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Author
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Topic: Weight vs. ET
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Ryan Wilke
Gearhead Posts: 2494
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 01-11-2002 04:34 PM
   
OK Racers:
How knows the formula for the trade off of weight to ET performance?If my car/driver looses 75#, what improvement can I expect to see in my ET? Thanks, Ryan 
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65_289
Gearhead Posts: 761
From:
Registered: Jul 2001
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posted 01-11-2002 04:40 PM
quote:
Originally posted by Ryan Wilke:
OK Racers:
How knows the formula for the trade off of weight to ET performance?If my car/driver looses 75#, what improvement can I expect to see in my ET? Thanks, Ryan
I have heard 100# = 1 tenth. But that doesn't make it true.
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1965 Coupe, Tremec 3550, Steeda Tri-Ax, Cable Clutch conversion, 3.25 gears, Biondo Line Lock, Ford XB3 longblock, x303 heads, B-Cam, 9:1 comp., Tri-y headers, cut-outs, Ford Racing high-torque mini-starter, Pertronix Ignitor & Flamethrower coil, 650 double pumper, Edelbrock RPM intake, K&N air, Holley electric fuel pump & AFPR, dual 2-chamber Flowmasters, Summit 3-way fronts, Rancho 5-way rears, 5-leaf springs, Chrome Export Brace, Griffen Radiator, Comp. Eng. subs.
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kid vishus
Gearhead Posts: 6590
From: middle of NC
Registered: Oct 2000
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posted 01-11-2002 05:00 PM
It all depends. On a car that is well balanced, 100 lbs does equal almost a tenth in the 1/4, and .06 in the 1/8. But on a car that is nose heavy, sometimes they will run just as fast with MORE weight in the back even though it adds weight overall to the car. My granada was very nose heavy, after I added 180 lbs of lead to the trunk, it actually ran the same et, but was much more consistent, especially in the 60'. And it actually ran its best 60' and fastest et with the lead in the trunk.
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Fastymz
Moderator Posts: 21275
From: Reno Nv USA M&M#1240
Registered: Apr 2001
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posted 01-11-2002 05:58 PM
Good point kid vishus,you have to get traction or it just dosen't matter.
I too have always heard that 100lbs=tenth.
Dose it matter on how the car is set up,I.E. like gears,motor,trans,or dose it work the same for every setup.So if you can get the driver to lose 200lbs you really see a difference. 
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65 coupe,351w,RPM intake,Carter625,shorty headers,2.5 exhaust, Flowmasters,C4,open 8" 2:80,Big Boss 429 hood scoop,Crager SS,Black Suede.
MEM#1240
https://mustangsandmore.com/ubb/Fastymz.html
[This message has been edited by Fastymz (edited 01-11-2002).]
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 01-11-2002 06:42 PM
A 100# weight loss helps a lighter car more than a heavy one and it helps a low h.p. car more than a high h.p. car.Here are some examples based on optimum traction for all runs. A hundred pound loss in each case. 300 h.p. 3000# car will run .14 faster
600 h.p. 3000# car will run .11 faster 300 h.p. 2500# car will run .16 faster
600 h.p. 2500# car will run .12 faster 300 h.p. 2000# car will run .18 faster
600 h.p. 2000# car will run .15 faster According to my 'puter anyway. 
SteveW
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Rustang
Gearhead Posts: 821
From: Clarion PA
Registered: Nov 2000
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posted 01-11-2002 06:51 PM
F=ma ------------------
'68 mustang 351 clevor- 10.92@124
'67 Stang, 351W -11.18@118
'69 351C Torino-14.90@100
'78 Pickup 351W-15.56@88
'79 Pickup 460 ET=??
http://www.rustang-racing.cityslide.com/contents/contents.cfm/712231
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 01-11-2002 09:04 PM
quote:
Originally posted by Rustang:
F=ma
Whatz dat mean??
SteveW
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I65Stang
Gearhead Posts: 6575
From: Folsom, CA
Registered: Jun 99
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posted 01-11-2002 09:05 PM
quote:
Originally posted by steve'66:
Whatz dat mean??
SteveW
Its either a new way to spell Sam or force=massXacceleration ------------------
Tim M&M Member #35
1965 Mustang coupe, 200 I6, Holley 2300, Clifford header, true duals w/ 26" Smithys
1988 Mustang GT AOD vert, 15.810 @ 88.871 mph 100% stock w/ no traction
1976 Silverline Comoro 18' trihull ski boat, 188 hp 302 I/O, another toy
http://all.at/mustang
https://mustangsandmore.com/ubb/I65Stang.html
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Mike_R
Gearhead Posts: 178
From: Indianapolis, IN 46237
Registered: Feb 2001
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posted 01-14-2002 11:58 AM
My brother had a 72 torino with a 460 and C6 tranny that weighed right around 4400 lbs that ran 12.70 @108 MPH. He took the engine , tranny, and rearend (third member) and put it in a 2800 lb Mustang and ran 11.15 @124 MPH right off the bat with no other changes. Entire drivetrain identical.So that's subtracting 1600 lbs and gaining 16 MPH and 1.55 seconds off the ET. In this case it almost fell exactly into the old 100 lbs equals .10 seconds.
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 01-14-2002 12:10 PM
I think for our purposes the 100 lbs = 1 tenth formula is the acceptable one. I have always subscribed to it and found that it works 99% of the time on a well balanced car. ------------------
Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
US Class Nationals link
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Ryan Wilke
Gearhead Posts: 2494
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 01-14-2002 12:34 PM
Thanks for all the imput, Guys! Ryan
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capri man
Gearhead Posts: 7611
From: doerun, ga.
Registered: Nov 2000
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posted 01-14-2002 01:03 PM
DOES THAT MEAN IN 1/8 YOU WOULD GAIN ABOUT
.6329113 SEC? 100 DIVIDED BY .158------------------
mike r
racing is real
everything else is just a game.
81 capri-7.56 @88mph 1/8
1.56 60 ft.
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Fastymz
Moderator Posts: 21275
From: Reno Nv USA M&M#1240
Registered: Apr 2001
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posted 01-14-2002 02:30 PM
So whats better more power or less weight for a race car.????
And which is better for strip and street car.SCOOP. ------------------
65 coupe,351w,RPM intake,Carter625,shorty headers,2.5 exhaust, Flowmasters,C4,open 8" 2:80,Big Boss 429 hood scoop,Crager SS,Black Suede.
MEM#1240 https://mustangsandmore.com/ubb/Fastymz.html
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Ryan Wilke
Gearhead Posts: 2494
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 01-14-2002 03:49 PM
SCOOP,
I'm sure there are others with more experience and smarter on this than I, but if I was pressed for a response, I have to say I don't think there is a apples-to-apples formula for what you're asking. BUT - considering what the others have said about front-to-back weight distribution and that you'd NEVER reduce weight that makes the car unsafe (as in braking ability, rollover protection, handling etc.) and remembering that as you make the car faster/quicker than what was provided with the OEM power, means you'll need BETTER brakes, impact protection than what was provided by OEM. I'd guess that, "Less weight is better than more HP"....for either a Race-only or Street/Strip car. Ryan [This message has been edited by Ryan Wilke (edited 01-14-2002).]
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 01-15-2002 12:56 PM
There is NO cheaper method of decreasing ET then reducing weight. Over the years I have seen some pretty ugly cars that run pretty fast for the motor that is in them. ------------------
Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
US Class Nationals link
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Fastymz
Moderator Posts: 21275
From: Reno Nv USA M&M#1240
Registered: Apr 2001
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posted 01-15-2002 01:10 PM
quote:
Originally posted by Moneymaker:
There is NO cheaper method of decreasing ET then reducing weight. Over the years I have seen some pretty ugly cars that run pretty fast for the motor that is in them.
Hey why were you looking at MY car when you said that. SCOOP ------------------
65 coupe,351w,RPM intake,Carter625,shorty headers,2.5 exhaust, Flowmasters,C4,open 8" 2:80,Big Boss 429 hood scoop,Crager SS,Black Suede.
MEM#1240 https://mustangsandmore.com/ubb/Fastymz.html
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capri man
Gearhead Posts: 7611
From: doerun, ga.
Registered: Nov 2000
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posted 01-15-2002 01:22 PM
no he was looking at mine scoop!!!------------------
mike r
racing is real
everything else is just a game.
81 capri-7.56 @88mph 1/8
1.56 60 ft.
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kid vishus
Gearhead Posts: 6590
From: middle of NC
Registered: Oct 2000
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posted 01-15-2002 04:54 PM
No he wasnt. Have you all seen my granada? It definatley wins the ugly but fairly fast and consistent award.
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MrWesson22
Gearhead Posts: 1286
From: Dacula, GA
Registered: Sep 2000
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posted 01-15-2002 11:21 PM
True, but isn't it usually easier to gain 10hp than drop 100lbs? The only truly cheap way to drop a considerable amount of weight is gutting your interior. After you've done that, you get into 'glass body parts, lexan windows, etc. Doesn't rotating mass (ie driveshaft) play a much larger role than just vehicle weight? ... just thinking out loud here.
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Neal
Member #723
[email protected] AIM: MrWesson22 69 Gulfstream Aqua Grande
351C/Toploader 4sp
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Rustang
Gearhead Posts: 821
From: Clarion PA
Registered: Nov 2000
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posted 01-16-2002 05:16 AM
I've heard every 10lbs taken off of rotational weight is equal to a tenth too. ( so much for F = ma!)------------------
'68 mustang 351 clevor- 10.92@124
'67 Stang, 351W -11.18@118
'69 351C Torino-14.90@100
'78 Pickup 351W-15.56@88
'79 Pickup 460 ET=??
http://www.rustang-racing.cityslide.com/contents/contents.cfm/712231
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Ryan Wilke
Gearhead Posts: 2494
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 01-16-2002 09:28 AM
WOW!
10# off rotational weight is similar in ET results as 100# off of sprung weight!? My understanding of examples of the different TYPES of weight would be: rotational weight (things moved by the crankshaft) = driveshaft, flywheel, ring/pinion/axles; sprung weight (things that don't move other than with the car) = passenger seat, spare tire; unsprung weight (things that move with the suspension) = brake drums/rotors, calipers, rims/tires. So it seems that equal weight loses in each weight TYPE results in different benefit gains at affecting ET. Is that right, Guys? Ryan
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capri man
Gearhead Posts: 7611
From: doerun, ga.
Registered: Nov 2000
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posted 01-16-2002 10:47 AM
10 lbs rotational weight =1/10th? never heard that but if it works here comes an aluminum driveshaft. i have heard that 1 lb of sprung weight =X lbs of unsprung weight but i cant remember what the X is. for some reason i want to think it is 7. maybe someone knows. thanks------------------
mike r
racing is real
everything else is just a game.
81 capri-7.56 @88mph 1/8
1.56 60 ft.
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Mike_R
Gearhead Posts: 178
From: Indianapolis, IN 46237
Registered: Feb 2001
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posted 01-16-2002 02:18 PM
I have seen a test in an article where they test different weight of wheels (steel vs aluminum vs lightweight tires vs heavy tires). It looked to me like they still hold fairly close to the old 100 lbs = .10 seconds. It may have been a little better like maybe as much as 100 lbs = .12 seconds, but not more than that. Of course this was just one article so who knows.If the rotational weight is that much better, I could sure help my car out alot. I'm running 25 lb steel magnum 500's all around and 25 lb tires up front. I've heard people say lighweight wheels and tires help your 60 ft time. Has anybody found this to be true. I need all the help I can get in that department.
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Rustang
Gearhead Posts: 821
From: Clarion PA
Registered: Nov 2000
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posted 01-16-2002 08:32 PM
I had to break out the old Hot Rods to make sure I wasn't tellin' a lie!
I know I've read it on more than one occasion, but I found in Hot Rod, April 1995 page 55 it says "Mopar Performance claims that shedding unsprung weight is 10 times more beneficial than in other parts of the car, and that each 10 pounds in unsprung weight COULD be worth as much as a tenth in the quarter mile."So I was a little misguided  ...I said rotational weight where-as they are saying unsprung weight. ------------------
'68 mustang 351 clevor- 10.92@124
'67 Stang, 351W -11.18@118
'69 351C Torino-14.90@100
'78 Pickup 351W-15.56@88
'79 Pickup 460 ET=??
http://www.rustang-racing.cityslide.com/contents/contents.cfm/712231
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Ryan Wilke
Gearhead Posts: 2494
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 01-17-2002 08:23 AM
I'm with you Mike_R!
Sounds like I also need to look harder for some good, used aluminum rims and loose my white, steel-spoked 'wagon wheels' Hey Guys: Do all of you agree with my examples of the different TYPES of weight?
(...just trying to be thorough...) Thanks, Ryan
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Just Strokin
Gearhead Posts: 754
From: Tuscaloosa, Alabama
Registered: Dec 2001
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posted 01-17-2002 09:37 PM
Here is the opportunity for the guys with 9" rears and 31 spline axles to drop a few ounces or a pound of unsprung weight
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chips67
Gearhead Posts: 663
From: louisville, ky, usa
Registered: Jul 2001
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posted 01-18-2002 07:09 PM
hey, whats up with that? never heard of a locker thats been "lightened"....is this a legitimate practice??? wouldnt this weaken the unit? ------------------
67 coupe, 650dp and rpm intake on 5.0 with afr 165 heads, 4 speed, 4.11's.....best so far is [email protected] in 1/8 mile with 1.79 60ft. time.
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70 Pony
Gearhead Posts: 1888
From: West Chester, PA, USA
Registered: Jan 2000
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posted 01-22-2002 10:26 AM
Got in on this late.......So Steve W.....the way I figure it, since I ran 4: 13.1's last year....If I go on a diet and lose 200 lbs, I should be right at 12.9......
One question....I weigh 165.....
Or should I just install the Auto Pilot ?------------------
EDDIE D
Resto Mod '70 Sport Roof
Arrest Me Red
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capri man
Gearhead Posts: 7611
From: doerun, ga.
Registered: Nov 2000
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posted 01-22-2002 10:43 AM
sunday i took out my 90lb spare tire. my car picked up from 7.69-7.70 to 7.61-7.62.
1/8. had no noticable difference in 60 ft times.------------------
mike r
racing is real
everything else is just a game.
81 capri-7.56 @88mph 1/8
1.56 60 ft.
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