So I have owned my 04 Rx8 for about a month now and have been looking at some serious power gains. I have an HKS legamax exhaust, SR pulleys, dual resonated midpipe, a ram air intake (don't know the brand came on the car, probably detrimental to HP but sounds cool , have searched the internets up and down for serious HP gains without having to potentially rebuild your engine every year seem pretty limited. Best option seems to be the pettit SC system at about 300 hp. My question is instead of seeking higher HP numbers what is the reasonable weight reduction one can potentially obtain on the 8?

Is there someone or some where that the body panels weights for the 8 are listed? I assume going full carbon on body panels, doors, trunk, hood, roof could really lighted the rig a lot. Plus lighter wheels, suspension, driveshaft, flywheel, rubber. Rear seats the huge center console

The numbers I've run assuming 200 HP stock 8 0.0667 power to weight ratio
250 HP 8 with bolt ons stock weight 0.0833 power to weight
stock 500hp 3175lb z06 corvette 0.1574 power to weight
250 hp 8 reduced to 2000 lbs 0.1250
300 hp 8 reduced to 2000 lbs 0.1500
250 hp 8 reduced to 1500 lbs 0.1667

I have no idea what is a realistically obtainable weight and would love to know weights of parts that have been removed if anyone has them.

 

First off your numbers for stock, and with bolt on's are way high. And your weight's are very optomistic.
Secondly, HP is irrelavent as horsepower equals torque (in ft-pounds) times RPM/5250.

Thirdly. Search and put on your flame suit.

 

Lightweight wheels are the best your going to get honestly.

Best bang for the buck are the Enkei RPF-1s, 18 lbs each and an inch and a half wider than stock. Saving weight and gaining traction.

In fact I'm selling my set right now if your interested.

 

Your approach is backwards. When you start out with a light car with low power, the best approach to skew the power to wieght ratio is to add power. If you start out with a heavy car with decent power, shed pounds.

The Rx8 is a very light car to begin with. Its not like starting with a 2 ton pig and dropping a thousand pounds. Most of the panels you'd be replacing would save you a pound here two pounds there. Our hood for instace is not any heavier than most of carbon hoods available. The cost would be astronomical for very small gains.

 

^^^^ Yup.... Hell even our driveshaft (MT, sorry AT's ) is made of Carbon Fiber... As for HP, there is millions of threads... the only way to get HP for our car is through FI... Id go with the Pettit SC as well...

 

Carbon panels are availible, IIRC you can get the entire body from Mazda Motorsports in carbon. you dont wanna know how much it will cost you, and its utterly stupid for anything but a professional track car.


and if nothing else you're gonna get flamed for this. obviously no clue what you're talking about. again with the exception of astronomical costs involved for purpose built track only cars, you will NEVER get anywhere close to 250 with out FI. 200-210 if you are lucky and this doesnt mean just randomly picking a brand of every aftermarket part and throwing it on there.

also, IMO for a car that EVER sees public roads... just 2500lbs is a lean mean stripped machine. I don't have a figure for you like: you can get to 2300lbs for a street car, keeping only necessities... but i can tell you that you will never get close to 2000lbs, much less 1500

I dont keep up with NOS, but you may be able to reach that power range with it. otherwise you're going to have to spend a few grand - to potentially a lot more than a few grand

and FWIW it seems to be the standard to refer to those ratios as LBS/HP... aka 12.7lbs/hp

go read

 

thanks for the reply's guys. I figured that weight would be one of the places where mazda would cut a few corners, even though the 8 is light. I work in the cycling industry so this is where I get my weight weenie mentality, it's not that difficult to drop 30% from the weight of a production bike. The problem with the majority of carbon fiber body panels is that they are designed for aesthetics only. I have looked at a couple of hoods and they are like 5 times thicker than they need to be! They are then coated with layer after layer of polyurethane or epoxy and then you end up with a hood that is heavier than stock.

I can't remember who makes it but there is a company that makes an aluminum driveshaft for the 8 that is I think 15 pounds lighter than stock. Now a properly designed carbon Drive shaft that can handle the same loads as that aluminum one should shed an extra 25-30% on top of that.

Not saying it would be cheap though. Neither is an $8000 FI solution, and then another 5grand when the seals catastrophically fail and you have to rebuild. Retaining stock reliability while upping the power to weight ratio would be really nice.

Commence Flame Here ........V

 

ah cycling, thats why the odd way of presenting ratios lol

you're right about the carbon parts.. but what you can get for full body from Mazda's programs are not like what you find in the aftermarket... they are purpose design.

in the long run, the $8K+ even if you make a mistake the first time, is DRAMATICALLY cheaper than what you seem to be thinking of

 

I'm on my way to FI for less than $5500 (CAD)

 

well hell, its been done here for under $3,500... prolly less... but for the typical project $8K is a good number, its easy to get well over htat

 

The drive shaft you're referring to weighs like 2 pounds less, not 15.
To lose weight on the rx8 you need to remove some serious stuff like the stock seats, the back seats, some heat shields, the intake box and replace it with an Aem intake. Re amemiya's catalyzer weighs only 2kg (4.something pounds) less than the stock one. A good exhaust... Lightweight wheels and brakes\brake disks etc.
Not talking about lexan windows and other stuff going any lower than 1250kg is a serious hassle. 1250 = 2750 pounds.