Hi fellas, I've always heard that 100 lbs weight reduction = a tenth off of your ET's. Has anyone ever documented there weight reduction and et gain because of it? I would also think that taking off weight in the front of the car is going to make a bigger difference in et drop. Any input on this or just general info from the weight reduction pro's? My goal this winter is to drop 150lbs while adding a chromoly 6pt cage. I've always focused on adding power but hoping knocking this weight off will get me a lower et thanks in advance!

 

That formula is roughly right up to a point. Also rotating weight has a bigger impact than dead weight

 

I have proved this theory several times when my car ran low 13's/high 12's. 100 lbs ~=0.1 second ~=1 mph. The faster you go though, the less this is true.

 

^^^This^^^

 

I dropped about 200 pounds and went from an ac ram air to a non ac ram air and my car dropped 2 tenths exactly. Mph was up 1.5.

 

I definitely saw .1 sec for every 100lbs when my car was in the 13s and even 12s. Not so much in mph consistently but definitely in ET.

Below 12s it didn't seem as big of a difference. Of course I had a lot of my weight saving mods done by the time I was faster than 12s also. Now every time I drop weight I end up adding power so it's not as good of good comparison lol.

I know rotating mass, like you guys mentioned, is way more because when I put my skinnies on the front of the car I get .2-.3 and that's only about 60lbs weight savings. But the skinny tires allow for much better weight transfer too so position of the weight is also important. It's definitely not cut and dried but you definitely save quite a bit of time with just a little weight reduction in the beginning.

 

I got .05 from skinnies. I was pretty disappointed and sold them.

 

Thanks for all the reply's! I'm running high 10's now. What I gather from you guys I'll probably drop around a tenth +or- a bit with 150 weight loss with those et's

 

I don't have data to post but I know for a fact my past data proved a 100lbs off my car = .1 give or take a little.

 

It's more complicated then just 100lbs = .1

It's also % of total weight 100lbs off a 4000lb car vs 100lbs off a 3000lb car.

 

Hot Rod magazine did a weight reduction drag test many years ago with a big slow car. Results were pretty impressive. As stated already though, the slower the car the more impressive the gains.

 

Certainly the lighter you get, the more impact it has.

Just like horsepower (just inversely proportional), the more you make, the less impact it has.

 

Hmmm.. It's almost like instead of comparing weight reduction to et drop, it should be weight reduction is the same as adding X amount of power.

Maybe every 100lbs reduced is equal to adding 10hp...

 

That's just kind of a rough estimation rule of thumb kinda deal. He was just explaining that theres other variables in the equation. I played around with the weight thing at the track and that's not a bad guestimation + or - some.

 

Well ive heard its the opposite....in a manner of speaking. This is all dynamic meaning there is no solid rule that fits every time. But how about when you remove 100 pounds from 5000 it has LESS of an impact then removing it from 2500 because its a smaller percentage of total weight. We often dont think this way because at 5k you're probably running 14s and at 2500 you could be running god knows how fast. We know its exponentially harder to go faster in general, so I never think weight reduction ever becomes insignificant, its just having to fight harder and harder to show a gain.

 

Approx 1 tenth for every 2.85% of static weight drop.

Rotational weight has so many different variables it's hard to calculate.