Metal removal at rear, opinions

[Ivan141]

The headlight covers weigh next to nothing, not much to gain from changing those. The bulk of the weight is in the rest of the mechanism.
Maybe you could benefit from some lighter sealed beam units, but I don't see creativity in that department passing scrutiny for a road registered car.
You could change the roofskin out for an FRP version, but again the gain is very little (albeit in the best place to remove weight), while the effort to install a new roof is high.

About the rear diffuser: building an effective diffuser is indeed something best left to capable engineers with a windtunnel (although I gather that the main thing in making them effective is running a very tight ground clearance). But making an undertray type of thing that keeps air out of the general area shouldn't be too difficult to create and test (compare with the same car without the undertray, use a magnehelic pressure differential meter to get solid measurements, if you ever read up on autospeed you'll know what I mean).

[4000GT]

Do you happen to know what the roof skin weighs? I know the fibreglass ones seem to be 3kg.

I didnt think about the light units themselves! Do you have a link to one you recommend? We can change that here not worries.

[Eircamae86]

Darren McNamara likes to chop us 86s & lighten them.
Does frp roof from memory, plenty frp on the site.

http://www.mcnsport.com/shop/listParts.p...y=Aero+Kit

[NoHachi]

Have you had the car on the scales yet? Any idea about current weight and front bias?

My guess is you'll need to work on the front, which is quite hard work/expensive.

Things from my list:
Front subframe replacement (significant)
Front lexan windshield (significant)
Lighter flywheel (prolly done)
Lighter intake (ITBs/prolly done)
Lighter exhaust manifold (racing ones are already light)
Remove Flip lights, replace with manual construction and led lights
Lightweight alternator or Daihatsu Denso one.
Lighter wheels,
Alloy Struts/dampers

Compared to that the rear is easy (chop chop)

[4000GT]

NoHachi Wrote:Have you had the car on the scales yet? Any idea about current weight and front bias?

My guess is you'll need to work on the front, which is quite hard work/expensive.

Things from my list:
Front subframe replacement (significant)
Front lexan windshield (significant)
Lighter flywheel (prolly done)
Lighter intake (ITBs/prolly done)
Lighter exhaust manifold (racing ones are already light)
Remove Flip lights, replace with manual construction and led lights
Lightweight alternator or Daihatsu Denso one.
Lighter wheels,
Alloy Struts/dampers

Compared to that the rear is easy (chop chop)

I have not had it on the scales yet, but I have done a lot of weight savings!

I have sub frame on the list too... I cant run a lexan window as the car is road registered, but the rear hatch and quarter windows are lexan. I have a light weight flywheel and exhaust manifold (side exit behind the passenger door. Which alternator do you recommend? I know some are suggesting Mitsubishi ones.

[oldeskewltoy]

maybe its time to build in a few more hp... ????? :wink:

[4000GT]

I really cant to anything else to my motor! Unless I turbo it, but dont want to as its class racing.

[4000GT]

Custom header (SS 304 in 1.5" diameter primaries and 660mm long, to a full 2.5" SS 304 exhaust, DEI header wrap
Custom Aluminium intake with CNC backing plate with built in 45mm velocity stacks.
3SGTE injectors
Coil On Plug ignition
Sliver top block (I grenaded a Black Top one) with balanced crank, ARP Bolts throughout, ACL bearings, Tomei rods, custom CP pistons, 15:1 CR.
288 degree 10mm lift Kelford Cams
Supertech 1mm OS valves, Supertech Valve Springs
Excedy Lightweight Flywheel
Setrab oil cooler and TRD oil filter with HKS adapter off the block
Moroso catch can (shortened to meet regs) with K&N filter
Half size radiator with alloy shrouding and electric fan
K&N 4" cone filter
ARP alloy heat shield
TRD oil cap
TRD 0.8mm headgasket
T3 Alternator pulley
AC deleted
MR2 Electric PS System

[NoHachi]

How about you start a separate thread for this car, with the odd vid thrown in for good measure? Or did I miss it?

Lotsa kitcar peoples use the Denso Alternators from Daihatsu cars. I think they can be found on the Move/Cuore/Sirion etc.
Weight is about 3kgs and they can be run at high rpm's supposedly. Usually that's a saving of around 2-3 kg's, not bad for 25$ at a junk yard.
There are racing alternators available as well. Lightest I've seen them was 2.5kgs for an alternator that will still power the driving lights etc.

[fax0815]

All the easy things to the chassis are done
The only things left to do on the chassis are:
-roofskin (lots of work)
-headlights with plastic lenses (relatively cheap)
-steering collumn (custom single carbon tube)
-carbonfibre dashboard
-carbon kevlar seats
-carbonfibre sheet bootfloor
-drill loads of holes with a holecutter in all the places were it doesn´t affect rigidity (cheap)

Don´t thinkt there is much to gain from doing changes to the subframe, unless you go for a full custom spaceframe thing, but I recon it will be more rigid but not lighter...

Time to think outside the box...
You should pay more attention to rotating/ unsprung weights:

Iirc 1kg unsprung weight equals 8kg static weight and there is a even bigger difference with rotating mass, which will not just reduce the weight and also help you in terms of acceleration, have a look at google for all the math behind it.

-get aluminium hubs (cheap) http://www.grp4fabrications.com/product_...cts_id=635
-lighter wheels
-don´t know how you with spool diffs in racing, but they´re half the weight of a LSD
-biggest gains can be made from everything before the gearbox (lightened internals)! Flywheel and clutch assembly, go for a smaller, lighter clutch.
What are you running?
I just completed this setup, twin plate carbon clutch, fidanza alluminium flywheel (will get a few more pockets to be even lighter) which works out at more than half the weight of a normal clutch but decreases the moment of interia as well.



This will make a lot more difference, than trying to save more weight on the actual chassis. Unfortunaltly a lot of people underestimate that...

Thats all I´ve got to say about weightsaving...
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