[B58 _gran_coupe_]

I drive an f36 and she's a heavy girl in corners.

Wondering if anyone has done any weight reduction projects with their F series and what they have managed to pull out.

Wouldn't go as far as rear seats or anything but maybe a CF hood and wheels.

Anyone done a similar exercise?

Is the juice worth the squeeze?

[dangerus_car]

A CF hood wouldn’t help you in cornering as it only save a bit. Try to retrofit f80 carbon roof first. Then carbon fiber trunk.

[Nickski06]

I just swapped my stock 400m wheels with A/S 3 runflats for a set of Apex wheels and Pilot Sport 4S tires. They were right at 8.5 lbs lighter each.

[toxik]

if you had an f30, i bet replacing the roof with an m3 carbon roof would make a difference since the sunroof is so heavy. lower your center a gravity. don’t think f36 has same shape roof.

[B58 _gran_coupe_]

Originally Posted by Nickski06

I just swapped my stock 400m wheels with A/S 3 runflats for a set of Apex wheels and Pilot Sport 4S tires. They were right at 8.5 lbs lighter each.

That's a big saving of unsprung weight. Did you feel.a difference in responsiveness with the lighter setup?

[freakystyly]

A lightweight battery would be good for 30lbs or so. Likely much cheaper than bodywork too.

Wheels are typically the best way to go tho. Even going from heavy winter tires to summers is very noticable (not applicable to you lol).

[Tommo3]

I find it funny that I wanted to fit an extra fuel tank in my car and all I got was ridicule on here.
Now along comes someone who wants to make his 1500kg lighter because it feels heavy. You would need to lose 400+ kgs to feel any difference. Try putting a 90 kg passenger in the car with a full fuel tank (about 40kgs) and see if you can feel the difference with that extra 130kgs. If you tell the truth rather than pretend that you are a superhero, then you won't feel the difference.
If you could lose 130kgs out of the standard car, then that will probably cost you the price of the car in Carbon and Titanium, and you still wont feel it.
Sell the car and buy yourself a BMW made F56 Mini JCW with well over 200 bhp, it make much more sense.

[Nickski06]

Originally Posted by B58 _gran_coupe_

That's a big saving of unsprung weight. Did you feel.a difference in responsiveness with the lighter setup?

Nope, but they look nice

I'm not a professional racecar driver testing and tuning to shave 1/10ths off of lap times. I'm not going to notice a less than 1% weight reduction. I only weighed them because as I was swapping them it was pretty noticeable how much lighter they were and I had a scale near by.

[Nickski06]

I added a strut tower brace too because the guy that sold me the wheels gave it to me. I didn't notice a thing adding that either

[johnung]

Originally Posted by B58 _gran_coupe_

That's a big saving of unsprung weight. Did you feel.a difference in responsiveness with the lighter setup?

It’s not just that it’s unsprung weight. More importantly it is a reduction in inertial weight. That increases horsepower, acceleration, improves braking, improves suspension, turn-in and even increases fuel economy.

The new APEX VS-5RS 18x8.5” ET40 square setup is super strong Forged and only 17.2 lbs compared to BMW 400M at 26.0 lbs. Even with a larger 255/40-18 tire you can save more weight over 225/45 runflats, about 10 lbs which you will absolutely notice. It can cut 1/2 second off 0-60 times.

You can also save 3.0 more pounds of inertial mass in each front wheel in you have 340mm or 370mm rotors, and you upgrade to Paragon full floating front rotors. (I’d request full crossdrilled like BMW puts on M2/M3/M4. See link

.https://paragonbrakes.com/2-piece-ro...e-m-sport.html

See post below for more details..

https://f30.bimmerpost.com/forums/sh....php?t=1996601

[B58 _gran_coupe_]

Originally Posted by Tommo3

I find it funny that I wanted to fit an extra fuel tank in my car and all I got was ridicule on here.
Now along comes someone who wants to make his 1500kg lighter because it feels heavy. You would need to lose 400+ kgs to feel any difference. Try putting a 90 kg passenger in the car with a full fuel tank (about 40kgs) and see if you can feel the difference with that extra 130kgs. If you tell the truth rather than pretend that you are a superhero, then you won't feel the difference.
If you could lose 130kgs out of the standard car, then that will probably cost you the price of the car in Carbon and Titanium, and you still wont feel it.
Sell the car and buy yourself a BMW made F56 Mini JCW with well over 200 bhp, it make much more sense.

This is a car forum for talking about mostly dumb car stuff. Don't be a cry baby, that's what Facebook is for.

[B58 _gran_coupe_]

Originally Posted by johnung

It’s not just that it’s unsprung weight. More importantly it is a reduction in inertial weight. That increases horsepower, acceleration, improves braking, improves suspension, turn-in and even increases fuel economy.

The new APEX VS-5RS 18x8.5” ET40 square setup is super strong Forged and only 17.2 lbs compared to BMW 400M at 26.0 lbs. Even with a larger 255/40-18 tire you can save more weight over 225/45 runflats, about 10 lbs which you will absolutely notice. It can cut 1/2 second off 0-60 times.

You can also save 3.0 more pounds of inertial mass in each front wheel in you have 340mm or 370mm rotors, and you upgrade to Paragon full floating front rotors. (I’d request full crossdrilled like BMW puts on M2/M3/M4. See link

.https://paragonbrakes.com/2-piece-ro...e-m-sport.html

See post below for more details..

https://f30.bimmerpost.com/forums/sh....php?t=1996601

Thanks, this is very interesting stuff.

My friend has a 340i with similar mods. I want to be more competitive against him.mainly.

I think they are circa 240lb lighter

[cfm56d7b]

Originally Posted by B58 _gran_coupe_

I drive an f36 and she's a heavy girl in corners.

Wondering if anyone has done any weight reduction projects with their F series and what they have managed to pull out.

Wouldn't go as far as rear seats or anything but maybe a CF hood and wheels.

Anyone done a similar exercise?

Is the juice worth the squeeze?

Other than reducing the body roll, do you have any additional and more specific goals where lower weight would be helpful?

[B58 _gran_coupe_]

Originally Posted by cfm56d7b

Other than reducing the body roll, do you have any additional and more specific goals where lower weight would be helpful?

Yes. Essentially getting closer to 340i RWD weight so I can be more competitive with my friends car which is similarly specced

[Tommo3]

Originally Posted by johnung

It’s not just that it’s unsprung weight. More importantly it is a reduction in inertial weight. That increases horsepower,

That is hilarious! Horsepower is measured in Kw, that power is produced by fuel and the engines ability to convert that fuel into power. Weight cannot produce nor increase horsepower without involving gravity.

[johnung]

Originally Posted by Tommo3

That is hilarious! Horsepower is measured in Kw, that power is produced by fuel and the engines ability to convert that fuel into power. Weight cannot produce nor increase horsepower without involving gravity.

The reference that I got it from I believe was talking about horsepower measured at the wheels. If the inertial mass of the wheel is reduced significantly, whatever work the engine does now spins the wheel faster which measures on a dyno as more horsepower. On a track it might measure as a 1/2 second faster in 0-60, and even a body length in the 1/4 mile.

[cfm56d7b]

Originally Posted by B58 _gran_coupe_

Yes. Essentially getting closer to 340i RWD weight so I can be more competitive with my friends car which is similarly specced

Got it. Thx!

I suggest to consider upgrading the suspension. Coilovers will transform the suspension behavior making body roll a non-event.

[B58 _gran_coupe_]

Originally Posted by cfm56d7b

Got it. Thx!

I suggest to consider upgrading the suspension. Coilovers will transform the suspension behavior making body roll a non-event.

That's definately on the horizon. He's running B8s and H&R sport springs and if feels razor sharp. Coilovers would be nice to play with though for sure.

[Tommo3]

Originally Posted by johnung

The reference that I got it from I believe was talking about horsepower measured at the wheels. If the inertial mass of the wheel is reduced significantly, whatever work the engine does now spins the wheel faster which measures on a dyno as more horsepower. On a track it might measure as a 1/2 second faster in 0-60, and even a body length in the 1/4 mile.

So what you are saying is that weight reduction of any kind increases acceleration, I would think that we all know that. It cannot increase any horsepower though, nor can it decrease power train losses.
To quote Albert Einstein "energy can neither be created nor destroyed - only converted from one form of energy to another" wheels do not contain any energy.

[johnung]

Originally Posted by Tommo3

So what you are saying is that weight reduction of any kind increases acceleration, I would think that we all know that. It cannot increase any horsepower though, nor can it decrease power train losses.
To quote Albert Einstein "energy can neither be created nor destroyed - only converted from one form of energy to another" wheels do not contain any energy.

No, No, No. It’s not just weight reduction. And it’s not just unsprung weight reduction. It is reduction of the rotational inertial mass that the engine power has to move at each driven corner- the weight of wheels, tires (and brake rotors). You keep replying with basic high school physics. This concept is more advanced.

It’s rotational inertial mass as it relates to automotive tires, wheels (and brake rotors).

An analogy would be Tour de France bicycle and rider. With everything else identical, if he had two sets of wheels/tires to experiment. One set is the typical lightweight racing setup. The other set are heavier mountain biking wheels and tires of the same diameter. The same rider (engine) will be able to accelerate faster and be more efficient over a race with the lighter wheel/tire setup.

Anyone who has ever ridden a bike with thin lightweight wheels/tires and a bike with heavier mountain bike type tires, knows that the lightweight wheels will win a street race with ease..

The same goes for a car. I’m not saying that lighter wheels/tires (rotational inertial mass) will provide more horsepower as measured at the engine’s crankshaft. But horsepower is typically measured at the wheels on a dyno. And it’s a more realistic prediction of Street performance. If dyno tests are done with 50lb wheels/tires at each corner, and then repeated with everything the same except 40lb wheels/tires at each corner, the lighter setup test results will show more power to the wheels.

There are many articles on rotational inertial mass reduction in wheels/tire setups that claim faster observed acceleration like up to a 0.5 seconds gained in 0-60mph measurements, and a car length gain at the end of a quarter mile. It also results in increases in efficiency as measured by miles per gallon.

Hope this helps.

[charlie fairmont]

Here's a good read and a good watch.

https://www.roadandtrack.com/car-cul...ght-explained/

[B58 _gran_coupe_]

Originally Posted by charlie fairmont

Here's a good read and a good watch.

https://www.roadandtrack.com/car-cul...ght-explained/

Super interesting read and video. I built a mk1 eunos roadster turbo almost 300whp in the early 2000s and I remember everything was amplified because the car was so small and light.

Switching to lightweight and smaller wheels with that car made a big difference on the track.