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RX-8 Race Weight

Old 07-05-2017, 11:47 AM
  #26  
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Originally Posted by TeamRX8 View Post
Still waiting for someone to build a Titanium power plant frame (PPF)
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Old 07-05-2017, 06:09 PM
  #27  
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it'd probably be cheaper and more weight savings to just get rid of it by adding a trans mount and custom fabbing a new rear subframe to mount the diff, or buy the one from V8Roadsters

Assumes any of that is allowed by whatever rules apply
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Old 07-06-2017, 01:19 PM
  #28  
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Originally Posted by TeamRX8 View Post
Still waiting for someone to build a Titanium power plant frame (PPF)
Would ovular tubular aluminum help much you think? Of course I'm offsetting the weight savings with the 20b though...

EDIT:
I'm thinking of the front sub frame... not the PPF...

Last edited by reddozen; 07-06-2017 at 01:48 PM.
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Old 07-07-2017, 05:16 AM
  #29  
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You have a whole other set of issues with a 20B fitment and an aluminum subframe isn't your solution.

Only commercial kit I know of, just fyi and proceed at your own risk, not an endorsement etc.

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Old 07-07-2017, 10:01 AM
  #30  
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Originally Posted by TeamRX8 View Post
You have a whole other set of issues with a 20B fitment and an aluminum subframe isn't your solution.

Only commercial kit I know of, just fyi and proceed at your own risk, not an endorsement etc.

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Interesting. That simplifies some of the process anyway. I'll weigh my options.
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Old 07-12-2017, 02:51 PM
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Originally Posted by TeamRX8 View Post
The 2004 - 2005 Base model (no DSC) RX-8 6-spd were the lightest around low-mid 29xx lbs from Mazda


I have this model: 2005 base 6MT no DSC/TCS

  • 3008 on NASA Dominion scale with ⅓ tank and me (17.4# wheels and 235/40 R888)
  • 2982 on NASA VIR scale w/ ⅓ tank and me (21# wheels and 255 street tires)
  • 2976 on NASA Summit scale w/ ~ tank and me (17.4# wheels and 235/40 R888)


NASA scales don't seem very consistent. I weight about 190# with gear on. That puts my car as light as 2786#.


I have full interior, A/C. The only weight major reduction is a HKS hi power exhaust, fortune auto 500 coilovers, U1R tractor battery (19#), lighter wheels, AEM intake, RB DR midpipe (not even sure this is a reduction). I have a larger CSF radiator which added weight back in, too.
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Old 07-12-2017, 03:41 PM
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Originally Posted by TeamRX8 View Post
Yeah, we're talking factory delivered. You changed the intake, cat pipe assembly, rear exhaust, wheels, and some shock/suspension changes, maybe a few more things.

I was at 2690# with full cabin and trunk interior with those changes but this was autox and no cage which I didn't get into since it doesn't apply to track

The only inconsistency is your understanding/comprehension.
Dude.

The inconsistency I was referring to was the back to back NASA scale weights. I don't have faith that they have been consistent between events (they may even be changing scales).

You're talking factory weight; I knew that. However, this thread is called "race weight". So I don't think my feedback has been off topic. I'm hoping it helps for people with similar mods to guesstimate their weight, but wanted to qualify by starting the NASA scales may lack accuracy and repeatability.
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Old 07-12-2017, 04:01 PM
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Originally Posted by TeamRX8 View Post
You caught me before my edit, so sorry about that. However the reply below and subsequent replies is what I was responding to. There's often a misunderstanding about the actual factory weight and I also later linked to the OE parts weight thread to further assist with his understanding. Well, and frankly "dude", you're not in the guy that needs to be trying to school long term members here considering you don't even know how to position bushings for max camber adjustment etc. ....
i know how to set them up for max negative camber; the idea was to position them to have less static camber but more camber gain. But since I also don't know how good it is to run the UCAs at such a step angle I've decided to play safe and just position the way they were probably intended.

But at 13.5" front ride height it seems like I could've gotten enough just with the oem eccentrics, so I wouldn't recommend those bushings to anyone unless they are looking for more camber at higher ride heights.
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Old 07-12-2017, 04:27 PM
  #34  
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I sincerely apologize. I deleted all that because it's not my intention to be that kind of person any more. The thing is you could have posted up your own information without any need to drag me or anyone else into it. Please consider it more closely in the future. Peace and out.
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Old 07-20-2017, 10:53 AM
  #35  
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I have an 05 sport (no traction control, no sunroof). We are at ~2,730 in DSP (autocross) trim. That's full interior minus speakers, AC. Race seats, lightweight battery, single exit exhaust (oem headers still). The rest of the weight loss gets expensive (brakes, lighter wheels, headers).












The car was 2,830 in stock trim with the same single exit exhaust (but with cat instead of resonator). 1/4 tank of fuel in both trims.

Last edited by Tamra; 07-20-2017 at 10:58 AM.
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Old 07-20-2017, 12:00 PM
  #36  
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Since I was able to get under 2700# in STX trim I'm hoping for low 26xx in DSP trim. A lot of OE parts are so light that you don't gain much plus I'm adding some weight back with the splitter/spoiler setup and bigger wheels/tires.
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Old 07-20-2017, 12:16 PM
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Originally Posted by TeamRX8 View Post
Since I was able to get under 2700# in STX trim I'm hoping for low 26xx in DSP trim. A lot of OE parts are so light that you don't gain much plus I'm adding some weight back with the splitter/spoiler setup and bigger wheels/tires.

That's really impressive! Our weight is with wide wheels/tires and aero.


I used the thread where you posted the weight of the OEM parts to estimate most of our weight loss, and weighed the before and after of the replacement parts, and my math showed 2,730. SCCA scales confirmed it although I know they aren't the most reliable.


hmm, how could we get down to low 26xx.... I bet we could save 12-15lbs on crazy nice wheels, not sure on the header? 5lbs?, probably 15lbs on brakes? We could lose the sliders on the driver seat (passenger seat doesn't have any) and drop 3 or 4lbs, but that's not practical since we have multiple drivers. The driver's seat is lighter than the STX limit anyway so there isn't more than a few lbs to lose. Maybe a little more in the exhaust if we did titanium or something. The clutch can't go any smaller/lighter or we won't be able to launch at pros. Battery is already about as light as you can go at just a few lbs. Now that I really think about it, I have no idea how we could drop another 100lbs in DSP trim. I see 40ish with a bunch of $$.


In fact, I'm impressed you got below 2700 in STX trim - how is that even possible with the AC system weighing 18lbs and your seats had to be around 15lbs heavier than mine, combined?


Less fuel maybe, but then you risk starving.


You don't have to answer, I'm just brainstorming/curious.
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Old 07-20-2017, 01:42 PM
  #38  
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It takes custom parts built for that purpose rather than the usual off the shelf stuff plus some rare stuff like sub-14# 17x9 wheels etc.
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Old 07-23-2017, 08:20 PM
  #39  
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Man I wish we were allowed under 3000. I am running T4 in SCCA and our min weight with driver was just upped another 50lbs to 3175! (oh and we have to run a 60mm intake restriction) I am a larger driver at 260lbs and I still have over 160lbs in ballast to make weight with a half tank of gas.
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Old 07-23-2017, 10:52 PM
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It's any wonder that the RX-8 does any better than it does in T4, jeesh
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Old 07-24-2017, 05:39 PM
  #41  
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Originally Posted by hufflepuff View Post
[...] RB DR midpipe (not even sure this is a reduction). [...]
I'm a bit late to the party, but the RB midpipe is nearly five lb lighter than the full cat. Still 1.5 lb lighter than a gutted cat. I weighed them all on a calibrated scale.
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Old 07-24-2017, 07:07 PM
  #42  
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That off the shelf stuff is still heavy. Use 20 Ga stainless tube with slip flanges and you'll double that reduction.
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Old 08-27-2017, 07:52 PM
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Finally finished and got to weight my car. This is not super accurate because it's a truck scale, I'll have more accurate numbers when I do the corner balancing. The car has an LS1 (aluminum, not a truck engine), T56 transmission, and very stout roll cage. Full tank and 150lb driver in it.
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Old 08-28-2017, 10:14 AM
  #44  
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Yah, that's going to be near the bottom of the calibration curve of scales rated for 20-30 times that weight. Most calibration methods are designed to have the greatest accuracy in the middle 75% of the range. When you get to either extreme, accuracy often starts falling off significantly.

The LS is probably 100-200 lb heavier than the Renesis and the roll cage is probably another 100+ lbs.
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Old 08-28-2017, 10:59 AM
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Keep in mind that the car is gutted to an extreme. No glass at the front doors. Custom wiring harness with just the very basics, custom brake lines, no ABS or anything. I was actually expecting it to be a bit lighter.
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Old 08-28-2017, 11:23 AM
  #46  
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I don't know that all those parts are worth upwards of 450lbs but I could be wrong.

Like you said, you'll have a better idea when it's corner balanced.
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Old 08-28-2017, 02:07 PM
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Originally Posted by NotAPreppie View Post
I don't know that all those parts are worth upwards of 450lbs but I could be wrong.

Like you said, you'll have a better idea when it's corner balanced.
Have you seen how much wiring (including huge caddies, computers, etc.) can come out these cars? I bet that was 450lb alone 😜 J/k. But seriously, it's a lot. Other heavy things that come to mind are, exhaust system, PPF and EPS rack that were all replaced with much lighter counterparts. These cars also have a ton in carpet, sound deadening material, airbags everywhere... but yeah, I'll provide a more accurate number when I get it. To be honest I don't think it will change much and as is the front/rear weight bias doesn't seem too terrible (F52.7% R47.3%).
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Old 08-28-2017, 02:37 PM
  #48  
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Sorry, forgot what forum area I was in and thought of it as otherwise stock rather than as a race/track car. Yeah, I can see that as being a good weight then. Good job!
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Old 08-29-2017, 07:38 AM
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The wiring harness from the dash to the headlights weighs almost 50lbs. Was SO happy to get that out of the damn car!
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Old 09-10-2017, 10:24 PM
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We weighed in at 2745 at Nationals this year - only 100 lbs heavier than the winning BRZ, who also is from our region.
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