Weight reduction

OK, I know we have a 3600+ lb car so small weight savings take a while to add up. However, the relatively minor changes I've made (especially for track days) seem to have made an arguably significant dent.

Enkei PF01 wheels/Hoosier R6 295/315:
Front 60 street vs 45 - 15 lbs each x 2 = -30 lbs
Rear 58 street vs 49.2 - 9 lbs each x 2 = -18 lbs
Corsa Extreme axle backs (pair) 54 lbs stock vs 24 lbs = -30 lbs
Kooks Off-Road H-pipe 32 lbs stock vs 17 lbs = -15 lbs
Side pipe delete 5.5 lbs each = -11 lbs
Kooks LT headers vs stock manifolds = + 3lbs
Roll bar, mounts & harness bar +69 lbs.
Rear seat delete kit +12 lbs.
Remove rear seats and belts and factory mounts -54 lbs
Swap to the Tiger Hood -17 lbs
Remove washer bottle incl fluid -8 lbs
Remove flat repair kit -5 lbs
Sparco race seat 35lbs versus stock seat 46lbs = -11 lbs
302S tow hooks +2 lbs
FRPP air-to-oil cooler +8 lbs
1-pc DSS aluminum driveshaft vs stock -21 lbs
DS saftey loop +10 lbs
Trunk liner -7 lbs
Passenger seat -46 lbs (track only)
Watts link versus panhard bar +15 lbs
Rear axle weights -5 lbs
Battery relocation kit +25 lbs
Remove A/C condenser, compressor, lines and belt -21 lbs.

Total weight savings so far is 116 lbs with passenger seat and 162 without it.

With a curb weight of 3630, I'm at 3514 to 3468 with or without the passenger seat.

 

[twistedneck]

If i had a lot of extra cash I'd get full carbon fiber doors inside and out (with the lexan sliding glass)
also lexan quarter windows.. Front and rear windshield use light weight glass.
Carbon fiber dash
Anderson carbon roof
Carbon fiber seats set as low as possible. (thats fun to drive)
Carbon deck lid

These changes would really save some weight high up from the ground.

Can we relocate the battery to the PS back seat floor boards? that way you can keep the 32lb factory battery and it actually helps the car handle.

 

[TeeLew]

Can we relocate the battery to the PS back seat floor boards? that way you can keep the 32lb factory battery and it actually helps the car handle.

Completely under-rated change &100% a positive (with the exception of a little extra battery cable weight). Anything to shift weight off the nose and onto the rear tires is an advantage.

 

[twistedneck]

Completely under-rated change &100% a positive (with the exception of a little extra battery cable weight). Anything to shift weight off the nose and onto the rear tires is an advantage.

I wonder if it would be better on the back trunk corner, or even deeper in the spare tire area? it would be closer to the centerline sure, but sits a lot lower there.

 

[TeeLew]

I wonder if it would be better on the back trunk corner, or even deeper in the spare tire area? it would be closer to the centerline sure, but sits a lot lower there.

It's best to keep it between the axles, so I sacrifice the vertical position to get the better position in plan view. I bet either is valid. The important part is getting it off the nose.

 

[JDee]

This isn't a simple solution topic for most of us. Battery cable is heavy and you need to upsize it from stock for longer runs that draw high amps like a starter circuit does. Added weight is not good no matter where it is.

I also tried the tiny batteries in the stock position and they were unreliable in starting a hot engine. Got real old when you hit the ignition and the engine went bump bump click click and didn't turn over. Had to carry a stock battery and cables, a real PITA. And a spin on track that kills the motor can result in a no re-start and you've just ruined everyone else's session when they have to get the truck out to tow you in.

I did this with my '16 and ultimately went back to a stock battery in the stock position. For a mixed use car it just made more sense. There was little to no weight saving once you figured in the heavy positive cable, it shifted some weight back but overall it added weight. Changing from a big battery to a small one for every track day was a PITA, plus the unreliability of the small battery to start a hot engine.

If this was a race car doing real racing then sure, you're going to do this. But most of us have mixed use cars and you can only strip out so much weight. For that use case there is no good solution.

 

[TeeLew]

This isn't a simple solution topic for most of us. Battery cable is heavy and you need to upsize it from stock for longer runs that draw high amps like a starter circuit does. Added weight is not good no matter where it is.

I also tried the tiny batteries in the stock position and they were unreliable in starting a hot engine. Got real old when you hit the ignition and the engine went bump bump click click and didn't turn over. Had to carry a stock battery and cables, a real PITA. And a spin on track that kills the motor can result in a no re-start and you've just ruined everyone else's session when they have to get the truck out to tow you in.

I did this with my '16 and ultimately went back to a stock battery in the stock position. For a mixed use car it just made more sense. There was little to no weight saving once you figured in the heavy positive cable, it shifted some weight back but overall it added weight. Changing from a big battery to a small one for every track day was a PITA, plus the unreliability of the small battery to start a hot engine.

If this was a race car doing real racing then sure, you're going to do this. But most of us have mixed use cars and you can only strip out so much weight. For that use case there is no good solution.

You did it wrong.

 

[Scootsmcgreggor]

You did it wrong.

Mind to share your thoughts on how to do it right instead of this wonderfully helpful post?

 

[TeeLew]

Mind to share your thoughts on how to do it right instead of this wonderfully helpful post?

Well, first, just completely throwing a 1% weight distribution shift (which is massive) out for a couple pounds of battery cable. He's already made his decision that weight is everything. Why take that statement at face value? With the older live rear cars, NASCAR teams used to qualify on full tanks because the rear weight distribution was more important than the overall. There are only a handful of fundamental changes you can make to a car and this is one of them. Disregarding it or arguing otherwise just makes me shake my head.

Second, in attempting to drop weight, he was going after light batteries that couldn't spin the motor over. That's not the fault of putting the battery in the back. There's just not that much of a voltage drop over the run unless you're using very marginal wire sizes. It's likely the fault of using inappropriate batteries.

My car is mixed use and I stuck the stock battery in the back about a month after I got it. It's been there ever since bothering no one for the last 50k miles. It helps in braking, forward traction and mid-corner balance. It's not just me saying this, it's Newton. Blame him.

 

[TeeLew]

Now I'm going to talk about something I've done to which seems to conflict with what I was saying above.

I've gone through quite a bit of effort to replace my cast iron differential housing with an aluminum one. I did make this change for several reasons, but chose to continue even though it will increase front weight distribution. The cast iron housing/torsen diff is 32# heavier than the aluminum housing / traction lok diff combo. 100% of this weight is taken on the rear axle. So it definitely hurts weight distribution to lose the weight here.

The difference between this and the battery in this is weight you don't *have* to carry. The battery is something you have no choice but to carry. The addition of maybe 5# of cable gives a favorable cg shift. We often carry a little extra weight to improve handling. To me, running the battery in front as a weight saving measure is similar to running a smaller front tire to save weight. Yes, it saves weight, but the car is slower in the long run.

 

[twistedneck]

Now I'm going to talk about something I've done to which seems to conflict with what I was saying above.

I've gone through quite a bit of effort to replace my cast iron differential housing with an aluminum one. I did make this change for several reasons, but chose to continue even though it will increase front weight distribution. The cast iron housing/torsen diff is 32# heavier than the aluminum housing / traction lok diff combo. 100% of this weight is taken on the rear axle. So it definitely hurts weight distribution to lose the weight here.

The difference between this and the battery in this is weight you don't *have* to carry. The battery is something you have no choice but to carry. The addition of maybe 5# of cable gives a favorable cg shift. We often carry a little extra weight to improve handling. To me, running the battery in front as a weight saving measure is similar to running a smaller front tire to save weight. Yes, it saves weight, but the car is slower in the long run.

And, you have better suspension quickness and less unsprung mass in the rear suspension! Did you notice right away the small bump compliance was better?

I have a set of aluminum valve covers i plan on putting on (these don't use the plastic coil covers) and they are clearly heavier than the plastic and in the wrong place but A. the look f'n cool and B. they don't let the engine dissipate heat as well as the aluminum ones. We all know how hot the coyote oil can get!

 

[TeeLew]

And, you have better suspension quickness and less unsprung mass in the rear suspension! Did you notice right away the small bump compliance was better?

I have a set of aluminum valve covers i plan on putting on (these don't use the plastic coil covers) and they are clearly heavier than the plastic and in the wrong place but A. the look f'n cool and B. they don't let the engine dissipate heat as well as the aluminum ones. We all know how hot the coyote oil can get!

I'd be lying to you if I told you i could tell a difference. The housing and diff were worth 32#, but I added a finned rear cover which added back 11# (it avoids a pump/cooler assembly). My total delta was 21#. That's a tidy little gain, but a butt has to be better calibrated than mine to feel it.