That definitely sounds more reasonable.

Good to have the real data. I'm kinda surprised actually that the wider Stillen piping didn't outweigh stock, and that the muffler difference was the big factor.

I suspect the heat sheilds came into play here.

I've edited my post to reflect the correct info but kept my old post above it so the thread still makes sense. I had been given the shipping weights rather than item weights.

I just removed the aluminum hatch this weekend...wish I had a scale handy but I didnt:shakes head:

It is VERY light though! I would estimate it weighed around 35-40ish pounds or so but again, I didnt put it on a scale so that's just an estimate.

i'd like a fiberglass hatch for the track pushing 10lb would be nice

side impact protection on the order of 5-6 pounds

eXo5 has his head in the right place. Play your own version of The Biggest Loser, or hire a horse jockey to run your car. That will be more worthwhile than airbag removal on many levels.

Luvzttz, this is the weight removal thread... we all have different reasons for removing weight from the car... there are some folks that have no purpose for side impact protection systems, and they will find the information useful. And yes, of course, losing body weight is one of the better options.

found this formula on the lotus forums. seeing as they hate weight this equation most likely has some truth to it.

save ~10 lbs gain 1 hp ** EQ: Y=(190*X) / (1984-X) where Y is (HP) and X is (lbs)

Back on the horse jockey angle, I've been working on that too. From all the work I've been doing on my 370Z in the Houston heat sweating like crazy all day, I've lost about 16 lbs since I bought my Z (down to avg 174 now from avg 190, big change for me). Kill two birds with one stone: install your own upgrades and automatically lose driver weight :)

^^awesome...

It's a massive motor, in a tiny lightweight car.
Carroll Shelby

(I had a post here about the whole converting weight into horsepower thing, but I posted it at 2:30AM and the math was totally wrong, so I'm killing it before anyone comments on it. I'll put up a fixed one later) :)

Oh yeah, I never came back and fixed this.

So the easy formula for calculating how much horsepower a given weight reduction is "worth" (in terms of HP:Weight ratio for acceleration, obviously this doesn't take into account effects on handling and balance):

E = (W/R)*H

Where E is your new "effective" horsepower, W is the starting weight of the car, R is the reduced weight of the car, and H is your actual horsepower.

For example, take a set of numbers not unlike a stock 370Z on a DynoJet (3320 lbs, 275 rwhp), and drop 100 pounds:

E = (3320/3220)*275 = 283.54

So 100 pounds off of the stock car is going to make the same acceleration difference as adding 8.54 horsepower.

How much the car weighs and how much horsepower you actually have can have a big effect on the outcome of this formula, which is why there isn't a universal "X lbs is worth Y horsepower" number for all cars, or even for one car given all the mod variations.

Let's look at a hypothetical TT 370Z which is otherwise stock (with some added weight for the TT system, let's say 550rwhp and 3400 lbs), and see what happens when we drop 100 lbs there:

E = (3400/3300)*550 = 566.67

So 100 lbs off of that car is effectively worth 16.67 horsepower.

Either way, in both cases you're gaining about 3% effective horsepower numbers for acceleration purposes, because you've dropped roughly 3% of the car's body weight.

So a good rule of thumb to go by from all of this, is that it's all relative to your starting weight. Think of your reductions as percentages, and that's how much they'll help your acceleration. If removing 20 lbs is worth 0.66% weight reduction on your car, then it's going to make a 0.66% difference in acceleration (or effective horsepower if you prefer to think of it that way for comparing to bolt-on power adders).

Keep in mind, as I said at the top, that this says nothing about the handling effects of dropping weight, and it especially doesn't cover the special case of rotating masses in the front or rear wheels (or the driveline or either end of the crankshaft, etc), which have a more pronounced effect that I don't know how to calculate :)