Highway8

iTrader: (11)

Thread bump.

Has the OP made any progress, any big weight reduction or plans?

I mentioned a few post up that I was going to have a custom crash bar made. I said I was going to use aluminum. That statement was when I was uneducated about metal, strength and weight.

My plan was to build an all custom front crash bar with aluminum. The idea was to move the bar higher to allow me to remove the plastic mazdaspeed piece at the top of the grill and improve air flow to the top of the intercooler which was mounted behind the crash bar.

After looking at the bar with my builder and working out the details, we came up with a good plan to meet my goal of less weight, improved airflow to the intercooler and keep the factory saftey feature of the crush cans.

Were going to remove the end caps and horizontal bar by removing the 6 spot wields on each end cap. He will be making new end caps and the horizontal bar with Chromoly plate and round tubing. Probably using .125" plate and 1.5" X .065 tubing. The tubing will be bent slightly to match the shape of the bumper. I will place some roll bar padding on the tubing.

Using the stock crush cans will insure the I still have the factory deisgned 5 MPH crash bar and using the chromoly will ensure strength but still remove significant weight. The factory crash bar weighs 16LBS. Most of the weight is the horizontal bar. I am guessing the crush cans only weigh 4 pounds or less combined, leaving 12 pounds for the horizontal bar. The 2 foot section of chromoly tubing will weigh 2-3 pounds and the two end plates another 2-3 pounds. So a total weight savings of 6-8 pounds.

Mounts for my splitter struts and a grand am style tow loop will be wielded on.

Cooling was also brought up. I have a FMI which created cooling issues. I went with a single custom intercooler and installed a secondary radiator to resolve the radiator temps, but my oi temps went way up. Come to find out, I installed my oil cooler lines upside down. I am going to remove the cooler, send it out for a Heat Dissipation coating and reinstall it with the lines correctly routed. I will add some foam sealant around the inlet duct to try and maxamize its cooling effeciency.

I am going to pull the single fluidyne cooler mounted on the drivers side. Send it out for heat dissipation coating and reinstall it with the lines ran correctly. At the same time I am adding some additional foam to maximize air flow.

I already had the bottom 4" cut off my intercooler to add a second oil cooler but now I am not going to install the second oil cooler (yet) and instead i will take advantage of the increased air flow to the radiator. Additionally I purchased some thin, flexible and yet strong plastic I am going to use around the intercooler to duct air to the intercooler and radiator. Intercooler is still going to get Heat Disspation coating and I increased the air flow to the top 4 inches of the intercooler by modifying the stock crash bar.

Weight Savings and increased cooling idea for NA vehicles:

Dont go jumping the gun just yet, let me make sure my oil temps are good first.

The idea is to remove the dual oil cooler setup. With the long lones and dual coolers it is both restrictive and heavy. A low effeciency to weight ratio. If you pull the entire oil cooler system. Use highpressure fexible 12AN lines and fittings with a real oil termostat ran to a single large oil cooler on the drivers side, My guess is that you will remove about 10LBS. I hav ethe stock coolers in my garage that I should weigh so you know what your starting with.

Additionaly, do the above crash bar modification and cut out or replace the factory plastic grill (if using stock bumper) to remove weight and improve radiator air flow. You can always tape up the bottom of the grill latter if you have more cooling then you need.

In all, I bet you could get almost 20lbs off the front of the car while improving radiator cooling, probably a wash with oil cooling, but the systems work together so keeping the radiator lower will keep the oil down too.

Like I said, I will find out soon if the single oil cooler will do the trick. BTW its a fluidyne DB-30416 Single-Pass Engine Oil Cooler. They have a DB 30417 dual pass unit that is the same size. Honestly it would be the better unit. I got mine for a great deal otherwise I would have done the 30417. These coolers are bigger then the stock duct openings but fit perfect into the mazdaspeed bumper openings.

TeamRX8

iTrader: (25)

it's relatively easy if you have no limitations like racing class rules etc. Then your only limitation is your wallet ...

c0ldf1ame

iTrader: (5)

just got corner balanced, my car is a pig T_T

TeamRX8

iTrader: (25)

care to clarify?

c0ldf1ame

iTrader: (5)

3168lbs with me in it, i think most of it is all the bracing i added on a while back, car is a GT, im on stock rims n tires right now so once i get my gramlights back it should help a little bit, other plans include getting rid of some of the bracing, and 2peice rotors, maybe another bucket seat for the passenger

TeamRX8

iTrader: (25)

OK, wasn't sure if you were referring to handling or weight

shr3da

anyone done any weight reduction recently? I have started on mine, however still making the interior appear reasonably attractive is another issue.

bse50

The only way to reasonably lose weight inside the cabin is turning the car into a proper race car... door panels, seats, airbags, glovebox, roof liner, audio all have to go.

If you know how to work with carbon fibre you could limit yourself to removing the center console and ashtray and making a cf cover while also replacing the glove box with a cargo net.
Ugly and without a really noticeable difference = waste of time though.

shr3da

I actually like the look of a nice clean race interior, but that's is getting a bit off subject.

Fiberglass or aluminium is also a good option for a replacement panel in the centre console, if cf is not an option.

Just thought this thread deserved a bump as there is some good info in here and to see any updates from previous members who posted in this thread.

bse50

I love how a race car's interior looks as well but in reality that's barely "clean".

An aluminium or frp panel would be an even easier solution, you're right. All you'd have to do would be cutting it to fit and using some long bolts to thread it on some of the existing holes.

An almost fully stripped rx8 + Fia compliant cage tops the scale at around 1250kg. Not exactly a feather weight (with 2pc rotors etc, lightweight battery and oe exhaust + aem intake, 2 bucket seats and harnesses, no aircon etc). You can shed some more weight with a lightweight exhaust setup, 17in wheels and tyres etc but to really lose weight the investment grows pretty fast. Without the FE45 cage it would be around 1190\1200kg.

shr3da

some good points, I would be happy to loose 100kg, when my suspension was set up it, and we put it on the scales it was just under 1400kg with me and petrol adding about 100kg.

I would be happy to loose 80 - 100 kg without spending too much money on replacing parts, battery, exhaust, wheels ect.

You can notice the difference when the rear seats are out or your lady friend is in the car, 100kg would be a substantial performance increase, in handling, braking and acceleration.


Right now my cars weight balance is 49.3% rear and 50.7% front, with 736kg on the front axle and 651kg on the rear I wonder how this will be affected with a stripped interior.

bse50

I would focus on the engine bay weight savings before stripping the interior.
Just an aem intake and lightweight battery (18lbs) would yield a noticeable difference. Mostly because you'd be shedding weight that's ahead of the wheel axle. The same weight removed from the interior might not be noticeable at all instead.
What do you use your car for? some mods may not be smart for a daily driven car though. Especially if it sits in stop and go traffic.

JantzenRX-8

iTrader: (9)

The center console really isn't that heavy. I had mine out the other weekend and i was really surprised how light it was. Not low hanging fruit by any means.

Here are some weights from my last weight reduction session. weights are in lbs.

Seat Belt (2) 3.56
Rear Seat Back (2) 12.42
Rear Speaker Grill (2) 2.86
Center part of rear deck 2.05
Plastic behind rear seat backs (2) 1.18
Interior 1/4 panel (2) 3.38
Trunk panel sides (2) 2.64
Center pass through 1.76
Seat belt receivers (2) 0.96
Child seat retainers (2) 0.22
Trunk carpet 2.95
Trunk plastic 2.24
Trunk jack holder 1.71
Rear seat bottoms (2) 10.58
Air pump 2.57
ACV Valve (I think...whatever is attached to the airpump and exahust manifold) 1.87
Misc engine bay parts (battery tray, engine hoist, air pump brackets, misc plastics etc) 5.49
Total: 58.44

Front speakers are about 3.5 lbs each, head unit is ~12 lbs. I haven't removed them yet though.

Spin9k

washer bottle/pump ~1.5lbs.

etzilon

It is a "1 pound less here, 1.5 pound less there" exercise. If you want 10+ lbs targets, you need to start looking at intake, exhaust (especially factory manifold), battery, A/C, etc.

Another "easy" target weight wise would be seats, but now you're dealing with safety, airbags, etc. which makes it really complicated.

blu3dragon

iTrader: (1)

Seems like the rear seats should be the first to go, followed by replacing the stereo with an ipod. 12 lbs just for the head unit is huge. Is that the base one, or GT spec?

JantzenRX-8

iTrader: (9)

Ah, good point. Mine is the Bose version out of a GT. It weighs ~12 lbs.

blu3dragon

iTrader: (1)

Interesting data, thanks for sharing. Is this a series 1 GT? Any weight saving mods so far?

I'm at 3125 lbs, 53% front/47% rear in a stock series 2 sport with 1/3 of a tank and me in the car. I estimate 2960 lbs (1342.6 kg) with no driver or fuel.

736/651 looks a lot like 53/47 to me as well...

TeamRX8

iTrader: (25)

getting weight off the rear is easy, the front not so easy,

balancing out the left side weight also not so easy without adding it all back

there are some other past threads on the forum with parts weights and what other people are at

shr3da

Good points something I had not thought of. This is definitely not a daily driver, except will retain some street legality.

its an AUDM 03 model (aus spec with leather seats, boose, and no sunroof)

I noticed a little less body roll when I removed the rear interior. Regarding the weight distribution I was just reading of the sheet that the suspension shop provided me with when we did a corner balance with my new coilovers, perhaps it does not take into account the weight in the middle of that car?

Team, I know you have done some weight reduction while not touching the interior, I have had a lot of trouble finding where it was documented on the forum?

I am all about balance, is it possible to unbalance your car from stripping the interior or other areas that will have a negative effect on the balance and untimely the handling of that car?

I have also removed the engine bay carpet/fiberglass lining, it weighed about 200grams

Spin9k

We all know how to loose weight, difficult as it is in the 8, as everyone here is pointing out. However, there is a point where body focused weight reduction is like pounding sand...painful and not very productive. When you reach that with your particular car, based on what you're willing to toss, it becomes more helpful to focus on optimizing grip, i.e., suspension tuning w/the goal of optimal tire/track contact, best rubber compound, wheel and tire weight, damping and overall suspension balance.

Beyond that, and often more important than grams alone, missed items are simply ridding your own body of both physical and mental burdens that discourage performance. Exercise and stamina help alot. Recording good track data for a circuit allows (with some quality time studying) calculating your optimal braking points, max cornering speed vs. your car's known lateral g's potential, and then the ability to practice these calculated results on circuit to see the results. You can often rid seconds not pounds quicker doing these things that others don't even realize are there for the taking.

olddragger

iTrader: (3)

the heaviest thing in the interior is the wiring harness. It is huge and heavy.
For a street car--there is nothing you can really do about it though.

bse50

Glass.
Heavy.
5mm lexan, around 50% lighter.

If you have a cage and the rules allow, cf roof. Cheap and saves weight way above the roll center.

I have also found a cheap (15$) washer tank than only holds 500cc of water. The aluminium bracket I built weighs 100g, the tank with the pump around 400g. The HID washer nozzles become unoperational.
Even the front fake grille weighs. An aluminium one saves some ounces.

You can make this car consistently lighter but it requires perseverance and most of the mods won't be noticeable at first, unless you do them all at the same time. A drill and a hacksaw can work wonders as well. Again, if the rules allow.

Most of the items worth removing are the same items that draw the line between a dedicated track car and a sporty daily driver. That's the real problem. Seats, wiring harness, seatbelts, airbags, steering wheel, door cards and panels, roof liner are all relatively heavy but extremely functional. There's no point in removing just "some" of them to be faster to go to the grocery store.
Cages are also heavy but they can be made to considerably stiffen the chassis (by welding them to the suspension pickup points ("struts") etc. They add a lot of weight but won't necessarily make the car a lot slower (gutted vs caged) despite bringing a lot of the weight loss back.

Aluminium uprights would be fun but they're generally sold for 4\5000$. Lightweight chromoly suspension linkage and tubular subframes would cost just as much.

All in all i'd say that the bare minimum for a caged rx8 would be 1200kg. 1180 if going nuts with a standalone ecu, no extra wiring, brake booster and expensive brake\suspension components.

More than weight reduction I guess we should be talking about "smart" weight reduction, based on our own, individual, needs.

Now, who can fab me a cheap titanium exhaust?

TeamRX8

iTrader: (25)

skip Ti for the exhaust, just make the the first several inches of the pipes exiting the exhaust flange 20 Ga. (0.035") Inconel 625 and the rest 20 Ga. T321 stainless

bse50

Inconel is extremely hard to find here, and way overpriced when compared to Ti... I mean, there's more difference between Ti\Inconel here than there is in the states.
Stupid third world country.