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

Jeff Lee · 07-02-2010, 10:33 PM

Quote:

Originally Posted by JRyan

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

From everything I have been told, that is correct. Before AHFS, HP and or index was adjusted heavily when one racer dominated.
I can run SS/G-H-I just like you. Kind of makes it a difficult decision which to run, huh?

Ed Carpenter · 07-02-2010, 10:44 PM

Jeff it doesn't make sense. H is at 3010. Why in the hell would you add 150 to get to I at 3160. So one guy was fast why did it effect all the indexes. Why didn't they hammer his combo? That's what they did to Robin Brown with the 283 stick in 07'

Jeff Lee · 07-03-2010, 10:30 AM

I guess that's just the way it is. Why don't you contact NHRA and see what can be done about it? Call NHRA Tech and ask for Pat Cvengros as he's the Committee Chairman of the S/SS Rules Committee.
Seriously, nothing will come of this posting here, you have to go to the source.
While your at it, get the stick indexes in line with the automatic indexes. For example, there's a .200 spread between SS/J & SS/JA. That's ridiculous!

Ed Carpenter · 07-03-2010, 06:12 PM

Jeff I did send a letter to NHRA a couple of years ago. They basically said to pound sand. My car needs to get the 299hp reduced. IHRA is 295hp. The 327/275 combo has been beat on for over 30 years. There's not alot left to be found in the horsepower dept. Were going to try a set of the RHS aftermarket heads this winter. But guess what the hp rating goes up to 304 when you do that. So well see.

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: 4,296 Likes: 2,383 Liked 3,181 Times in 972 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

07-02-2010, 10:44 PM	#8
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 Jeff it doesn't make sense. H is at 3010. Why in the hell would you add 150 to get to I at 3160. So one guy was fast why did it effect all the indexes. Why didn't they hammer his combo? That's what they did to Robin Brown with the 283 stick in 07' __________________ Ed Carpenter 2005 Chevy Cobalt A/SM Race Engine Development

07-03-2010, 10:30 AM	#9
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 3 Times in 3 Posts	Re: Weight vs ET I guess that's just the way it is. Why don't you contact NHRA and see what can be done about it? Call NHRA Tech and ask for Pat Cvengros as he's the Committee Chairman of the S/SS Rules Committee. Seriously, nothing will come of this posting here, you have to go to the source. While your at it, get the stick indexes in line with the automatic indexes. For example, there's a .200 spread between SS/J & SS/JA. That's ridiculous! __________________ Jeff Lee 7494 D/S '70 AMX

07-03-2010, 06:12 PM	#10
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 Jeff I did send a letter to NHRA a couple of years ago. They basically said to pound sand. My car needs to get the 299hp reduced. IHRA is 295hp. The 327/275 combo has been beat on for over 30 years. There's not alot left to be found in the horsepower dept. Were going to try a set of the RHS aftermarket heads this winter. But guess what the hp rating goes up to 304 when you do that. So well see. __________________ Ed Carpenter 2005 Chevy Cobalt A/SM Race Engine Development