Rhys

Right then reading another post as regards to weight of a car to its performance! Obvioiusly its going to impeed it get of the line and going a fair bit if 300kg heavier. Though how would this extra weight imposed on the fact if u accelarate from say 60-70mph upwards does it still have the same impact or does the weight become a less of a factor?

Might be a dumb question but can someone give me a good reply?

TiB

iTrader: (1)

I take it your presuming traction isnt an issue?

if it isnt an issue then power to weight is everything no matter what speed,


Lee

bud-weis

acceleration is all about power/weight ( as said above,presuming you have grip )

don't think it makes much odds on top speed mind

Rhys

Yeah thats what i thought, been seen on another post someone said cant remember who that weight doesnt come into it so much in higher speed. Maybe they meant in top speed and not acceleration.

Infact for me the weight help with traction of the line SO im proberly quicker heavier to 60 lol

Anonymous

Accleration is about power to weight at the bottom end, it becomes increasingly about power to aerodynamics as speed increases.

So if you took a car like Rods saph for example and added 300kg more, i bet it would still crack 200mph in 1.5 miles, but it would be 10mph slower at the end of a quarter.

Anonymous

Rhys, think of it this way, as you get to higher and higher speeds, a bigger percentage of the cars power is used up fighting to get the air out of the way and far less of it to accelerate the car.

So if 2 cars have the same power curve and gearing and 1 car is a little heavier but more aerodynamic, then at low speeds it will accelerate slower but at higher speeds it will acclerate more quickly.

Rhys

Yeah i get you Chip!! When i started thinking about it more i was knida knowing the outcome! I should have thought more before posting


Kinda wish i didnt fill my car up with sounds etc, but hey ho live and learn! lol

TiB

iTrader: (1)

Only if your talking in percentages. in reality it will still be faster accelerating if its lighter.

Anonymous

Real world example, 2 cars with the same tuned XE engine in them

200bhp caterham, top speed is lower than a 200bhp astra, weight is much lower though.

Off the line the caterham wins.

There is a point where they accelerate the same, then from there on in its in the astra's favour.

Anonymous

No thats not true at all.


Take a caterham with a top speed of 130mph and 200bhp
Take an astra with a top speed of 150mph and 200bhp

Do you really think that caterham will get from 120-130 quicker than the astra?

If so, you are not thinking about it enough!


Think about the amount of BHP available to accelerate each car.

Imagine the caterham needs 80% of its power to maintain than 120mph but the astra only needs 50% of its power to maintain it, due to better aerodynamics.

Even if the caterham is half the weight of the astra, the available power to accelerate with is less than half the amount (40bhp versus 100bhp) so the caterham has a worse power to weight ratio in terms of the power actually available to acceelrate it.


Not actual numbers, but not a million miles off either!

TiB

iTrader: (1)

Rhys is only talking about one car not 2 lol

You take one car and make it lighhter it will go faster

TiB

iTrader: (1)

I was refering to your quote about rods car

Anonymous

Agreed, at any speed if its the same car the accleration will be worse with more wieght, thats fooking obvious

Also the top speed will be lower with more weight, but not by a lot.
(increased friction from the tyres)

TiB

iTrader: (1)

Chip,

ever heard the expression "mountain out of a molehill"???

Anonymous

Yes mate, your mum said it to me when i got an erection

TiB

iTrader: (1)

A simple question was asked so a simple answer was all that was needed in my mind,


are you trying to take stu's essay title? he wont be best pleased you know?



Lee

89xr2

Chip, I think i'm correct in thinking i've read before that you're in the IT industry. Are you/were you a software engineer? You certainly seem to have an engineers mindset and style of writing.

TiB

iTrader: (1)

My mum likes women ha ha ha

Anonymous

Have you heard the one about "simple things please simple minds?"

Anonymous

Im a journalist

Yes mate, i have a software engineering background, originally after uni i was programming ECU's for control boxes in power stations (quite similar to automotive stuff really, watch a few inputs, trigger a few outputs etc)
My job has kind of blurred since then though and i dont ever really do any "hardcore" programming much anymore, i spend a lot of times in meetings and looking at requirements and all that crappy business stuff now

Anonymous

I think thats why she said it, i was wearing a mini skirt at the time and i think she thought it was my clit that was raising it up at the front

89xr2

Cool. You're good at making everything easy to understand, it's good for us retards

TiB

iTrader: (1)

No mate... enlighten me please?

TiB

iTrader: (1)

Easy mistake to make

Anonymous

If i do, will you accelerate quicker?

Anonymous

TiB

iTrader: (1)

By jove i think he's got it folks,

Welcome to the post that the rest of us have been replying to pal

Stavros

Agree totally with Chip.

Once you up to big speeds (well, over 100mph anyhow) weight is a much smaller percentage of it.

Anonymous

Me too, ive just been giving other detail too about the way it effects it because i know Rhys well enough to know that his mind will be interested beyond the original question, so i was being pre-emptive with the questions he would have asked if someone just said "yes it will"

TiB

iTrader: (1)

Oh no, here we go again


Better still... Rhys. can you please change the post name to "Discussion about power to weight and aerodynamics" please ??


Lee

Anonymous

Its a dicussion forum, why on earth would you be using it if you dont like things discussed?

TiB

iTrader: (1)

Fair enough, discuss away.....


i dont see the relevance of discussing something that hasn't been asked on this post. if you want to babble on to your hearts content (which you are entitled to do so as it is a discussion forum ) start a post up and help everyone out by making them become one step closer to being as knollegable as yourself


The question that has been asked is about adding or taking away weight and the effects that has on a car, it still takes X amount of power to move X amount of weight, it then takes more power to move a certain weight at higher speeds due to air resistance, therefore what you said at the begining is only correct if talking in percentages etc???


Do you still not agree?

Anonymous

Im not entirely sure what you think im disagreeing with?

If you mean do i disagree that the same car with less wieght will accelerate quicker at any speed then no i dont, as i said an hour ago:

TiB

iTrader: (1)

?????

Anonymous

Tib, that was before we cleared up the confusion over wether it was the same car or wether there were aerodynamic differences too, as above if its the same car and hence all other things are equal then yes my statement is incorrect as mentioned in loads of replies since we cleared that up.

Anonymous

I think theory & reality part company when talking acceleration, The theory says lose weight & shorten gearing, but I prefer to add ‘ within available grip’.
Have stripped mine & use 15” wheels & it went nowhere fast only lots of wheelspin.
Add interior, spare wheel, full tank of Petrol & 19” & 0-100 6.8 so much for theory.

Power & gearing all that counts on Topspeed + good brakes & Big Balls.
Rod

andre_k

iTrader: (2)

STFU TiB and let chip enlighten us!




if this forum was full of yes and no answers, it would be shite!

Anonymous

Andrek, TiB was just trying to clarify a point that i had wrong as i slightly misunderstood the question. (ie thinking it was about 2 different cars not one that lost 300kg, as obviously thats not something that happens very often for a road car!)
His point about weight always effecting acceleration is perfectly correct (although obviously a small part of the picture as a whole)