The value of weight, or lack there of...

[Boudy]

I am curious what effect weight has on lap times. Since weight is used as an equalizer in many areas of our series I assume there must be some standardized assumptions used as a reference.

Just wondering what's being left on the table by us guys running 100+ lbs heavy.

Boudy

[edrock96GT]

Well, at Cresson I was about 2-3 seconds a lap off of Dr. Frank and about 4-5 seconds off of Marshal and I'm about 270lbs over weight.

That's my excuse and I'm sticking to it. :D

[michaelmosty]

If you are 100 lbs over then I would do everything possible to remove the weight. Obviously certain platforms are easier than others and things change if you have an accusump, fire bottle, big oil pan, extra cage bars, cool shirt, etc.
I am not an engineer but from what I know the weight doesn't play that big a factor until you reach the limits of the tires, brakes, etc and the performance starts going away.
That being said each individual needs to use their platform to the best of their ability utilizing their specific advantages. In the fox's case it is like hitting a brick wall with regards to aero but is the lightest platform. I had a disadvantage on the 4th gens on the straight but could capitalize more later in the race when the tires started to fall off. Sam is just a freak of nature and would gain on everyone everywhere. :^)
Just take that bLinG wing off, it isn't needed on a CMC car anyways. :^)

[way2neary]

I think Marshall needs to "weigh" in on this topic. As I recall, the less weight you have, the more effective your brakes become. So under that theory, given the same hp to weight ratio, a lighter car would be able to brake later. Especially when you factor all of us are using similar brake setups.

Just mt 10 cents.

[BryanL]

For some it maybe a need to leave something (food) on the table.(laughing)
Mosty is probalby right that unless you are close to the limits it doesn't play a huge role. But the occasional drag racer in me tells me that at our weights/power in a quarter mile every 100 lbs should be worth a tenth. Though how that translates to us is anyones guess. I know some say that they can tell a difference in 50 lbs which I can't.
In my case its making all the difference since I have to run 50 lbs heavier than everyone else-otherwise I would be a trophy girl.

[ShadowBolt]

In my case its making all the difference since I have to run 50 lbs heavier than everyone else-otherwise I would be a trophy girl.

Your not the only one Lone Ranger. I have to run 50 lbs over and I have the push away from the table issue. I come off track about 60 lbs. over my 3220 min. Jay was way over in R1 (like 80 lbs.) and 12 lbs in R4. Lap times are very close even with an almost 70 lbs. reduction.

JJ

[evarner]

Have to be careful where the weight is placed as well. 100lbs of well placed weight could actually make a car faster or at least handle better. :D

[BryanL]

Your not the only one Lone Ranger. I have to run 50 lbs over and I have the push away from the table issue. I come off track about 60 lbs. over my 3220 min. Jay was way over in R1 (like 80 lbs.) and 12 lbs in R4. Lap times are very close even with an almost 70 lbs. reduction.

JJ
I wish my min weight was that low. Mine is still 50 over yours but I don't have the table issue so I come off around 3280 which puts me right at your weight.

[kbrewmr2]

100lbs of well placed weight could actually make a car faster or at least handle better. :D

Yup - my car on certian tracks (ie ones with low speed right handers) is faster with the ballast in vs ballast not in the car. Placement is key to preventing the wheelspin I fight in those corners

[Al Fernandez]

Bryan its crazy your car is that heavy and Randy's is at minimum considering he outweighs you by about 100lbs! Get rid of some of those wires in there ;)

Boudy...you gotta drive more than once a year man. The car is fine!

[Alien]

Bryan knows that too. Just look at his Pinwood Derby trophies.

[AllZWay]

Bryan knows that too. Just look at his Pinwood Derby trophies.

And everyone knows you can't win a Pinewood Derby without cheating the rules. :D

[BryanL]

Al-if you weren't busy playing with gerbils you might know that I am at my minimum weight. But also my car isn't one of those illegal LAW cars.

Pretty tough to cheat in Pinewood unless you have someone on the inside but I sure was accused of it by all the Texas Instruments engineer dad's that were making wheels on the lathe and building computer models at work. I built my car when my older brother was in cub scouts and that car would kill everyone at the test/tune night. I ran a different car the first year that got 2nd but was slower then "The Mongoose".

Ken-how in the world do you get your car to have wheelspin?

[marshall_mosty]

Weight can be viewed several ways:

1. It takes horsepower to accelerate additional weight.
2. It takes more brakes to deccelerate additional weight.
3. Tires have more ultimate grip with more weight (static weight plus downforce), as the traction force a tire can produce is the coefficient of friction of the surface times the vertical weight applied downwards on the tire.

#3 is the most interesting as you will also put more heat into the tire with more weight. As long as you don't exceed the operating temperature of the tire, you are at a benefit. The moment you overheat the tire, you lose out on the benefits of the weight gain.

4. Weight can hurt you in the corners if it's located above the cars C.G. as it transitions weight more drastically off the inside tires than weight at or below the C.G.

5. Weight below the C.G. will have a self leveling effect, trying to upright the car in a corner. This is good to put weight on the inside tires as well. More contact patch, more sq. in. of rubber on the surface = faster corner speed.

So, to summarize, if you are already overheating the tires, you need to LOSE weight or get a wider tire. If you are not able to get the tires up to temperature, you can add weight or get a narrower tire.

On a side note, we didn't talk about the horsepower required to accelerate a heavier (wider) tire/wheel versus a lighter (narrower) tire/wheel, the extra braking required to stop the rotating inertia of the heavy (wider) tire/wheel versus the lighter (narrower) tire/wheel, or the aero drag of a wider versus narrower tire which takes more horsepower to accelerate. That's a different lesson for a different day.

[kbrewmr2]

Ken-how in the world do you get your car to have wheelspin?
Open Diff + Body Roll

It is pretty torquey for the small amt of horsepower it makes too

[BlueFirePony]

On a side note, we didn't talk about the horsepower required to accelerate a heavier (wider) tire/wheel versus a lighter (narrower) tire/wheel, the extra braking required to stop the rotating inertia of the heavy (wider) tire/wheel versus the lighter (narrower) tire/wheel, or the aero drag of a wider versus narrower tire which takes more horsepower to accelerate. That's a different lesson for a different day.
Or the time it takes to for a heavier (wider) ass to egress the car ....