Modified Roadster Track Width

[gasblender37]

Aerodynamically speaking, should the front end width be the same as the rear end width or does it really matter??
Thanks,
Skip

[bearingburner]

If there both the same width then you punch one hole in the wind.

[gasblender37]

That's what I was thinking.
Thanks,
Skip

[tallguy]

I don't disagree with anything said so far, but want to offer my two cents' worth. . .

I think we can all agree that with regards to total ("frontal"?) area, less is better.

This suggests/implies that track width should and/or could be minimized.   

Having said that, there may be an advantage in having the rear track wider than the
front track if this results in the center of pressure being generously behind the center
of mass, in order to help prevent sideways sliding if/when traction is lacking.  For
most vehicles, this may well not be an issue. 

[gasblender37]

tallguy,
Thanks for your insight.
Skip

[Dynoroom]

I have a modified roadster, & it's all wrong......

My opinion is frontal is everything in this class, because they all have bodies anything you do before the body proper has little if any effect.
Sp the best approach is the smallest tire / wheel package, smallest body package, do your best to streamline protrusions, and have a good power package. Not much else you can do.

With my car I run tall tires, different track widths, & a '27T body. I would do SOME things differently if I built it today, I just might not say what....

[gasblender37]

I have a modified roadster, & it's all wrong......

My opinion is frontal is everything in this class, because they all have bodies anything you do before the body proper has little if any effect.
Sp the best approach is the smallest tire / wheel package, smallest body package, do your best to streamline protrusions, and have a good power package. Not much else you can do.

With my car I run tall tires, different track widths, & a '27T body. I would do SOME things differently if I built it today, I just might not say what....

As I have said before...
"I reckon if this stuff was easy, everyone would be settin' records"
Skip

[kiwi belly tank]

I'm a liner & lakester guy but here's my thoughts.
Size Matters! "T" bodies are small but they have a lot of shape diversion to create turbulence. "A" bodies are cleaner but bigger.
Take a look at a Crosley roadster body & see what You think, smaller, cleaner & the inner fender is way inside the body line.
The American Austin Bantam is another likely candidate. Built in America with Austin of England driveline but you might want to seek SCTA approval on that one.
Everything you hang out in the breeze is drag, a biga$$ blower or scoop stops a lot of air. If blown is your bag then think centrifugal or turbos & get em inside the body.
Try not to be influenced by what others have done & then build the same $hit, on a good day you might go as fast as they have.
Front tire width is somewhat more important than axle width. Keep suspension components inside the nose & run the tie rod in the shadow of the axle & that is easier to do with a straight axle as apposed to a dropped axle.
The biggest obstacle is drag.
  Sid.

[RichFox]

Austin/Bantam roadsters are legal and do run. Do you have a picture of the Crosley roadster? i have not seen one and would like to see what it looks like.

[jdincau]

Modified roadsters must be 1923 through 1938, The Crosley is post WWII

[4-barrel Mike]

With enough HP, it may not matter as much.   





Mike

[jdincau]

Here is the Crosley Hot Shot roadster Rich. It had a SOHC four that was quite popular in road racers and small hydroplanes.

[kiwi belly tank]

The Crosley roadster came out in 39 but i was thinking the class went up to 48 but after a look in "The Book" i see it's 38.
  Sid.

[Stan Back]

They had some pre-war roadsters -- 2-cyl. -- but I don't think they meet the '38 cut-off.  Real strange, tho.

I still wonder about the success of the Contrivance Special and their dozen GMR records with a 23-25 T body, which most of us think isn't as aero as the 26-27.

Davidson's roadster may not be all that tiny, but with all the things he's got stuffed into it, it probably couldn't be any smaller.  And, of course, it's built as a Gas/Fuel (I call them Altered) Roadster, yet steps up to run Modified with a few changes.

[Dynoroom]

The Contrivance roadster does many things different/better than most. Proves to me frontal is #1, but they do a few other things right too.

Tried to find 2 pictures with similar views.