Ok, so I've noticed a lot of people talking about cutting weight on their cars. My question is how much weight do you have to save to make a difference, and at what price is it worth it? I have some experience in cycling, where weight is also a big consideration, and you can get into mega bucks for titanium and carbon fiber parts. The general rule for cycling is that if you save a gram by spending a dollar then its a reasonable upgrade. (ie. if you buy a new seat that is 100grams lighter than your current one for $100 then its not such an unreasonable purchase) Is there a similar rule of thumb for cars? 1lb/$1? 5? Thanks!

 

the rule of thumb is every 10lbs, you gain about 1 hp. so if you can save 100 lbs from your car, its like gaining approx 10hp.
so if you have a car that has 300hp at 3000 lbs, it should go the same speed approx as a car with 250hp at 2500 lbs give or take a little.


the point is, every little weight saving adds up and can make a noticeable difference.

 

Another rule of thumb: every 100 lbs amounts to 0.1 sec in the 1/4 mile.

 

a hair over 14lbs would equal 1hp.

there is one owner in Europe that spent quite a bit of money ~20K if I remember correctly, and got the car down to 1700lbs. Keep in mind it was a race car and not a normally driven car.

One thing to be cautious of, is where the weight is being removed from. The ligther, single piped exhaust is an easy way for your car to lose 40lbs. But what concerns me the most is where it is - its in the rear. I personally love understeer, and this just dials in more oversteer that I would need (if I had that exhaust) to adjust the car even more to dial in more understeer. So, adjustments to shocks and/or tires and/or wheel weight/size will need to compensate for that loss in the rear.

If you can do the single exhaust and then do something similar under the hood, that would compliment the change in the rear, that would be optimal. The CF hood, might shave 1lb if that. A header will shave ~10lbs., but if you add a STB or Xbrace you add that right back.

 

Schatten,

Actually the way weight reduction works is that it is based on the power to weight ratio of the car.

The S2000 has 240hp, 2800lb which equals 11.7lb/hp. Therefore you would need to eliminate 11.7lb from the car to experience the equivalent of 1hp gain. Note that as the car gets lighter, you need to remove less weight to gain one hp. Say you eliminate 200lb of weight from the car. The new power to weight ratio is 240hp/2600lb = 10.8lb/hp. Therefore you'd only need to remove 10.8lb to experience the equivalent of 1hp gain. Of course, the catch is that as the car gets lighter, it gets progressively harder to lighten it further. . .

Mmmm, fun with math!

 

danke =)

 

Not sure what you're saying here, but in general, adding weight
to the front moves balance towards understeer
to the rear moves balance towards oversteer
since the tires at that end have more weight to move around the corner.

Also relevant to the discussion of weight reduction is where.
If 1lb. off the body = 1x,
1 pound off parts rotating at wheel speed = ~3-5x, depending on the radius (lighter wheels being more beneficial than lighter axles)
1 pound off parts rotating at engine speed = ~10+x, also depending on where

The S2000 was built pretty light as is; parts that normally shed a lot of pounds - a CF hood for example - is only a few pounds lighter than the S2K's aluminum piece. If you look at some of the fancy CF parts made by Amuse or whomever, $1 per gram of weight reduction is about right...

A lean stock-class autocross S2000's competition weight is ~2650 lbs. with about 250 crank HP. That's 10.6 lb/hp, not bad!

 

I love OVERSTEER!!! Pump up those rear tires, beef up that rear sway bar, and let's do some 4-wheel drifting, baby!!

John

"Understeer is understeer and oversteer is oversteer, and oversteer will always be faster."
-Frank Williams

 

Anyone know how Amuse took off 100 kg without removing the AC? Sounds like a good way to shed some weight off while keeping a daily driver....

 

In this thread we talked a lot about ways to save weight... some of the big ones were:

Delete Air Conditioning
Delete Cruise Control
Delete Factory Stereo and Speakers
Minimize noise and vibration damping/absorption materials
Replace Leather seats with lighter cloth-covered seats (get rid of passenger seat altogether?)
Lightweight 16" or 17