Ima2nr

ok, I know the easiest mod is:



1) take out the spare tire

2) racing seats?

3) carbon sunroof panel insert?

4) aluminum doors /bonnet? (where can I buy these)?

5) driver go on a diet?

6) remove rear seat backs?

7) remove front drive shaft / front gear box?

8)

9)

10)

please add to/ modify my list....

AVoyvoda

Realistic weight savings (road). Weight in lbs, * = unsprung weight

Replace front seats for buckets 60
Remove sunroof 44
Remove engine undertray 14
Replace windshield washer tank for smaller 15
Delete aircon and coolant 47 plus 3 hp
LW clutch and flywheel 13+
* Replace wheels for lighter 25+
Delete rear seats, rear shelf, replace door panels with RS 54
Delete front drive shaft, gear box 100+
CF hood 33
Light weight battery 20+
Remove interior sound proofing, up to 68
Delete power steering 22 plus 3 hp
Alu doors incl col. bar, delete power windows 40
Replace front wings with cf 25
Light weight exhaust 20+

Minimum weight - race - including full tank and all fluids: 2225 lbs (stripped out, cf body parts etc)
Minimum realistic weight - road - 2,600 for na
Minimum realistic weight - road - 2,700 for turbo

Removing spare is un-wise, as its included in front crash structure of the car.

Overall aim is to remove weight from the back rather than the front. CF hood, light weight battery, front drive shaft removal etc will do the opposite and you may end-up with a nose-light car that's lost its overall balance. Also a car that's no longer comfortable to drive (too noisy, hot, no rear seats etc). Removing components needs careful thought.

Personally, I'd get the best wheels, brakes, tires and suspension I could afford, to increase my driving pleasure and not worry too much about the rest. 993 tts were never built to be light weight.

TB993tt

So what happens when you have to drive the car with the space saver on, does one have a "compromised" crash structure, how did this get past the safety authorities ?Does it really make a difference? Porsche turbos were rear wheel drive for 20 years before 4WD came out, and the GT2 handles OK

AVoyvoda

It's the space saver that's part of the crash structure. In case you are wondering if this is just folklore (as I did) checked frontal crashed 964/993s with a large repairer in Germany. Cars with the space saver in place sustain far less damage than without.

"Porsche turbos were rear wheel drive for 20 years before 4WD came out, and the GT2 handles OK"

You are right, of course. My point was that these cars were designed for approx. 40/60 front/rear weight distribution. The "easy" weight savings are in the front. One should try and maintain the 40/60 ratio by saving weight at both ends.

TB993tt

Is'nt this a little bit more complicated than this ?

If its part of the crash structure then Porsche was allowed to sell a car (for many many years) which when fitted with the space saver had an unsafe crash structure ?

Does "sustaining less damage" mean less deformation and higher Gs/risk of injury for occupants -is there any data on this ?

I could never draw a proper conclusion on this, I suspect when Porsche first put the spare in there, noone thought very much (relative to today) about its affect on the "crash structure" - it stayed there 'til '98 and Porsche just kept quiet about it until they designed the newer "safer" (probably) front end of the 996 series.

AVoyvoda

I think it has a lot to do with front impact crash testing that was introduced in the late 80s at the time the 964 was launched. Since 964/993 chassis are identical, my best guess is that Porsche retained the spare as a crash feature until the 996, which was a completely different design.

Does "sustaining less damage" mean less deformation? Exactly. Was told (by the German repairer, a large operation specialising in crashed 911s) that the deformation in the front is much deeper without the spare. His strong recommendation was "do NOT remove". Why risk your health for a few pounds less weight?

TB993tt

But is the "deeper deformation" more hazardess to the occupants or did it absorb more of the impact ?
Would a repairer know ?
Could it be that Porsche had no where else to put the space saver regardless of its role in the crash structure ?
It would be great to get an inside line on this one - as your list above points out, the 12kg saved by no spare is a simple saving compared to some of the other areas.

Red9

Sorry to get back to the topic buuut!
Doors-- Carbon Fibre ( alum extraordinary cost and rare) - can have all internals fitted or delete
Front Guards -- C/F or F/Glass
Bonnet -- " "
Front and rear bars -- not much weight saving buy some possible with C/F
Tail-- a lot of weight in tail - go to GT2 in C/F
Go 2 W/D as per Gt2 -- saves a lump of weight
Glass-- RS /GT2 L/weight or plastic
Sunroof and all components( how far did you want to go??)
Removing many components that are only necessary to create comfort will save a lot of weight.For example -I have 993 GT2 track car down to 1095KGS( 2409 pounds) and think it would be very little more to be saved as there is nothing in that car to save( maybe 20 KGS (44 pounds) if you went fanatical . I am currently finishing a 993 Turbo to GT2 look and spec that still has road going comfort levels( A/C etc) but paying some attention to weight saving so will have a weight number soon.

TB993tt

Spare in or out

Jean

This is a very interesting subject indeed. Avoyvoda has done his homework over the past 2 years in the pursuit of the ultimate lightweight setup. He even got aluminum doors at a modest price

Just one thing I would like to pinpoint and that is concerning the rear weight bias, contrary to what I usually read, it is not a really a good idea, there is much more to it. One of the strongest points in Porsche handling on the track and especially excellent braking is exactly is rear weight bias, not really the brake calipers. Upon braking (nose diving), the further back the center of gravity and mass is, the better the car will brake. Complex vehicle dynamics are involved as to why the rear biased weight is better, I can recommend some interesting reading on the subject.

As far as over vs under steer and the weight bias impact on that, the impact can be very easily corrected with the right suspension setups.

Acropora

https://rennlist.com/forums/showthre...ghlight=weight
Weighed the stock mufflers vs light b&b ones= 15lb difference total
Stock exhaust vs fabspeed cat bypasses= 15lb diff total
Have still yet to take a driving course...=best bang for buck
Recommend Viperbob's 2wd conversion kit... 100lb diff and IME best mod after new shocks.

Jean

4 993TTs with 2WD conversions on this thread alone, does that tell you something?

AVoyvoda

The real issue is: at what point should you stop?

Deleting: Aircon, sunroof, air-bags, power steering, power windows, rear wiper, soundproofing, radio, engine insulation, windshield wash, under-seal, spare tire, 4wd for 2wd, comfort seats etc and,
Replacing: Cf body parts including doors, hood and rear deck; cf bumper bars, lw exhaust, lw clutch and flywheel, plastic windows, sequential trany, huge tires, monoballs, steering arms, floating disks, bigger turbos, 3.8 cylinders, intercooler, light weight wheels, lw battery, MOTEC, traction control etc

All of the above will get you a lighter and much faster car. But you pay a price in terms of safety in some cases, and comfort in others.

Key is knowing exactly what you want (fast road car, semi-racer, out and out racecar) and modifying accordingly.

Geoffrey

I read recently that the new Champ car has a 40/60 weight distribution which they consider ideal. It is the fact that most of the mass in a 911 is located at the end of the car that it becomes an issue. I think people confuse the two.

TB993tt

I fired an email off to Germany to the boys I know and trust, who are amongst the most experienced in the racing scene for 993 based cars.

Here is the typical Germanic reply:

You can remove the spare wheel.It is not a part of the crash structure!