View Full Version : Weight


revhappy
11-06-2002, 06:14 PM
Did anyone catch the weight listed on the german review?

1340 KG..which should equal 2,948 lbs.


I hope this is not final because this is more than I was hoping for
(<2,900 lbs)

PoLaK
11-06-2002, 06:34 PM
i have it on a "reliable" soruce that the weight will be under 2800 pounds.

RX7 Guy
11-06-2002, 06:39 PM
I’ve got a fanatical appreciation for lightness so I totally understand your concerns but by today’s standards, a four seat, rear wheel drive, 250 hp car that weighs less than 3,000 is phenomenally light. For example, the new MINI which is wrong wheel drive, only has 115 hp & is shorter than a Miata by several inches weighs 2,550 Lbs.. Don't get me started on that pig of a 350Z; take a buddy along & you'd still weigh less dispite having two more seats.

BlueAdept
11-06-2002, 06:49 PM
Hmmmm.... I'm also hoping for a light car... here's my previous post on the subject...

http://www.rx8forum.com/showthread.php?s=&postid=13175#post13175

Basically I don't know exactly if they were measuring the same thing but my 91 accord was bigger than this car and is listed only 3020 or somthing so I recon it's gonna be much lower than the previously listed 2970.

Hopefully it's 2790.... but a lot of guys here recon that's impossible... we'll wait and see I guess! I have a weigh bridge at work... so we can settle it once I get a car.

zoom44
11-06-2002, 07:05 PM
make sure all the fluids including petrol are completly full before you do or people on here will be argueing over if you weighed it properly:D

RX7 Guy
11-06-2002, 07:07 PM
BlueAdept,

All things being equal, rear wheel drive will add roughly 0.7 Lbs. of weight for each Ft Lb. of engine torque. So figure the RX-8 has about 113 Lbs. allocated to the prop shaft, chassis torsion load reinforcements & differential harness…It’s a necessary evil to avoid the massive understeer & unsporting handling associated with front wheel drive configurations.

revhappy
11-06-2002, 07:09 PM
I agree by today's standards...it is relatively light...but I wouldn't say its impossible for it to come in lighter.

The Celica is not too much shorter than the RX8..has 180 HP...and weighs 2,500 lbs...and is arguably the best handling mass-produced FWD car. Obviously, a RWD car will weigh more with a longer drivetrain (maybe 200 lbs??).

I wonder just how much weight is added by making it a true four seater as opposed to a 2X2 (assuming they made the car shorter) and having the suicide doors.

Anyway, this car is still months away, so who knows, things may change. I've waited a year and a half, what's a few more months without having car payments!

BlueAdept
11-06-2002, 07:18 PM
Originally posted by RX7 Guy
BlueAdept,

All things being equal, rear wheel drive will add roughly 0.7 Lbs. of weight for each Ft Lb. of engine torque. So figure the RX-8 has about 113 Lbs. allocated to the prop shaft, chassis torsion load reinforcements & differential harness…It’s a necessary evil to avoid the massive understeer & unsporting handling associated with front wheel drive configurations.

What materials is that based on... most of the backbone and prop shaft etc in this car is carbon fibre....

zoom44
11-06-2002, 07:23 PM
they could just go back and scrape off an ounce(or gram) of every part and cut a millimeter off every hose and then weigh it!:D that would take off a bunch!

RX7 Guy
11-06-2002, 07:30 PM
Revhappy,

Interesting you mentioned the Celica…I debated between using it as a “Best in Class” example or using the MINI as a “Worst in Class” example. Don’t get me wrong. I really admire the MINI, actually, I admire anything that isn’t a ^%#$$@ SUV these days.

Anyway, the Celica is about as light as you can get using conventional engineering. Everybody raves about Honda’s VTEC technology…Hello, what about Yamaha’s contribution to the Celica’s super high power to weight ratio engine which contributes greatly to the Celica’s overall lightness. But you already touched on my point which is that the RX-8 will weigh something like 400 Lbs. more than the Celica. For that, you get more: power, room & structural rigidity all with the drive wheels located at the correct end of the car.

Grimace
11-06-2002, 07:54 PM
The Celica uses some pretty crazy stuff to acheive that light weight. The engine block, for example, is made of a lightweight aluminum composite that allows only 5 mm between cylinders. The sunroof is made of plastic rather than glass for addition weight savings. I could go on and on.
Of course, the RX-8 has some extreme measures to save weight. Carbonfibre driveshaft, for example.
So why the descrepency? Lots of reasons, but these are the main ones:
1. Chassis stiffening - much required on the RX-8 because of its unusual door layout and no B-pillar
2. RWD (as mentioned above).
3. Higher vehicle content (more goodies to play with)
4. Two extra doors.
5. Overall big size

By the way, comparing the RX-8 to a 91 Accord isn't fair, although on the surface it appears to be. The amount of safety gear that cars today have compared to cars a decade or more ago is ridiculous. Much more stiff, side door beams, multiple airbags, etc. Ever check what a 2003 Accord weighs? :)

revhappy
11-06-2002, 08:02 PM
RX7 Guy.

The 2X2 light weight RWD sport coupe has got to be one of the rarest cars.Would it be fair, given the Celica example and the FWD -RWD weight conversion, that given current technology, you could see a RWD sport coupe as light as 2,613 lbs (2,500+113)? That would put us near the M3 in terms of the power-rate ratio!

The Yamaha in the Celica is nice, but it needs to rev higher...the power band is a little too narrow.

RX7 Guy
11-06-2002, 08:13 PM
BlueAdept,

What materials are you basing that on?

I changed the steel prop shaft on my ’87 RX-7 about a year ago & I’d guess that it weighed about 15 Lbs.
I know that the RX-8’s prop shaft is carbon fiber but it’s longer & it has to carry an additional 26 Lbs. of engine torque (162 Vs. 136) so it’ll probably weight about the same.

Accessing the weigh increase associated with rear wheel drive configurations is very complicated…For instance, if the car already has great chassis rigidity, not much weight will need to be added to carry the torsion loads imparted by the prop shaft. Also, FWD transaxles weigh much less than a transmission & differential individually but FWD transaxles have problems like torquesteer which can’t be assigned a weight value. The 0.7 rule of thumb I used assumes an average length wheel base, longer wheel bases would have greater multipliers. It really goes on & on but I’d say that 0.7 is a fairly decent way to estimate the weight penalty.

RX7 Guy
11-06-2002, 08:18 PM
Grimace,

RE: Your points 1 – 5…

I never knew big purple creatures could be so articulate & insightful. I’ll never watch a Mickey D’s commercial the same way again.

RX7 Guy
11-06-2002, 08:28 PM
could you see a RWD sport coupe as light as 2,613 lbs (2,500+113)?

Absolutely…I agree completely Grimace’s points regarding where the weight is. Personally, the dimensions of the Celica suite my needs better than those of the RX-8 & the geometry is more pleasing to me….Just loose the Bubble Gum styling (I’m 38 & have owned my ’87 RX-7 for 15 years. Can you imagine a 53 year old man driving around in one of those things…I think not), put a rotary engine in it & send the power to the rear wheels.

Sputnik
11-06-2002, 08:45 PM
Originally posted by revhappy
I agree by today's standards...it is relatively light...but I wouldn't say its impossible for it to come in lighter... But remember, it costs money for it to come in lighter. So in reality, it IS impossible for a mass-produced $30k car with those options to come in any lighter.

---jps

Hercules
11-06-2002, 08:48 PM
Originally posted by Sputnik
But remember, it costs money for it to come in lighter. So in reality, it IS impossible for a mass-produced $30k car with those options to come in any lighter.

---jps Never say never :)

Hopefully it will be lighter, maybe it won't. Either way at under 3000 lbs, it says a lot for it's nimbleness. Now Mazda needs to fine tune suspension settings and let this thing rip on over to R&T and C&D... and we will have our cake and eat it too, and laugh in the face of all those nonbelievers :)

Grimace
11-06-2002, 08:53 PM
Originally posted by RX7 Guy
Grimace,

RE: Your points 1 – 5…

I never knew big purple creatures could be so articulate & insightful. I’ll never watch a Mickey D’s commercial the same way again.

LOL
Thanks... I think! :D

ZoomZoom
11-06-2002, 09:35 PM
Originally posted by Grimace

By the way, comparing the RX-8 to a 91 Accord isn't fair, although on the surface it appears to be. The amount of safety gear that cars today have compared to cars a decade or more ago is ridiculous. Much more stiff, side door beams, multiple airbags, etc. Ever check what a 2003 Accord weighs? :)


I have...

2003 Honda Accord DX – 4Cyl – 160HP – Manual Transmission - Curb weight 2989
2003 Honda Accord LX – 6Cyl – 240HP – Automatic Transmission – Curb weight 3309
2003 Honda Accord EX – 6Cyl – 240HP – Automatic Transmission – Curb weight 3360

Enough said!

Note: LX and EX models are not available in manual transmission. Information source Honda USA web site.