GC8 weight ideal and some questions

[Guest]

Hi

I know the weight of the car from factory 1270kg,

I have just weighed my car and it comes in at 1180kg with full cage fitted but had a 1/3 tank of fuel.

Does anyone know the size of the fuel tank? so I can calculate the weight of the fuel, I have just found out the density of petrol is only approx 0.75 gcm depending on temp which is gutting. As 1L of petrol only weighs 750g I wish it was more like 2 gcm.

I am trying to work out ways of reducing weight further, how much weight do you think a carbon fibere bonnet will save over a type ra aluminium one?

I am also looking at changing the fmic to tube and fin design which saves weight over the bar and plate. Any other suggestions where I can save weight I don't really want to go down the cf panel route apart from the bonnet.

Car has already had aircon, heating removed and fully stripped? the rear doors ahd ve been completed strip internally and have just a metal plate covering them window is bolted in place, front doors have been converted to wind up only.

i would love to get down to below 1150kg but don't know how fesable this is without the cf panels.

[sultan]

i think most cheap cf bonnets will be heavier than the alloy factory ones. perhaps look at lighter wheels and composite windows.

you should have a 45L tank i believe

[GC8E2DD]

FRP guards? Gut the doors? Cut out the wheel well? Lexan windows? I seem to remember when this last came up people thought 1100 would be easy ...

[Guest]

txs for the replies, cutting out the wheel well is a good idea i dont use it. Already gutted doors. what is FRP ?

[GC8E2DD]

Fibre reinforced plastic. I'm guessing it's significantly lighter than steel,and a lot cheaper than CF.

[sultan]

fibre reinforced polymer, aka fibreglass. i have frp gaurds, i don't really think there's much if any weight saving there, facto gaurds are pretty light if i remember correctly when comparing them

[Optical]

im guessing you have small brakes and a 5 speed trans?

im gutted as my GC weights 1245kg haha. yeah serious $ to start reducing weight after cutting out as much of the surplus steel as you can

[Guest]

txs for the explanation of frp didn't know that.

I have 330 mm front discs and standard 4 pots with endless pads, the rear is tottally std.

Yes i have std 5 speed in there, can't think where I can cut more steel out of the car.

[newsuba]

Standard fuel tank size is 60L.

Lightweight models had smaller 50L tanks.

[petrolheadjman]

on the density / mass / weight of petrol. Its weight will not change depending on temperature!! Mass (weight) does not suddenly appear.

[Scoobydoo]

On the topic of bonnet weights - I enquired about a carbon bonnet from Redline, it was a fibreglass bonnet with a single carbon overlay over the top. It was 1kg HEAVIER than my factory RA bonnet. (11kg compared to 10kg for factory bonnet)

A FULL carbon bonnet however are about 6-7kg, but cost in excess of over $1000 for a good one (Seibon, etc)

[Dv8er - FSTWRX]

Light weight battery, drill/hole-saw holes everywhere (the supports on the underside of the boot, bonnet, anywhere you can without it falling apart). You still have dash in too don't you? can always take that out and just leave the speedo cluster. Remove lights if you haven't already. Don't eat double downs.

[funkytown]

Taking out the heater core and aircon fan unit drops a little. Removing the rear window mechanism and locking them shut remove central locking or electronic windows. Other than what has already been suggested.

Optical - what state of weight loss is yours? Did you see my weights pre sound deadening removal last weekend? Have also since done a 5kg dry cell as well. So expecting just under 1200kgs with brembos as a 6mt.

*I can't verify the scales are 100%. Just the ones at the tip.

[Guest]

 petrolheadjman said:

on the density / mass / weight of petrol. Its weight will not change depending on temperature!! Mass (weight) does not suddenly appear.

Sorry but you're totally wrong, I know I am a industrial chemist.

Density is defined as mass per unit volume, as temperature effects volume it affects the density. There are two parameters when looking at density not just one which is what you are assuming with your statement. Pressure also changes the number but I am not going into the triple point argument of solutions.

dv8er: yeah still have dash well half dash in there, not too keen on losing this the car is still going to be road leagal so this limits me too.

Funkytown, I have gutted the doors already, it seems the rest of the weight reduction is going to be had thought and expensive. Battery is another option still have standard should save a little.

[Joker]

Fibreglass guards are great on race cars - they make a mess on contact! stick with steel....

paint it black and call it carbon fibre roof - worth at least 5kg

[Optical]

 funkytown said:

Optical - what state of weight loss is yours? Did you see my weights pre sound deadening removal last weekend? Have also since done a 5kg dry cell as well. So expecting just under 1200kgs with brembos as a 6mt.

*I can't verify the scales are 100%. Just the ones at the tip.

Hmm not sure, remind me?

Ive only removed aircon (-10kg?)

Added 6mt (+45kg), brembos (60kg in total, +15kg?), big intercooler (+5kg?), big radiator (+5kg), other coolers (+5kg), big exhaust (+5kg?).

I'd say it would have been well under 1200 to begin with...

how much does the sound deadening weigh?

[funkytown]

estimates between 10-12kgs for me and i havent touched the firewall stuff yet.

[Jammasta]

Wouldn't trust the tips scales. I had as low as 1170 with me in it at the welly dump. V5R.

[GC8E2DD]

Only 10kg for the aircon? I thought it was more. That means I ended up with a heavier car removing the aircon and fitting V7 STi wheels =\

[Munkvy]

Have you taken the angle grinder to the car yet?

Cut out the skin underneath the bonnet, doors and boot (by skins I mean the steel skeleton). Cut out all brackets that are no longer used. Cut basically anything that gets in your way that doesn't have wires or fluid in it!

Then pull the loom out and remove the wiring that is no longer needed.

If you had a rear windscreen wiper and or antenna remove them and their associated electric components.

Put in a smaller windscreen water sprayer.

Remove mufflers from your exhaust (real race cars don't need mufflers after all!) and shorten it to a side exit.

Then put the driver on a diet (thats the hardest bit if you ask me! I have yet to win there).

[off2harrys]

yea air con only 10kgs and sound deadening in wagons is just over 10kg aswell may be less in sedans ??

[Guest]

 Munkvy said:

Have you taken the angle grinder to the car yet?

Cut out the skin underneath the bonnet, doors and boot (by skins I mean the steel skeleton). Cut out all brackets that are no longer used. Cut basically anything that gets in your way that doesn't have wires or fluid in it!

Then pull the loom out and remove the wiring that is no longer needed.

If you had a rear windscreen wiper and or antenna remove them and their associated electric components.

Put in a smaller windscreen water sprayer.

Remove mufflers from your exhaust (real race cars don't need mufflers after all!) and shorten it to a side exit.

Then put the driver on a diet (thats the hardest bit if you ask me! I have yet to win there).

No havent angl grinded anything too scared to as i still want it road legal, i am looking at side ext for exhaust but not sure it will be allowed on the road. I do need a diet i should probably lose 10kg myself. Most of the unecessary wiring has been removed.

[aim]

 petrolheadjman said:

on the density / mass / weight of petrol.

Lol... Critically, that doesn't actually make any sense, those are not the same things weight (force) changes with acceleration (gravity), density changes with temperature (heat), and mass changes with speed.

It's like saying Subaru/Sony/Nike make awesome office chairs

[DRFVDR]

 ballsrburning']

[quote name='Munkvy said:

Have you taken the angle grinder to the car yet?

Cut out the skin underneath the bonnet, doors and boot (by skins I mean the steel skeleton). Cut out all brackets that are no longer used. Cut basically anything that gets in your way that doesn't have wires or fluid in it!

Then pull the loom out and remove the wiring that is no longer needed.

If you had a rear windscreen wiper and or antenna remove them and their associated electric components.

Put in a smaller windscreen water sprayer.

Remove mufflers from your exhaust (real race cars don't need mufflers after all!) and shorten it to a side exit.

Then put the driver on a diet (thats the hardest bit if you ask me! I have yet to win there).

/quote]

No havent angl grinded anything too scared to as i still want it road legal, i am looking at side ext for exhaust but not sure it will be allowed on the road. I do need a diet i should probably lose 10kg myself. Most of the unecessary wiring has been removed.

The exhaust outlet CAN NOT be any closer than 200mm from an opening (door/window) if u can get the side exhaust further away than that then all good( like is it a coupe)

[Tony]

 DRFVDR']

No havent angl grinded anything too scared to as i still want it road legal, i am looking at side ext for exhaust but not sure it will be allowed on the road. I do need a diet i should probably lose 10kg myself. Most of the unecessary wiring has been removed.

The exhaust outlet CAN NOT be any closer than 200mm from an opening (door/window) if u can get the side exhaust further away than that then all good( like is it a coupe)

But isnt it ok in a 4 door (caged race car) as it should now be re-registered (or whatever you have to do) as a 2 seater since the rear seats etc are no longer used therefore you can have your exhaust exiting just before the rear wheel. Thats where mine is anyway, and I have no issues with getting a WOF.

[quote name='Munkvy said:

Remove mufflers from your exhaust (real race cars don't need mufflers after all!) and shorten it to a side exit.

With the factory cast headers I had no mufflers at all in my exhaust - full 3 inch to side exit, and it was fine - I never got told off at the track for being over the DB limit, but it was possibly a little too loud for street driving, but in saying that I had driven past a few cops and they never did anything?

When I changed to my new headers which are full equal length, the car was crazy loud! Had a horrible sharp bark to it and had to fit a bullet muffler/resonator thing in the middle of my exhaust - that took away the bark and now the car is probably quieter than a lot of other Subarus I hear driving around!

But it is noticibly louder inside the car with a side exit (and no interior).