STX Weight Savings
 

I'm sure all of this information is buried in the STX thread, but I'd like to get some specific feedback. I see some of you reporting weight down into the mid 2700s and I am nowhere near that, even starting with a base model car.


Here's what I have done so far, what am I missing?

Car is a 2007 base model sport package, which is supposed to be 2886 lbs from the factory. I never weighed it in stock trim, so I don't know.

Current weight: 2858 lbs with 1/8th tank of gas.


What I have done so far:

Wheels (15.6ish lbs)
Single exit somewhat lightweight exhaust (Header back)
Intake (Modified AEM to be ST legal)
Plastic engine cover removed
Stock intake system removed
Battery box removed
Washer fluid tank empty



What I know is still missing....

Seats (If able to hit 25lb min with slider, this could save 25 lbs per pair over stock sport seats)
Battery (Current battery is 26lbs, 2 lb LiFe battery could save 23 lbs)
Brakes (2 piece front/rear rotors will save 13.8 lbs, then another lb or two if I upgrade the calipers)
Tires (I'm currently running 255s, going to 245s will save 4lbs)


So with what I know is missing, my theoretical weight is in the 2790s. Where's the other 40+ lbs?


Thoughts/Questions:

Remove the front strut bar? Does it benefit the car enough to offset weight?
I'm running PSS9s. Don't know if these are heavier than stock shocks, but likely lighter ($$$$) options out there. I know just reducing the spring diameter from 70mm to 2.25in (57.2mm) will lighten up the shocks.
I'm currently running a stock rear bar, which weighs nothing and a Hotchkis MX-5 front bar (27mm). Would a 3 piece Speedway set up be any lighter?


What am I missing?

2 Piece rotors would save you a bit of weight, its not drastic as the other bits but its still weight savings :)

lots of custom mods specifically for the purpose rather than off-the-shelf purchases



Ps: all the specific feedback info was already posted in the STX thread(s). If you really want to know, rather than maybe have people who think they know and either regurgitate it up incomplete and/or incorrectly, you would be best served devoting your time to reading it directly there. Generally speaking, this is what distinguishes the knowledgable members from the rest. Real knowldege requires time and effort, at least for most people.


.

So you contributed a paragraph to tell me to sift through a thread (search noob) that has 131 pages and 3255 post to try and find the information I am looking for, instead of taking the same amount of time and contributing to the cause. Do you think that I have not done that already?

I feel I put together a constructive post and am looking for the outliers that I am missing. If you do not have any constructive input, please save yourself the time and us the frustration of reading your counterproductive posts.

Hi Shawn,

Welcome to STX.

I don't have the answer to your question, but I'll share my info as a comparison.

Last time I weighed my car, it was ~2720 with 1/8 tank. That's with aluminum shocks, 8" front springs, 7" rear springs, 8 lb battery, ~27 lb seats, header-back exhaust, a hollow steel front swaybar (Racing Beat), 2-piece rotors, aluminum front calipers, and a steel/aluminum front shock tower brace. I did not have a rear swaybar installed at the time. Team's car was even lighter in STX trim, and I think a good chunk of that was in the exhaust.

From what you've listed and what my car weighs, I can't really account for the other 70 lbs. Any chance your scales are reading high? Did you forget to remove your trunk junk?

A few additional random thoughts...

• I think you might be underestimating the weight loss on the brakes by about 10 lbs
• Chances are that your exhaust could probably be lighter
• My car is a 2004, so I have the smaller starter
• Talking about how light my car is reminds me what a hack driver I am

Good luck with the build. An STX RX-8 is a really fun car, even if it's not "the" car anymore.

Dave.
Thanks for the informative response. I agree, I need to find another set of scales to compare against.

I'll have to do some more research on brakes. If the loss is ~25lbs of rotating unsprung mass, that's huge.

I took the time to try and teach you a greater lesson. My bad.

What does an STX legal AEM intake look like?? Just curious.

With Rotational and unsprung weight even small #s go a long way.

The filter has to be in the area where the VFAD was located. You aren't allowed to remove the plastic tray that is under the VFAD, which is required to be removed for the AEM piping to extend down into radiator inlet area behind the front bumper. So you can either add a straight short pipe with a very short filter just past the radiator support, or you have a 90* elbow and then have a filter running sideways in front of the radiator support. In either case it requires a filter that will fit in there with the plastic VFAD tray across the bumper support in place. There's not much space, so not just any filter will do.

Alternatively you can have a box filter housing in the engine bay similar to OE, like Racing Beat or custom.

or you just google RX8 STX legal intake:

ICEngineering: STX RX-8: STX Legal Intake

TeamRX8, Highly aware of the SCCA rules for STX, as I have been running SCCA for 12years. I was just curious as to what Fourwhls had personally done with his setup, as maybe he tried something different. I can't get to creative out here with CALI smog laws, so I have the OEM box which is hard to improve upon anyways.

Cool, that's mine! But it's not an AEM.

Yes, it was nice of you to blog all your mods, the trials and tribulations. I linked it because it both demonstrates the concept as well as an alternative choice.

Update....My scales were off. Put the car on the scales the Match Tour last weekend and weighed in at 2778# with 3/8 tank of gas. Right where I thought it should be.

I am happy that the difference in weight is an even percentage. The car had a cross weight of 49.9/50.1 on both sets of scales with driver.

....Back to your regularly scheduled programming.

So does anyone have a list of heavy items easily removed to save weight, I'm talking anything that's not needed for racing that weighs the most-excluding seats already have that one covered. What I'm getting at is to have some kind of list from heaviest things that can be removed for weight savings for a autox day. Thank you

Strip as much as you can if it's track only car

A/C condenser
Radio Unit
Door Panels
Speakers
Amp from the trunk
Sound Deadening materials
Lighter set of wheels
remove the entire center console
Remove the CAT and Stock Exhaust replace it with light weight single exit
Don't bother with CF hood, your stock aluminum hood is lighter

That's all i can think of

thanks for sharing the numbers and setup!