x 133 =1315
Safety Car
Joined: Dec 2002
Posts: 3,655
Likes: 24
From: Charleston SC
11.73x117=1372.41
Stupid calculation indicates I need more traction and to make it worse the dumb thing is correct. Like I realy needed some wizbang math problem to tell me I suck at the track
Stupid calculation indicates I need more traction and to make it worse the dumb thing is correct. Like I realy needed some wizbang math problem to tell me I suck at the track
Team Owner
Joined: Sep 2003
Posts: 20,170
Likes: 672
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Using this calculation, my 86 should be spinning wildly down the track.
13.8 * 99 = 1366
Cept these runs were without tire slip.
Maybe since I'm running an automatic,
the calculation is figuring in the TC slip?
13.8 * 99 = 1366
Cept these runs were without tire slip.
Maybe since I'm running an automatic,
the calculation is figuring in the TC slip?
Safety Car
Joined: Nov 2004
Posts: 4,991
Likes: 5
From: The Pines South Jersey
Originally Posted by JrRifleCoach
Using this calculation, my 86 should be spinning wildly down the track.
13.8 * 99 = 1366
Cept these runs were without tire slip.
Maybe since I'm running an automatic,
the calculation is figuring in the TC slip?
13.8 * 99 = 1366
Cept these runs were without tire slip.
Maybe since I'm running an automatic,
the calculation is figuring in the TC slip?
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Pro
Joined: Jul 2003
Posts: 543
Likes: 0
From: DFW Texas
Heard of doing this calculation back in the early 1980's. I think the magazine was Popular Hot Rodding and the author called it "Figuring the Hook Factor." When I started my own racing I was watching "Stock" class NHRA cars. They ususally have very low 1310 numbers but man they make they make those "stock" cars run. They also know how to make a stock chassis work, no ladder bars or after market four link rear suspensions. 
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
I like to use this method to see how close my ET is to optimum for power developed.
Say I had a trap speed of 104 mph with an ET of 13.02 sec (these are actual numers from a copla years ago). Using the above method I see that best expected ET would be:
ET = 1357 / 104 = 13.04 sec.
This told me that my actual ET is the best I could do with the HP available.
If your calculated ET is lower than the actual, then basically you need a harder launch. This could mean the need for a higher stall TC and/or sticky tires. For the stick shift guys it could be a little more complex??
Say I had a trap speed of 104 mph with an ET of 13.02 sec (these are actual numers from a copla years ago). Using the above method I see that best expected ET would be:
ET = 1357 / 104 = 13.04 sec.
This told me that my actual ET is the best I could do with the HP available.
If your calculated ET is lower than the actual, then basically you need a harder launch. This could mean the need for a higher stall TC and/or sticky tires. For the stick shift guys it could be a little more complex??
