Mods VS weight reduction or have it both ways!
Thread Starter
Race Director
Joined: Oct 2002
Posts: 10,864
Likes: 198
From: Southern CA
Mods VS weight reduction or have it both ways!
Have any of the old timers or performance junkies done a calculation that approximates how much hp/torque you need to make to get the same performance gain that you get by shedding weight & leaving the mods alone.
For example, lets say I remove my roof panel (replaced by xbar) and spare tire. That's probably 75 lbs or so. Throw in a plexi (?) rear hatch (we're a coupe). Glass weighs a lot. We're up to 150 lbs? I'm guessing these weights.
That gains me x tenths in the straight line game & also some cornering & top end.
How much hp/torque would I need to make to equal these gains?
Thanks! :flag
For example, lets say I remove my roof panel (replaced by xbar) and spare tire. That's probably 75 lbs or so. Throw in a plexi (?) rear hatch (we're a coupe). Glass weighs a lot. We're up to 150 lbs? I'm guessing these weights.
That gains me x tenths in the straight line game & also some cornering & top end.
How much hp/torque would I need to make to equal these gains?
Thanks! :flag
Burning Brakes
Joined: May 2001
Posts: 1,163
Likes: 13
From: Coto de Caza CA
Re: Mods VS weight reduction or have it both ways! (froggy47)
Well the glass top is about 21lbs, the solid top is about 28lbs, the bar must weigh something.... the spare and jack are about 30lbs. So more like you might save 50lbs without the brace. Also most drag strips will not let you run without a top. :seeya
Melting Slicks
Joined: Jan 2002
Posts: 2,784
Likes: 3
From: Atlanta GA
Re: Mods VS weight reduction or have it both ways! (froggy47)
The rule of thumb is usually around 100lbs of weight is - .1 (one tenth)
The roof isnt that heavy at all..... I dont know how much the spare tire delte will give... Im thinkin about pullin my out some day......
The roof isnt that heavy at all..... I dont know how much the spare tire delte will give... Im thinkin about pullin my out some day......
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Re: Mods VS weight reduction or have it both ways! (froggy47)
IMHO you'd be better off going for more power. Sure less weight is good, but you can completely strip the car and drop a couple hundred pounds, lets say you manage to remove 400 pounds. That's about 4 tenths. Alright, so you've got the faster time but you've also got a stripped car. If you just added say 40 horsepower you've got the same gain and haven't had to remove the first thing out of the car.
I'd go for keeping all the safety and luxury intact and adding power. Now if you wanted an all out drag car, you'd want to strip it down AND make more power.
Rough rule of thumb is that 100 pounds equals 1 tenth of a second. Also 10 hp roughly equals 1 tenth of a second. After a point it becomes a lot easier to add 10 horsepower than it does to shave 100 pounds.
I'd go for keeping all the safety and luxury intact and adding power. Now if you wanted an all out drag car, you'd want to strip it down AND make more power.
Rough rule of thumb is that 100 pounds equals 1 tenth of a second. Also 10 hp roughly equals 1 tenth of a second. After a point it becomes a lot easier to add 10 horsepower than it does to shave 100 pounds.
Race Director
Joined: Oct 1999
Posts: 13,298
Likes: 14
From: Somers NY
Re: Mods VS weight reduction or have it both ways! (Nathan Plemons)
Nathan
Your right about being easier to add HP than remove weight..However here is what I did to remove weight..
Remove mufflers 15lb each, went to 8" Converter saved another 20lb.. Changed from stock wheels to Weld Pro Star saved 50lb just in the front, & about 15 in the rear.
Removed front sway bar (dont need it to go straight) removed spare, & jack 30 lb..
Total app 125 lb + I gained HP removing mufflers, & 1.6 RR. Also the smaller is 3000 stall, & its also lighter..
Oh I forgot add +10 lb for extra tranny cooler...
I will beat most LT4s in the 1/4 ... however my car is not set up for twisties, or VERY long trips, though I do drive 100 miles one way to race..& 100 home every weekend..
[Modified by Red96Coupe, 10:12 PM 4/2/2003]
Your right about being easier to add HP than remove weight..However here is what I did to remove weight..
Remove mufflers 15lb each, went to 8" Converter saved another 20lb.. Changed from stock wheels to Weld Pro Star saved 50lb just in the front, & about 15 in the rear.
Removed front sway bar (dont need it to go straight) removed spare, & jack 30 lb..
Total app 125 lb + I gained HP removing mufflers, & 1.6 RR. Also the smaller is 3000 stall, & its also lighter..
Oh I forgot add +10 lb for extra tranny cooler...
I will beat most LT4s in the 1/4 ... however my car is not set up for twisties, or VERY long trips, though I do drive 100 miles one way to race..& 100 home every weekend..
[Modified by Red96Coupe, 10:12 PM 4/2/2003]
Elite Torch Red Member
Joined: Sep 1999
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From: Exit 89 GSP,Lakewood,NJ The Land Of Mojo
Cental/South NJ Events Coordinator
CI 1-2-3-4-5-6-7-8-9-10-11-12 Vet
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St. Jude Donor '03-'04-'05-'06-'07
Re: Mods VS weight reduction or have it both ways! (Red96Coupe)
My setup is just about similar to JP's
Every little bit helps, but what kills me is with all the weight saving I did, I put it all back with all the junk I'm hauling in the hatch.
Every little bit helps, but what kills me is with all the weight saving I did, I put it all back with all the junk I'm hauling in the hatch.
Race Director
Joined: Oct 1999
Posts: 13,298
Likes: 14
From: Somers NY
Re: Mods VS weight reduction or have it both ways! (Mr Mojo)
My setup is just about similar to JP's
Every little bit helps, but what kills me is with all the weight saving I did, I put it all back with all the junk I'm hauling in the hatch.
Every little bit helps, but what kills me is with all the weight saving I did, I put it all back with all the junk I'm hauling in the hatch.
Instructor
Joined: Sep 2002
Posts: 210
Likes: 0
From: Southfield Michigan
Re: Mods VS weight reduction or have it both ways! (froggy47)
So since I lost 30lb and plan on shedding a nother 20 that should give me .05 more in the 1/4 mile. :cool: And it's all free. Would hate to lose a race cuz of my gut heh.
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Burning Brakes
Joined: Feb 2002
Posts: 825
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From: Pittsburgh PA
Re: Mods VS weight reduction or have it both ways! (BookSmart)
another plus for reducing weight rather then increasing HP is when on the street less weight will also help braking and handling :yesnod:
Drifting
Joined: Jan 2002
Posts: 1,261
Likes: 4
From: Middle River MD
Re: Mods VS weight reduction or have it both ways! (MIke350)
I had my stock wheels off the other day to get some new tires put on.
Those things are heavy! (89 17x9.5)
If I spent a lot of time at the track, I would probably look into lighter wheels as mentioned above. Its got to make noticeable a difference.
Those things are heavy! (89 17x9.5)
If I spent a lot of time at the track, I would probably look into lighter wheels as mentioned above. Its got to make noticeable a difference.
Team Owner
Joined: Jun 2002
Posts: 21,510
Likes: 0
From: On a Wisconsin Death Trip
Re: Mods VS weight reduction or have it both ways! (HeeHaw89)
As StealDads67 said, 100 lbs is good for a tenth of a second in the quarter mile. That's what I've always been told. Also I work with snowmobiles a lot and the rule some guys go by is 7lbs = 1 hp. So we always run as little fuel as possible. Of course, a lot of other factors come into play in a sled due to the cetrifugal clutch transmission system and dropping weight sometimes changes the tuning on your clutches... :confused:
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Re: Mods VS weight reduction or have it both ways! (froggy47)
There are equations on my site that predict HP from launch weight and trap speed. You can put these in Excel and play with the numbers to predict one parameter knowing the other two. You can then convert trap speed to ET, or the ideal ET. I think for my Vette 80lb of weight reduction = 10hp gain = 1mph gain in trap speed.
I did the spare tire & jack delete, usually run with about 1/2 tank of fuel (at 6lb/gal that's about 60lb reduction from a full tank) and run 1/4-1/3 tank of fuel at the strip.
I did the spare tire & jack delete, usually run with about 1/2 tank of fuel (at 6lb/gal that's about 60lb reduction from a full tank) and run 1/4-1/3 tank of fuel at the strip.
