paul v6
|
| posted on 19/9/05 at 09:53 AM |
|
|
How heavy???
Hi guys,
Having discussed "Losing weight" Ive decided a BEC is the way forward (anyone wanna buy a 2.9 cologne and 4x4 box  ) My intention is to
use a blade motor and keep the chassis as light as possibe. I'm sure a number of guys here on the forum have already done similar so does anyone
have any idea how little a finished car can weigh??
Paul
[Edited on 19/9/05 by paul v6]
|
|
|
|
|
smart51
|
| posted on 19/9/05 at 10:10 AM |
|
|
MNR have had a VortX RT+ with a fireblade engine weighed at 397kg.
Your choice of components will affect this a lot but I guess if you use lightweight components you can beat this. I believe that the RT+ had a full
roll cage not just a braced roll hoop.
|
|
|
paul v6
|
| posted on 19/9/05 at 10:17 AM |
|
|
That is Light!! In that case my target will be sub 400kg, are there any affordable lightweight components that would help achieve this target??
Paul
|
|
|
smart51
|
| posted on 19/9/05 at 10:49 AM |
|
|
Affordabe? Yes. Lightweight? Yes. Both? No!
THe Vortx RT uses sierra bits, heavier steel and has a triangluated roll hoop rather than the full cage. It weighs 30 odd kg more than the RT+. You
have to pay lots for the good stuff.
My my secret Excel acceleration model, I estimate that 30kg weight saving will get you 0.2 seconds faster to 60 and 0.5 seconds faster to 100 in an R1
engined car weighing 500kg including the driver vs 470kg including the driver. Only noticable on a race track I think.
|
|
|
Hellfire
|
| posted on 19/9/05 at 11:21 AM |
|
|
quote:
Originally posted by smart51
MNR have had a VortX RT+ with a fireblade engine weighed at 397kg.
Your choice of components will affect this a lot but I guess if you use lightweight components you can beat this. I believe that the RT+ had a full
roll cage not just a braced roll hoop.
Could you be more specific as to what components were used to achieve this weight - Lite GRP or C/F, wheels, diff hubs, calipers etc. At initial
reading I thought 'yeah right-oh' but then I think this response is better!  Sub 400Kg is very difficult to achieve without spending
DAFT sums of money!
The Cateringvan Supalight is 500Kg FFS... is that a typo?
Mention the sub 400Kg at your peril!!!
[Edited on 19-9-05 by Hellfire]
|
|
|
Mad Dave
|
| posted on 19/9/05 at 11:22 AM |
|
|
397kg sounds too low to me!
My ZX9 Indy weighed in at 468 with half a tank of fuel, thats 71kg less. Where on a 7 style car can you save 71kg???
|
|
|
Hellfire
|
| posted on 19/9/05 at 11:25 AM |
|
|
Hmmm, sounds to me like those figures quoted are VERY optimistic. Chassis and running gear on MNR aren't too dissimilar to those of a MAC#1 or
MK.
Without spending Serious cash - and I mean SERIOUS - you'd be lucky to get a car that weighs in at less than 450kg wet.
Realistically, using Sierra running gear (Front Hubs, Calipers, diff etc) you'll probably be around 480 - 500kgs.
Stick lightweight calipers and disks on and you may get the weight down to about 460kg.
After this you're looking at lightweight hubs, Quaiffe diffs and titanium nuts and bolts = ££££££££££££££££
With a blade engine, aim for between 450kg and 500kg (dependant on how deep your pockets are!!)
You can tell those were biased weighing scales... get Chris Mason's calibrated one's in to find a true weight....
[Edited on 19-9-05 by Hellfire]
|
|
|
smart51
|
| posted on 19/9/05 at 11:35 AM |
|
|
I don't remember the spec of the MNR off hand. It did have raceleda alloy fronts with solid discs. The RT+ uses thinner but stronger steel in
at least some of the chassis. It was in Which Kit as part of their VortX story early on in the year. Ordinary VortXes like mine with the sierra
stuff will weigh more of course. The question was "what is achieveable" not "what is commonplace".
|
|
|
Mad Dave
|
| posted on 19/9/05 at 11:52 AM |
|
|
My chassis is standard and I have tried to use light weight components where I could. The areas that could be lighter on the MNR compared to mine are
the chassis, uprights and any difference in the wheels and tyres. To shave off 71kg I would have to bin all my wheels/tyres and uprights completely
|
|
|
Hellfire
|
| posted on 19/9/05 at 12:05 PM |
|
|
I'd like to be proven wrong, but I don't see how 397kg is achievable with a Seven style car.
|
|
|
ady8077
|
| posted on 19/9/05 at 12:07 PM |
|
|
Hi
Theres a spec of a nice R1 Striker here
http://www.kerryandjane.com/index.shtml?section=striker&subsection=info
420 Kg's at SVA
Adrian
|
|
|
Hellfire
|
| posted on 19/9/05 at 12:14 PM |
|
|
Always be cautious of the weight at SVA. This is only a combination of the front and rear axle weights and is definitely not the cars true weight.
Its like putting one foot at a time on some weighing scales and then adding the two weights together.
|
|
|
smart51
|
| posted on 19/9/05 at 01:32 PM |
|
|
bit of guesswork here
solid front discs are, what, 2kg lighter than vented each?
alloy front calipers 1kg each
alloy uprights and hubs 4kg per side?
thin wall steel in the chassis may save 10kg?
untrimmed seats 2kg each?
that's 28kg. a kilo or so in the wheels and tyres makes up the difference between the vortx RT and RT+ as stated by Which Kit. I bet that
there is more than 5kg per wheel and tyre combination between good ones and bad ones
use 0.5mm thinner aluminium for the floor and you could save 2 kg. MNR use a very light radiator and fan. Use a smaller header tank and save 1kg for
that litre of coolant just on it's own. Plastic cycle wings will be 1.5kg lighter than GRP for the pair.
Does your car have rear discs. I'm told that drums weigh less, though I can't confirm this.
Interior trim panels must weigh a few kilos. You don't need them all. Have you got a boot box? I bet that weighs 5kg
Of course your car doesn't have a windscreen or heater. Could you fit a smaller battery. Do you have a bike loom and car loom? did you cut
out all the wires you didn't need or did you tie them up?
Is your car painted? It sounds silly but paint weighs more than a kilo per litre.
Some things make hardly any difference but added together. lose 70kg from your car? If you are ruthless with the details.
That said, I haven't bothered with mine. Sierra uprights and calipers, LSD, rear disks and vented fronts, boot box, interior trim, GRP cycle
wings ... For a road car it makes so little difference. It can be done though and without mentioning carbon fibre.
|
|
|
Hellfire
|
| posted on 19/9/05 at 01:51 PM |
|
|
I know people who have tried all of the above and a lot more besides.
They struggled to get any less than 420kg.
|
|
|
adam_moore
|
| posted on 19/9/05 at 02:14 PM |
|
|
Surely the best way to spend your pennies is to maximise the power to weight ratio which may be better achieved by tuning up the engine for extra
horse power and saving a little weight in the obvious areas (unsprung mass etc...).
For example
150 bhp and 450 kg = 333 bhp/tonne
150 bhp and 400 kg = 375 bhp/tonne
160 bhp and 430 kg = 372 bhp tonne
170 bhp and 450 kg = 378 bhp/tonne
|
|
|
Mad Dave
|
| posted on 19/9/05 at 02:18 PM |
|
|
quote:
solid front discs are, what, 2kg lighter than vented each?
alloy front callipers 1kg each?
untrimmed seats 2kg each?
Got them!
quote:
Interior trim panels must weigh a few kilos. You don't need them all.
Only trimmed the tunnel.
quote:
Could you fit a smaller battery.
Fitted a Varley Red Top at 5kg
quote:
Do you have a bike loom and car loom? did you cut out all the wires you didn't need or did you tie them up?
Made the loom from scratch.
quote:
Is your car painted? It sounds silly but paint weighs more than a kilo per litre.
Black gel coat (black...is that heavier than yellow?)
[Edited on 19/9/05 by Mad Dave]
|
|
|
speed8
|
| posted on 19/9/05 at 02:54 PM |
|
|
quote:
Originally posted by adam_moore
Surely the best way to spend your pennies is to maximise the power to weight ratio .....
Surely the cheapest way to reduce weight in some cases is to cut down on the pies. Doesn't matter if you get it down to 400kg, if the driver is
120kg it defeats the purpose.
Fair enough if you are a little guy but most folk seem to get the expanding waistline syndrome as they get older.
Yes, I know you are talking about unladen weight. I'm joking.
|
|
|
David Jenkins
|
| posted on 19/9/05 at 02:59 PM |
|
|
In my car, one of the heaviest items is the nut holding the steering wheel!
David
[Edited on 19/9/05 by David Jenkins]
|
|
|
smart51
|
| posted on 19/9/05 at 03:14 PM |
|
|
Mad Dave,
Wow, didn't expect you go argue point by point. I was just trying to suggest that it is the details that make the difference.
I am told, by the way, that black gel coat is the heaviest. Pink is supposed to be lighter
|
|
|
Mad Dave
|
| posted on 19/9/05 at 03:45 PM |
|
|
I'm not arguing, its just to show you that I have tried to make my car as light as I could and it still weighs 468kg. Chris Mason's Blade
powered Indy was very similar to mine and weighed a few kg less.
My next build will be lighter still using the same upright/hub assemblies and AP Racing brakes as the Caterham R400. This will save no more than 10kg
though.
|
|
|
Memphis Twin
|
| posted on 19/9/05 at 04:22 PM |
|
|
There's a guy in our car club who sprints a Blade engined road-legal Striker. It has been set up on an accurate flat patch and weighs @390kilos.
No bullsh*t.
Just a few pointers in trying to acheive low weight:
A drum- braked Escort live axle is much lighter than a Sierra independent set-up. 30 kgs lighter!! (been lots of discussion on the Caterham 7
website). With an alloy diff. nose it's lighter still.
13" wheels are lighter than 15" wheels. 13" X 6" Revolution 4 spokes are about the lightest readily available 6" alloy
you can get hold of. Mine weighed 4kg each on my Striker XFlow. They can be had used for as little as £120 a set.
High tensile cap-head (Allen head) bolts are much lighter than hex-head (and more professional looking).
A VW Polo alloy rad is very efficient and incredibly light compared to a Ford Escort etc.
A Triumph Spitfire steering column and rack is significantly lighter than any Ford you care to mention, and dirt cheap from a Triumph breaker. The
standard column cowling is alloy. The rack is quick enough for a Mallock Clubmans car so should be OK on a road car!
I could go on, but I'll be here all day. My GSXR1100W engined Mallock hillclimb car weighed in at 325kgs with a modified Morris Minor rear axle
(the diff carrier is alloy as standard!), Triumph rack and uprights etc. The one I'm building now could well have a modified air/oil cooled
GSXR1100 motor (no heavy engine coolant and pipe work), and probably not even an oil cooler.
I'm not suggesting eveyone goes out and gets Triumph and Morris Minor stuff! I was just trying to indicate that there is usually a cheap,
readily available and lightweight alternative to the usual heavy Sierra gear.
Cheers...
|
|
|
Memphis Twin
|
| posted on 19/9/05 at 04:28 PM |
|
|
PS
I'm ditching the modified Locost book chassis and building my own from 3/4" and 1/2" 18guage....
|
|
|
Mad Dave
|
| posted on 19/9/05 at 04:40 PM |
|
|
I appreciate that the sierra parts are heavy, but I just wanted to build a standard Indy fairly quickly and cheaply. I was originally building it
with an open diff and drum brakes, and standard sierra front brakes. Supposed to be a no nonsense track car but when others around were building to a
higher spec I didn't want mine to be overlooked so changed to LSD and Wilwoods!
"Triumph and Morris Minor stuff" I know someone who owns a company that manufactures new components for Morris Miners and Triumphs
[Edited on 19/9/05 by Mad Dave]
|
|
|
marc n
|
| posted on 19/9/05 at 05:09 PM |
|
|
quote:
Hmmm, sounds to me like those figures quoted are VERY optimistic. Chassis and running gear on MNR aren't too dissimilar to those of a MAC#1 or
MK.
hellfire using your mk as a referance
chassis is t45 / cds thinwall mix, weight saving to erw 35 kilos, compared to our standard chassis. dont forget we have a proper integral cage as a
stressed member that is structual not bolted.
wishbones t45 as opposed to erw saving .5 kilo per wishbone ( accounting for the fact roadcar has heavy transit drag links and maxi ball joints )
alloy uprights, callipers, drive hubs, drilled discs etc as opposed to sierra, got to be at least 3 kilos a side probably more !!!!drum brake rear end
converted to discs, difference between shafts is 2.5 kilos each , diff is 2 kilos lighter, diffrent bearing housings and drive flanges another 1 kilo
per side
lightweight bodywork, ( inc carbon fibre ) with return edges no alloy trims etc in cockpit area,
integral dash panel and engine sealing panel in scuttle, plus aeroscreen
alloy footwell panels as opposed to steel
alloy fuel and brake lines
single strand f1 spec wiring loom
just with what i know weigh less we have saved 53 kilos ,
then add the bodywork diffrence etc and you can see where the saving comes from
[Edited on 19/9/05 by marc n]
|
NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
|
marc n
|
| posted on 19/9/05 at 05:36 PM |
|
|
quote:
The Cateringvan Supalight is 500Kg FFS... is that a typo?
caterham superlight runs a k series with six speed sequential box, had two of them myself and can confirm the race ones where a tad lighter than
this
weighed at msa events and on our intercomp pro scales £2500 worth recalibrated 6 months ago
[Edited on 19/9/05 by marc n]
|
NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
|
