Topic: My weight loss program.

[ophidia31]

Well, Im bored and decided to partake in some parts removal for some weight loss.

Edit:Taking into consideration the added weight of the chassis bracing and heavier swaybars, Im about 43.25lbs lighter than stock but better handling/chassis stiffness that wasnt there before. When all is said and done with what Im willing to remove from the car, not including weight savings from the new exhaust and battery, going to take my car to Planet Miata by my house since they have some race scales and can get an accurate reading on weight at all four corners and my weight distribution. Basically feels like going into the lions den since I see miatas as a direct competitor to kappas, but they have what I need and they know what theyre doing there.

Here is what Ive done so far:


Removed Weight:

Sunvisors: -1.3lbs
VCIM: -2.1lbs
Trunk lid carpet: -1.9lbs
Trunk carpet: -3.8lbs
Foglight projectors: -1.2lbs
Monsoon amp: -2.1lbs
Monsoon sub enclosure: -9.8lbs
FE2 front swaybar: -7.4lbs
FE2 rear swaybar: -5.7lbs
Xm module w/ bracket: -1.7lbs
Underdash panels: -1.4lbs
Removed wiring/cabling: -4.2lbs
Misc brackets/fasteners/deadening: -9.1lbs
Stock tunnel brace: -4.5lbs
Stock mirror: -1lbs
Rear panel: -9.7lbs
Side panels w/ speakers: -4.8lbs
Stock radio w/o face: -5lbs
Door speakers: -3.6lbs
Side cupholder: -.3lbs
Drivers carpet (w/o mat): -5.2lbs
Passengers carpet (w/o mat): -4.7lbs
Stock single catback: -37lbs
Stock cat: -10.5lbs


Added Weight:

Z0K front swaybar: +12.9lbs
Z0K rear swaybar: +11.6lbs
DDM race tunnel brace: +10.25lbs
DDM probeam: +6lbs
LatinVenom FCB: +6.5lbs
New cipa 8x2 mirror: +.5lbs
Solo single w/ resonator: +41.5lbs
Solo highflow cat: +5.5lbs


Anyway, after taking out the useless wiring and re-wrapping it, this is what Im left with. With both seats back and center console cover back on, its not that bad looking. Im thinking of maybe painting the exposed areas black so it doesnt stand out as much. Dont mind that wire mess on the center console, didnt get that all squared away yet. Also, have no tunes right now. Going to have to deal with it until I get the new stereo.

[1LILNDN]

So right now you lost about 37LBs so far not counting the trim           

[ophidia31]

Thatd be correct if I didnt have anything suspension/chassis upgrades.  Going from FE2 sways to ZOK sways added 11.4lbs to the car. Then adding the extra weight of the new race backbone, probeam, and latinvenom brace probably puts me up to an extra 27lbs or so. In the end, Ive only removed about 10-12lbs from the car.  Oh well, plan on shaving some lbs with the new exhaust and then lightweight battery later on this year. Debating on pulling the floor carpet. The bright side is anything I do now, shy of F.I, will take weight off the car. 

Oh yeah, and to add that surprisingly there really is not much noise added into the car from not having those panels. I mean, road noise did get touch louder along with the exhaust when you get on the pedal a little, but that doesnt really bother me. Its clanks, bangs and squeaks that get to me.

[2kwk4u]

So without that carpet panel on the underside of the trunk, does any bare metal / sharp edges rub on your top when it's stowed in the trunk?  At least the weight you've added all lowers your center of gravity...

[Brazen17]

How much weight do you save with a light weight battery vs. stock?

[ophidia31]

So without that carpet panel on the underside of the trunk, does any bare metal / sharp edges rub on your top when it's stowed in the trunk?  At least the weight you've added all lowers your center of gravity...

Didnt see anything that may be hitting it when it was down. Next time I go to put it down Ill look, but dont think there will be any issues. And good point about the center of gravity. Didnt think about it that way.

How much weight do you save with a light weight battery vs. stock?

Didnt do one yet, but I would have to assume that you would save around 15lbs going from the stock to a lightweight. That seems to be the mean average.

[elff]

So you have effectively added 4hp.

Just curious, what is the end goal of your vehicle being lighter?

[J_Bond]

Love this post. I've done all these reductions as well, along with the lightweight battery and rear diffuser delete, and it has allowed me to pull excellent quarter-mile times.  I still need to do the lightweight brakes that Elff has and order my ultraleggeras.  I think with Norm's hood and 13lbs racing seats added to that I'll be much closer to my 13.9 second goal without running boost. 

[ophidia31]

So you have effectively added 4hp.

Just curious, what is the end goal of your vehicle being lighter?

Boredom teamed up with better handling and acceleration? Want to do as much as possible without having to resort to forced induction yet. Plus its free.

Love this post. I've done all these reductions as well, along with the lightweight battery and rear diffuser delete, and it has allowed me to pull excellent quarter-mile times.  I still need to do the lightweight brakes that Elff has and order my ultraleggeras.  I think with Norm's hood and 13lbs racing seats added to that I'll be much closer to my 13.9 second goal without running boost. 

It doesnt seem alot of guys want to take stuff out and drive their cars everyday. As long as I can get this car down to a 0-60 for 6sec Ill be happy. Thats what my last car was around and was plenty quick enough for me needs. If I end up less, just a bonus.

As for the rear diffuser delete. I have something a little more extreme in mind but taking alot for me to pull the trigger and do it. Its basically cutting off the two wings that are left when you pull the diffuser off then fill any holes underneath with some thin abs to stop any air from getting kicked up into them. Kind of reminiscent of the old detomaso panteras. Done correctly, I think it will look pretty good. I sat and stared at my car for at least an hour one day looking at different angles so Im pretty confident it wont be bad.

[elff]

It's going to take a lot of weight to make a change.
I think the rule of thumb is 10hp will equate to .1 second quicker in a 1/4 mile
So that's 100hp to drop your 1/4 mile time down a single second.

J_Bond, do you have the general rule of thumb for how much sprung and unsprung eight translates to HP.
I believe the rule is 10lbs of sprung weight = 1 hp
But rotating weight and unsprung weight is a little more but I don't know the formulae

[J_Bond]

Glad you asked:

First, I’ll compare 1 lb on the car with 1 lb on a wheel:

The TKE = 1/2 x the mass x (velocity squared). For a 1 pound mass (lbm) on the car going 60 mph (= 88 ft/sec), the required TKE = [1/2] x 1 lbm x (88 x 88) ft ft / sec sec = 3872 lbm ft ft / sec sec

The RKE = 1/2 x the rotational inertia x angular velocity squared. The rotional inertia (RI) = mass x (radius squared). The angular velocity (w) is in radians = rev/sec x 2 pi radians/rev.

Assuming that the wheel and tire mass is lumped at a diameter of 18” (= radius of .75 ft), a 1 lbm on the wheel has an RI = 1 x (.75 squared) = .562 lbm ft ft.

With a tire circumference of 76” (= 6.33 ft), 88 ft/sec is 13.9 rev/sec. w = 2 x pi x 13.9 = 87.3 rad/sec

So RKE = 1/2 x .562 lbm ft ft x 87.3 x 87.3 / sec sec = 2143 lbm ft ft / sec sec.

Taking 1 pound off a wheel saves both TKE and RKE. But the ratio compared to taking a pound off the chassis is only 1.6 = (3872 + 2143) / 3872. That is, taking 1 pound off a wheel is the same as taking 1.6 pounds off the chassis FOR THE PURPOSE OF ACCELERATION.

[ophidia31]

I knew that taking weight off the wheels/drivetrain is better than off the chassis. Yes, what im taking off doesnt equate to a large performance gain, but it is better than having it on the car. I dont believe in a weight taken off to hp number either. I think thats all bs thrown around on forums by people that want to put their car on a higher plain in their minds. Your engine makes this much hp, removing weight doesnt magically add that hp to the engine. The only thing that would measure a hp increase would be less rotational mass on the dyno and even then you will never get above what the engine is putting out. Other wise its all theoretical numbers to me which dont mean a thing. Physical 1/4mi and track times are what mean something to me.

[J_Bond]

let's just calculate for rolling mass:

Stock wheels and tires weight total = 216lbs

Ultraleggeras and DWS tires total weight = 164lbs

total weight loss = 52lbs.... then multiply by 1.6 = TOTAL WEIGHT LOSS of 83lbs

now throw in the lightweight brake kit = 11lbs per corner so 44lbs total

44 x 1.6 = 70.4lbs reduction

now 70.4lbs + 83lbs = 153.4 total weight reduction from rolling mass

Now body weights added:

now throw in an additional loss of 40lbs from Norm's hood = 193.4

then throw in my lightweight battery = 208.4lbs

racing seats are estimated to be about a 42-48lbs reduction depending on how the brackets are made and which seats chosen = 253.4lbs (approximate)

now add 37lbs from Ophidia's deletions:  290.4lbs

SOLO exhaust is another 30lbs reduction = 320.4lbs

SOLO hi-flow cat another 5lbs reduction = 325.4lbs

7lbs for stock airbox and engine cover delete 332.4lbs

shorter springs and shocks ??????  i know they're lighter, but I don't know how much!!!!  so... 340-350lbs adding them in?  maybe?  I've looked all over the web for the answer....

theoretically, if you pulled the top out the back for fun, that would put you at around 400lbs of weight reductions. (but I'm not going to do that lol)

Saturn Sky curb weight of 2,870 - 400lbs = 2,470lbs

[J_Bond]

I believe the rule is 10lbs of sprung weight = 1 hp

Let's say that statement is true....  that means subtracting 400lbs takes a base Sky from 177hp to 217hp.  Add in my mods with ECU tune and let's say roughly 225hp to 227hp.  Not too shabby.

Now imagine that setup with just a little boost!  YIKES! 

[ophidia31]

now throw in an additional loss of 40lbs from Norm's hood

7lbs for stock airbox and engine cover delete

Unless norm or anyone else makes a stock looking hood, i wouldnt be doing that unfortunatly. Dont want that kind of flash from the hood he currently makes or any current hoods avilable.

And do you have the separate weight for the engine cover? And is that just the front airbox or did you replace the piping from the tb to your new filter as well? Do you also have the resonator tumor still hanging around? Right now, Im just missing those weight of the resonator and engine cover as theyre not on the car either but I chucked them so I cant weigh them myself.   

[elff]

J_Bond
22 lbs for the brakes.
The rears are the same weight the fronts are 11 lbs lighter on each side.

[Critterman]

Let's see what I can do to confuse the issue

06 stock N/A  7.8 sec 0 to 60, 16.8 1/4  143 hp at the wheels
06 DDMIII S/C kit, 24lbs lighter wheel and tires, add 90lbs of sound deadining  4.6 sec 0 to 60, 13.6 1/4 mile, around 270 hp at the wheels

[J_Bond]

Let's see what I can do to confuse the issue

06 stock N/A  7.8 sec 0 to 60, 16.8 1/4  143 hp at the wheels
06 DDMIII S/C kit, 24lbs lighter wheel and tires, add 90lbs of sound deadining  4.6 sec 0 to 60, 13.6 1/4 mile, around 270 hp at the wheels

Except that Road & Track ran a 15.8, and I personally ran a 15.4 before doing any mods except tires....

Account for the fact that I weigh 135lbs, and know how to drive at the track

[ophidia31]

Not really confusing. You basically doubled the stock hp/tq so to not see any gains from that, you would need to almost add another 2500lbs back to the car. Now the front to rear weight ratio is where you see your difference by adding the s/c and all the extra plumbing to the car.

[elff]

I knew that taking weight off the wheels/drivetrain is better than off the chassis. Yes, what im taking off doesnt equate to a large performance gain, but it is better than having it on the car. I dont believe in a weight taken off to hp number either. I think thats all bs thrown around on forums by people that want to put their car on a higher plain in their minds. Your engine makes this much hp, removing weight doesnt magically add that hp to the engine. The only thing that would measure a hp increase would be less rotational mass on the dyno and even then you will never get above what the engine is putting out. Other wise its all theoretical numbers to me which dont mean a thing. Physical 1/4mi and track times are what mean something to me.

Actually it isnt just theory.  It's all about the weight to power ratio.
if you increase Power than you make this weight to power ratio better

At the same time if you reduce weight, you make this weight to power ratio better.

So lets makes this easier. 

3000lbs/300hp = a power to weight ratio of 10lbs/hp

If you reduce the weight by 10 lbs
The ratio becomes
2990/300hp = 9.966666666667

If the weight stays the same but you increase the HP by 1
The ratio becomes
3000/301hp = 9.9667774

So that rule of thumb is pretty darn close.

[Critterman]

Except that Road & Track ran a 15.8, and I personally ran a 15.4 before doing any mods except tires....

Account for the fact that I weigh 135lbs, and know how to drive at the track

I know what road and track did, I also know what I did totally stock with around 1100 miles on the car.  And I weigh in about 100 lbs heavier and I always ran with a full tank for consistency..   Add to that I hadn't been to the track in over 30 years

[J_Bond]

I know what road and track did, I also know what I did totally stock with around 1100 miles on the car.  And I weigh in about 100 lbs heavier and I always ran with a full tank for consistency..   Add to that I hadn't been to the track in over 30 years

Critter,  I hope I didn't offend you by stating my stats!       I just wanted to make clear why my numbers have been so good.  I also know that no car ever comes from the factory EXACTLY the same.  Dyno tests have shown significant increases and decreases in power on different cars of the same make and model.  I may have gotten lucky!   I will say, I drove a bone stock Sky LE5 the other day, and with all of my mods, TCU and ECU tuning as well as weight-reductions, my Sky truly feels MUCH different to drive! 

[Sol Asylum]

J_Bond don't forget the big variable auto vs manual trans.  I know Critter's is a manual what was the road and track, or even your car.  And if I am not mistaken the stock tires changed between model years.

[JimmyBaja]

While numbers are being quoted...
I have an automatic, stock hp came in at 139 with a best 1/4 mi at 15.8.
DDM stage II brought me to 225 hp with a best 1/4 mi at 13.57
The car with all the mods & my200lbass & 1/4 tank of gas weighed in at 3190lbs.

[ophidia31]

Actually it isnt just theory.  It's all about the weight to power ratio.
if you increase Power than you make this weight to power ratio better. At the same time if you reduce weight, you make this weight to power ratio better. So lets makes this easier. 3000lbs/300hp = a power to weight ratio of 10lbs/hp. If you reduce the weight by 10 lbs The ratio becomes 2990/300hp = 9.966666666667. If the weight stays the same but you increase the HP by 1 The ratio becomes 3000/301hp = 9.9667774. So that rule of thumb is pretty darn close. (condensed that for sake of space)

Im not saying you or anyone else is wrong, I just find it hard to believe that stuff 100% when everyone and their mother quotes this formula or that formula. Ive seen too much calculator performance thrown around I just get annoyed by it sometimes. I like hard numbers shown by track times or putting the car on the dyno or scale to get the true weight (not what some magazine says they are) Once you have those raw numbers, then you can go to the calculator and figure out you front to rear weight ratio or power to weight ratio etc.