Drag Racing Tech - weight reduction-worth it?

my friend just started doing some weight reduction to his trans am and he said he lost around 200 lbs so far how much would this improve him in the 1/4 if he was consistent?

so thinking of trying to do some weight reduction to my SS what would be some good things to get rid of or change to get the weight down? is it worth it or not?

Unless its alot (i.e.500lb+) i would say not worth it for a DD but if its a race car go for it..good way to tell put about 200lb of weight or a friend in you car and make a pass see how much you loose.

i heard but not sure every 100 lbs lost is .1 off your time. also heard that when doing weight reduction reducing weight of parts that move has a considerable change oppose to like seats and inner fenders. parst that move would be leighter wheels, driveshaft axels.

my friend just started doing some weight reduction to his trans am and he said he lost around 200 lbs so far how much would this improve him in the 1/4 if he was consistent?

so thinking of trying to do some weight reduction to my SS what would be some good things to get rid of or change to get the weight down? is it worth it or not?

the lighter you get the bigger a deal it becomes. If you are talking about 50lbs in 3800lb car well it might be worth 0.01 maybe but if its 50lbs in a 2000lb car its huge.

see my friend changed his seats out, took out the rear seats, spare tire & jack, t-tops holders, air condition, and now he just ordered a carbon fiber driveshaft... it just doesnt seem like he's gaining alot through doing that to me...

:wrongforu

Weight is always good to get rid of, but it can become impractical for a DD (you gotta have seats, spare tire, jack, large fuel tank, stereo, accessories, ect.). For a race car, obviously strip it down as much as possible. :)

see my friend changed his seats out, took out the rear seats, spare tire & jack, t-tops holders, air condition, and now he just ordered a carbon fiber driveshaft... it just doesnt seem like he's gaining alot through doing that to me...

here is the laymans ruile of thumb i have observed. Your observations may vary. a light fast car will be more wieght sensitive then a heavy fast car.

2 car both run 9.00 one wieghs 3800lbs the other wieghs 2500lbs.
You add 100lbs to each car.

the 3800lb monster drops 0.005 the 2500lb car drops 0.20. why you ask becuase the wieght added to the pighter car makes up a larger percentage of its overall weight. Now it takes alot less power to go 9.0 in a 2500lb car since the light car is already at a power disadvantage it gains more Et then the heavier car which has 30% more power so the small 1% change in wieght is negligable.

As said before, rotational mass especially can help multi-fold compared to stagnant weight. For instance the average is around 2 tenths for skinnies, however if you took off 30 or so lbs from the interior its not nearly going to give you those kind of gains. If you're going to do serious weight reduction, do it where it counts.

As said before, rotational mass especially can help multi-fold compared to stagnant weight. For instance the average is around 2 tenths for skinnies, however if you took off 30 or so lbs from the interior its not nearly going to give you those kind of gains. If you're going to do serious weight reduction, do it where it counts.

even that one is sometimes up in the air and this is why. Once you have the moment of inertia IE the wheel or shaft starts to spin the amount of force required to accelerate that mass after moment of intertia is massively lower. there are flywheel calculator out there for engineers if you want to calculate this stuff out.


A comprehensive plan of wieght reduction is the best method for sucess. Start finding 2-3 lbs here and there next thing you know you've dropp 400lbs without sacrificing much.

i can say i was bittin by the weight reduction bug myself. Now mine isnt a daily driver so it dont bother me at all. So far i took out almost everything besides the dash, seats and the interior panals (carpet is out). No heat/ac, ps, abs, i mean its damn near gutted. So far its in the 400-450 lbs lost. Look at my front end in my sig, took so much weight off the front end it sits up a lot higher. Im a bicycle mechanic for a race team so i know a lot about rotating mass. If you have a light frame with heavy wheels, it still pedals like a tank. So yes, REMOVE the rotating weight! same with my motor. I deleted every acc. off the motor, all im spinning is a alternator. So with all the heavy pullies off and not spinning, my motor revs a lot faster because im not spinning all that mass. To put it in eaiser terms, think of it this way....

take rotating weight and times is by 2
standing weight... take a longer crap in the morning, lol.

On motor my car only makes 400RWHP but it runs 10.79@123.62 in the 1/4. I think the car weights around 3170 with me in it. With weight reduction, some guys never see you coming!

Most of my weight reduction was done to help offset the wieght of the BBC. Of course its not a DD but driven some during the spring-fall months anyway. So everything I've gotten rid of really didn't help much anyway.

The accepted rule of thumb is 100lbs removed is worth 1 tenth and 1 mph.

Paul :judge:

In regards to roational mass it depends IMO. Lighter flywheels allow the engine to rev faster but store less energy. A heavier flywheel will store more energy so when you shift the engine doesn't bog as much because of the rotational energy in the flywheel. This is a part that has an RPM going up and down. Now parts like the driveshaft, wheels, and tires you would want as light as possible because you never reclaim the energy. They just spin faster and faster, so the light they are the less HP they will consume in the process.

Exactely imflyn. They sell heaver flywheels for dirtbikes so it doesnt stall at lower speeds because of the heaver mass it keeps the engine running. Thats all about your set-up with your car though. But yes, everything else get as light as poss.!

IMO weigth reduction is worth it. :)

my friend just started doing some weight reduction to his trans am and he said he lost around 200 lbs so far how much would this improve him in the 1/4 if he was consistent?

so thinking of trying to do some weight reduction to my SS what would be some good things to get rid of or change to get the weight down? is it worth it or not?

You claim to have a low 9 second 4th gen, yet you ask a question like this? :bs:

i didnt build the drag car thats why it says newest edition my dads friend had it built by a shop and didnt ever run it so we got it for a steal basically.

its well worth it to me, track prepped im at 3200 w/ driver. once i get the kmember and arms im looking to be 3150 w/ driver. im 140lbs.

on the street i put the carpet and interior panels back in, and the street tires.

-brandon

Weight reduction was the best mod for my LT1 car.

The accepted rule of thumb is 100lbs removed is worth 1 tenth and 1 mph.

Paul :judge:


That depends on your power level. 100 lbs on my car has shown to be .06 to .07 sec. I have a friend that has run several fast NHRA Comp eliminator cars, and changes classes by adding or removing weight, and he says he can figure on .05 sec per 100 lbs. Of course, he makes a couple hundred more hp that I. :)

I tell guys pounds are the same as hp.

Does this make sense?


On a heavier car 100 pounds is not that high of a percentage of weight. Say 100 pounds out of a 4200 pound impy is not that much.

Now 100 pounds out of a 2800 pound car would be a lot more and cut more time because its a higer percentage of weight being pulled?

For example (just throwing out numbers)

10 pounds in a 100 pound go cat is a 10% weight reduction

10 pounds in a 1000 pound car is a 1% weight reduction.

Does this make sense?


On a heavier car 100 pounds is not that high of a percentage of weight. Say 100 pounds out of a 4200 pound impy is not that much.

Now 100 pounds out of a 2800 pound car would be a lot more and cut more time because its a higer percentage of weight being pulled?

For example (just throwing out numbers)

10 pounds in a 100 pound go cat is a 10% weight reduction

10 pounds in a 1000 pound car is a 1% weight reduction.

Not in my experience. Many years ago (late 1960s) I race NHRA Stock Eliminator '56 Chevys. I began with a 9 passenger station wagon with the 225 hp solid lifter 2 X 4 bl carb engine. We were restricted to 7" slicks, and about all there was available were Marsh recaps, so the wagons hooked better and ran a lower class to boot. (Classes are shipping weight divided by hp) Firestone and Goodyear came out with real race tires, so hooking a sedan was easier. The big old wagon was hard on parts, besides ugly. I changed to a 210 series 2 dr sedan, (450lbs) lighter. The wagon ran a best of 14.07, the sedan ran 13.50s right off the bat. Hadn't touched the engine, same drive train. The sedan weighed 3150, my TA weighs 3285 right now. 100lbs was more than 1/10th with that small '56 engine, less than 1/10th with this car I have now. One of the 10.5 Shoot-out cars I help dropped some weight & saw less than .05 from a 100 lb weight loss. He is about 3500 lbs right now, but makes 969 rwhp on my dyno all motor (1175 hp on Reher & Morrison's Super Flow engine dyno 2 days before), I can't measure what it makes on the bottle, I just get a flat line at 1250 hp. The more power you have, evidently the less a 100lb weight loss will get you. I haven't seen where vehicle weight has much to do with it.

go kat's sound fun. haha

go kat's sound fun. haha


they are, i race them nationaly.

-brandon

Hmmm very interesting Ed.

definitely worth it, IMHO

To go fast, it all about power/weight ratio. Look at motorcycles, weigh nothing and go 200+ mph with 130ish hp. Make your car weigh 800lbs like a motorcycle and youll hang with John Force, lol.

I have a lot of weight out of my car yet it still looks stock on the out side, I have not chopped it up you could still DD this car. right now I am at a 3250 race weight and I am 150 pounds. The only missing thing on the interior is the back seat. But will be adding weight as I will be doing a Rollbar. But still need to do a few more costly weight reduction mods.

Dan

SLPSS99 what all did you do if you dont mind me asking...

SLPSS99 what all did you do if you dont mind me asking...

Where to start,
Bumper Supports!
AC!
Heat!
Radio! and Speaker!
lightweight carpet
light seats
skinnies
15X10s out back
inner fenders!
abs!
PS!
QA1's and Springs
No power Brakes/Brake booster
all susp. is chromoly and tubular
Basically all the free stuff on the weight reduction list

Dan

the rule of thumb is 100lbs equals .1 off of your et but there are many factors to consider such as hp, tq and total weight. you dont see as high of an improvement on a high horsepower car because the power to weight ratio isnt changed as much say you have a
1000lb car 100hp your power to weight ratio is 10lbs/1hp
a 2000lb car 100hp = 20lbs/1hp
now say its a 4000lb car and you have 1000hp power to weight would be 4lbs/hp
now say 3900lbs with 1000hp= 3.9lbs/hp
now it should be easy to see how depending on the application what losing weight really does for you.
just for the hell of it something a little closer to our cars.
3500lbs with 300hp = 11.66lbs/hp
3400lbs with 300hp = 11.33lbs/hp
3500lbs with 400hp = 8.75lbs/hp
3400lbs with 400hp = 8.5lbs/hp

the rule of thumb is 100lbs equals .1 off of your et but there are many factors to consider such as hp, tq and total weight. you dont see as high of an improvement on a high horsepower car because the power to weight ratio isnt changed as much say you have a
1000lb car 100hp your power to weight ratio is 10lbs/1hp
a 2000lb car 100hp = 20lbs/1hp
now say its a 4000lb car and you have 1000hp power to weight would be 4lbs/hp
now say 3900lbs with 1000hp= 3.9lbs/hp
now it should be easy to see how depending on the application what losing weight really does for you.
just for the hell of it something a little closer to our cars.
3500lbs with 300hp = 11.66lbs/hp
3400lbs with 300hp = 11.33lbs/hp
3500lbs with 400hp = 8.75lbs/hp
3400lbs with 400hp = 8.5lbs/hp

wouldn't hp/lbs be better to think about than lbs/hp...that would be like saying cubic inches/hp...much better to have the ratio hp/cubic inch...anyways :chug:

In my 2700 pound car 100 pounds doesn't equal a tenth. A 130 pound me ran a 5.997 on a Saturday night in good air then the next morning my 225 pound dad ran it in way worse air and horrible track conditions and still ran a 6.071. Every pass I had .02 better in the '60 and 2 more MPH.

Pays to be skinny.

im talking about a 1/4 mile track not a 1/8 mile track i should have specified that. and the reason i put down lbs/hp rather then hp/lbs is it shows a more dramatic difference between the weight change. and to some people its easier to compute whole numbers rather then fractions rather then say the difference like with the 3500 300hp which would be .85hp/lb vs. 3400lbs 300hp .88hp/lb. its easier to see that actually makes a difference to the performance imo

In my 2700 pound car 100 pounds doesn't equal a tenth. A 130 pound me ran a 5.997 on a Saturday night in good air then the next morning my 225 pound dad ran it in way worse air and horrible track conditions and still ran a 6.071. Every pass I had .02 better in the '60 and 2 more MPH.

Pays to be skinny.
see how in the 1/8 its still .074 different thats damn near a 1/10th which it would be in the 1/4.

see how in the 1/8 its still .074 different thats damn near a 1/10th which it would be in the 1/4.

Well, the DA was a factor in it being as high as .074.

Another run for me the night before was a 6.050 with a 2600 DA with a track temp around 85. My dad was running with 2900 DA on a 130 degree track and still running 6.071's.

Regardless this isn't the greatest comparison given it's different tracks/weather and you are right about me picking up even more in the 1/4 mile because of the lack of weight I was just trying to provide an example.

We might put my dads 548 which has run a 6.06 in a 3150 pound car into my car that will be 2825 with me in it so I am hoping to gain around 2 tenths via less weight then put it on alcohol to gain another one so hopefully some 5.60's.

they are, i race them nationaly.

-brandon

Do you know ryan stringfield? He is a good friend of mine that races shifter karts.

nah i dont know him, he may race in a different national series, im in the Road Race Enduro Series.

-brandon

I started with removing my rear seats, Now i went all out removing seat brackets, carpet, and lots of cutting. My car is a daily driver :)

read the thread about the fastest stock internal ls1, and check his weight!! Nuff said........

http://www.ls1tech.com/forums/showthread.php?t=598343