Weight loss time

[Driftin_AW]

Hello my predominantly-foreign friends :)

I'm still a busy little bastard with running a Formula SAE team, and doing uni and such, but I've started thinking about some stuff I'd like to do over summer (which is happening soon down here). To give the briefest of updates on where I'm at right now:

http://www.twobrutal.co.uk/forum/images/recovered/2007/10/197.jpg
The car is fully certified and road legal, I drive it every day, I even finally got my arse into gear and did some painting on it, but it have generally received very little love in the last year or so.

So anyway, in the past year I've become somewhat competent with a number of things I was formerly pretty crap at; I can tig weld reasonbly well, am now pretty handy at machining, and have gained a lot of experience in composite part manufacture. I'd really like to apply the aforementioned skills to making some parts for the MR2, particularly with a goal of making it significantly lighter.

As you may also recall, my car on the cornerweights weighed 1068.5kg, with about a 43% front weight split. I'm happy with the split, but have pretty arbitrarily set myself a goal of bringing the weight down to under 1000kg, without making any big sacrifices to drivability and such. So what's the plan? I've already done most of the quick and easy things:

- Lightweight seats
- Removed carpets
- De-spoilered
- No aircon
- Celica alt
- No spare tyre
- Reasonably small stereo - just a headunit, 6.5" component speakers, and a small amp
- Lightweight exhaust (really couldn't be much lighter)

So where do I go from here? The list on the following website has given me some good ideas:
http://www.jekylhyderacing.com/weight.htm

What I'm thinking at present is that I'll try to:
- Make an exceptionally lightweight composite bonnet, should save 10kg at least
- Finish my 1-piece boot/engine lid and use it as a plug to make a mould for an exceptionally lightweight boot/engine lid - should save another 10kg
- Replace the steel components in the ducting I made for the radiator mods, either with aluminium or composite parts. Maybe 3kg there
- Make some composite mirrors to replace my motorised ones. Should save 4kg-ish, motorised mirrors are heavy
- Take to a couple of my engine mounts with a mill and remove some excess material, should save about 1-2kg
- Look into some lighter wheels, although funds may make this difficult
- Look at doing something with the headlights, but I'm not sure if I can afford to buy any headlight units to build flush mounts.

So I've got maybe 30kg of weight savings there, which means I'm nealy 40kg short, so has anyone got any ideas of where the rest could come from? New front fenders would be an option, but I don't think there's much bang-for-buck to be had, as they're reasonably light already. I've also thought about composite ARBs but I haven't thought of a good way to implement them on a McPherson strut setup yet. There's also the option of manufacturing some tubular suspension arms, but this will require re-certifying my car, which I'd like to avoid!

So please, send any ideas you may have this way :)

[MartG]

Removing the steel bumper bars and just leaving the skins will give over 10kg. Chipping off the bitumin soundproofing in the cabin is another 7kg. Are perspex windows legal where you are ?

[Driftin_AW]

I think you can use plexi/perspex windows if you have a motorsport authority card (basically something that says your car is safe for, and competes in, motorsport). Not sure if I want to ditch the bumpers though, although I could make some more out of aluminium

[weegaz22]

all depends on what you are willing to sacrifice really, id like to loose a bit of weight in my car but its a road car, be different if it was just a track car where you could loose a lot of weight by removing entire interior, blower fan, heater matrix, dash, gut the doors etc,

its all stuff that will make it a worse daily driver

loose the stereo and buy an mp3 player, my car doesnt have one

[Rosssco]

Remove sideskirts.

Doors always seemed heavy to me, so gut the internals and remove electric parts including the electric window motors (if you can get a hold of the wind down part in replacement).

If you don't use the boot, remove the firewall, and weld in a replacement strut section to maintain strength...?

Rear window seems a fairly simple design, so could you fabricate a lightweight replacement and install this? Obviously you wouldn't have a demist function then (use the old demister button as a turbo boost button :thumbsup: ).

Of course if your happy with the current weight distribution of the car then what ever you do to the front or rear, you will have to take this into account and remove weight else where...

[Jim-SR]

its amazing how much the small things add up. spent a morning gutting a friends AE82 Corolla GT the other month and we were just taking out bits of plastic trim here and there, rear seatbelts, etc. we didnt take anything out that weighed more than a few kg on its own. by the end we had a big box full of stuff, the rear bench seat, seatbelts, plastic trim and clips, etc. it weighed in at over 40kg. youd never have thought it though just to look at what we removed

the big items where savings can be made are...

seats - std weigh in at 16-20kg, even cheap bucket seats tend to be under 10kg

bonnet - standard item apparently weighs 14kg, and you could make a fibreglass one 5-7kg in weight

engine lid and boot - engine lid is pretty light, the boot isnt crazy heavy but it has a spring mechanism and stuff that add to the weight. you could probably lose 5-8kg here

bitumen sound deadening in the cabin weighs around 7kg (as said)

spare wheel - around 15kg and probably the easiest weight reduction possible :D

but then you have to start factoring in the smaller stuff. door cards, the underside dashboard covers, rear speakers, all the trim around the roof and the rear windows (some of them are steel backed!! and they weigh about 1-2kg), headlining, a-pillar trim, b-pillar trim, seatbelts (replace with harness belts, intertia reels weigh more than harnesses), replace the front strut brace with an ally item, remove the spare wheel locating bar (black frame in the frunk which the spare wheel sits within), remove the standard inlet and replace it with a cone filter somewhere (its a long inlet tract, and it doesnt really need to be, plus there is a resonator box, etc), stick polycarb windows in for the rear quarter windows and the rear screen, lose the automatic aerial in the boot, remove all the carpets and sound deadening from the boot, lose the oil cooler and just run a transfer pipe instead (the oil temperatures arent a huge issue on the MR2, i think you could probably get away without the cooling), etc, etc

theres plenty of places where you can lose cumulative weight, and end up losing 50-80kg without really realising it!! just a question of taking the time and effort.

[Driftin_AW]

haha, unfortunately most of the stuff that you've mentioned is already gone (boot spring, lightweight seats, spare wheel, spare wheel brace, underside dashboard covers, rear speakers, inlet is very short - look in my pic gallery, no aerial, the only oil cooler is the stock 3sgte one which is pretty light and I'd want to keep, no carpet in the boot)

I could completely gut the interior - I did this on my old Celica GT-Four but it certainly made it a loud sucker to drive, otherwise once I've done the stuff I listed earlier I will be just about at the end of the road I think, in terms of stuff I can remove without having to make big sacrifices.

[adamh]

hello malc, how about a cro-moly fly, toda / hks,fidanza ally, bullet steel wheel, all around 5kg lighter than stock, dont worry about the improvements to throttle repsonse!. you can remove/turn some off the stock even and save around 1.5kg without any adverse effects. as for mounts, I've always fancied bulk allumnium mounts tig-welded (engine side), easy to machine aswell, ditch one of the rad fans if you havent allready, change any steel IC piping to alluminium

[OlberJ]

Or how about working out the bhp per tonne gain and just adding sum more power? :whistle:

[adamh]

one more thing that handy volumetric number 1000g = 1000ml.. any savings to be had in the bore size of your charge cooling .. whats the system hold?, can you refine that by reducing the bore size, you could knock a Kilo per litre off fluid wise.

[weegaz22]

be very very careful when modifying flywheels, if it goes then it will let go with enough energy to cut through your car and you

ive seen the damage a flywheel coupling plate for an engine dyno can do when it lets go, it sank itself into the test chambers doors...these doors were made of steel, the flywheels weighed more

infact theres pics floating about on the net of a wrecked skyline cos its modified stock flywheel let go, owner was very lucky it never took his legs off

[weegaz22]

http://www.pcformat.co.za/modules.php?name=Forums&file=viewtopic&t=25103&postdays=0&postorder=asc&start=0

[adamh]

http://www.pcformat.co.za/modules.php?name=Forums&file=viewtopic&t=25103&postdays=0&postorder=asc&start=0
wow, thats some damage, just like a rod going through the block. ive been machining flywheels for some years now and rotors, never seen that happen gaz / heard even until now. thats a firm point taken for sure. it must have fractured some how.. inbalance or heat induces stress / cracks, and it would then go at the weakest point, through a bolt hole. good show. on second thoughts malc lol

it does not look like its had any work done to be honest although.

[Marksman]

Even more scary on a car with a transversely mounted engine. :eekdoor:

Owen.

[superchargedsam]

fuuurk

[weegaz22]

ive been machining flywheels for some years now and rotors, never seen that happen gaz / heard even until now.


decapitated owners cant come back and complain adam lol :hidesbehi

[Driftin_AW]

adam, the w/a intercooler system holds about 4L so 4kg, could possibly save a kg there but I'd have to do some measurements of temps first to make sure I wasn't harming performance. I could definitely ditch the pump for a much lighter Davies Craig unit, probably save 2kg there too.

Radiator fan is already a single plastic one with a lot of the bracing cut out, not sure I can save much weight there

Flywheel could be a good avenue to go down, I wouldn't machine it down though, would rather go for a completely new one. Will have to see how money is on that front

My IC piping is non-existant so there's nothing I can save there. I was thinking inlet and exhaust manifolds are pretty hefty, could probably save 4kg by redoing them both with tubular units.

Engine mounts I could even redo using some chromoly tubing and smaller bushes to replace the gigantic rubber bits, might look in to that one.

Generally there is a lot of weight in the engine, I'd be pretty keen to go silly one day and start mowing bits out of the head to reduce weight :D I wonder if I could do a new rocker cover, that thing is heavy. Ooooh I wonder what temps it sees? Probably a bit much to do a carbon one (unless I can find someone that does them high temp phenolic resins)

[adamh]

decapitated owners cant come back and complain adam lol :hidesbehi
they come with a gaurantee.. for life ;)




you could certainly save some weight on the inlet mani with some careful design, get on that prog that went your way a long time back, draught your design, choose material, then in the 'tools' menu you can use the mass function, it does the hard work with the volumetric calcs and just splurts out the weight/mass respective to the density of chosen material from database, you can apply welds onto the design aswell, now thats lazy lol

[Driftin_AW]

sorry Adam, I turned my back on SolidWorks and I'm all about Pro/Engineer now :)

[adamh]

sorry Adam, I turned my back on SolidWorks and I'm all about Pro/Engineer now :)
mutiny! ooo-arrrr. maybe i'll have a dabble one day.

[OlberJ]

U'll be needing a pirate copy of that then?