I've been off sick for a couple of weeks so had a bit of time on my hands, so decided to ponder this subject. As well as adding mods to increase the power of our cars, its well known that reducing weight can give great results. What I have been interested in was what would work for a road car without compromising its useability, comfort and practicality. In fact many of these things I have done to my car, so until I actually weigh it, I wanted to calculate how much it should weigh after my mods.

I've read up a lot of the threads on ours and also the 964 forum and used other members' figures, although I'd welcome any corrections. Incidentally, I've used the conversion of 1Kg to 2.204lbs.

My starting point is that our cars, according to Porsche, weigh in at 1470Kgs 'wet' (ie. with a full tank of petrol).

Reading the latest edition of GT Porsche magazine which has an article about a 3.3 TurboS, it quotes the weight (dry) at 1290kg. Assuming a full tank of petrol at 50kg (77 litres), the wet weight is 1340kg. As the S has lightweight aluminium (or is it carbon?) front hood, back lid plus spoiler, doors, and also bucket seats, I've allowed 60Kgs giving a target weight for our street car of 1400kg. This will give a meaningful 5% weight saving on the standard cars.

I've assumed the same weight for a standard 3.3 and 3.6 as each has its pros and cons. the 3.6 has lighter bumper frames, but heavier wheels, maybe brakes, etc.

Here we go:

Removal of engine undertray - 6kg (debateable whether this part benefits)
Remove of front fogs, replace with ducts - 2kg (not legal in some countries)
Remove some of the carpet underlay - 5kg (Only a fraction of total sound proofing to keep road noise comfortable)

Removal of air injection system and pipes - 10kg (check local laws for all exhaust mods)
Remove cat, use bypass: -5kg
Remove muffler, use g-pipe: -9kg (NB: some say the double bypass is too loud)
Remove wastegate cat, replace with gutted pipe - 2kg
Replace OEM baffled tailpipes with aftermarket - 2kg (some tailpipes are lighter than others!)
Replace OEM headers with race headers WITH heat (remember this is a road car) eliminating several feet of pipework - 13Kg

*The following 3 items are unsprung mass, so the benefit will be maybe 4 times the weight saving *
1. Replace standard suspension with modern sports setup - >5kg
2. Lightweight flywheel - <9kg
3. Lightweight clutch assembly - 2kg

Replace large standard air filter assembly with cone filter - 3kg
Replace OEM wastegate with modern Tial - 2Kg

Replace airbag steering wheel - 3kg
Sunroof delete (replace with carbon panel) - 10kg (although someone quoted this as 20kg!)
Rear wiper delete - 2Kg

This totals weight savings of 90kg, giving a full weight of 1380Kg, well below our target weight.

Of course, you could replace your turbo seats with Recaros although awkward for daily use. Some other seats maybe more appropriate eg. Cobra Misanos: another 10Kgs?

I have ignored panels and removal of spare tyre as these compromise crash resilience, and this is a road car.

And for those of us who have working aircon, lets leave it in for comfort

Hope this helps and excites
Mark

PS: Some mods ADD weight:
Bigger turbo (eg. HFS) + 5Kgs
Third brake light: +2Kgs
Wheels, hi-fi....and .....
.......Roll cages!! But those are for track junkies

 

I personally won't bother with most of the things you mentioned. But as an engi-nerd my target weight reducing items are, in order of cost/benefit:
Rotating
Unsuspended
Distance-from-CG (moment of inertia reduction)

Under these guidelines my first things (since I already have light wheels and tail) is the flywheel and then the air injection, A/C and other heavy ancillary crap in the engine compartment (hung way off the back of the car outside the wheelbase) I gutted the rediculous stereo amps and subs the day I brought the car home. I rewired the speakers to the headunit and have yet to actually listen to it. I'm an aircooled-faithful; the best music in the world comes from this car's engine.

 

Mine weighs in at 1280kg wet with 1/2 tank of fuel, and an extra 4 ltrs of oil due to ruf extra oil cooler. This is due to air con delete, sound proofing delete, replaced with modern replacement, rear seat delete, SPG frount seats, light weight rear screen, rear wiper delete, light weight exhaust, cat delete, lwt clucth and fly wheel.

 

I will be going down this road as well. I'd like to hit the sound deadening pretty hard replacing with somthing a bit lighter. Any experience with Dynamat and the like? I don't want the car to smell like tar.

Don't forget RS door panels. Also, there are seats that are non power but not racing shells that may be a good option for a street car. Looking into this myself.

Hey X1...on the tail. Do you still have shrouding that directs air to the intercooler like the stock tail. I have a lighter fiberglass tail but am going to have to fabricate something.

RT

Where can one get the wiper plug? I am going to remove mine and would like to plug it until i put in the new glass (which will be forever away).

 

See this thread as well.

https://rennlist.com/forums/showthre...highlight=diet

RT

 

My car is 1.250kg with an empty tank.
Fiberglass hood, rs-battery (36A), rs-carpet, rs-door panels, roll cage, sparco seats, no heat, no aircon, no air injection, no radio, no airbags, no rear wiper, B&B headers with heat exchangers removed, no cat and no muffler, but the list of things to remove is still long...

RT, look at www.appbiz.com they have rs-carpets and door panels at good prices. Would recommend the RS-foam plug for the rear seat (you should be able to find the part nbr on this forum, if not let me know).

If I would do things over I would choose the rs-door panels with pockets, they look really good and the pockets are really useful.

The wiper plugs can be bought from Porsche (I did that), perhaps cheaper to use other sources.

 

Ag,
Here's a link for good wiper delete bung:
http://www.promaxmotorsport.com/rear_wiper_del.htm

Impressive weights Staffan & James! Mine works out at 1386kg (with full tank, 50kg) which I am pleased with as a true daily driver with all the goodies still in ie. sunroof, aircon, most sound-proofing :-)

 

My car scaled at 3,085lbs wet.
Ag, no I don't currently have the IC shroud, but I'm supposed to pick it up from the PO next week as the IC can be almost too hot to touch after even moderate driving. I need the engine to be pulling through it rather than just around it.
I'm ambivalent to pull the A/C. Though I know it's a huge chunk of weight and the compressor is in an obstructive place, I will hate myself the day I decide to reinstall it and have to refill all that R12 ($$$). No, I don't use it, that's what the windows and sunroof are for.

 

Yep I am planning RS carpet. Did you do away with all sound deadening or is there "RS" sound deadening?

The thick block of cheese under the driver foot is particulary sad. Id like to do a foam replacement of some sort.

RT

 

IMO biggest sprung weight savings is in removing the stock cats, exhaust and heat exchangers and replacing with a straight pipe running directly off of wastegate, light weight muffler running directly off of turbo and light weight header (no heat). This will save you are around 100lbs alone.

The next biggest is to get rid of the entire AC system including compressor, cooling fan, lines, pulleys, etc. Around 60 lbs of stuff I understand.

The third is to lose 20 lbs from the old wasteline

Getting rid of unsprung weight is lot more expensive (light weight wheels, etc.)

Now if they could only make light weight gasoline ...

 

They do; it's called more boost

 

Seats! When I took my sports out, I could not believe how heavy they were compared with the Recaro's. I agree on the headers and exhaust as well. Having picked up the boxes with the headers and exhaust, then picking up the stock boxes, huge difference. door panels also weighed more than one would think. Weight savings is cheaper than building HP most of the time. It helps the handeling and braking more than anything in my opinion.

 

I removed everything, my wife cried (no kidding) when she saw the car completly gutted, thought I destroyed it permanently, she was very pleased when I got the new carpet in the car looks really good.

Don't know if there are any RS sound deadening underneath the carpet in general, but part from the "foam plug" there is a RS sound deadening piece available that you can install on the firewall inside the car (not using the right word here, I have a picture somewhere). I installed this piece, should I do this again I would go without it.

I only have a carpet on the passenger side, saved the front part of the that thick material on the driver side. It's a temporary solution, my plan is to make a RSR type of wooden plates instead. Unfortunatly the RSR wood plate is no longer produced and Porsche is out of stock, at least that's what my Porsche Motorsport vendor tells me (they where like $40 usd).

 

I like that...need a US source so I don't get murdered on the exchange.

RT

 

With respect, I don't think these items:
2. Lightweight flywheel - <9kg
3. Lightweight clutch assembly - 2kg
are "unsprung" weight.

I'd look at the suspension (as you have done), wheels, brakes+calipers, front hubs and rear axles for unsprung weight savings. I estimate you could lose as much as 42 kgs in unsprung weight if you went all the way.