Performance Gains via Reduced Weight

[Gibla]

The epic Readers Ride via @Petrus

https://mail.google.com/mail/u/0/#inbox/FMfcgxwLtkTNMXjGBHlZwBFdXRSnftld

contained many references to large and small reductions in weight he has managed to achieve (along with references to his multiple # of girlfriends)

To date, he has managed to get under 900kg from a starting point of 1060kg (SMT box PFL) so 160kg+ weight saving

 I am seriously contemplating some car weight reduction(this author would be a brilliant sp. also :-)

spare wheel - done this am
pas pump
aircon
lighter wheels
lighter battery

*note* this won't achieve Petrus levels of weight saving, maybe something like ~50kg 

fwiw. my 6sp FL has 1110 kg marked as its tare weight in the documentation (UK V5)

I live in the countryside so pas isn't as important as if I lived in an urban area, similarly, aircon has very rarely if ever been used by me (although could see very occasional use in demisting or on the odd occasions roof off + totally stuck in traffic on a hot day)

Comments, thoughts etc ?

[Dev]

 The only reason I keep my air conditioning is for the odd chance the window get fogged up which has happened. This can cause visibility issues that can be dangerous. The defroster setting removes moisture from the air.

Apart from that you can take off a good amount of weight but there comes a point where you have to make a decision if you want a kit car or a fully functioning car that looks the part. What I did was replace a part with a lightweight part that looks as good or better than the part it replaced. I still want my car to have a factory like look like I didn't mess with it unless you know what the factory car looks like. 
 That has been my strategy because losing all the weight you can is not everything, balance is for a street driven car and there are some comforts I will not part with.

[Topdownman]

Maybe before you start you could work out how much you can save, then add that to your car and see the difference in feel between the two?

Not exactly comparable I know but may give an idea of the effect before any committment?

As a principle, you have to apply weight saving to everything for the gains to add up like Petrus has done so its best to be sure!

[Mark A]

Loose the soft top?

I'm thinking of removing mine running with a 1/2 cage and a hard top most of the time and then lift the hard top off for weekend runs etc.

[Petrus]

Maybe before you start you could work out how much you can save, then add that to your car and see the difference in feel between the two?

Not exactly comparable I know but may give an idea of the effect before any committment?

As a principle, you have to apply weight saving to everything for the gains to add up like Petrus has done so its best to be sure!

Jason @Ardent   did my suggested MR2 (rotational moment of inertia) experiment and was .... euh... convinced :-)

Mine is wéll under 890 kg now and I hope to get to 880. This is with 10 kg of fuel.
The ´curb weight´ as given on vehicle registration document is supposed to be with spare, tool kit and full tank.

BEFÓRE you go adding lightness  to your car in serious it is paramount to have your priorities clear:
- how MoT legal do you want to be? P.e. changes to catatlist and/or muffler
- how much creature comfort do you want? P.e. take the sound equipment out, strip the interior of some soft bits like carpet
- what is your perception of safety? P.e. taking out the explosive bags, delete/lighten front/rear crash bar

Then there is your budget. Lighter wheels are all advantage but not cheap. Same thing lightweight bucket seats which add a world of driver support = improve your steering.
A cf bonnet and/or rear deck is ´just´money and véry convenient lightness added.

Lastly be aware that a seriously lighter car will respond seriously much quicker and though that is a huge positive when braking, not everybody will like the reduced MR2 and will perceive it as seriously nervous twitchyness.
As you can read in my thread, with say 15%  less weight, the ground clearance increased. That cán be handy but it is in this case a valid reason to cut down the OEM springs a wee bit. Front a whiff more and get the slightest bit of rake improving stability at speed.

All in all I think the ´try it first´ is a good one.
You can get a very good idea by topping up the fuel tank, add passenger and finally a 30-40 kilo concrete garden parasol socket with the spare.
So; choose a road you like and know very well, say 10 twisty miles with ideally a few roundabouts you can go roundand about on.

Drive it with the car empty. No need to push it. Just drive spiritedly. Remember that it is NOT about performance, not about acceleration but about how it changes direction and the braking.
Load up, drive it several times. Enough to get sort of accustomed.
Shed the extra load, the spare wheel/tool kit and go again. Once is enough.

Right.
The quick way to make large steps is:
Delete the frump plastic; replace spare and tools with a foam can, lightweight battery, lightweight muffler, lightweight wheels, no precat tubular exhaust manifold, delete p.a.s.
That is an adult male passenger worth already but with two, three times the dynamic effect because the passenger sits in the middle, whereas most of the shed stuff is at the far ends and the wheels are unsprung/rotating at double the road speed.

From thereonwards it is about your priorities. Heck, you can even fit a lexan windshield!

[Petrus]

Anything experienced yet @Gibla ?

I´ve done a step backwards refitting the OEM cat :-(

Still at it with the mould for the bonnet. This should be twice as much óff as I put back with the environment saver.

[Gibla]

Nah, no progress other than ditching the 'spare' run-flat(as before)

Great advice from yourself and other contributors in this thread, it was quite revealing that at the same time last week with the @puma2  road trip featured the only occasion of 1-up driving. My other half is a very weedy 50-60kg max, which is roughly the weight saving I am expecting to achieve once I get started in earnest. Such a noticeable difference in responsiveness experienced, steering even more super pointy and accurate than before ie 'change of direction'.

I also need to examine advisable 'bracing' for my unfettered FL at the same time, out on the open road my driving style(fairly modest speeds) has rarely led me to think I need anything to assist me,:- except over really badly broken roads at low speed, where the front especially, seems to be in need of something to assist it. I am rather confused about which of the @Snelbaard,@Carolyn  braces would be the most useful with the front of the car.

[Petrus]

I am rather confused about which of the @Snelbaard/ @Carolyn  braces would be the most useful with the front of the car.

You nééd nothing.
Only if you start pushing slip angles will you be able to push farther with bracing.

Lighter wheels are a safety thing as much as a performance one; they reduce stopping distance; bracing ... nah.
So I would say to drop Dev a mail about the door spacers and leave it at that for the moment.

Now if you wánt to go bracing, then:
1. Snelbaard´s belly plate.
2. Carolyn´s (or another) strut brace.
3. Snelbaard´s FMB.

It, the bracing, is not the subject of your thread though, quite the contrary ;-)

[Gibla]

re
'So I would say to drop Dev a mail about the door spacers and leave it at that for the moment.' < duly done and ordered.

Further comments re. bracing duly noted :-)

[Roj]

This list may be of use...

https://www.mr2roc.org/forum/index.php?topic=12479.msg152748#msg152748

[Petrus]

Just swapped the rear wing supports for a 440 gram lighter combo 3D printed by my son. The whole wing now is under 3 kg.!!!

[Gibla]

This list may be of use...

https://www.mr2roc.org/forum/index.php?topic=12479.msg152748#msg152748

Very! along with a treasure trove of other previously unseen info. Thanks for the heads up :-)

[Dev]

 I found that you can take off a good 100LB before things start to get difficult and expensive.
 I thought about removing the sound insulation  material under the carpet since the weight was significant until I rode in an owners car that already did so and it was unbearably loud but most of all annoying with the echo in the cabin. 
  When you start adding bracing you end up putting the weight back on. Carbon fiber hoods can make a little difference but they yellow and often times don't fit right. If you paint it you just added weight back negating gains in weight reduction and the costs are just too high for real carbon fiber and not fiberglass. 
 
You get to a point where you do the best you can but in the end what is more important is not overall weight reduction but having the car fun to drive. Reducing unsprung weight in my opinion is the best way to actually feel the difference but it can be expensive.

[Petrus]

Like with all Dev, the fysics is indicutable; less is more concerning sportscarness 
Per example; the lighter it is, the shorter it will stop.

Whether is makes for more ´cár´ is a matter of personal preferences and priorities. Perceived comfort and looks are but two as subjective as real aspects sometimes at odds with adding lightness.
As there is no discussing the effectiveness, there is no discussing the perception.

100 lbs is not much of a challenge and still 5% so not to be sneezed at.

Yes, lighter wheels are weight saved where it counts; objectively. Again, whether an owner thinks it money well spent is a different world 

Me, I also have much fun faffing with the car and no not all adding lightness; added bracing and aero, even functionally useless stuff for looks.
Currently trying to make a mould for the bonnet in grp (hood at your end). Worth the effort/money for the weight reduction? Nah, probably not. Still cool and thát ís worth it imo.
Júst like the 3D stuff my son makes for me. Not worth the marginal result on the car. Very much worth the learning experience for my son and the emotional value for mé.

Looking forward to corner weigh my car. Will be a little bit inaccurate per corner but the total will be realistic.
Worth the effort doing it myseñf when I have a weigh bridge accross the road? Náh, not at all. I think it however só cool to faff about with the scales hooked up to the laptop 
Fun with the car, while nót driving it 

[Petrus]

Btw @Gibla , the 1110 on your V5 is with spare, tools & full fuel, no driver.
My PFL has 1060.
The FL is from about 50 kg. heavier depending on options/year.

The much published sub 975/985 kg. is JDM, no airbags, no options, no fuel.

[Gibla]

Spare wheel ditched - as previously(but must get one of those flippin' foams jico)

Exide LiPo battery arrived- jeez it's diddy in size n weight

Slowly getting there!

Will have a good chat with far more knowledgeable folks in the coming weeks before I fully commit to ditching the pas and air-con (if removed, I would keep these jico)

Lighter wheels :- yep, as long as pleasing on the eye design AND a 'reasonable' weight saving...but £$ will dictate when this is feasible.

Seats :- as per pas and air-con. lighter ones obviously exist, BUT to maintain harmony with t'other half something comfortable has to be an important factor. Another expensive item probably, so will have to wait.

Body panels :- nah,

Zorst :- nah, had recently lined up a 'good condition' TTE, but I had a cracking drive out in between the showers yesterday + decided 'why change anything, it's running sweetly'!!!

Removing the soft top :- not practical for me really, as it lives outdoors all year round

[Gibla]

You can lose a lot of weight on the car if you go extreme, but the question is how pleasant it is then to be in the car? No carpets, bare metal, hard plastic seats, etc. Yeah, no doubt it performs much better when it's so much lighter, but at least to me it doesn't offset the quality of life loss aka the insides looking raw and unrefined as if the car has been left outside and was stripped for parts by thieves. Especially worthy of thinking if you have regular passenger who might not appreciate spartan interior at the cost of lost comfort and utility.

Comment duly noted, and I fully agree with the sentiments expressed. It's most certainly not my intention to trash what is a perfectly good car to produce a stripped out 'racer' rather trimming out some items that really are surplus weight whilst maintaining the essential creature comforts.

[puma2]

You can lose a lot of weight on the car if you go extreme, but the question is how pleasant it is then to be in the car? No carpets, bare metal, hard plastic seats, etc. Yeah, no doubt it performs much better when it's so much lighter, but at least to me it doesn't offset the quality of life loss aka the insides looking raw and unrefined as if the car has been left outside and was stripped for parts by thieves. Especially worthy of thinking if you have regular passenger who might not appreciate spartan interior at the cost of lost comfort and utility.

Comment duly noted, and I fully agree with the sentiments expressed. It's most certainly not my intention to trash what is a perfectly good car to produce a stripped out 'racer' rather trimming out some items that really are surplus weight whilst maintaining the essential creature comforts.

other cars are available may as well buy a Lotus Elise ha ha 

[1979scotte]

You can lose a lot of weight on the car if you go extreme, but the question is how pleasant it is then to be in the car? No carpets, bare metal, hard plastic seats, etc. Yeah, no doubt it performs much better when it's so much lighter, but at least to me it doesn't offset the quality of life loss aka the insides looking raw and unrefined as if the car has been left outside and was stripped for parts by thieves. Especially worthy of thinking if you have regular passenger who might not appreciate spartan interior at the cost of lost comfort and utility.

Comment duly noted, and I fully agree with the sentiments expressed. It's most certainly not my intention to trash what is a perfectly good car to produce a stripped out 'racer' rather trimming out some items that really are surplus weight whilst maintaining the essential creature comforts.

Alan you are yet to enjoy a standard roadster for any length of time.
As someone who has marched speedily in to extensive and expensive
 modifications on both his 2s could I offer some advice.

Take some time to enjoy it as is.

You won't make it much faster or handle much better with small weight losses imho. Especially if like me you are in the 100kg+ club.
I often think the best performance gain I could do for my 2 is loose 20kg 😆

[Gibla]

Good advice on all counts especially the personal weight loss :-)

I have owned a '2' before, maybe 3-4 years ago for ~12 months before I foolishly traded it in for ..... a Polo Gti (don't laugh, please)

[Gibla]

@puma2
re '
other cars are available may as well by a Lotus Elise ha ha ' < if only the purse strings would allow, plus I strongly suspect I wouldn't fit into one :-)

[Topdownman]

@puma2
re '
other cars are available may as well by a Lotus Elise ha ha ' < if only the purse strings would allow, plus I strongly suspect I wouldn't fit into one :-)

Where is your sense of adventure?!

https://www.youtube.com/watch?v=ZOMXCW7uK4U&ab_channel=CarThrottle

[Petrus]

@puma2
re '
other cars are available may as well by a Lotus Elise ha ha ' < if only the purse strings would allow, plus I strongly suspect I wouldn't fit into one :-)

Also the MR2 is fundamentally an easy to drive quite comfortable car. You can shed weight, add performance.
With an Elise you can not add the fundament of comfortable runabout.

In other words, you can change the MR2 to have a bit more hard core side when you wánt that and still have an easy to live with car for the rest of the time.
Mine is quite lively, some would say skittish but it remains the easy to live with quite comfortable runabout. Carpets or stereo are not comfort things for me. A compliant suspension is, having breathing space is, etc.

Unless you go silly hard/low springs with matching shocks, the MR2 Roadster stays an easy to live with car.
Same goes for power. The 1ZZ makes for a lively car that does not bite you. As long as you don´t go to yonder side of 200 hp it stays forgiving.

It is a fundamentally friendy, forgiving car. Responsive, very responsive, to changes but fundamentally easy to live with.
Not many cars like that.

[Joesson]

@puma2
re '
other cars are available may as well by a Lotus Elise ha ha ' < if only the purse strings would allow, plus I strongly suspect I wouldn't fit into one :-)

Where is your sense of adventure?!

https://www.youtube.com/watch?v=ZOMXCW7uK4U&ab_channel=CarThrottle

That does look vaguely familiar!!

[1979scotte]

@puma2
re '
other cars are available may as well by a Lotus Elise ha ha ' < if only the purse strings would allow, plus I strongly suspect I wouldn't fit into one :-)

Also the MR2 is fundamentally an easy to drive quite comfortable car. You can shed weight, add performance.
With an Elise you can not add the fundament of comfortable runabout.

In other words, you can change the MR2 to have a bit more hard core side when you wánt that and still have an easy to live with car for the rest of the time.
Mine is quite lively, some would say skittish but it remains the easy to live with quite comfortable runabout. Carpets or stereo are not comfort things for me. A compliant suspension is, having breathing space is, etc.

Unless you go silly hard/low springs with matching shocks, the MR2 Roadster stays an easy to live with car.
Same goes for power. The 1ZZ makes for a lively car that does not bite you. As long as you don´t go to yonder side of 200 hp it stays forgiving.

It is a fundamentally friendy, forgiving car. Responsive, very responsive, to changes but fundamentally easy to live with.
Not many cars like that.

They don't become less forgiving over 200hp imho.
Just too fast to fully enjoy on the road with your foot down.
I found my sp240 turbo to be very friendly it's only the ridiculous torque to weight you get from say a V6 that probably makes a 2 really bite. In the dry anyway. In the wet different story.