Lightweight Battery & Other weight saving ideas...

A

alexman

Member
Ok, so performance exhaust (in the case of RPI back boxes are much lighter), changing seats for recaros etc (lighter than stock again), genuine CSLs and lightweight battery are weight saving options. Any other good ideas?

Also, what battery have people gone for as a lightweight alternative and was there actually much of a weight saving?
 
Ok so with all this weight saving what performance improvements do you hope to achieve - £ cost per 1 bhp improvement would be interesting.
 
Alexman, are you planning to race the car? I don't see what you would hope to gain by saving a little weight. Wouldn't you be better fitting better springs/shocks and maybe brakes if you want to improve track performance?
 
paddy wright said:
for real life use and performance what gains will you really see?
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Always a trade off between money/performance and the gains for our cars are generally minor. Having said that, why mod the cars at all? Buy a supercar and be done with it. The enjoyment that I get from the car comes from driving it and working on it, in just about equal parts. When it comes time for a new battery, I will change out to something lighter and maybe smaller. There will be a slight increase in cost over a oe/equivalent battery, but the return in the enjoyment of researching and then having something different is sufficient justification for me. Will saving 5 to 10 lbs of weight make a difference on the street? Not really. Better gas mileage or acceleration? Not that anyone will ever notice. It's just one of those things that makes some of us happy.
 
I swapped out to a Hawker battery. Halved the weight and size which compensated or the increase in weight of a quad exhaust system. Primary reason was to allow me to cut down the battery box size.

Worked perfectly on a 3.0i auto for well over a year.
 
alexman said:
Ok, so performance exhaust (in the case of RPI back boxes are much lighter), changing seats for recaros etc (lighter than stock again), genuine CSLs and lightweight battery are weight saving options. Any other good ideas?
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Go on a diet? :)
 
Big thread this but you might find it interesting. The guy installs one of those tiny batteries too (among other things). http://www.bimmerfest.com/forums/showthread.php?t=185835
 
All arguments about exponential cost per incremental gain in power/weight ratio aside... I have to admit to an interest in this topic.

Assuming like for like comparison (and apols if this has been done before) Z4MC kerb weight in Europe is quoted as 1495Kg versus 1395Kg for the Z4C 3.0Si isn't it?

Obviously the cast iron block and the additional muffler don't help but is the difference really 100Kg? I appreciate that other individual heavy items where there may be differences between the two cars (gearbox, diff) may play a role too, but...

Oh, and I manage to keep myself down to around 70Kg on a good day so not much more to come off me. :wink:
 
ga41 said:
Big thread this but you might find it interesting. The guy installs one of those tiny batteries too (among other things). http://www.bimmerfest.com/forums/showthread.php?t=185835
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That is the best Z4 thread I have read so far. :thumbsup:

Only took 4 hours too! - Although I only understood about 1/3 of what was said, I still found it interesting :D
 
Pulled this up from my notes on a discussion from another BMW forum. A common replacement battery for three series cars are those from the Mini-Cooper. The thread compared the oe Mini batteries to the oe CSL batteries and they appeared to be identical in all aspects. The Mini/CSL battery runs approximately 15 lbs less then the oe Z4 battery (some variation due to brand differences) and price is in line with a standard replacement.
 
Scouse Tony's easy weight saving tips:
  • Use some laxitive and spend an hour on the loo - saving 1/2kg
  • Drive in socks (seelskin are good as they're thicker than normal socks & waterproof) or barefeet - saving 1/2kg
  • Burn your tyres out until you've only got 2mm of tread (still legal) and ridding yourself of 6mm of rubber - saving 1/2kg (of important unsprung mass)
  • Remove standard aerial & replace with stubby - saving 0.1kg
  • Ensure petrol tank is never full - saving 750g per litre
  • Remove junk (CDs, wallets, carpets, MP3 players, sat navs, passengers, passenger seat, battery cover, boot floor cover - saving 5-10kg

Total saving of upto 20kg for very little cost

BTW, the CSL battery is a 55ah battery, ours is a 70ah battery (the Mini uses everything from 46ah to 70ah depending on spec & model) - although the CSL battery is about half the price too.
 
AlanJ said:
Ok so with all this weight saving what performance improvements do you hope to achieve - £ cost per 1 bhp improvement would be interesting.
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^+1
In addition where is the weight being removed from.
If it's not coming off the front axle, what's the point.
 
Just get yourself a set of light weight wheels.. My new wheels weight 16kg or c35lb less than stock - i'm also lead to believe that for every kg of unsprung weight saved this converts to x 4 of weight elsewhere. If this is true, then it converts to about 64kg :driving:
 
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