Striker got weighed today, 600K, lardarse

[David]

John

As you'll remember from your physics, Newton postulated p=ma (force equal to mass x acceleration). That can be restated as a=p/m.
If we (only slightly rashly) assume that you'll get the same amount of force applied through the rear wheels of a car that is 25kg lighter, and we also assume that the car we wish to lighten weighs 625kg with driver at present, then existing acceleration is going to be p/625 and the new acceleration is p/600. Resolving those fractions shows you that your new acceleration will be 4% faster than before you lost the lard.

To answer your question, I think you'd notice it on track (out of every corner), but I doubt you'd notice on the road because you very rarely can use the full capabilities of your car. However, since when did boring logic inhibit upgrade-itis?

David

[The Knobs]

Just weighed one of my wheels and tyres, 17 kilos each. So if i go the 13" route with lighter front upright and brake set up, that should give quite a reduction. I would like to get down below 550 if possible but without spending the cost of an R500 in the process Will have to give Mel a ring to see what the price of the list of bits i would need.

Is it a straightforward job fitting rose joints to the rear wishbones ? Some pictures of a before and after would be handy if anyone has any.

[Werner Van Loock]

Just weighed mine and the 5,5x13 minilites with yoko's A048 185/60-13 weigh in at 13kg
The compomotive 6x13 with the same tires 13,5kg

So that's a possible saving of 4kg/corner of weight that's doesn't only reduce overall weight, but also unsprung weight and rotational mass!!!

So going from 13" to 15" and reducing flywheel weight has a reverse effect

Maybe that's also something you can do, don't know wich lump you have, but a lighter flywheel is also rotational mass and overall weight reduction.

As my engine will be in bits in the next couple of weeks I'm planning to get a lighter flywheel fitted.

[The Knobs]

I have an aluminium flywheel fitted so thats one good thing. I will also be ditching the Weber throttle bodies in favour of some Jenvey ones as well as a bit more head work, so i will weigh the swarf taken out when porting

The car goes very well as it is, but another 20bhp and 30 + kilos lighter makes a huge differance to power to weight ratio, and as you say the all important unsprung weight loss. Hopefully go from 300bhp/ton to 350+ by next year.

Its bordering on obsession already.

[Strikerxe]

John

As you'll remember from your physics, Newton postulated p=ma (force equal to mass x acceleration). That can be restated as a=p/m.
If we (only slightly rashly) assume that you'll get the same amount of force applied through the rear wheels of a car that is 25kg lighter, and we also assume that the car we wish to lighten weighs 625kg with driver at present, then existing acceleration is going to be p/625 and the new acceleration is p/600. Resolving those fractions shows you that your new acceleration will be 4% faster than before you lost the lard.

To answer your question, I think you'd notice it on track (out of every corner), but I doubt you'd notice on the road because you very rarely can use the full capabilities of your car. However, since when did boring logic inhibit upgrade-itis?

David

David

Its a long time since I did physics . I understand you maths but is that not over simplifying things ? What about the effect of drag ? Would a car with say 400bhp/ton that weighed 500kg accelarate faster, slower or at the same rate as one with the same 400bhp/ton but weighed 1000kg ? Surely there must be a speed where more power is more benificial than less weight for acceleration ? Our cars are pretty un aerodynamic so that speed could be quite low Not trying to be picky just trying to justify more power I've no upgrades planned for this winter yet

Having said all that I understand that the weight that has been accelerated has also got to be stopped as well as go round corners so yes less weight is better .

You're right I'm sure I wouldn't notice a 4% increase in performance on the road , I'm not sure I'd notice it on a track either to be honest

Does you car get double driven by drivers of different weights ? Just wondered if there was a measurable difference in times that was the same as the difference in weights ? ( if only life was that simple )

John

[The Knobs]

What sort of battery is the best to go for, and the best place to buy one ?

[petercoll]

I have recently fitted an Odyssey PC680. It is a lot lighter amd smaller than a standard car battery, and very happily turns my crossflow over.

Will try and remember where I bought it from.

Pete

What sort of battery is the best to go for, and the best place to buy one ?

[petercoll]

Here you go:

http://www.tayna.co.uk/ODYSSEY-PC680-P3107.html

Pete

[The Knobs]

Cheers

Let the weightloss commence

[David]

Does you car get double driven by drivers of different weights ? Just wondered if there was a measurable difference in times that was the same as the difference in weights ? ( if only life was that simple )

John

John

Chris is around 17kg heavier than I am. Over the season, we have been about evenly matched on lap times. He beat me by a few tenths at Croft and murdered me at Hethel (he's just braver ), I beat him by a few tenths at Curborough and Llandow, and we shared the honours (one all) at MIRA. However, whilst he may be braver (or more skillful), the data-logging is unequivocal: I get out of the corners faster.