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IS 350 Weight Loss Program

50K views 54 replies 28 participants last post by  Piggity  
#1 ·
The IS350 is a heavy lady with a curb weight of 3527 pounds. I'd like to get some more performance out of her with some creative ideas. Moreover I want to reduce my 0-60 to the mid fours. As we all know, power to weight ratios mean a lot in regards to a vehicle's performance (take the lotus elise for example).

I'd like to see if anyone can come up with some unique ways to shed some weight off of our 350s and still retain the interior features (ie I'm not removing my nav etc). Let's set a goal for 100 lbs.

I'll start. The current wheels weigh approximately 26.5 for the rear and 26 for the front. Using the F sport wheels (20.5F and 21.5R) as a swap, I can shed approximately 21 lbs from my 350 (you could go with volks for a little more to shed if you prefer). This has an added bonus of shedding unsprung weight as well, but that's a different story.

So, we've got 79 pounds left to go. Let's hear some ideas...
 
#2 ·
carbon fiber hood should reduce the weight a little.
 
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#6 · (Edited)
Use light 17" wheels. Less unsprung weight=more agility, less rotational moment=better accelleration.

Get rid of the useless rear seat.

Empty the trunk of everything including the spare.

Buy a lightweight battery.

Only fill the gas tank to 1/2 (51 lbs less than when full)

Remove the manual and all the junk from your glove box.

Keep the winshield washer bottle 1/2 empty (4 lbs less than when full)
 
#11 ·
not attempting to rip the is350 apart. let's try to keep to keep the car as stock as possible without ripping out things like seats, stereo, etc.

I'm looking for CREATIVE ways to address some weight reduction. So far, I've got a decent list of the following mods:

1. Wheels (would anyone go with 18s over 19s for additional savings?)
2. Ceramic disc rotors that replace oem (not only will this reduce weight, but will also increase stopping performance when driven harder)
3. Light weight battery (looking for something with great performance and will not die after a couple of days from sitting. a loss of at least 10 pounds is preferred)
4. considering removing the spare tire and using fix-a-flat. i've not had experience with it though. any thoughts on this???
 
#18 ·
2. Ceramic disc rotors that replace oem (not only will this reduce weight, but will also increase stopping performance when driven harder)
Not sure how realistic this is from a cost standpoint. Something like a two piece rotor would be much more realistic.


3. Light weight battery (looking for something with great performance and will not die after a couple of days from sitting. a loss of at least 10 pounds is preferred)
Odyssey PC925 (or rebranded breatherin). I LOVE this battery. From my experience, the PC650 super light weight motorcycle batt is just a bit too thin on reserves. The PC925 is really the sweet spot especially considering the ISx50 has quite a few electronic doo dads.
 
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#14 ·
Carbon fiber will certainly make your wallet lighter... you'd have to replace fairly big parts of the car to get huge weight savings though and except maybe a hood it'd be custom parts

Wheels- Absolutely I'd go 18s. In fact that's what I plan to do with mine if I ever find a nice set of lightweight 5 spoke rims that look good.

Fix-a-flat will get you home, but you won't like what it does to the TPMS sensor supposedly-
Canned Fix-a-Flat and TPMS! Bad!

AAA (or Lexus roadside) will come tow you for free though if you leave the spare at home.
 
#19 ·
IS-F lotta car for a lotta money

STI - I know that the car is performance oriented, however coming from a lexus to a car with a sticker of 36k that does not have any of the following felt like taking a step back for 300 ponies and AWD. STI does not have, power seats, heated/cooled seats, auto-dimming rear veiw mirror, navi/bluetooth/voice commands, front seat leg room (THATS FRONT SEAT, we know the rear is equivilent), or a sunroof. If I was coming from a Scion, STI would be awesome, unfortunately I have been pampered by my IS for too long to go back to that level of amenity.

EVO - my fat ass dont fit! Well the ass does, the duty belt does not. And given all the brake problems Mitsubishi had with the release of the previous eclipse (three recalls within 6 months, the last of those being spontaneous failure of the brake booster assembly) I really dont feel that great about putting people I like or love in one. My personal preference.
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I have heard people talking about wheels, nobody has mentioned tires. Not alot of difference between different ones but may have a 5-10 pound total depending on what width you get, summer/winter/all season compounds and tread life expectancy. May be a spot for some research.

Another spot to shed a couple of pounds would be in some of the excess sound insulation, such as the inside liner on the under side of the trunk lid, and under the hood. Remove the pretty engine bay covering panels for a couple of pounds. Aftermarket intake would remove the huge factory set up for a savings of a couple of pounds. Depending on the materials involved an aftermarket exhaust may help a bit. If you dont use the backseats, pulling the seatbelts may not be a bad idea. I wouldnt pull the seats tho, that would look tacky imho.
 
#21 ·
I think its worth .1 second on my 0-60 time to have a spare tire, just me.
And just to note:

3527/306 = 11.526
3427/306 = 11.199 (losing 100 lbs)

3527/316 = 11.1614 (keeping weight and adding 10hp)

If you let the numbers do the talking, you should probably just try to tack on 10hp rather than gutting you're car, but that's just me.
 
#25 ·
shaving 100 lbs. is not going to have big improvement in acceleration. if you can shave 200 lbs, that might make some difference, but still will not make your car run mid 4 seconds. if you are that inclined to get to the mid 4 seconds, get a different car.
 
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#26 ·
i hate to shatter your dream, but your plan is completely unrealistic.

using the ISF as an example. its weight to power raitio is about 9.1 lbs per horse. the IS350 stock is ~ 11 lbs per horse. if you want the IS350 to get to 9.1 lbs per horse to achieve 0-60 of 4.5 seconds, your IS350 needs to lose at least 750 lbs to get close to 9.1 lbs/ horse. even if you removed back seat, changed to carbon fiber panels, lightweight wheels, eliminate spare, and other engine compartment lightweight upgrades, you still could not lose 700 lbs. not to mention the cost involved and what kind of car you will end up with. and even if you could eventually get to that point, you still have to upgrade brakes, suspension to handle the car right.

if you care so much about 0-60, your most sensible approach is to get a different car.
 
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#28 · (Edited)
Hi everyone I am new to this site! My name is kyle wanted to say hi and comment a little on this thread.

People keeping saying that if they want there 0-60 to be low do this and this to get mid 4 seconds. Seeing as these cars come stock 0-60 in 4.9 seconds as tested by motor trend(I think) wouldn't take much. Note the evo x does 0-60 in 4.9 as well and quater in 13.6 where I think motortrend tested our cars to be 13.5!!!

I own a 3000gt and have done a lot of time trying to get the weight down as much as I could possibly. I did everything from gutting the car to light weight parts. Now I dont suggest gutting the car since 1.its a lexus(why buy a lexus to loose the comfort?) or 2. unless you want this as a track toy!

The biggest things I noticed when i did my weigh in after loosing roughly 400lbs! was hood! The hood on a 3000gt is somewhere around 50-60lbs give or take forget the true weight and the hood I bought was light enough to straight arm one hand! The lexus hood I believe seems a little bigger(if anyone knows the weight please feel free to add that), so you could imagine by going carbon fiber hood you could loose significant weight. Could probably drop at least 30 plus lbs with a hood.

Another big weight lose is exhuast system. You would be surprised how heavy a full exhuast actually weighs compared to aftermarket! On a 3000gt depending if its non turbo-turbo you could loose somewhere around 50 lbs. For the lightest obviously a single shot exhuast will be lightest.

Other things are like stated intake, wheels are gunna be the best, hell even a flywheel makes a few lb difference plus it makes the car rev happy. Not to mention full exhuast intake probably looking at a extra20-30 hp give or take depending on the cars habits with exhuast/ little more with a single shot exhuast and intake. Plus you get that little extra sound.

If wanting lower et times go with exhuast and intake loosing weight and gaining power at the same time will be the best thing you cna possibly do to still retain a lot of interior features

Edit: another thing that will knock a considerable amount of weight is coilovers! Much smaller and adjustable, this is if you want to sacrifice ride comfort. Not to mention with less weight of coilovers and the adjustablility you will be able to set your car up for better launches meaning better et times
 
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#30 ·
The biggest things I noticed when i did my weigh in after loosing roughly 400lbs! was hood! The hood on a 3000gt is somewhere around 50-60lbs give or take forget the true weight and the hood I bought was light enough to straight arm one hand! The lexus hood I believe seems a little bigger(if anyone knows the weight please feel free to add that), so you could imagine by going carbon fiber hood you could loose significant weight. Could probably drop at least 30 plus lbs with a hood.

Another big weight lose is exhuast system. You would be surprised how heavy a full exhuast actually weighs compared to aftermarket! On a 3000gt depending if its non turbo-turbo you could loose somewhere around 50 lbs. For the lightest obviously a single shot exhuast will be lightest.

Other things are like stated intake, wheels are gunna be the best, hell even a flywheel makes a few lb difference plus it makes the car rev happy. Not to mention full exhuast intake probably looking at a extra20-30 hp give or take depending on the cars habits with exhuast/ little more with a single shot exhuast and intake. Plus you get that little extra sound.
IS350s don't have flywheels.

And full exhaust and intake don't add 20-30 hp to these cars. A full (ie illegal, remove cats) exhaust adds about 12 hp. Any legal axle-back only adds about 7. No intake adds more than 5. So at best you're talking 12 hp legally, 17 illegally.
 
#34 ·
BTW a clutch and a flexplate are pretty much exactly the same thing.

The only difference is in the application. Damn you take things literal some people say flywheel some say flexplate all mean the same thing
 
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#37 ·
They're really not.

A flexplate is a thinner, lighter part in the first place. They'll typically run in 6 pound range for OEM and maybe 4 lbs for a lightened after market one., and they go on automatic transmissions.

A flywheel is heavier, often in the 16-20 pound range, with "lightweight" ones ranging from 8-12, with a few just starting to approach the weight of a "normal" flexplate, and they go on manual transmissions.

There's a lot more weight to be "saved" on a flywheel than on a flexplate, because it's a much heavier part to start with. Why that is the case has to do with them having different strength/size requirements by connecting either a clutch (flywheel) or a torque converter (flex plate).

I recognize some folks might misuse the terms, but they're really not the same item. You sure can't swap one for the other.
 
#44 ·
Also to add to a douchery comment from you look at the picture you provided of the 3/s flywheel compare it to the 3/s flywheel I provided the pic then compare the flywheel you provided to the camaro see why some people call them flywheels???? If you can't figure that out and still wanna be a OCD little prick then be my guest. I didn't claim to know everything about cars in fact I stated this is jut a generalization from other cars I have seen. I know there was a flywheel of some sort that is on a auto. Not to metnion some people refer to automatic flexplates to flywheels (see link).


1976 Chevy GMC Camaro Flywheel - Automatic

Shop 1A Auto® for Chevrolet Camaro Flywheel Automatic Transmission 2.8L 173ci V6 1982-87 for your Camaro

eBay Motors: 82-86 CAMARO Z28 FIREBIRD TA V8 AUTOMATIC FLYWHEEL (item 220361141497 end time Mar-15-09 01:04:14 PDT)

Automatic transmission flywheels: Bulkpart transmission parts

I can keep going but pretty sure even you will get he point
 
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#48 ·
pretty much. The flex plate bolts onto the crankshaft, then has additonal bolt holes in them, then torque converter bolts slide through one side of those holes and bolt into the torque converter. The flywheel bolts onto the crankshaft as well, but has a smooth surface on the other side that the clutch friction material can grab onto. And thats basically the only difference.
This is from the exact guy who I quoted earlier BTW
 
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#49 ·
One attaches to a fluid coupling device, one attaches to a mechanical coupling device, that's a pretty large difference.

But as relates to THIS thread the relevant difference is there there's a LOT of weight to save with replacing a flywheel on a manual, and there's very very little weight to save replacing a flexplate on an automatic. Because a flywheel is a much heavier part to begin with.

You can replace a 20 lb OEM flywheel with a 6 pound after market flywheel on some cars, which would be a very noticeable difference.


Compared to replacing a 6 lb OEM flexplate with a 4 pound after market one. Which is sure as hell not worth the labor of dropping the transmission.
 
#50 · (Edited)
kkilmore, tune down your attitude a notch. Keep it civil and drop the name calling. I edited most of you post and cleaned the language a bit.

I am not quite sure why you're so angry and taking this such heavily. Secondly, the information that you are given and trying to fight so hard for is completely wrong. Knightshade's information is the correct information.

Flywheel and flexplate are two totally different component.s They both however act as a connection between crankshaft and transmission. A flex plate's main purpose in a engine is to be a gear that rotates the motor at intial start. It has no other purpose besides that. If every auto transmission vehicle was started any other way besides the use of a starter there woulnd't be a need for a flexplate.

A flywheel has TWO purpose;
1. Gear to start the vehicle
2. A friction area to connect the tranmission and motor. Without a flywheel a manual transmission vehicle will go nowhere.

Yes, you are correct that the two terms are used interchargably but it's typically misused by the average joes and not someone who has some knowledge about vehicles.
 
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#51 · (Edited)
er...well...
you could take out the 3 rear headrests too i guess, it doesn't really look tacky and you actually get a better view out the back but im not sure how much weight would be removed

and also maybe taking out the engine cover and the plastic pieces covering the rest of the engine?
 
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