Ultralight cars...how low can you go?...

Lotus made them from 1957 to 1972, and then licenced the design to Caterham, who haven't been able to prevent numerous others from building clones.

 

There is a whole world of 7-esque clones and homebuilts. Quite a few with T-esque bodywork.
Here's a tube frame T:
https://www.jalopyjournal.com/forum...dified-journey-to-the-end-of-the-road.685236/
This car has to be pretty light. Mike

 

Google Locost.

 

A friend has about a 400hp, modern SBC engine with 5spd in his Stalker II. About 1600 lbs I think (not sure if that includes him). Carrying the extra baggage isn't a problem. See: http://stalkercars.com

Slightly OT, one thing I've never been able to research is overall weight versus tire widths. A light nimble car doesn't need a wide tire, eh? Especially in the rain on public roads. So how do you do the math on optimum tire widths / contact patches versus weight bias / track widths / etc.?

 

What a can of worms this could be. Lots of other factors to consider, such as tire compound, tire diameter, and gear ratios, just to name a few.
Are you talking with regards to straight line full acceleration traction or at the limit cornering adhesion ??? Again, two different animals.

 

Seems I have had a post deleted - reason given.......... "LS stuff ".
The post is quoted in post #124. The point of it was solely about chasing power to weight ratios, regardless of what engine is used. The LS thing was brought up by someone else, and is definately not my preference. The deletion seems a bit harsh....................but hey, whatever.

 

Well, consider the average, say, 2200 lb, deuce roadster hot rod - discounting suspension designs as a trad rod would be very similar if not identical to old Betsy - and just considering overall weight, hp and tire size.... The car average deuce rod is probably lighter than the stock 32 roadster but nowhere near the sub 1200 lb weight the OT is wondering about. In theory, you wouldn't need tires any wider than a stocker with the same weight, but in today's environment you'll be driving it far faster than any new 32 was ever designed for - just to keep up with the traffic on the interstate. How wide should you go to compensate for the extra hp and speed, especially in the curves? Too wide a tire and you'd hydroplane easily if caught out in the rain in a super light car, too narrow and you'd understeer off or loose the tail in the curves for lack of grip. And when is the car too light don't you start to loose mechanical grip, too? In planning my next build (an 1800 lb, Model A coupe) I've tried to find out if there is a formula, but with no luck. Between Firestone or Goodyear and the car manufacturers, how do they calculate the correct size wheel and tire for something so simple as new economy car? You don't see 10" wide tires on stock Civics. Back to the light car idea, you could also screw up your tire sizes with aesthetics - bigs n littles? or super wide road racer or autocross tires? You could easily build yourself into a car that has tires totally unsuited for the daily driving or long trips, based on nothing more than "the look" you want. I'd like to find out what formula the engineers use for tire size and overall weight, be it an econobox or Mustang GT350. Then go from there.

 

Ariel Atom runs 7" and 9" wide wheels and 195/50R/15 or 205/50R15 fronts and
225/45R16 or 245/45R16" rears so width does not seem to bother them but I had a Road Runner with L60s that could not climb a hill in the rain without spinning the whole way.

 

How much do they weigh? I realize they also have far more sophisticated suspensions and lower CGs etc that probably help with grip if the tire is there to use. But what about a T modified with straight axles? Would Ariel specs be overkill on that? Or just ugly?

 

https://www.jalopyjournal.com/forum/threads/the-no-frame-model-a-modified.1079177/page-10

Right now it's at 1400lbs with a lot of fat yet to trim. I just need to stop starting other projects and get back to it. I can easly see it getting to 1100lbs, and I'll have to fight to get it under 1000lbs.

 

Atom weighs 1350lbs. The tyres look short to my eyes; could do with some more diameter.

 

Years ago I had an OT MG Midget that I stripped to racecar functionality, lowered it 3/4" in the rear and 1 1/2" in the front, stuck a J C Whitney header on it with a homemade side pipe, and mounted a set of B60 13 bias plies on 6' Vega wheels. When it rained I was holding up people in the slow lane.

 

A first generation Lotus 7 ( 1957 -1960) A development of the British " Specials" in effect the British equivalent of a Hot Rod,

 

You've seen this: https://www.jalopyjournal.com/forum/threads/specials.720448/ ?