how much et time does each 100lbs of car weight cost

So what if it doesn't rip off a 14, 15, or 16 sec passo No:
You can ask anybody anything on here, and all we can do is speculate.
Thing is, nobody knows what it will do until you find out, with a timeslip:TU:
Aint nothing better than foot to the floor, smoooooth track, no cops, kids or traffic to pull out in front of you! Its your slice of 1/4 mile heaven!
Run your Buick for all its worth, then report back:Brow:
NOBODY will laugh at you, or judge you at the track, we all have a common interest, that's making whatever were driving run better!
One trip down the 1/4 mile and you'll be hooked:TU::TU:

 

ya thats what I'm afraid of!!

 

Here is my family's secret drag racing formula.

Lowest weight + Mostest Power + Bestest Grip = Lowest ET.

For over 65 years.

 

I can't explain it any clearer than my truck and motorcycle analogies, my friend. You're waaaaaay over thinking things. Do what's been suggested and go run your car. Then take away weight, go faster, add power, and go faster. Its that simple. Good luck and let us know how it goes.

 

You are forgetting something in your equation. There is also feasibility which is what this thread is about.

Feasibility - A feasibility study aims to objectively and rationally uncover the strengths and weaknesses of an existing or proposed venture, opportunities and threats present in the environment, the resources required to carry through, and ultimately the prospects for success. In its simplest terms, the two criteria to judge feasibility are cost required and value to be attained.

 

You're forgetting something that drives people to excel...the paradigm shift.
Do what you want with it, find a way alter perceptions to get the picture to make sense.
Don't overthink that one, just start something and develop goals when you can hone in on what you want.

 

Anyone who does a feasibility study on fun, has yet to experience it.

Go have some.

Go have lots of some.

Then go back and have some more.
:bglasses:


Life is short.
Just like the quarter mile.
When you start getting "way down there", it is amazing how fast it is all over.
And we only get one pass...

 

Every 100 pounds removed is certainly not the same. Meaning if have 100 pounds of stereo stuff in the truck, or pull the seats and spare tires, that will not make the same differance as 100 pounds or rotating weight, like wheels and tires, brake drums and rotors. Even things like rotating weight inside the transmission. I have seen a couple cars switch to aluminum drums in the transmission. A weight savings of maybe 12 or 15 pounds but pick up .5 sec with that 12 or 15 pounds. Things like those trans parts, brake drums and rotors, wheels and tires, driveshaft, carriers, etc. They all take exponentially more power to get moving.

 

To demonstrate the principle, Hot Rod did an article in 1987, 'Caddy Hack', where they took a 1970 Cadillac and proceeded to reduce it's weight from 6780 lbs to 2900lbs, doing 1/4 mile runs during the process. One of the most memorable articles ever!

>>"The staff took a ’70 Cadillac Coupe De Ville, loaded it with dudes and surfboards to make it weigh 6,780 pounds and ran 17.22 at 80.01 mph at the dragstrip. Then they cut the entire body off the car, reducing weight to 2,900 pounds and improving e.t. to 13.55 at 100.83"<<

Do the math and that's 3.67 seconds for a 3880 lb weight reduction = 9.46 tenths per hundred pound weight reduction.


See the whole article here:
http://www.cadillacpower.com/forum/viewtopic.php?p=28293

 

does their inertia once moving also then reduce the needed horsepower to keep the vehicle moving thus leaving some unused horsepower available for acceleration?

 

thats .094 per hundred pounds. so about a tenth second per hundred which is consistent with some of the other posts. interesting. so a hundred pounds is worth a tenth second no matter how big and heavy the vehicle is.

lets think of this. Larrys car weighs 4050lbs ready to launch. My car weighs 4400 ready to errm ahem cough cough 'launch'. Thats only 350lbs or .3 sec difference due to weight. And they say my car is not meant to be a fast car like its some huge car. He runs 11s I only want 13.9 if I even want to drag race the car which Im not sure I do. Now I want to know how much hp is needed per 10th sec. Like if larry ran 11.5. how much more hp would larry need to run 11.4?

 

You are describing the flywheel effect at shift recovery, helping blast the vehicle forward momentarily when the spinning mass is abruptly shifted.
A heavy flywheel helps you keep from stalling the engine at a fast clutch release.
You are also touching on something difficult to equate with common dyno procedures.
Basically, lighter engine components rev up faster and don't always show up as power increases on the dyno without factoring out inertia.
Components spinning at engine speed are worth appx. 15x the effect of dead weight removal from the vehicle.
Short deck engines like Ford small block with light components can out accelerate higher powered but heavier rotator engines.
So, what hurts the take off and shift points can accelerate harder above those rpm points.

The examples of a very light/heavy vehicle supercedes the general weight rule because it skews the power or torque to weight ratio.
Power to weight ratios hold more true to ET's.

 

not just the fywhee though. arent the wheels and brake rotors/drums also flywheels that keep the car moving forward with their inertia? the bigger and heavier the wheels the more inertia no? so all else equal if one car has big heavy wheels and another car doesnt but both cars weigh the same, wouldnt the big heavy wheels provide and inertial advantage to forward movement resulting in less of a hp needed to accelerate?

 

In my Non engineering opinion, I say wheels and tires, rotors and drums contribute nothing to help forward motion, as they do not produce any work, such as the engine does, they're just along for the ride

 

I suppose you'd have to fight those to go faster as each moment goes by.
The energy from a flywheel spinning 6000 and being forced to instantly slow to 4500 at the shift with the end result being a kick in the pants is ONLY at the launch and shift, it still has to be fought all the way down the track.
Everyone here has been citing well documented info.
There's probably some good race car engineering and chassis books out there.
I think I've read that wheel speed weight is roughly 3x dead weight.
I recall the Herb Adams chassis book using some formula to calculate the acceleration change for wheel mass loss.

 

OK, Gary, here it is in the plainest terms possible so noone has to explain it any further.....the heavier something is, the less difference 100 lbs will make in the elapsed time of a quarter mile. The lighter it is, the bigger the difference it will make. Period. End of story. Go run your car. Change something. Run it again. And see for yourself, in the real live world, what difference it makes.

 

My experience, heavier wheels like old orig. steel Cragar SS's, slowed 1/4 times slightly. The Buick rallyes aren't light enough, but they have the look we like.

 

Nah Rotational weight reduction is where it's at, everything can Rev and move quicker resulting in less time spent getting it to move IE faster mph and ET