After watching Top gears ultra lights i was wondering what weight would a standard road car have to loose to have the same power to weight ratio as a 2zz?
Assuming a 2zz typically makes about 180bhp in an MR2 you would need to lose about 250kgs with a 1zz ie about 25% of the car's kerb weight. But it would still accelerate a bit more slowly due to the higher gearing.
As above 250kg to get same bhp per ton.
But all weight is not the same, loosing unsprung weight will have a much greater effect on handling and acceleration than sprung weight. And also where you are removing the sprung weight will effect the balance of the car.
Quote from: "Jrichards20"As above 250kg to get same bhp per ton.
But all weight is not the same, loosing unsprung weight will have a much greater effect on handling and acceleration than sprung weight. And also where you are removing the sprung weight will effect the balance of the car.
removing 250kg from a roadster seems madness!
So that's what... soft top, carbon bonnet and engine lid, all plastics out, radio out, AC out if present for the sprung. Should make it quite nimble as well.
Then lighter wheels with AD08Rs or the like and inverse coilovers or coilovers with separate hydraulics for the unsprung.
Does that make 250kg? Think I'd rather have a bit more luxury and put a 2zz in s:) :) s:)
My track '2 is as stripped out as possible (I've even cut off all brackets etc that aren't 100% needed) , but still weighs 975kg (but that is with 2x bucket seats, a full 6-point cage, oil cooler, standard exhaust, lots of bracing, a hard-top, and half a tank of fuel). I reckon that without a cage, hard top, and only a driver seat, it would be nearer 825kg.
Even worse than I thought then s:) :) s:)
So basically at 250kg we're talking full on stripped track spec.
Quote from: "shnazzle"Even worse than I thought then s:) :) s:)
Shove in a bigger motor, and keep all the refinements!
Quote from: "MR TWO"Quote from: "shnazzle"Even worse than I thought then s:) :) s:)
Shove in a bigger motor, and keep all the refinements!
Exactly.
Quote from: "shnazzle"Even worse than I thought then s:) :) s:)
So basically at 250kg we're talking full on stripped track spec.
Mine is fully stripped and track spec'ed, it's nowhere near. To get anywhere near 800kg you'd be talking an open rolling chassis with a seat - so no use or track or road.
Quote from: "shnazzle"Quote from: "Jrichards20"As above 250kg to get same bhp per ton.
But all weight is not the same, loosing unsprung weight will have a much greater effect on handling and acceleration than sprung weight. And also where you are removing the sprung weight will effect the balance of the car.
removing 250kg from a roadster seems madness!
So that's what... soft top, carbon bonnet and engine lid, all plastics out, radio out, AC out if present for the sprung. Should make it quite nimble as well.
Then lighter wheels with AD08Rs or the like and inverse coilovers or coilovers with separate hydraulics for the unsprung.
Does that make 250kg? Think I'd rather have a bit more luxury and put a 2zz in s:) :) s:)
Completely agree, getting the car down to around 750KG is a joke. Realistically never going to happen unless you basically rebuilt the car from different parts from the ground up.
My goal is to keep mine under 1000kg and I don't think that will even happen.
Yeh agree with the above, your realistically not going to lose 250kg, The cars already light for a production road car !
You may be able to lose that much from a big weighty car with lots of heavy extras that can be removed but not a 2
Quote from: "shnazzle"So that's what... soft top, carbon bonnet and engine lid, all plastics out, radio out, AC out if present for the sprung. Should make it quite nimble as well.
Then lighter wheels with AD08Rs or the like and inverse coilovers or coilovers with separate hydraulics for the unsprung.
Does that make 250kg?
That makes about 60kg. I have lost about 55kg and I still have soft top, original hood and engine lid and plastics. Radio is gone but still have speakers. About 125kg weight loss is possible and still be street legal. Maybe even more, not sure if I have thought every possible place where you can shed weight. Of course that is only with ~normal~ budget. With unlimited budget that 250kg weight loss is within the realms of possibility.
Quote from: "shnazzle"Think I'd rather have a bit more luxury and put a 2zz in s:) :) s:)
Fun thing is that even with worse power to weight ratio lighter car is faster on twisty track. s:wink: :wink: s:wink:
I'm sure MilesH mentioned his roadster weighs around 850/860kg and that's with a roll cage.
Didn't the guys the the bike engine one get just over 600kg with fibre panels
Quote from: "M.R."Quote from: "shnazzle"So that's what... soft top, carbon bonnet and engine lid, all plastics out, radio out, AC out if present for the sprung. Should make it quite nimble as well.
Then lighter wheels with AD08Rs or the like and inverse coilovers or coilovers with separate hydraulics for the unsprung.
Does that make 250kg?
That makes about 60kg. I have lost about 55kg and I still have soft top, original hood and engine lid and plastics. Radio is gone but still have speakers. About 125kg weight loss is possible and still be street legal. Maybe even more, not sure if I have thought every possible place where you can shed weight. Of course that is only with ~normal~ budget. With unlimited budget that 250kg weight loss is within the realms of possibility.
Quote from: "shnazzle"Think I'd rather have a bit more luxury and put a 2zz in s:) :) s:)
Fun thing is that even with worse power to weight ratio lighter car is faster on twisty track. s:wink: :wink: s:wink:
jeeez all that is only 60kg? I underestimated how light Toyota made this stuff s:) :) s:)
Makes it all even more ridiculous trying to get to 250kg less.
The prospect of a light car is very appealing, hence Lotus Elise etc.
Quote from: "shnazzle"Quote from: "M.R."Quote from: "shnazzle"So that's what... soft top, carbon bonnet and engine lid, all plastics out, radio out, AC out if present for the sprung. Should make it quite nimble as well.
Then lighter wheels with AD08Rs or the like and inverse coilovers or coilovers with separate hydraulics for the unsprung.
Does that make 250kg?
That makes about 60kg. I have lost about 55kg and I still have soft top, original hood and engine lid and plastics. Radio is gone but still have speakers. About 125kg weight loss is possible and still be street legal. Maybe even more, not sure if I have thought every possible place where you can shed weight. Of course that is only with ~normal~ budget. With unlimited budget that 250kg weight loss is within the realms of possibility.
Quote from: "shnazzle"Think I'd rather have a bit more luxury and put a 2zz in s:) :) s:)
Fun thing is that even with worse power to weight ratio lighter car is faster on twisty track. s:wink: :wink: s:wink:
jeeez all that is only 60kg? I underestimated how light Toyota made this stuff s:) :) s:)
Makes it all even more ridiculous trying to get to 250kg less.
The prospect of a light car is very appealing, hence Lotus Elise etc.
The new elises now weigh over 900kg. For all the comforts of an MR2 I think Toyota did very well making it as light as it is.
Quote from: "4dvti"I'm sure MilesH mentioned his roadster weighs around 850/860kg and that's with a roll cage.
It does indeed. Bits that people may have missed include:
Door bars (full cage with side bars means they are not needed).
T45 roll cage tube used resulting in a comparatively light cage with thinner diameter tubing
Electric window motors and all associated parts
Single skin bonnet and bonnet (not replacement items, just single skin the original Toyota parts as they become lightn enough anyway)
Tie down bars (front and rear) that are welded to the chassis for use at the factory I asssume)
Drivers seat only and very lightweight
Full cage means a reduced need for under body bracing (tested and proven)
Lightweight battery
Next step would be a single skkin hardtop, but as no one makes them yet all the prices I have been quoted would include me paying a large cost towards the moulds, which makes it unaffordable. But if this was done I can see another big weight reduction gain.
I am not a person who believes in speding £'s on buying carbon fibre parts etc to loose a few grams. My idea has always been to make the car as light as possible at an affordable price.
Quote from: "MilesH"Electric window motors and all associated parts
How much those weight?
Quote from: "MilesH"Tie down bars (front and rear) that are welded to the chassis for use at the factory I asssume)
Care to be bit more specific? Not sure what you mean about those tie down bars.
Quote from: "MilesH"Lightweight battery
This is definitely one of easiest and cheapest place to shed some weight. I have 860g LiFePO4 battery, so that is nearly 12kg weight loss.
Quote from: "MilesH"Next step would be a single skkin hardtop, but as no one makes them yet all the prices I have been quoted would include me paying a large cost towards the moulds, which makes it unaffordable. But if this was done I can see another big weight reduction gain.
Have you checked VIS Carbon Fiber Hard Top? Bit expensive tho and not sure about weight. Roof is on my weight saving list too. Soft top weights over 15kg and OEM hard top 22.4kg, so there is definitely big weight savings if done properly.
Not sure if it is common knowledge, but OEM exhaust system is bit heavy. I have lost about 15kg there. PPE header, PPE midpipe and DIY muffler. And it is from great place too, all behind rear axle.
I cut out my soft top but retained the seat belt mount 'cross bar' and everything I got rid of was dead on 20Kg. You do actually have to cut some metal to get rid of that - some of the pivots are welded in.
Just buy a Caterham
Quote from: "JoeCool"I cut out my soft top but retained the seat belt mount 'cross bar' and everything I got rid of was dead on 20Kg. You do actually have to cut some metal to get rid of that - some of the pivots are welded in.
Off topic but I didn't understand that at the time; I remembered looking at the removal instructions and it never mentions cutting metal.
Quote from: "MilesH"Quote from: "4dvti"I'm sure MilesH mentioned his roadster weighs around 850/860kg and that's with a roll cage.
It does indeed. Bits that people may have missed include:
Door bars (full cage with side bars means they are not needed).
T45 roll cage tube used resulting in a comparatively light cage with thinner diameter tubing
Electric window motors and all associated parts
Single skin bonnet and bonnet (not replacement items, just single skin the original Toyota parts as they become lightn enough anyway)
Tie down bars (front and rear) that are welded to the chassis for use at the factory I asssume)
Drivers seat only and very lightweight
Full cage means a reduced need for under body bracing (tested and proven)
Lightweight battery
Next step would be a single skkin hardtop, but as no one makes them yet all the prices I have been quoted would include me paying a large cost towards the moulds, which makes it unaffordable. But if this was done I can see another big weight reduction gain.
I am not a person who believes in speding £'s on buying carbon fibre parts etc to loose a few grams. My idea has always been to make the car as light as possible at an affordable price.
Miles that is brilliant - can we persuade you to do a more detailed thread on your car!?
I have the Rogue/P&P 6pt cage so it's never going to be as light as your T45. I've been considering losing the electric windows and door innards and replacing all the glass with lexan windows - have you done this? I understand that it's a bit trickier with frameless windows. That aside my car i similar to yours (not too much bracing, bonnet/boot inner skins cut out etc). I'm hugely impressed you've got it down to 850kg!
Quote from: "shnazzle"Quote from: "JoeCool"I cut out my soft top but retained the seat belt mount 'cross bar' and everything I got rid of was dead on 20Kg. You do actually have to cut some metal to get rid of that - some of the pivots are welded in.
Off topic but I didn't understand that at the time; I remembered looking at the removal instructions and it never mentions cutting metal.
It's mental. You can un bolt the soft top very easily, on the support bar that runs across the car just behind the shoulders. But that support bar located the upper seat belt mounts and also clearly braces the mid section of the car significantly.
The pivot points for the main hoop look like they should just drift out after you've taken the bolts out, but there are tubes in there that act as the main pivot and try as I might I could not drift them out, I think the tubes are actually welded in place.
Then there are 2 additional pivot points which look like they should just undo on an Allen bolt, but they are tab welded in place meaning you have to at least cut the pivot bolt, but may as well cut the whole locating tab off of the support bar.
There's no way of taking the soft top off of the seat belt bar without cutting metal.
Weight reduction is primarily a sum of many small changes. An aftermarket full exhaust sheds a fair amount of weight. The rear body pannels are suprisingly heavy as is the engine lid.
Thanks to technology lithium batteries are an easy way to shed some solid weight.
I found that aftermarket suspension arms were significantly heavier than factory. They use thicker gauge steel of lower quality to reduce costs.