compact weight

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compact weight

Postby jerseypug » Thu Jul 30, 2015 12:14 pm

i built my compact with a 318 m42 engine but wanted more power, i fitted a 328i engine and kept the 318 gearbox. the weight of the car with the 318 4 cylinder steel engine and half a tank of fuel came to 1140kg. the weight of the car with the 328i aluminium engine and nearly out of fuel comes to 1150kg
unfortunately the weigh bridge i use rounds up or down to the nearest 10kg and half a tank of fuel could weigh around 15kg meaning the weight difference between having the 318 and 328 engine could be anywhere around 25kg which is much less than i thought it would be.
im a long way off the 1000kg that i would have liked the car to weigh
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Re: compact weight

Postby lahondal » Thu Jul 30, 2015 1:12 pm

mine is 1076kg full of fuel with m42 engine
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Re: compact weight

Postby jerseypug » Thu Jul 30, 2015 7:46 pm

how did you manage that? i have removed as much as i can from tailgate and bonnet, removed loads of wiring and the door bars. i have left the front glass electric windows and heater but can't see them weighing loads. it still has the under seal and a few of the original brackets and i suppose they all add up.
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Re: compact weight

Postby Garry.M » Thu Jul 30, 2015 9:40 pm

I've weighed both engines which were almost fully dressed - like for like bits still on and it was around 15kg of difference. I've seen a compact race car that was fully stripped of all underseal, excess brackets including the std rear springs platforms!,,, the cars had to retain the std heater and elec windows and it came in at around 1000kg. Now I then went and weighed all the extra bits you need for a rally car - another seat and harness,, hand held ext, mudflaps and bkts, sump guard, tank guards along with the extra weight of the 188mm diff over the 168mm,,,, I came up with around 80kg extra weight over a race car
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Re: compact weight

Postby jerseypug » Fri Jul 31, 2015 8:56 am

15kg difference between the engines is nothing, i wonder how the weight compares front to rear with the different engines and the 328i having some of its weight further forward. when stripping the car i seemed to be removing weight a lot easier from the rear rather than the front which would not help. i have the compact cup bolt in cage which is very good but also quite heavy and i have electric glass front windows as i find the plastic sliding openers don't let much air in when it is hot. i read somewhere that the 2000cc weight limit is being reduced quite a bit which will make mine way over the limit. i could always go on a diet.
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Re: compact weight

Postby bruvs1 » Fri Jul 31, 2015 9:32 am

At the last count , fully loadedthe m54compact with spare wheel etc was 1150, bit heavier now with an iron block :-/
http://www.bruvsmotorworks.co.uk 320is, 330is rallying!
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Re: compact weight

Postby lahondal » Fri Jul 31, 2015 1:27 pm

1076kg mark:

-I took 16kg from each front door (plastic windows).
-4kg from bonnet reinforcement.
-Heater and accesories removed.
-I ditched all the stock wiring and made a custom simplified wiring loom.
-Rest of the windows 4mm polycarbonate.
-Fiberglass bucket seats 9kg each, (stock are really heavy).
-CrMo 11point roll cage, only 32kg.
-Front and rear bumpers with reinforcements removed, they weinght near 3-4 kg each, no more.
-Dashboard reduced to a minimum. Digital dash too.
-Fuel vapour system removed.

Under seal is on, too much work for only 12-14kg.
No fiberglass used, i hope in the future i can reach 1045-1050 full of gas by buying a fiberglass bonnet, front wings and tailgate.
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Re: compact weight

Postby Garry.M » Sat Aug 01, 2015 12:29 am

Chris Ransley can make the std wiring loom 9-10kg lighter,,, std is just over 14kg and mine is 3.8kg
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Re: compact weight

Postby jerseypug » Wed Nov 16, 2016 1:32 pm

lahondal wrote:1076kg mark:

-I took 16kg from each front door (plastic windows).
-4kg from bonnet reinforcement.
-Heater and accesories removed.
-I ditched all the stock wiring and made a custom simplified wiring loom.
-Rest of the windows 4mm polycarbonate.
-Fiberglass bucket seats 9kg each, (stock are really heavy).
-CrMo 11point roll cage, only 32kg.
-Front and rear bumpers with reinforcements removed, they weinght near 3-4 kg each, no more.
-Dashboard reduced to a minimum. Digital dash too.
-Fuel vapour system removed.

Under seal is on, too much work for only 12-14kg.
No fiberglass used, i hope in the future i can reach 1045-1050 full of gas by buying a fiberglass bonnet, front wings and tailgate.


what does the fuel vapour system do and is it heavy? I crashed the car and while I'm working on it decided to get rid of the heater and glass electric front windows trying to get more weight out of it. i originally had the sunroof sealed in place with a steel sheet over it which has now all gone, taking a lot of time and work but hopefully worth it.
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Re: compact weight

Postby mrfuzzyfelts » Wed Nov 16, 2016 4:14 pm

Mine is 1260!

Really dont see how i can get anymore out of it.. I have stripped and cut what i can.

But my diff, shaft, arm setup on the back is much heavier, although i dont mind low down weight
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Re: compact weight

Postby samdemange » Thu Nov 17, 2016 9:24 pm

1040 kg with full tank for my 328 ti but the roll-cage isn't installed
add HP make you faster in straight line
lose weight make you faster every where
(colin chapman )
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Re: compact weight

Postby jerseypug » Fri Nov 18, 2016 6:16 pm

i am fitting all the fibreglass bits soon so will be interesting to weigh it again. i have been in a compact in a big crash would rather be in a heavy safe BMW than a light escort. still want to get it as light as i can without spending lots of money

mrfuzzyfelts wrote:Mine is 1260!

Really dont see how i can get anymore out of it.. I have stripped and cut what i can.


you could always remove the front 2 cylinders ;)
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Re: compact weight

Postby lahondal » Mon Nov 21, 2016 2:41 pm

jerseypug wrote:what does the fuel vapour system do and is it heavy? I crashed the car and while I'm working on it decided to get rid of the heater and glass electric front windows trying to get more weight out of it. i originally had the sunroof sealed in place with a steel sheet over it which has now all gone, taking a lot of time and work but hopefully worth it.


I think the system recirculates the fuel tank vapour to the inlet to reduce the emissions or smell of petrol in the cabin. Is not heavy, maybe 2kg, but all helps.

Now mine is 328ti, not weighted yet, but i made a single exhaust system as light as i can, (stock exhaust is VERY heavy) and i hope i raise the weight only around 20-25kg.

Next season will begin with the fiberglass.
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Re: compact weight

Postby jerseypug » Tue Nov 29, 2016 11:20 pm

just got back from the uk with the fibreglass panels, heated screen, plastic windows and a 5kg battery. hopefully that should make a noticeable difference in the overall weight.
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Re: compact weight

Postby jerseypug » Wed Jan 11, 2017 7:44 am

i pulled out the plastic fuel breather container that is behind the rear panel and it has 3 pipes connected to it and it weighs very little, 1 blue pipe goes to the engine bay (mine had been disconnected and left open ended a long time ago) there are 2 black pipes that i presume come from either side of the fuel tank. the steel covers either side are quite heavy and when they are removed there is a steel reinforcing bar that looks like it is connected to the jacking point so am going to leave those and the tank, move the blue breather and put some lightweight panels where the steel ones originally were.
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