A HP vs weight question???
TECH Enthusiast
Joined: Aug 2005
Posts: 701
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From: crossett, Arkansas
lets give the idiot award to 95_formula lol. a 03-04 cobra is without question or debate faster than an ls1 stock for stock. ok back onto topic.
i agree ive heard the 100lbs thing also. another thing it also wheel size. rotating mass plays a huge factor also. i went from 16s all aorund to 17 front and 18s rear. and it slow me from 13.0 to 13.3 consistently. and those c5 wagon wheels weight probly only another 2-7 lbs more each. i can only imagine how much chrome 18" rims slow you down
i agree ive heard the 100lbs thing also. another thing it also wheel size. rotating mass plays a huge factor also. i went from 16s all aorund to 17 front and 18s rear. and it slow me from 13.0 to 13.3 consistently. and those c5 wagon wheels weight probly only another 2-7 lbs more each. i can only imagine how much chrome 18" rims slow you down
11 Second Club
Joined: Aug 2005
Posts: 804
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From: Tampa, FL
Originally Posted by blackened05
from what i've seen weight becomes less of a factor at higher speeds as well. lighter weight will get you through the 1/8 quicker, more hp/tq will get you through the 1/4 quicker
Teching In
Joined: Nov 2003
Posts: 44
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it is an continuasly adjusting equation. To claim any rule of thumb is rediculous.
taking 100 out of a a 3000 pound car does something different than taking 1000 out of a 4k pound car.
100 pounds out of a honda is something you will REALLY feel. A CRX with a camera man has a HUGE disadvantage. Its like adding a 300 pound balast to your F body.
When my stang weigh 3000 even, I consistantly gained 1 tenth when dropping 54 pounds, my passenger seat.
1tenth =/= 1mph =/= 10rwhp
10 rwhp can be huge or ver small depending on what type of mod and where it affects the entire powerband. Some mods that add 10 rwhp add 30rwhp in other places.
taking 100 out of a a 3000 pound car does something different than taking 1000 out of a 4k pound car.
100 pounds out of a honda is something you will REALLY feel. A CRX with a camera man has a HUGE disadvantage. Its like adding a 300 pound balast to your F body.
When my stang weigh 3000 even, I consistantly gained 1 tenth when dropping 54 pounds, my passenger seat.
1tenth =/= 1mph =/= 10rwhp
10 rwhp can be huge or ver small depending on what type of mod and where it affects the entire powerband. Some mods that add 10 rwhp add 30rwhp in other places.
Alright, too many different opinions in here. Lets try this........... 2 identical '02 LS1 Z28's with equal drivers...............except one has a 100lb advantage.........how many rwhp would it take for the second car to beat the first? 
Administrator
Joined: Jan 2002
Posts: 45,841
Likes: 5
From: Earth
Originally Posted by 95Snoozer
it is an continuasly adjusting equation.
equations huh?
Last edited by unit213; Feb 2, 2007 at 06:02 PM.
Launching!
Joined: Jul 2004
Posts: 204
Likes: 0
From: Arizona.
The weight thing is tricky. For one thing, pulling 100lbs of the front of the car will be worth a lot more than a 10th if you have traction issues out of the hole.
Also, if you pull 100 lbs off a 2000lb car, its going to have a much bigger effect than if you pull it off a 4000lb car. The percentage difference is just much greater with a 2000lber.
I suspect the 100s/10th rule is pretty applicable for a RWD car from 3000-4000 lbs.
Weight reduction will reduce the inertia of the car. Newtons law. Objects at rest want to stay that way and so on. So the more acceleration you have (AKA lower gears) the more inertia is a factor. Thats why lil' hatches which theoretically have a better power to weight still get pulled up top by a big heavy powerful car. In the upper gears its all about overcoming wind resistance.
I once dug up some equations that figured that out. It was pretty cool. We figured out that adding a thousand pounds to a theoretical car killed its low down (and hell even general) acceleration but only affected its theoretical top end by like 10 MPH.
Also, if you pull 100 lbs off a 2000lb car, its going to have a much bigger effect than if you pull it off a 4000lb car. The percentage difference is just much greater with a 2000lber.
I suspect the 100s/10th rule is pretty applicable for a RWD car from 3000-4000 lbs.
Weight reduction will reduce the inertia of the car. Newtons law. Objects at rest want to stay that way and so on. So the more acceleration you have (AKA lower gears) the more inertia is a factor. Thats why lil' hatches which theoretically have a better power to weight still get pulled up top by a big heavy powerful car. In the upper gears its all about overcoming wind resistance.
I once dug up some equations that figured that out. It was pretty cool. We figured out that adding a thousand pounds to a theoretical car killed its low down (and hell even general) acceleration but only affected its theoretical top end by like 10 MPH.
Launching!
Joined: Jul 2004
Posts: 204
Likes: 0
From: Arizona.
Originally Posted by 95Snoozer
it is an continuasly adjusting equation. To claim any rule of thumb is rediculous.
taking 100 out of a a 3000 pound car does something different than taking 1000 out of a 4k pound car.
100 pounds out of a honda is something you will REALLY feel. A CRX with a camera man has a HUGE disadvantage. Its like adding a 300 pound balast to your F body.
When my stang weigh 3000 even, I consistantly gained 1 tenth when dropping 54 pounds, my passenger seat.
1tenth =/= 1mph =/= 10rwhp
10 rwhp can be huge or ver small depending on what type of mod and where it affects the entire powerband. Some mods that add 10 rwhp add 30rwhp in other places.
taking 100 out of a a 3000 pound car does something different than taking 1000 out of a 4k pound car.
100 pounds out of a honda is something you will REALLY feel. A CRX with a camera man has a HUGE disadvantage. Its like adding a 300 pound balast to your F body.
When my stang weigh 3000 even, I consistantly gained 1 tenth when dropping 54 pounds, my passenger seat.
1tenth =/= 1mph =/= 10rwhp
10 rwhp can be huge or ver small depending on what type of mod and where it affects the entire powerband. Some mods that add 10 rwhp add 30rwhp in other places.