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Right Lets discuss your weight.

mangogrooveworkshop - 27/12/05 at 12:37 PM

Not you who ate all the pies drank way too much beer and wine........the car.

Found this spread sheet at http://www.speedysteve.co.uk/
Steve seems to have nailed the truth with this script. It was Chapman who said for speed build lightness........so what weight saving could your car get.......wheels , dampers ,uprights, seats, yourself(lol)

quote:

Weight is the 7’s blessing and enemy.Why can we out corner, out brake and out perform all these hot hatches and performance cars?

The answer is simple...The laws of physics!

7’s weigh less therefore they go better.

A light 7 will go better than a heavy one.

The standard 7 is an excellent trade off between performance and usability. However, on average between 50 – 80 kgs can be shed and the extra performance unleashed is startling.

You can throw power at the problem but that is expensive and only gives an improvement in one aspect. You may in fact end up with a car that is more difficult to drive and only marginally quicker on a circuit.

I have produced an Excel spreadsheet of accurately taken weights to show what a difference attention to detail can make. Did you know that a Ford live axle weighs a full 5 kilo's more than its Ital equivalent?

[Edited on 27-12-05 by mangogrooveworkshop]

Volvorsport - 27/12/05 at 02:03 PM

well i guess my volvo axle is much heavier than an escort - id still never want to use an ital axle , sends shivers down my spine

Jasper - 27/12/05 at 02:13 PM

I'd rather add a few bhp to the engine than start shedding weight, I don't believe it's necessarily cheaper to shed weight than add bhp. especially as these are light cars to start with and BHP is getting much cheap.

SixedUp - 27/12/05 at 02:39 PM

Even if the extra BHP is free, heavier cars wont handle as well, because higher weight imparts more momentum, which takes more effort to overcome when you want to change direction.

Lighter really is better from the perspective of handling, though of course, its not the only thing to worry about. Back in the real world any of our cars are considered very light, so I suspect its not something to get too paranoid about

Cheers
Richard

steve_gus - 27/12/05 at 05:14 PM

just remember that the light minimalist design of Chapman gave lotus one of the highest, if not highest, rate of mortality for any F1 team. They had the first postumous F1 champ after Rindts suspension broke at Monza.

Id prefer a 50 kilo penalty on my car and reaching an old age myself...

atb

steve

[Edited on 27/12/05 by steve_gus]

chrisg - 27/12/05 at 06:52 PM

Reminds me of the famous Sevens list discussion about whether it was agood idea to drill bolts down the middle to save weight.

A fifty page thread about saving a quarter once, by men who mostly have necks like birthday cakes.

Eat less pies.

Don't take a pasenger.

Take your other keys off your key ring.

no laces in the shoes.

How far is too far?

Cheers

Chris

Mark Allanson - 27/12/05 at 06:57 PM

Going for a dump before you drive?

steve_gus - 27/12/05 at 07:01 PM

didnt shumacher not pee and dump before the season driver weigh in a few years back - at that time the driver was weighed once, pre season.

Reconed it was worth a couple kilo and 0.000001 or whatever secs per lap as he would be 'underweight' during the actual race...

atb

steve

[Edited on 27/12/05 by steve_gus]

bob - 27/12/05 at 07:15 PM

quote:
Originally posted by chrisg
Reminds me of the famous Sevens list discussion about whether it was agood idea to drill bolts down the middle to save weight.

A fifty page thread about saving a quarter once, by men who mostly have necks like birthday cakes.

Eat less pies.

Don't take a pasenger.

Take your other keys off your key ring.

no laces in the shoes.

How far is too far?

Cheers

Chris

That was well put chris,i remember the boy ison saying he lost 8 secs a lap at donighton one year with yourself as a passenger

chrisg - 27/12/05 at 07:46 PM

True.

Of course I've lost quite a bit since then.

He should have me in all the time, might stop him rearranging the scenery so much!

Actually I probably had a close shave, I once went out in the GT1 with him.

Without a seat.

or a harness.

I must have been bloody crackers.

and it took me twenty minutes to get out.

Cheers

Chris

David Jenkins - 27/12/05 at 07:47 PM

In my car, the one item that could lose a lot of weight is the nut holding the wheel!

David

steve_gus - 27/12/05 at 11:14 PM

carrying a passenger in a 'well sorted' seven has got to add about 15% in weight?

(450kg with 75kg driver = 525kg) car with a 75kg passenger - 600kg

thats gotta have an effect, even without a manly build such as chris's.

atb

steve

Mark Allanson - 27/12/05 at 11:30 PM

quote:
Originally posted by David Jenkins
In my car, the one item that could lose a lot of weight is the nut holding the wheel!

David

I agree, I weigh about 100kgs, my car weights 700kgs wet and loaded (6 gals of fuel, tool kit, etc), still drives better than a production car

Jasper - 28/12/05 at 10:22 AM

quote:
Originally posted by hicost

I was also told a few years ago 250bhp normally aspirated is as good as 400bhp turbo charged. Still never had it proven though.

I dont know if that helps?

That dosn't seem right to me given that a certain 270bhp Cosworth Duratec normally aspirated couldn't pull away from a 270ish bhp turbo Cosworth up twist hills....

smart51 - 28/12/05 at 02:34 PM

There are a few strange replies to this thread. I'm almost amused. A 100kg saving can transform a car's performance and handling but people argue about saving half an ounce by drilling bolts. Forget the half ounce and save me 100 kg.

Someone said that Colin chapman's F1 car had a higher than average mortality rate. So what, making your car lighter will make it less safe? Replacing a 2.0 DOHC engine for an R1 engine will make it less safe? Fitting solid discs insteadof vented ones? Using thinner but stronger steel can potentially increas the strength of the chassis not decreasing it.

A carefully specced seven can weight 20% less than an average one, whatever that means. Are you sure that adding 20% more power to your engine would cost any more, if building from scratch? remember that weight saving will improve the braking and cornering whereas your extra BHP won't.

Give me the weight saving any day, so long as you do it the right way without weakening the design - there's no reason why you should.

steve_gus - 28/12/05 at 08:24 PM

smart51 - when you have ponced around on lists like this for five years, you tend to see lots of whacky ideas that are intended to make the car better.

Ive seen many bollox conversations (as a poster mentioned earlier) on the TOL sites about minimalist design and weight saving.

I think id rather have a powerful torquey car like Highcost's than a skimpy weight reduced four wheeled surrogate motorbike. Id rather have the 400+ cossie HP, with a windscreen, spare wheel, and proper seats than a 170hp bike engine with a tube of puncture sealer and a plank to sit on
But thats just me.

My point about Chapman was in my insignificant view, that I wouldnt hold him to be a guru to follow when designing a road car. He made racing designs that were minimalist and likely barely safe for anything more than a few 100 miles of racing.

I once heard it extolled that chapman used a single bolt to hold three suspension assemblies together. You save two bolts, but run the risk of three simultaneous failures should one bolt fail.

atb

steve

[Edited on 28/12/05 by steve_gus]

Simon - 28/12/05 at 08:25 PM

One of my first jobs is to lighten mine (now it's SVA'd) - all the nice heavy Vinyl covered MDF can be binned and replaced with 20swg ally.

That should be good for 15 kgs

ATB

Simon

steve_gus - 28/12/05 at 08:29 PM

and 0.08 secs improvement to 60?

atb

steve

smart51 - 28/12/05 at 08:36 PM

quote:
Originally posted by steve_gus
I once heard it extolled that chapman used a single bolt to hold three suspension assemblies together. You save two bolts, but run the risk of three simultaneous failures should one bolt fail.

Exactly my point. Argueing over 50g of bolts is pointless but changing lowest cost steel chassis tubes to thin wall CDS (welded by a competent tradesman of course) can save a sizeable amount and may improve safety not reduce it.

smart51 - 28/12/05 at 08:42 PM

quote:
Originally posted by steve_gus
I think id rather have a powerful torquey car like Highcost's ... than a 170hp bike engine with a tube of puncture sealer and a plank to sit on

Fitting a bike engine instead of a car engine doesn't seem to have turned my car into a plank, with or without puncture sealer. It did save about 100kg though and that's a 100kg that hasn't made the car any less safe. And it didn't remove any suspension bolts.

By the way, rather than 0.08 sec change from 0-60, 100kg would increase my BEC's time from 3.9 sec to 4.5 sec, about a 16% improvement.

[Edited on 28-12-2005 by smart51]

zxrlocost - 28/12/05 at 11:58 PM

bike engines are better than car engines simple as

and they sound better

where do you draw the line comparing

you could carry on and mention the word Dax Rush hayabusa Turbo

Simon - 29/12/05 at 03:07 PM

quote:
Originally posted by zxrlocost
you could carry on and mention the word Dax Rush hayabusa Turbo

Yours for £30+ grand!!! Certainly not the philosophy we're working to.

I have a busa engine in my busa, and it's fantastic.

I have a R V8 in my Deimos - I got a nice torquey motor in both (relevant to their weights!!)

ATB

Simon

Jasper - 29/12/05 at 04:41 PM

quote:
Originally posted by zxrlocost
bike engines are better than car engines simple as

and they sound better

Not after 3 hours at motorway speeds they don't, they just give you a headache.....

No point getting into a car versus bike engine discussion though as we're taking about very different cars. A 150bhp lightweight bike engine car is just a totally different animal to a 250bhp powered car with full weather gear, big seats, heating etc etc. They may be the same 0-60mph, and they may well compare on the track, but they will be totally different in terms of comfort and useability, especially over long distances. It just depends on what you're build a car for.

[Edited on 29/12/05 by Jasper]

steve_gus - 29/12/05 at 05:27 PM

Jasper - did you sell your car cos you didnt like the bike engine aspect?

I had the feeling that Locodude also regretted his swap from a xflow to a bike motor....

atb

steve

Jasper - 29/12/05 at 05:33 PM

I was selling it due to not being happy with the bike engine set-up yes, but luckily for me crashed it into a tree and got a good few extra £££ from the insurance and selling off the rest on Ebay.

Anyway, yes, I found the BEC excellent on track and good on local country roads, but I then realise I wanted a sports car for much more than that. I wanted to be able to do long distance rallies (GOME) and drive it regularly long distances through Europe and a BEC is not ideal for this. Hence this time building a car with more weather protection and powerful car engine.

steve_gus - 29/12/05 at 06:19 PM

that was a nice looking car - shame it went that way

Essentially the reason why i didnt attempt to build a standard locost - i wanted something for touring rather than high speed blasting around country roads - i think id get fed up of a seven pretty quickly.

atb

steve

derf - 30/12/05 at 05:42 PM

I don't thgink that drilling holes in boltsis exactly a great idea, but it is spot on in terms of moving in the right direction.

Even though you may only save 1 kilogram by lossing a small piece of weight, do that 100 times and you have 100kg's.