Project Weightloss: SM 02 WRX Wagon
05-30-2013, 02:59 PM
#1
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Project Weightloss: SM 02 WRX Wagon
So whenever I have a spare hour I just start taking things off my car I don't deem nessecary. This is basically a log for myself and others about weights associated with certain parts, and my quest for lightness.
So the way I started was to go through the SCCA Rulebook for the SM class and pick apart each rule to define what I could and could not remove, here is what I have gathered so far:
K. Rear passenger seat(s), including restraints and associated hardware may be removed.
O. Radio/Stereo and airbag equipment and/or its component parts, in-cluding wiring, control modules, antennas, amplifiers, speakers and
their enclosures, etc. may be removed provided the part added, removed, or replaced serves no other purpose. Any visible holes that
result from the removal of equipment must be covered with a cover of unrestricted material. Covers may be used to mount gauges,
switches, etc.
Q. Ballast may be added. Ballast must be a maximum of 50 lbs. per
segment. It must be securely mounted within the bodywork.
Rules used to determine weight allowances here:
2. Supercharged or turbocharged SM and SSM engines will be classified on a basis of adding 1.4L to the actual displacement. Forced
induction SMF engines will add 1.0L to the actual displacement
Cars running tires with a rated width of 275 mm or less on all four
wheels may compete at a minimum weight 200 lbs less than their
calculated weight.
AWD: 1800 lbs + 300 lbs per liter
Supercharged or Turbocharged SM engines: Add 1.4L to the actual
displacement.
Some Calculations:
2.0L turbocharged engine, modified displacement of 3.4L
300x3.4 = 1020lbs
1800+1020 = 2,820lbs
-200lbs (running 245 series tires) = 2620lbs
Realistically, there is no way I will be able to achieve this weight given the current rules. However, I can try to get as close as possible. I am going to be doing this a little backwards, I don't have a weight for the car yet. I am first going to take out as much as possible and then weigh her, then add the total of what I took out and see how well we did.
Pieces removed:
Rear Small Seatback:
Rear Large Seatback:
Rear Bottom Seat:
Replacement Pieces:
New Front Seat(One seat weight, not including brackets/sliders):
So the way I started was to go through the SCCA Rulebook for the SM class and pick apart each rule to define what I could and could not remove, here is what I have gathered so far:
K. Rear passenger seat(s), including restraints and associated hardware may be removed.
O. Radio/Stereo and airbag equipment and/or its component parts, in-cluding wiring, control modules, antennas, amplifiers, speakers and
their enclosures, etc. may be removed provided the part added, removed, or replaced serves no other purpose. Any visible holes that
result from the removal of equipment must be covered with a cover of unrestricted material. Covers may be used to mount gauges,
switches, etc.
Q. Ballast may be added. Ballast must be a maximum of 50 lbs. per
segment. It must be securely mounted within the bodywork.
Rules used to determine weight allowances here:
2. Supercharged or turbocharged SM and SSM engines will be classified on a basis of adding 1.4L to the actual displacement. Forced
induction SMF engines will add 1.0L to the actual displacement
Cars running tires with a rated width of 275 mm or less on all four
wheels may compete at a minimum weight 200 lbs less than their
calculated weight.
AWD: 1800 lbs + 300 lbs per liter
Supercharged or Turbocharged SM engines: Add 1.4L to the actual
displacement.
Some Calculations:
2.0L turbocharged engine, modified displacement of 3.4L
300x3.4 = 1020lbs
1800+1020 = 2,820lbs
-200lbs (running 245 series tires) = 2620lbs
Realistically, there is no way I will be able to achieve this weight given the current rules. However, I can try to get as close as possible. I am going to be doing this a little backwards, I don't have a weight for the car yet. I am first going to take out as much as possible and then weigh her, then add the total of what I took out and see how well we did.
Pieces removed:
Rear Small Seatback:
Rear Large Seatback:
Rear Bottom Seat:
Replacement Pieces:
New Front Seat(One seat weight, not including brackets/sliders):
05-31-2013, 12:43 AM
#2
Cool. I need to start this as well on the EVO. Probably just easier to drop some body mass but I think I'll work on the car first! Did you get a chance to weigh the car before you started?
05-31-2013, 11:48 PM
#4
I'm doing the same thing with the miata.
Difference is, I'm at 1.8L + forced induction + 2wd + 275 tires or under, so my min weight is 2050. It's actually doable. I removed AC, stereo/wiring/speakers, any unneeded wiring, light seats, 2.3lbs battery, seat belts, roll bar, aid bags + sensors, emissions.
More expensive things that I may consider later are lighter alternator, carbon hood, trunk, fenders, Ti exhaust.
Difference is, I'm at 1.8L + forced induction + 2wd + 275 tires or under, so my min weight is 2050. It's actually doable. I removed AC, stereo/wiring/speakers, any unneeded wiring, light seats, 2.3lbs battery, seat belts, roll bar, aid bags + sensors, emissions.
More expensive things that I may consider later are lighter alternator, carbon hood, trunk, fenders, Ti exhaust.
06-01-2013, 12:48 AM
#5
I think that the biggest weight reductions requiring money would include bumper beam (aluminum) front and rear,subframe, battery and exhaust for the Subaru. The deltas would be large.
The rest would be free (just gut).
You may want to attack it based on the heaviest structures that you can modify separate from the ones you can remove completely.
The rest would be free (just gut).
You may want to attack it based on the heaviest structures that you can modify separate from the ones you can remove completely.
06-01-2013, 01:05 AM
#6
Well, based on the rules, I can go to 2820 but I'll get no where near that. I saw one guy get his X down to just under 3000 but heck, I can't live without A/C. I'd be happy with ~3300. I'm use to being slower than Cory anyway..........
I'll keep watching this thread as it gets me motivated...
I'll keep watching this thread as it gets me motivated...
06-01-2013, 05:48 AM
#7
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I think that the biggest weight reductions requiring money would include bumper beam (aluminum) front and rear,subframe, battery and exhaust for the Subaru. The deltas would be large.
The rest would be free (just gut).
You may want to attack it based on the heaviest structures that you can modify separate from the ones you can remove completely.
The rest would be free (just gut).
You may want to attack it based on the heaviest structures that you can modify separate from the ones you can remove completely.
Subframes are prohibitively expensive.
Battery will be replaced with an oddesy 610 mounted in the spare tire well.
Exhaust is something to consider, however, I really like mine =(
.
06-01-2013, 11:35 AM
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Some input/advise since I have experience in all this.
Should've weighed the vehicle beforehand including the balanced weight. (Weight each of the wheels bears.)
This way if you really want to follow all the rulebook covers, implies, or has shades of grey, you'll benefit the most.
What am I implying here? Well, if you unbalance the vehicle while reducing weight it is no-good. Now, if say you lighten the car while retaining it's balance characteristics you will have an advantage most other novice to mid-pack racers don't expect.
I know you probably already are factoring this in the fact you can add ballasts later on. Keep in mind you'll also have to figure vehicle dynamics once you've pulled parts versus a recorded baseline at each tire.
Nice topic too!
Hole saw, c-clamps, and dimple-die kit FTW. (Need the c-clamps to compress the dimple-die tool.) Use caution where placing the holes and dimples. Remember the structure is designed with translated forces and shear forces factored in. Put a hole or dimpled hole where it shouldn't be and you've just changed the safety characteristics of your unibody. Too bad Vermont SportsCar is so far away, I'd say take a look at how they handled these bits.
/GeekFest
Should've weighed the vehicle beforehand including the balanced weight. (Weight each of the wheels bears.)
This way if you really want to follow all the rulebook covers, implies, or has shades of grey, you'll benefit the most.
What am I implying here? Well, if you unbalance the vehicle while reducing weight it is no-good. Now, if say you lighten the car while retaining it's balance characteristics you will have an advantage most other novice to mid-pack racers don't expect.
I know you probably already are factoring this in the fact you can add ballasts later on. Keep in mind you'll also have to figure vehicle dynamics once you've pulled parts versus a recorded baseline at each tire.
Nice topic too!
Hole saw, c-clamps, and dimple-die kit FTW. (Need the c-clamps to compress the dimple-die tool.) Use caution where placing the holes and dimples. Remember the structure is designed with translated forces and shear forces factored in. Put a hole or dimpled hole where it shouldn't be and you've just changed the safety characteristics of your unibody. Too bad Vermont SportsCar is so far away, I'd say take a look at how they handled these bits./GeekFest
Last edited by TheFozz; 06-01-2013 at 11:41 AM.
06-01-2013, 01:01 PM
#11
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Car Info: 02 WRX Wagon
Its only ~15 lbs saved on a tube subaru front subframe, but the real benefit is that tight feeling you just can't get any other way but tubing a bunch of stuff together. It's a similar feeling to the first drive with fender braces on the car, but magnified 10 fold in every direction. It felt so good in the front that I gave up on having a street car and caged it. Now I'm saving/waiting for an excuse to get the rear subframe and t-bar for another ~25 lbs savings and more stiffness. Still, it's not the BEST value for your dollar, and when you stuff it you'll end up tweaking the whole chassis instead of a cheap, replaceable, OEM subframe.
tss | TSS Rear Subframe
By your rule set I would be allowed 300(2.5L+1.4) +1800(for AWD) -200(for 245/40/17) = 2770lbs
My wagon was down to ~2880 wet before I replaced the OEM passenger seat(~35lbs) with a Sparco Fighter seat and custom rail. I still have the heater box to pull out (~45 lbs), passenger air bag unit (~20), and I'm thinking of ways to gut my rear doors while keeping some kind of adjustable window. It seems like I might actually be able to hit that 2770 number, which means that you can also get pretty close.
tss | TSS Rear Subframe
By your rule set I would be allowed 300(2.5L+1.4) +1800(for AWD) -200(for 245/40/17) = 2770lbs
My wagon was down to ~2880 wet before I replaced the OEM passenger seat(~35lbs) with a Sparco Fighter seat and custom rail. I still have the heater box to pull out (~45 lbs), passenger air bag unit (~20), and I'm thinking of ways to gut my rear doors while keeping some kind of adjustable window. It seems like I might actually be able to hit that 2770 number, which means that you can also get pretty close.
06-01-2013, 01:22 PM
#12
Oh I like this thread...
Would that make much of a difference if you were to corner balance the car anyway?
I think an interesting thing to do would be to way the car off the suspension and see how the weight is distributed across the chassis. Obviously the CG will move towards the left front. But it would be cool to know by how much.
**** dude, I knew you were doing work on that thing. But DAMN.
Some input/advise since I have experience in all this.
Should've weighed the vehicle beforehand including the balanced weight. (Weight each of the wheels bears.)
This way if you really want to follow all the rulebook covers, implies, or has shades of grey, you'll benefit the most.
What am I implying here? Well, if you unbalance the vehicle while reducing weight it is no-good. Now, if say you lighten the car while retaining it's balance characteristics you will have an advantage most other novice to mid-pack racers don't expect.
I know you probably already are factoring this in the fact you can add ballasts later on. Keep in mind you'll also have to figure vehicle dynamics once you've pulled parts versus a recorded baseline at each tire.
Should've weighed the vehicle beforehand including the balanced weight. (Weight each of the wheels bears.)
This way if you really want to follow all the rulebook covers, implies, or has shades of grey, you'll benefit the most.
What am I implying here? Well, if you unbalance the vehicle while reducing weight it is no-good. Now, if say you lighten the car while retaining it's balance characteristics you will have an advantage most other novice to mid-pack racers don't expect.
I know you probably already are factoring this in the fact you can add ballasts later on. Keep in mind you'll also have to figure vehicle dynamics once you've pulled parts versus a recorded baseline at each tire.
I think an interesting thing to do would be to way the car off the suspension and see how the weight is distributed across the chassis. Obviously the CG will move towards the left front. But it would be cool to know by how much.
Its only ~15 lbs saved on a tube subaru front subframe, but the real benefit is that tight feeling you just can't get any other way but tubing a bunch of stuff together. It's a similar feeling to the first drive with fender braces on the car, but magnified 10 fold in every direction. It felt so good in the front that I gave up on having a street car and caged it. Now I'm saving/waiting for an excuse to get the rear subframe and t-bar for another ~25 lbs savings and more stiffness. Still, it's not the BEST value for your dollar, and when you stuff it you'll end up tweaking the whole chassis instead of a cheap, replaceable, OEM subframe.
tss | TSS Rear Subframe
By your rule set I would be allowed 300(2.5L+1.4) +1800(for AWD) -200(for 245/40/17) = 2770lbs
My wagon was down to ~2880 wet before I replaced the OEM passenger seat(~35lbs) with a Sparco Fighter seat and custom rail. I still have the heater box to pull out (~45 lbs), passenger air bag unit (~20), and I'm thinking of ways to gut my rear doors while keeping some kind of adjustable window. It seems like I might actually be able to hit that 2770 number, which means that you can also get pretty close.
tss | TSS Rear Subframe
By your rule set I would be allowed 300(2.5L+1.4) +1800(for AWD) -200(for 245/40/17) = 2770lbs
My wagon was down to ~2880 wet before I replaced the OEM passenger seat(~35lbs) with a Sparco Fighter seat and custom rail. I still have the heater box to pull out (~45 lbs), passenger air bag unit (~20), and I'm thinking of ways to gut my rear doors while keeping some kind of adjustable window. It seems like I might actually be able to hit that 2770 number, which means that you can also get pretty close.
06-01-2013, 02:11 PM
#13
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There is some good info (though, admittedly, among a lot of bull****) in this thread: NASIOC Weight Reduction thread
06-01-2013, 06:04 PM
#14
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Thats what my wagon looks like for the most part, however no sound deadening. Also, I am required to leave in all the plastic trim bits.
Update:
Seatbelts are out, I will weigh all that + some misc brackets that broke off tomorrow.
Still need to:
Take out rear speakers
Oddesy Battery relocated to spare tire well
Possibly remove some deadening tar
Maybe something with the front bumper beam but I don't know what exactly is allowed and what isn't allowed.
Update:
Seatbelts are out, I will weigh all that + some misc brackets that broke off tomorrow.
Still need to:
Take out rear speakers
Oddesy Battery relocated to spare tire well
Possibly remove some deadening tar
Maybe something with the front bumper beam but I don't know what exactly is allowed and what isn't allowed.