Lightest steel frame car? Lightest car on 13s?

[Adambomb]

OK, here's a new, possibly random bit of bragging rights: Who has the lightest car with a steel frame? Who has the lightest car on 13s?

As of 2010 California, ISU had a steel frame car on 13s that came in at an official weight of 373 lbs. Anyone beat that in either/both of the categories above?

[FS Alum]

Brookes isn't far behind...379 lbs I think (someone correct me if I'm wrong) with a steel spaceframe on 13s.

With cars that light, why still on 13s? Clearly you guys are talented enough designers to get a steel car that light so packaging the suspension shouldn't be over your heads. 10s would seem more in line with you're car's design philosophy and you would benefit from an increased sprung/unsprung mass ratio...the importance of which I believe is underestimated in this competition.

[AxelRipper]

we're at 400 with 13's and getting lighter. We would run 10s if our pullrods would package in them properly (I think that was the reason anyway)

as far as lightest car on spaceframe, I do believe both Penn state and TU delft have broken the 300 lb mark with a spaceframe.

[Zac]

Penn State has also been right around 370 with a spaceframe and a 600.

[AwesomeAlvin]

Single Cylinder or 4 Cylinder?
Wings or No Wings?

Adding those specs would make this thread ALOT more meaningful.

Cheers!
AA

[bob.paasch]

Originally posted by FS Alum:
With cars that light, why still on 13s? Clearly you guys are talented enough designers to get a steel car that light so packaging the suspension shouldn't be over your heads. 10s would seem more in line with you're car's design philosophy and you would benefit from an increased sprung/unsprung mass ratio...the importance of which I believe is underestimated in this competition.

Not to mention the potential difficulty in getting 13s up to operating temperature with a car under 180kg.

[Adambomb]

Originally posted by AwesomeAlvin:
Single Cylinder or 4 Cylinder?
Wings or No Wings?

Adding those specs would make this thread ALOT more meaningful.

Cheers!
AA

In our case single, no wings, so basically the lightest of the light in those aspects (which is why they weren't mentioned).

Personally never gave much thought to the importance of sprung/unsprung mass ratio...may have to think about that some more. Although with some appropriately sized CFRP rims the difference in unsprung mass could be relatively small I imagine. With 3-piece Mg center Keizers (13x6 front, 13x8 rear) we're currently at about 21-22 lbs unsprung mass all around. I suppose we could probably lose 3 lbs a corner or so with some good CFRP rims, maybe 4 or more with centerlocks.

Beyond that we've honestly never really thought too hard about 10s. Don't have a ton of data, nor is the data we do have very pretty, but what we've got suggests the 13s have no problem getting up to temp (main reason we haven't looked at 10s much). The overall footprint wouldn't appear to be drastically different what with having roughly the same ballpark height and width, so from a [half-blind] guess it would appear you're more or less trading rim diameter for sidewall height, which also brings a drop in cornering stiffness. Although there is the option of the LC0 compound with the 10s, which frankly I know very little about, and would like to look at. As for packaging, surely we could, just not sure if we'd prefer to.

I haven't seen Penn State's 2010 car, although I remember their 289 lb single car from 2009. I'm guessing the jump from 289 to 370 came a good chunk from the engine and a bit from not being able to use Ti for the chassis anymore. That's still pretty damned impressive for a spaceframe with a four.

OK, so Penn State and TU Delft have taken the podium for space frame cars. So that leaves:

A. 13" cars under 373 lbs?
B. Are 13s on a sub 400 lb car even a good idea?

And......GO!

P.S. I would love to just wave around some fantastic competition results, but unfortunately we STILL had teething issues with the single that left us high and dry at competition (for the second year in a row), so unfortunately we really don't have any sort of benchmark for it or anything. Would have actually been nice if we would have finished endurance (or autocross) so we could have contributed to the Optimum G tire temp testing. Although, when it works, it sure does FEEL FAST!

[Yellow Ranger]

I know OUs 09 car was 396 with a twin (the ape is pretty light) and wings. We ran 20.5x7 hoosiers and really didn't have any problems getting them up to temperatures. Didn't do any testing with the 20.5x6 although, I think if we have hotter than hell temperatures at FSAE West again (a la 06/07) it might cook them pretty quick...

[Zac]

I haven't seen Penn State's 2010 car, although I remember their 289 lb single car from 2009. I'm guessing the jump from 289 to 370 came a good chunk from the engine and a bit from not being able to use Ti for the chassis anymore. That's still pretty damned impressive for a spaceframe with a four.

The jump was the other way, they were running at 370-ish for a couple years in a row, when they were running the 4-cylinder and 13" Avons. In 09 they dropped about a hundred pounds just from the engine and wheel package change. From what I remember the 08 and 09 cars looked pretty similar to each other.

but I don't think they ever ran a full titanium frame. they used to hava ti rear subframe but that obviously got dropped because of rule changes.

but I honestly haven't seen anyone struggling to get some heat into their tires because they have a light car. I think usually it has more to do with the aggressiveness of the driver and the suspension setup than anything.

[AxelRipper]

penn state at MIS this year was 293 IIRC.