FVD bar saves 12 lbs,and it isn’t that crazy expensive.
but what about just removing? It’s only a 5 mph impact bar....

 

That's kind of a personal risk tolerance question. On my first 996TT I did remove the much heavier rear bumper beam altogether at the point of doing some exhaust work, and I didn't have any mishaps. But I couldn't shake the thought of what would happen if I was rear ended and had no impact beam there...meaning I kept wondering how it would work out for me. I haven't removed any since as I feel like it is too much unnecessary risk from my point of view. I can see doing a replacement aftermarket beam and being better with that, even though I know from the insurance point of view it's probably similar to no beam at all.

 

As some have already said you need to think about your endpoint. I went through this exercise with my first track car and you end up with a super expensive track car that is worth way less than what you started with. You had better enjoy it. You are much better off buying a race car (a cup car would be sweet) than going to the bitter end with a street car. If you are building your car to comply with a racing spec then that is great but they usually have a minimum weight anyway that probably isn't going to be much affected by 1-off carbon pieces. I'm not saying don't do it - I did and I ended up with a very fast 944T that can outpace a prepped stock 997 GT3 but I could've purchased something like a 996 Cup for what I have into it and it for sure can't hold a candle to a 996 (or later) Cup or a Cayman GT4 clubsport.

Lexan windows are very light, and they always look dirty or cheap and they scratch easily and get hazy with extended UV exposure - basically it totally sucks, but its light, and it is less likely to break into dangerous sharp pieces. So it's fine for a track-only car. I'm guessing the factory rear window on the RS cars is higher quality somehow, I haven't had the pleasure of seeing those.

 

Unsprung weight question,So I am looking at a brake system that includes rotors hats and calipers that says it will save me about 5 pounds of unsprung weight per corner call it 20 lbs of unsprung weight .I have heard all kinds of comparisons between unsprung and sprung weight ranging from 1 pound of unsprung weight is equivalent to 4 pounds of sprung weight on up to it is like saving 16 pounds of sprung weight.Any one who can help with quantifying this comparison more accurately?TIA HOM

 

The 3-4:1 ratio is for rotating mass (mainly unsprung in a car) vs sprung. However, suspension adjustments will most likely be required if enough weight (unsprung or sprung) is reduced.

This is why wheels, tires, and brakes are so crucial to a car's performance. Most people don't appreciate what a positive impact a set of lightweight wheels, tires, and rotors will do to a vehicle's performance. Keep in mind, crankshaft, axles, LSD internals, clutch kit, and others are also rotating mass.

Either way, weight is the enemy of performance.

 

Is it fair to say then that non rotating unsprung weight reduction (like a caliper ) has a lower than 4 multiple or perhaps no multiple just the same as reducing sprung weight?

 

AFAIK, unsprung (non-rotational) and sprung weight are considered the same, although as I stated, I recommend compression and rebound adjustments if enough of the unsprung weight value has changed.

Also, keep in mind when discussing rotational weight; mass further away from the center stores more energy. Which is why race cars continue to use the smallest diameter wheel possible. It's partly why I run 18s on my 997.1GT3RS with lightweight, forged aluminum wheels, and ceramic rotors. The bigger wheels typically mean higher weight and they move this weight further away from the center; dually detrimental from an inertia perspective. This principle should also be followed when designing the wheel itself; the more one can place the weight towards the center, the better. Which is why I've never understood individuals who spend money on adding horsepower, and trying to reduct weight on their vehicles and yet not wanting to change their wheels and rotors for something lighter.

Remember, reducing any weight is good, sprung or otherwise, but reducing rotating mass will have the greatest impact.

 

So then reasonable to assume that replacing rotors and calipers (already using 18” wheels)is a reasonable way to reduce unsprung weight and a reduction of 20 lbs of unsprung weight would yield results similar to reducing about 80lbs of sprung weight?😃

 

Well not exactly. Remember the caliper is not rotating mass.

 

Recently looked into weight savings myself. Robert Linton has a very interesting thread in the 991 3 sub forum regarding 911 R Weight reduction. It's a fascinating read, and I asked him about the 1:3 or 4 ratios I often hear. His response is below. As you can see, he suggests far more conservative ratios than a lot of people use.
https://rennlist.com/forums/991-gt3-...reduction.html

 

I hate the sunnroof, as I'm tall (6'5") and with a helmet it's tight.

From an old thread, a user named NorthVan - he stated it was a 45 pound weight loss. He states he didn't use a CF roof as he only had a half cage.

45 pounds off the top of the car is a pretty awesome weight delete.


https://rennlist.com/forums/997-gt2-...-complete.html

 

45 lbs is a significantly incorrect number. The actual savings is right at 26lbs, give or take a few ounces.

 

Remember reading that thread. Do you remember rough cost you paid? Feel free to pm

 

Do you feel the 45 pound number might be more accurate for a steel/sunroof car to be converted to a carbon roof? Do we know how much the steel roof skin weighs compared to aftermarket carbon roof skin?

 

The OEM roof skin was about $450, OEM windshield $500, used "like new" OEM headliner $500, misc interior pieces $50, labor $1500. All in about $3000 some 8 year ago. Front and rear window has to come out, the rear one is reinstalled. The headliner is the most expensive if you have to buy new from dealer. 8 year ago it was $2k, would hate to see the price now.