Weight Reduction

[scom_01]

hi guys. im sorry if this is on the wrong section but i couldnt find it anywhere and thought i would just put it in here.

if people could just put down what they have done for weight reduction of any form that would be very helpfull.

also the benefits of for example a lightened flywheel

thankyou

[DR 180]

Only use weight reduction measures seriosuly for trackdays or drags.

Take out back seat, spare wheel, subs, anything heavy, carbon fibre bonnet, half tank fuel.

Light weight rims make a big difference in speed also.

[scom_01]

Only use weight reduction measures seriosuly for trackdays or drags.

Take out back seat, spare wheel, subs, anything heavy, carbon fibre bonnet, half tank fuel.

Light weight rims make a big difference in speed also.

oh ok.. well what about a lightened flywheel., how much can that cost and what are the benifits

[GTS4WD]

oh ok.. well what about a lightened flywheel., how much can that cost and what are the benifits

They are about $400 odd.

The benefits is that the engine will rev out quicker as there is less unsprung mass bearing down upon the engine.. Same thing goes for lightened drive shafts.

Down side off lightened flywheels is that its harder to get the car off the line quickly and is easier to stall. Another down side is that a lightened flywheel can't cope with high temperatures and can develop stress fractures and this can transfer over to the clutch.

In terms of weight saving.. how hardcore do you wanna go? On top of what DR180 said.. you can also remove;

Sound deadening

Power steering

Air con

power windows

audio items

fibreglass quarter panels

fixed back carbonfiber/kevlar/fiberglass race seats

choped reo bars

Edited July 27, 2008 by GTS4WD

[GTS4WD]

Another down point of lightened flywheels is that you will get less engine brake when chaning down gears..

[R338OY]

There isn't much you can remove/lighten without a compromise. I mean safety/defects/expense/extra noise

IMO only take the above advice (it's all correct) if you're serious about circuit/drag and have some dollars to spend on lighter parts. The heavy bits are up front, but are expensive to replace (bonnet, fenders, engine components). SO removing too much from the rear (speakers, spare, tool bag, boot trim, rear seat, wing etc) will worsen the weight distribution. Expect less grip where it's needed most.

A fair few people here have returned their flywheels back to stock after going lightened. It's annoying to drive on the roads.

IMO the best thing for a street car is try not to ADD weight, as a minimum.

Hope you work it out mate. Cheers

Edited July 27, 2008 by R338OY

[G0DZLR]

hi guys. im sorry if this is on the wrong section but i couldnt find it anywhere and thought i would just put it in here.

if people could just put down what they have done for weight reduction of any form that would be very helpfull.

also the benefits of for example a lightened flywheel

thankyou

what car are you working off as the base?

[INVRTD]

ay guys sorry to but in but whilst talking about weight distro i guessed wouldnt mind, i am thinking of dyno matting the boot space entirely to improve sub sound and kill road noise a bit do you recon that its worth the effort and $$$

[R338OY]

ay guys sorry to but in but whilst talking about weight distro i guessed wouldnt mind, i am thinking of dyno matting the boot space entirely to improve sub sound and kill road noise a bit do you recon that its worth the effort and $$$

Depends how badly you want to increase the sound.

[Chef_32]

figure out how much dynamat you need, the density of the stuff is on their website so you can figure out how much it will weigh things down. If its important to you to reduce the noise, then do it.

[HEKT1K]

dude just eat less... im lucky to be not a massive guy (175cms, 55kg) so that helps

[SKiT_R31]

dude just eat less... im lucky to be not a massive guy (175cms, 55kg) so that helps

not a massive guy? lol at that weight your not half a massive guy, lol...

Some thing thats not mentioned so much here that ill add, is that rotating weight means more than static weight (static weight being dead weight held by suspension, and rotating being, engine/drive train)

So lighter wheels, drive shaft, clutch, flywheel, balencer, even crank/rods/pistons all make a big difference. As for lightened flywheels being undrivable? I think the opposite, i love my light flywheel, makes down shift throttle blips so quick, effortless and smooth, car revs quicker etc. No problems with stalling etc, might be more noticed on laggier turbo cars etc, also depends on your gearing etc (i have fairly short gearing for a 3L @ 3.9:1). Lightweight wheels make a big difference also, even brakes....

what was mentioned with the weight distribution is correct, but you can change your suspension accordingly to suit. I don't have a spare or jack etc, i run an rb20det gearbox (lighter than 25det) but have my battery in my boot to help out distribution (if its a 32) you could also get a lighter battery. Less fuel in the tank, pretty much anything else you can look at and replace with some thing lighter or remove all together, sound deadening/carpet, aircon condenser + radiator, shit behind dash, stereo gear, replace window glass, exhaust, windscreen washer and full radiator overflow, whatever floats your boat.

but remember, theres not tooo much of a gain with removing static weight you'll be able to shed, so its about compromises for performance vs comfort, for example, its a bit of work but you can probably take over 20kg of sound deadening/carpet/underlay just out of the cabin, but do you want the noise and vibration?

unless its dedicated track or your going for broke, I'd leave it stock appart from easily removable items, like rear seat (that you can put back in), and lightened drive train, if thats what your into.

[djr81]

Another down point of lightened flywheels is that you will get less engine brake when chaning down gears..

This may sound massively pedantic, but what you have said is not 100% correct.

Basically a heavier flywheel needs more energy to increase its rpm relative to a lighter unit.

So when you change down a gear it will INITIALLY give you more engine braking.

However after that point it will give you less engine braking because its greater stored energy (kinetic energy - again relative to a lighter unit) needs to be soaked up by engine friction & braking etc.

So basically a heavier flywheel will absorb more energy to get it up to speed, but then give it back when you try and brake.

As an aside that means when you don't change down gears a lightened flywheel will increase your braking performance.

[GTS4WD]

As an aside that means when you don't change down gears a lightened flywheel will increase your braking performance.

Under braking.. the force of the wheels slowing down Via braking) is greater than the force of ineria and gravity acting on the the flywheel to slow it down..

So the force of the brakes slowing the the car and hence the engine, as it is in gear, will over come the force of the flywheel attempting to slow the engine down..

And besides.. its easier to stop/slow down a rotating object of less mass than one with more.

[nizmonut]

hmmm i think the easiest way to describe the gts4 in my shed is what is in it rather than what isnt in it,

interior wise,

a seat

2 seat rails

3 pedals

a handbrake

a gear lever

a steering column and wheel

1 seat belt.

the dash board has been hollowed out to a shell of it's former self leaving only the things required by law, i e the fan to the windscreen, indicator stalk, light switch, hazard light switch, window wiper switch and gauges. oh and a horn.

doesnt have a roll cage yet

under the car

all components related to the suspension and drive line,

all plastic and anything bolted to the chassis that doesnt help performance is gone.

the bumpers are fibre glass skins with no subframes, the bonnet is the same, along with the gaurds and side skirts,

im currently saving for fibreglass rear qauters and may skin the doors if i can find sombody who can do them.

so far it has gone from a curb wieght of 1420 kgs down to 1158 kgs.

i think if this was done to a gtst it would be even lighter not having the 4wd system.

[djr81]

Under braking.. the force of the wheels slowing down Via braking) is greater than the force of ineria and gravity acting on the the flywheel to slow it down..

So the force of the brakes slowing the the car and hence the engine, as it is in gear, will over come the force of the flywheel attempting to slow the engine down..

And besides.. its easier to stop/slow down a rotating object of less mass than one with more.

I have no idea what you are trying to say. Something about gravity, right?

Braking friction & engine friction (or pumping losses if you like) both act to remove energy from the car & hence slow it down.

The kinetic energy of the flywheel constitutes part of the energy needing removal.

The less kinetic energy a car has (for a given speed) the easier it is to slow down.

A lighter flywheel stores less kinetic energy....

If you are changing gears (either up or down) you are simply trading some linear kinetic energy (ie of the car going forward) for some rotational kinetic energy (ie the flywheel going around). All of the energy (whether linear or rotational) needs to be gotten rid of to slow the car (assuming it is in gear). The advantage of the lightened flywheel is less energy is needed to spin up what is ultimately a useless piece of junk and can instead go into making the car go quicker in a straight line.

Anyway the heirachy of dealing with weight goes in the following order.

1. Reduce unsprung weight.

2. Reduce the inertia of any rotating components.

3. Reduce static weight.

4. Relocate weight, ie lower, away from the more heavilly loaded axle and closer to the middle of the car.

Basically item 1 is the most important & then in descending order items 2, 3 & 4. At the end of the day, though, you do what you can.

[GTS4WD]

I have no idea what you are trying to say. Something about gravity, right?

lol.. it makes sence in my head..

[nizmonut]

lamens terms...the lighter the car, the bigger the skid marks.