I know this is going way back, but when you had the PC680 in the stock location, did you use a custom bracket or anything to hold it in place, or could you use what was there from the stock battery?

You can't use the stock battery mounting ties unfortunately. I used an old mount that I had from my old time attack 350Z. I have been trying to find something similar to sell, but can't find anything like that. I have no idea where the one I used came from or who made it lol. If I start getting a lot of people asking for it then I suppose I can find a CNC shop in town that can make custom ones.

Nice thread - not sure how I missed it before.

Re: hp/lb wasn't the old school formula for every 100lbs you lost you gained the equivalent of 10ish HP? Time to hit the tread mill boys ;) I gained 5hp in two years of going to the gym in every car I drive - sweet! Maybe I should try driving by remote control for another 17.5 HP gain...

For the fluids (washer fluid) wouldn't the easiest measurement be to empty out the tank then measure what you fill it back up with to figure the volume out. Dunno what the specific gravity of washer fluid is but its probably pretty close to water so we'll say 1kg per liter....

Anyone use Lithium Maganese technology for batteries? Might be time to whip up an ultralight battery pack - what kind of capacity would be a decent target to shoot for? Cranking amps isn't going to be an issue here.... Peak voltage is going to be 16.8V and nominal is 14.8V - does anyone know if this needs to be regulated down or is there a regulator already in place after the battery?

Any weight specs on the Stillen exhaust or intake components?

I didn't weight the stillen exhaust but can tell you the muffler was HEAVY... I had another shop build a muffler for my z as well - eventual sold it - but it was about half the weight of the stillen muffler i'd guess... stillen was clearly focused on HPs, not LBs

FYI and thanks to Dean at Stillen (man their support is AWESOME - can't say the same for other companies I've been dealing with lately).....

Cat back exhaust - 90 lbs + 40lbs from stock - ouch
High Flow Cat - 15 lbs -6 lbs from stock
G3 Intake - under 10 lbs

UPDATE: Sorry there was a little miscommunication and I listed the shipping weight here instead of the actual.... thanks Josh for the real world data although if I drive around with the shipping crate I'm still right ;P

Stock Exhaust

Muffler Section - 26.8lbs (highly inefficient)
Y-Pipe - 11.6lbs
Resonated Y-Pipe - 15.6lbs
Total: 54.0lbs

STILLEN Exhaust

Muffler Section - 39.6lbs (proven huge hp gains)
Y-Pipe - 11.3lbs
Resonated Y-Pipe - 14.4lbs
Total: 65.3lbs

Difference: +11.3lbs and 18whp

suppose at least the weight distribution from stillen exhaust goes to the right places... low and back

I can't see how the CBE weighs 40 lbs. more. :ughdance:

I just PMed Josh@Stillen to confirm.

I'm sorry for the confusion, I'll confer with Dean if that's where you got the exhaust numbers. Here's the correct info:

Stock Exhaust

Muffler Section - 26.8lbs (highly inefficient)
Y-Pipe - 11.6lbs
Resonated Y-Pipe - 15.6lbs
Total: 54.0lbs

STILLEN Exhaust

Muffler Section - 39.6lbs (proven huge hp gains)
Y-Pipe - 11.3lbs
Resonated Y-Pipe - 14.4lbs
Total: 65.3lbs

Difference: +11.3lbs and 18whp

Also note that the weight is at the lowest point of the car, over the rear wheels, which will increase traction.

Quick work Josh, thanks!

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 :)

:tup:

O.K. Two questions:

1. DD - you responed to one of my questions on this earlier regarding HFCs. While the HFCs will not make that car THAT much louder, you noted they would change the tone. If I was running an Amuse R1 Titanium catback and Y pipe, would HFCs make the Z louder? I am not sure if that can truly be answered, but I appreiciate any thoughts.
2. The Nismo flywheel and clutch that shaves 20 pounds is very cool, but how much would that affect the already noticiable shifter vibration??

Any thoughts/experiences/comments are greatly apprecieated guys!!

Yes they would make it louder. The stock cats restrict more noise than high flow cats do no matter what setup you have for the rest of your exhaust.

Just use moment of inertia calculations to determine how much you will save off the rotational mass change. I can do it later - too many ppl watching me @ work lol

Oh my - looks like he did my calculations for me!!

Please do, I'd love more information on how to calculate the effects of changing the rotational masses (as in lighter wheels and brake rotors), but I'm not really familiar with the math/physics involved.

ok if we assume the wheel is a uniform disc... of weight M then the moment of inertia of that wheel is 1/2 * M * R^2 ... so... with a 19'' wheel - lets say it weighs 25lbs the moment of inertia is about - 1/2 * 25lbs * 19 * 19 = 4512 lb*inch^2

now lets say the new wheel weighs about - 24 lbs so a 1lb saving... moment of inertia = 1/2 * 19 * 19 * 24 = 4332 lb*inch^2

ratio of difference = 4% less moment of I w/ 1lb diff in wheel

so ... what that tells us is... roughly - shaving 1 lb off per wheel - makes it 4% easier to spin that wheel ... hope that makes sense :p

EDIT: for more info: http://hyperphysics.phy-astr.gsu.edu/Hbase/tdisc.html

Nice. I have some followup questions though:

1) Does it make any difference whether the weight is being dropped from the driven (rear) or rolling (front) wheels? I'm inclined to think it doesn't matter, as the engine is pushing both rotationally, assuming no appreciable tire slip being factored in for a simple case.

2) How do we apply this to the car as a whole in order to determine how much effective % difference in acceleration a weight drop at the wheels makes? Let's say I run the numbers for the whole wheel/tire package at all 4 corners, using the combined weights of the tire+wheel at each corner and the radius of the tire+wheel. Let's say I shaved off 4% per corner. That doesn't really mean the same in terms of overall acceleration numbers as, say, a 4% drop in car body weight does it?

I would imagine one would have to calculate moment of inertia stuff for all rotating masses (so the hubs, rotors, wheels, tires, etc, plus the driveshaft, the rear axle, the rear diff, the transmission, the flywheel, the engine itself, etc??? it's a long list), and then somehow combine that and the static weight of the car into some final number for how much force has to be applied to move the car a foot, and then see what % that number drops from removing weight at just the wheel as a percentage of the whole, right?

Very interesting discussion going on here.. check this out.. kinda funny and really shows the effects of saving weight on performance.

SCC Technical Assistance Program

so i see what your saying......all i need to do is chop off 1,000 lbs of crap off my car, render it useless, but, ill have a 12 second ride at least:icon18:

great link BTW

Chop SHop Race Car?
 

Alternatively, buy a car design to for the race track if that what's your after.

DUDE!!!! That was Freaking Hilarious!!!! basically ur left with wheels an engine 1 seat and a floor board! :roflpuke2::roflpuke2::roflpuke2: And the funny things is... They are still slow!:bowrofl::stirthepot::inoutroflpuke:

That formula assumes a 1984 lb car also known as a lotus. It's just a power to weight formula. It seems a little off too should be something like

equivalent horsepower= (hp*original weight)/(original weight - amount removed)

or say Ehp=(332*3232)/(3232-100)

Ehp=1073024/3132 Ehp=342.6 so a 100lb savings = 10.6 horsepower

But you aren't making more horsepower it just means you now have the same power to weight as the guy with the stillen exhaust

^^ :icon14:

:iagree: this looks like the euro thread.