I don't understand...

[craig-ultima]

Maybe someone can explain this to me:

Carrera GT with all its carbon fiber stuff weighs 3042 lbs. The Ultima, with a slightly heavier engine and steel chassis weighs 2150 lbs. The freestream car (which really is more like lingerie than a car) with all its carbon fiber and much lighter engine weighs only 1100 lbs.

I have also been looking at the Cobra as a possible next poject and it weighs 2800 lbs (steel chassis and fiberglass body as well). These weight differences seem really large to me. I would have thought the Carrera would be way lighter, and the freestream a bit heavier.

[builder]

Just a guess, but... Take a look at the relative size. I think the Porsche may be longer, taller, and has a wider cockpit than the GTR; the Freestream probably not as big.

The engine in the GTR is probably heavier than the Porsche, too.

Also, the Porsche probably has more sound-proofing materials, more ample seats, electric windows, multiple air bags, other electronics, ABS, and the chassis had to pass DOT standards for cars sold in the USA.

[peterpsg]

The cobra also has the engine at the front, so you have the extra weight of a rear diff & main driveshaft...

I've been looking at the cobra's as well, nice, I'm trying to find the best chassis to graft a Kirkham all alluminium body on!!! :-)

[Hugger Z]

OK, here is what I found:

Ultima: 4000mm Long
1850mm Wide
1070mm Tall

Carrera GT: 4613mm Long
1921mm Wide
1160mm Tall

Freestream: 4038mm Long
2000mm Wide (Front), 1624mm Wide (Rear)
1078mm Tall (Engine Intake, cockpit was much lower than this point)

Based on the overall dims the Porsche has more overall volume and therefore is easier to understand the heavier mass. The Freestream is very minimalist (no storage or extra room anywhere). The freestream also has only a 2.4L engine with all of the lightweight internals for high revs. This is a large amount of weight loss for them compared to the 5.7-7.0L V8's most of the Ultima's Run.

>> Edited by Hugger Z on Friday 24th February 15:23

[fluxen]

The Carrera GT is a big car, but the major difference in weight is safety equipment and electronics, as noted above. Modern cars that have to meet road safety requirements are much heavier than their predecessors, due to crumple zones, side impact anti intrusion requirenets, etc, etc. The Ultima and cars like it don't have to meet any of these requirements. You can't compare a tube frame car to a production car for that reason. Aside form safety stuff, pop the hood on an Ultima and a street car and look at all the additional crap under the hood on the production cars. A/C's, heaters, smog equipment, power steering, brake booster, abs, wiper resevoirs, etc. That stuff adds up to a LOT of weight. Hell, a cat can weight 50lbs alone

And the cobras around here tend to weigh more like 2500lbs or less. I think your weight might be a bit high there, or you're comparing cars with full fuel tanks to those without. Keep in mind a full 20 (US) gal fuel tank weighs approx 150lbs.

>> Edited by fluxen on Friday 24th February 18:22

[craig-ultima]

Thanks. This is all insightful.

I just checked out factory five's website and their 63 Cobra Mark 3 weighs 2150 lbs (dry weight), so you are right - that 2800 lb number I quoted must be wrong.

The weight of the freestream is still astonishing. I hope it isn't like a real F1 car in that bits fall off about every 15 minutes.

[chuntington101]

well i think it should be conpulseary for a critical compoent to fall off a F1 car at 5 min intervals! might make the racing more interesting then! lol

Chris.

[fluxen]

Really, the weight of the Freestream isn't that remarkable, given that the majority of small sports racers and formula cars weigh less than 1250 or so. In the US, the most competitive cars in DSR (D-Sports Racer) tend to weigh less than 1,000lbs. This is the class that 1 litre Radicals run in, and they're at something of a weight disadvantage. There are a lot of track cars under 1,000lbs, though they usually run motorcycle engines these days, which helps.

Even my "Beck" Porsche 550 Spyder replica weighs 1200lbs and it's very low tech, basically a faithful reproduction to the originals aside from the fiberglass body (vs. AL), and the cheaper VW motor. More info here if interested: http://wurthmotorsports.com/Beck_Pors

[boomerkk]

Hugger Z said:

The Freestream is very minimalist (no storage or extra room anywhere). The freestream also has only a 2.4L engine with all of the lightweight internals for high revs.

The engine weighs 85kg and the gearbox weighs 30kg. Also look at this picture and I think you'll agree with me that the Freestream takes minimalism to a new level

www.pistonheads.com/pics/news/13064/freestream_T1-2-L.jpg


>> Edited by boomerkk on Tuesday 28th February 21:03

[builder]

fluxen said:

In the US, the most competitive cars in DSR (D-Sports Racer) tend to weigh less than 1,000lbs.

I think the D class Sports Racer has a 1,000 lb. minimum and a 1 litre maximum.

[zumbruk]

boomerkk said:

Hugger Z said: The Freestream is very minimalist (no storage or extra room anywhere). The freestream also has only a 2.4L engine with all of the lightweight internals for high revs. The engine weighs 85kg and the gearbox weighs 30kg. Also look at this picture and I think you'll agree with me that the Freestream takes minimalism to a new level www.pistonheads.com/pics/news/13064/freestream_T1-2-L.jpg

Quite lardy by Jedi standards; 400kg & 155bhp ...

[fluxen]

Not to hijack the thread, but DSRs with motorcycle engines have a minimum weight of 900lbs WITH the driver in the car and are allowed up to 1000cc. DSRs with pushrod engines are allowed up to 1300cc and must weigh at least 1000lbs with driver.