Colin Chapman, that revered saint of minimalism, famously said “To add speed, add lightness.” Needless to say, his words have become a mantra of sorts for track enthusiasts everywhere. Lowering curb weight is one of the ways to improve acceleration and cornering ability. It is a key area of focus for enhancing our cars’ performance on track. Proof of how well a lightweight setup can work in real life is the Honda S2000 CR (Club Racer) which deletes the soft top entirely and even has a trim that deletes air conditioning and the radio for those seeking a purer track experience.
It’s all simple physics really. A lower mass needs less power to accelerate and a lighter curb weight puts less stress on the tire thus resulting in a higher cornering speed limit for the tire. Braking performance and longevity of pads and rotors will also improve as the braking components are not as loaded by a lower mass. Fuel efficiency, while not quite in the Prius league, will also see some improvement.
Let us now look separately into the various areas where weight reduction can be done beginning with unsprung weight, or the weight not supported by the springs of the car. This includes wheels, suspension and tires. I picked Enkei RPF1 rims to replace my stock rims not only as they had the offsets I was looking for, but also for the 5.5 kg (12.12 lbs) of weight savings they provided. Changing to a set of aftermarket coilovers by Tein to improve handling also helped shave approximately 8 kg (17.6 lbs).
Significant weight savings can also be realized from shaving weight from the interior and exterior parts of the car. The boot (trunk) trim, tools and spare tire can be removed for weight savings of close to 15 kg (33 lbs). Installing a racing seat serves a dual purpose of both providing proper support for the driver while also reducing curb weight. One could approximately save a total of 9 kg (19.8 lbs) by installing racing seats for both the driver and passenger. A picture of the Recaro Profi SPG that I’ve chosen for my ride is below.
A Mugen FRP hardtop or the factory hardtop might weigh more than 20 kg (44 lbs), but when coupled with removal of the soft top (including the motors), might actually net you a 10 kg (22 lbs) overall weight loss. Should your budget permit and if your car is primarily driven on track (as mine is), buying lightweight carbon fiber parts such as doors and fenders will also contribute towards shaving more weight off your car.
Installing aftermarket parts connected to your engine and transmission can also lead to a lower curb weight. A good example would be carbon intakes from companies like J’s Racing or Password JDM which can save up to 2.5 kg (5.5 lbs) over the stock air box. Even larger gains come from the exhaust system where a J’s Racing exhaust manifold, J’s Racing titanium dual exhaust and Invidia test pipe could possibly drop 5.5 kg (12.1 lbs), 17.5 kg (38.6 lbs) and 2.5 kg (5.5 lbs) respectively for a total of 25.5 kg (56.2 lbs).
The mass that is rotated by the crank is a critical weight impacting engine response and the AP1 flywheel is a good 4.5 kg (9.9 lbs) lighter than the stock AP2 flywheel although, should your budget permit, you could find aftermarket flywheels from companies such as Toda which save up to 5-6 kg (11-13.2 lbs). Finally, while often overlooked for weight reduction, an aftermarket replacement battery such as one from Odyssey, could save up to 4.5 kg (9.9 lbs).
I must state that the numbers quoted above are approximates, as it was practically not possible for me to weigh each item individually. I recently sent my car to be weighed on a scale at a scrapyard and the display read 1,180 kg (2,601 lbs) with a quarter tank of petrol. The relatively large rounding error of that scale means that my car could be anywhere from 1,176 kg (2,592.6 lbs) to 1,184 kg (2,610.3 lbs). I compared the measured weight from the scrapyard scale to a spreadsheet I compiled to tally up the loss of weight from each part that also included the added weight of other modifications such as the GT wing I installed and found I was not too far off the mark. I have plans though to weigh my car on corner scales some time in the near future in order to get more accurate numbers.
Since alignment settings and even tire pressure settings are dependent on the weight of the driver combined with the car, I have embarked upon the all-important driver mod to lose weight and improve my personal fitness. I fully expect that a lighter me will be able to more fully realize the performance gains that weight reduction bestows and keep reciting the Chapman mantra as I go about my daily life. How about you? Do you see any on-track benefit from lowered weight? Will you be one of those S2000 drivers joining me on this drive to add lightness?
Images courtesy of Krazik and C32b
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on Sep 19th, 2011 at 5:46 pm
could you inform us on the total of money you spent on your way to this amazing resulting weight? as soon as I got the car removing as much weight as possible was my priority but after spending about a third of what I paid for the entire car I’ve only managed to get rid of about 15-20kgs
on Sep 19th, 2011 at 6:47 pm
@Stefanos: Maybe you could share with us what you spent on? The total cost of all brand new parts is approx 12-14k USD although I got some parts 2nd hand and my titanium exhaust thrown in as part of my new car purchase from my dealer.
on Sep 19th, 2011 at 10:29 pm
that aint weight loss
I have no windshield wipers, no rear view, no softop motors, no airbags, no heater, no dash vents even, super light brakes tiny battery ect ect ect
on Sep 20th, 2011 at 5:05 am
Nice write up! About 200 lbs. of weight savings there, by my calcuations. A medium-large man in the passenger’s seat makes you only AS heavy as my S.
I’d hate to give up the practicality of a stock height car (speed bumps) or the subtle styling that would be corrupted so badly by an enormous wing like that.
I’m no purist, one can tell. Haha.
on Sep 20th, 2011 at 2:16 pm
I shall join thee on thy journey of lightness. . . once I get enough money of course :-/
on Sep 20th, 2011 at 4:52 pm
For some perspective, I only paid about $24k for my car. We’re talking about half the cost of my car just to drop 200lb? While I completely agree with “Add lightness” or “weight is the enemy” it seems that $12,000 could be better spent in other areas, such as increasing horse power, bigger (and lighter) brakes, etc etc. Of course some of your mods do increase performance in more ways than just lightness, but dayum!
Good article though. I think many people don’t realize just how much weight really is the enemy.
on Sep 20th, 2011 at 4:59 pm
I’ve been on the journey for a little while. I’ve deleted the soft top, RPF1′s, full exhaust (on the way), and coilovers. Steering wheel is also on the way, not that it helps, but it’s a start as I plan to get a roll bar, seat, harness, then consider gutting (it’s a good debate between keeping it streetable or going full race. I’m glad it’s not my dd, and paid off!
on Sep 20th, 2011 at 5:22 pm
@ Samir: Dont have an eye for aesthetics, just went with what works heh.
@Andy: $$ is always the concern which is why i’m pretty much done with modifications.
@habitforming: slightly different perspective since where i am in Singapore, a brand new S cost me about 100k USD (-_-”). The power adding parts I got are just about all that are legal, so I’ve kind of reached the ceiling to keep the car street legal. Didn’t really wanna go SC/TC since the local climate is very hot and I don’t want to start running into reliability issues.
@Cody Red: You are lucky over where you are that cars can be paid off quickly as they cost way too much in my country.
on Sep 20th, 2011 at 6:44 pm
@c32b: ok that makes a very large difference, then!
on Sep 20th, 2011 at 7:54 pm
why not go on a diet? I would assume most have some weight to shed haha
on Sep 22nd, 2011 at 5:19 pm
@Thriceover: I am doing exactly that together with daily exercise, sometimes twice daily.