weight reduction - any ideas?

[glacialmoraine]

So, reducing weight is a performance mod that is easier than upping horsepower, and it directly impacts power to weight ratio. I couldn't find a thread that lists good ways to reduce weight and keep a car streetable, so here we go...

How much weight does removing the bumper rebars and keeping the cover save (86+ I think)

How about all carpet, and sound padding?
Carpet in trunk?
plastic in frunk?
Plastic in wheelwells?
plastic body kit?
Door panels?
spare tire (only while racing)

what other areas can be cut? How much weight can be cut without completely stripping it (removing dash, doorpanels, etc. etc.)

Don't have an mr2 yet, but I'm shopping around. Soon maybe.

thanks,

GM

[mr2parts.net]

My trunk has nothing in it because I had my quarter panels fixed and the carpet in it was nothing fantastic. I am not sure how much weight it saved, but I will tell you that my trunk gets HOT!

So if anyone does this, it is pretty safe to say, you have a trunk with no function at all. I made the mistake of putting a gallon of milk back there in a paper bag and when I got home, the milk was hot.

[Medusa]

I wouldn't remove the plastic in the wheel wells, it will negatively impact your aerodynamics and make it REALLY noisy.

And mr2parts.net is right, my trunk gets pretty warm with the liner in it. I wouldn't take the liner out unless I was racing.

And if you are driving your car on the street, I wouldn't remove any bumper supports (I am assuming this is the rebar you are talking about), that is a great way to get yourself killed in a collision.

Honestly, without starting to strip the interior, there isn't too much weight reduction you can do. You can replace heavy parts (Wheels, steering wheel, seats, etc.) with lighter ones. You can strip the stereo system and Ac out also. There is sound insulation gunk underneath the carpeting which you can pull off the frame, which should save you a dozen or so pounds IIRC.

[Wheelman_13]

-Removing the bumper beams will not significantly increase likelihood of death in an accident. It will however increase the likelihood of something more expensive getting damaged in a small collision. think radiator, rear bodywork/exhaust/etc. A non-airbag wheel is a much more dangerous conversion than removing the bumper beam.

-As mentioned AC/Heater core/radio/antenna motor & associated wiring all will save quite a bit of weight.

-Going with an FRP or CF hood and/or trunk will save a good bit of weight. I didn't realize how hefty the trunk lid/spoiler was until I took mine off over the winter.

-there is a backing plate that is behind the plastic under-dash panel in the foot well that weighs a few pounds but doesn't really do anything.

-You could remove the carpet and discard the padding underneath and put just the carpet back in if you wanted to keep it.

-Lightweight battery

-lighter seats will go a long way

-convert to fixed headlights

-Lexan rear window if you are going to be hard-core about it. If this is just going to be a hard-parker with a braggably low weight, this isn't worth it because you lose defogging ability.

-buy a slick-top/sunroof car in the first place with no power steering & wind-up windows = ~300lb savings vs. T-Top.

-consult a medical professional to determine if you are at an ideal weight. between last autocross season and this one I lightened my "car" by ~10 lbs just by running a bit and not eating so damn much

-Drain the windshield washer fluid

-Remove the wipers (if you are in so-cal)

-I usually start an autocross event with the fuel light just starting to glow, and it has yet to starve out. Gas is heavy ~8-9 lbs/gallon or something like that.

-discard every other screw holding the bumper covers on

-completely discard the passenger seat, if you are that concerned with weight, you don't want some porker sitting over there anyway.

-light-weight lug nuts

ok, I'll stop now.

[tstoney82]

plenty of exercise and a sensible diet.........

try getting rid of everything you dont want or need. removing a/c pump, lines, and so on can save weight and add power. you can also remove the passenger seat (and put it back in when you go on dates) this should save about 30 lbs. if its leather, it would be more. but you can go further than that and take the carpet and padding out and save more weight that way.

[mr2parts.net]

Originally Posted by Wheelman_13

-Going with an FRP or CF hood and/or trunk will save a good bit of weight. I didn't realize how hefty the trunk lid/spoiler was until I took mine off over the winter.

I can attest to that. For my '85, I attained a rare CF trunklid. Stock OEM trunklids WITH a spoiler weigh 25lbs. My CF trunklid only weighs 7lbs

[FrankYates]

Just the sound deadening off the back wall is near 10lbs I think (I still have it sitting in a bag in the garage), I'm in the process off removing it off the floor pans as well I'll weigh it all when I'm done. The padding on the back of the carpet is pretty heavy as well but I kept it to reduce some engine noise at least. A lighter exhaust would help to just make sure it still has some back pressure.

[328FTW]

Originally Posted by FrankYates

A lighter exhaust would help to just make sure it still has some back pressure.

Backpressure is the worst thing in an exhaust, you want exhaust speed not backpressure, in other words don't use oversized pipe on your n/a. A 4 inch exhast system on a 1600 is what kills torque not backpressure. Not being rude or anything just sick of the backpressure=torque myth

[glacialmoraine]

328ftw

In a way the backpressure myth is sort of right, but the pressure is an effect not a cause.

Gas comes out of the exhaust port at x pressure, y speed. If the size of the exhaust pipe is too big, pressure and gas speed decrease. If the size of the pipe is correct, pressure stays the same and velocity is maintained. The pressure of a gas is tied to how big of a hole you are trying to stuff it through. Smaller hole, higher speed, higher pressure. Bigger hole, slower speed, lower pressure.

The pressure is of little consequence, it is a neseccary symptom of the velocity remaining high, but the pressure is ultimately higher in a system with proper exhaust speed, than one that is too slow. So, there is higher pressure in a good exhaust than a bad one that is oversized. But, there is a lower pressure than with one that is too small.

Anyway, you are right in that adding pressure doesn't help, but other people are somewhat right in that maintaining some pressure is good, they just aren't understanding that the pressure itself is incidental, the exhaust velocity is what really matters.

So, back to the main subject, i've heard the exhaust is a big weight pig, so there is another area to reduce weight for sure.

I had a VW scirocco that I removed the US bumpers, which weighed a ton, and put on german bumpers which were very light. Either one is just as safe, its a damage issue. Bumpers do little in serious crashes, but a lot of crunch protection in small ones.

So i guess there is nowhere to get fiberglass engine or trunk lids anymore?

GM

[FrankYates]

I just finished off the sound deadening and weighed it all,
Off the back wall = 9lbs, 9oz
Off the floor pan = 7lbs, 9oz
Total = 17lbs, 2 oz

Ans I understand back pressure is undesirable but keeping it around what it has stock, until you mod the engine, helps with its performance.

[mk15mr2]

I would imagine rotational mass would do a lot for the mr2's especially with the low torque we have. Light wheels, buying same size tires from different brands actually have different weights. (tire rack specs section) Lighter flywheel with lighter pulleys are always nice. Oh cut off muffler, who needs that anyway?

[tjmr2]

Pitch the radio - tape deck - CD, amps, speakers, & grills. Don't forget the sub woofer under the drivers seat.

[streetrack 3vz ht]

muffler is way heavy plus its in the rear which means when you remove it your car will change directions easy..

you can drop 25 lbs and still use a lightweight muffler

when i got my v6 i removed the rear spoiler 15 lbs , trunk hinge 4 lbs , engine rain guard 3-4 lbs or so

lightweight muffler is next for me

lightweight wheels are huge and a flywheel does more then just remove weight , a heavy flywheel acts like a gyro which hurts the ability of your car to change direction

[mr2parts.net]

You could also ditch the interior sun visors and put a strip of tint / vinyl across the top of the windshield.

[fvillota]

take the engine out!
you'll save major pounds.
lol
just messing.. I'm taking notes if i ever do a race car. nice advice guys

[glacialmoraine]

So, what if we extend the question, now what about weight reduction mods that keep the car street legal, but little else.

Anyone know the weight of:
door cards
dashboard other than gauge cluster
center console
headliner
entire climate control system

this could get fun, I bet with enough shedding one could get a streetable car under 2k. just don't drive when you might need to defrost the windows...

gm

[328FTW]

Originally Posted by glacialmoraine

this could get fun, I bet with enough shedding one could get a streetable car under 2k. just don't drive when you might need to defrost the windows...

I saw an awesome simple solution to that the other day on a rally car, he removed all the vents etc so had no defrost so he put one of those wire defrosters for rear windows on the front. It heats the window and keeps it clear, you can get them from parts stores to suit different models, just pick one that is the right size. It was one of those "why didn't I think of that?" ideas.

You do have to look through it but it is hardly noticable once you are used to it.

[Wheelman_13]

How does that work, is it like a bit sticker with the wires running through it or something?

[glacialmoraine]

Another option on defrosting, is to roll down the windows. Frost is caused by the inside of the car being warmer and moister than the outside. If you roll down all the windows, the temperature and humidity equalize, and no more frost. I drove a VW van in the winter for years with no heat, I just opened the vent windows and directed cold air at the windshield, and dressed really warm. Since the MR2 doesn't have vent windows you would have to roll down the main windows to equalize temp at the windshield. brr.

[mr2parts.net]

Or just leave your windows down ALL the time so there is 100% equalization at all times