Weight vs ET

Ed Carpenter · 07-02-2010, 07:25 AM

If you lightened a car 150 lbs what would the ave gain in ET be???

jmcarter · 07-02-2010, 07:34 AM

The approximate number has always been a tenth per hundred pounds, but there are variables of course....I always use the Wallace Calculators for quick reference and know many others do as well; here's the link

http://www.wallaceracing.com/Calculators.htm

Ed Carpenter · 07-02-2010, 09:06 AM

I used following data on wallace

ET 10.05
MPH 130.00 at 3050lbs

wallace says at 2900 lbs

ET 9.88
MPH 132 and change

Ok why then does NHRA list SS/G at 10.45 index SS/H at 10.50 SS/I at 10.55 etc
difference in weight from H to I is 150lbs yet only 5 between indexes????????????

Michael Beard · 07-02-2010, 09:13 AM

Because physics didn't create the index system.

In my 4-cyl FWD car, 215 pounds was nearly HALF A SECOND, in the 1/8th mile! If I recall, a similar change in my Volare was about .12 in the 1/8th.

Adger Smith · 07-02-2010, 09:30 AM

Good answer Michael.... Index system was created by Man and then hit/altered by man and his race cars performance!

JRyan · 07-02-2010, 08:28 PM

Ok why then does NHRA list SS/G at 10.45 index SS/H at 10.50 SS/I at 10.55 etc
difference in weight from H to I is 150lbs yet only 5 between indexes????????????

Ed, the REAL reason stems from way back and the answer is two words: Danny Helmer.

Jerry

07-02-2010, 07:25 AM	#1
Ed Carpenter Live Reporter Join Date: May 2006 Location: Dripping Springs, Tx Posts: 2,709 Likes: 186 Liked 520 Times in 132 Posts	Weight vs ET If you lightened a car 150 lbs what would the ave gain in ET be??? __________________ Ed Carpenter 2005 Chevy Cobalt A/SM Race Engine Development

07-02-2010, 07:34 AM	#2
jmcarter VIP Member Join Date: Dec 2008 Location: Richmond Hill GA (and Port Ludlow WA) Posts: 4,302 Likes: 2,399 Liked 3,204 Times in 977 Posts	Re: Weight vs ET The approximate number has always been a tenth per hundred pounds, but there are variables of course....I always use the Wallace Calculators for quick reference and know many others do as well; here's the link http://www.wallaceracing.com/Calculators.htm __________________ Jim Carter 2340 Super Stock 2340 SST/2340 Stock Set another place at the table

07-02-2010, 09:06 AM	#3
Ed Carpenter Live Reporter Join Date: May 2006 Location: Dripping Springs, Tx Posts: 2,709 Likes: 186 Liked 520 Times in 132 Posts	Re: Weight vs ET I used following data on wallace ET 10.05 MPH 130.00 at 3050lbs wallace says at 2900 lbs ET 9.88 MPH 132 and change Ok why then does NHRA list SS/G at 10.45 index SS/H at 10.50 SS/I at 10.55 etc difference in weight from H to I is 150lbs yet only 5 between indexes???????????? __________________ Ed Carpenter 2005 Chevy Cobalt A/SM Race Engine Development

07-02-2010, 09:13 AM	#4
Michael Beard VIP Member Join Date: Sep 2002 Location: Columbus, OH Posts: 4,060 Likes: 0 Liked 13 Times in 9 Posts	Re: Weight vs ET Because physics didn't create the index system. In my 4-cyl FWD car, 215 pounds was nearly HALF A SECOND, in the 1/8th mile! If I recall, a similar change in my Volare was about .12 in the 1/8th. __________________ Michael Beard - NHRA/IHRA 3216 S/SS

07-02-2010, 09:30 AM	#5
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: Weight vs ET Good answer Michael.... Index system was created by Man and then hit/altered by man and his race cars performance! __________________ Adger Smith (Former SS) Last edited by Adger Smith; 07-02-2010 at 09:31 AM. Reason: sp

07-02-2010, 08:28 PM	#6
JRyan Senior Member Join Date: Apr 2003 Location: Aberdeen SD Posts: 645 Likes: 30 Liked 112 Times in 31 Posts	Re: Weight vs ET Ok why then does NHRA list SS/G at 10.45 index SS/H at 10.50 SS/I at 10.55 etc difference in weight from H to I is 150lbs yet only 5 between indexes???????????? Ed, the REAL reason stems from way back and the answer is two words: Danny Helmer. Jerry