Fabio421

Snipe, I wasn't trying to be derrogatory when I said " a little bit" of performance. I was only saying that I am not ready to throw away a large part of my car in order to save weight. I would do it in certain cases but not all. For instance, I was recently contemplating the replacement of my power seats with some light weight manual seats. This was not purely weight driven. I was having trouble w/ my head scrubbing the ceiling of my car. So I was gonna mount some manual seats, which can be mounted lower, and save some weight at the same time. Then I realized that I had never tried the middle button on my power seat to see what it did. Vioala! It lowered my seat to a height where I can fit. ( By the way, I feel really dumb for not realizing that earlier) Now I don't need to replace my seats so I wont be saving weight.
My car is a driver not a racer. ANd here in Florida, air conditioning is a necessity more than a luxury. I think it great that you guys are stripping the weight from your cars. I'd love to take a ride to see what the difference is. Hopefully I will see you at SITM this year.

PorKen

My poor old OB - which barely scratches 200hp/225tq* to the pavement - doesn't have any 'bog' anymore at 2900ish lbs**. I put the hammer down, she takes a big gulp, and goes like mad.

I am still surprised when I put the pedal to the floor, because I drive around all day with the throttle just cracked open.

__________________
* When it's below 40f degrees outside.
** 3100 with the nut behind the wheel.

FRporscheman

What about something goofy like filling the tires with a lighter gas, like Helium? That might be overkill, but it might give the hardcore weight-trimmer something to add to his/her list.

Lance J

nitrous can fill a tire also

AJK

m21sniper,

I'm curious as to how you calculated your weight-HP relationship. I got more like 7 HP/100 pounds of weight reduction

"Just for the record, it's not a 'little bit' of performance bro. Shaving 300lbs from a 3300lb car is the same as adding about 40 horsepower.*"

.

slate blue

Lance let everybody know where you're driving so they can avoid you, no need for everbody to spontanously combust with you, I think you meant nitrogen, not nitrous.

m21sniper

Here you are man:
http://www.network54.com/Forum/42613...hp-+It+Depends

slate blue

That link was very enlightening, thanks very much, as to this quote

Don't forget apart from acceleration, you must consider the handling, why do you think those Lotus Elises are so fast around a track? Can't be because of their 1.8 liter engines can it. Weight is a killer, in an F1 car they shave off weight up high just so they can reposition it lower in the car, that is the ballast, minimum weights to be maintained.

It is also less strain on the car's componants.

Cheers Greg

AJK

I agree about the other advantages of less weight, especially in the wheels. My thought was in how much can be gained in acceleration with respect to weight reduction. For instance, could I detect the difference by removing the AC? How about the AC and the stock exhaust system together? My use is on the street only, no track time.

AJK

I just went thru the link posted by m21sniper and get about 7 HP/100 pounds of weight reduction for our cars.

m21sniper

It really depends on the model.

For my Shark, at it's current weight and power level, one HP = approx 9.9lbs.
So for me a loss of 100lbs would be the equivelant to 10hp.

If my car was 1000lbs lighter, it would only require approx 6.5lbs to = 1 HP.

7lb/HP is probably about right for a bone stock S4.

m21sniper

You may not be able to always 'feel' a loss of weight, but i assure you, physics will.

Another one of those general rules of thumb is that an increase of 10hp OR an equivelant decerase in weight(for my car that would be 99.4lbs), will decrease 0-60 and 1/4 mile time by approx. .1 second.

A .1 sec margin of victory for a car running a trap speed of 100mph in a 1/4 mile run equates to 14 feet of distance.

So if you did JUST THE EXHAUST(assume a 30hp gain and loss of 50lbs in weight), and you raced an otherwise identical shark, you would beat it by approx .4 seconds, and would have a margin of victory of approx. 56 feet(or about 3 lengths)

Remember, these are just general rules, and will vary depending on the exact example cited.

Fabio421

There is also a difference in performance gains depending on whether you are removing sprung or unsprung weight. Removal of unsprung weight will result in a higher net performance gain than the same lbs removed from the sprung weight. I'm not sure about the formula's involved. I'm sure with a little time and google you could find out.

By the way. I recommend clicking the link that sniper provided. It is a very educational post.

Lance J

hey snipe my car weights a little less than your car now. my 79 not my s4 which i had to sell.. man i miss that car. but yeah with weight reduction and bolt on his 83 auto us beat my 83 euro auto. by that much. about 3 cars. from a dig. but when it came to topend my euro has longer legs and better cams for highway pulls. with a turbo @ 7 psi you'll spank that ferrari. lol

m21sniper

I'm not really sure how much diff. there is btw sprung and unsprung weight either, to be honest.

PS: thanx for the compliment, you are very kind.