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

I read the whole thread and got to the next to the last page before I figured out how old it was but it shouldn't be that difficult to come up with a decent little "real" hotrod.

I don't have my metal specs cheat sheet with me but a stick of 1-1/2x3 tubing doesn't weight that much and one length will easily make a T bucket style frame if you do the cuts right.

Tube axle front end from one of the suppliers and a complete engine,trans rear end out of an early 70's rear drive four banger sedan. Or go hot lick and use one of the later all aluminum four bangers.

With a T style body either steel or glass and complete but minimal trim and a spartan but drivable interior the car should be under 1200 lbs pretty easy and sure wouldn't break a bank account.
Put a souped up Honda Vtech or a Busa mill in a little car like that and look out world.

 

my dwarf car, licensed and titled as a 1931 chevy, was a real race car made street legal, 1989 1100cc V-twin honda, DOT slicks, its a blast, love or hate, it gets looks every where l take it.
it weighs about 1200lbs. abou 80hp and 70 fpt.


heres my friends street legal sprint car, changed the track rules and went to more modern style of race cars so he made a toy to drive around town, it weighs 1500lbs, 500hp, 450 fpt fuel injected small block chevy, his is titled as a home built hot rod.

later

 

1961 austin healey sprite, 120hp, 1380 cc, datsun 5-speed, disc front , 1/4 elepictic springs rear, about 1400lbs, ready to go , can buzz down the freeway @ about 80 all day, i think if you get to light in weight you'll have to worry about cross wind , being seen in traffic,etc, when i was a kid about 40yrs ago, i thought of t-track style roadster [Bo Jones style], small motors, light cars = fun. RD

 

On that Sprint car converted to street use, were those flaps behind the rear and ahead of the front tires mandated by the state of Washington? If yes, do they require this on all fenderless cars? The car looks killer except for those flaps!
Dave

 

they used to but changed the law for roadsters to a fair whether law, l told him take em off it'll look better, l hope he listens.

 

here is the great steve wittman with his alum. olds V8 powered tailwind he built in the mid 60's when those engines first became available. knarly sound - fast - and light.
http://www.youtube.com/watch?v=WsH-j4pF4fE&feature=related
i live in illinois, built a two place vehicle 16 years ago powered by a 4 cycle automotive engine.
weighed 525 lbs. and would go 146 mph in level flight.
took my girlfriend with me in it to nebraska, and ohio. and myself to florida four times.
although i must say, i wouldn't want to be involved in an accident on the road in it.
i think of that when i see the soccer mom in my rear view mirror with the cell phone on her ear, riding my ass with a huge suv.

 

This one is tagged, inspected, has lights, turnsignals, muffler, etc.
Larry T

 

My roadster is under 1400. Ford Zetec power, T5 tranny, mag Hildebrand quicky, Duce rails, all steel body.

Rex

 

Morgan have a steel chassis, with a steel or aluminium body built on an ash wood frame.

 

The Ecotec is what I'm using in my roadster and the plan is for under 1800 lbs. The engine is less than 300 lbs and the 5 speed is less than 100 lbs. The drag racers are getting close to 1400hp out of this small 4 cylinder, but 300 to 350 is quite easy to achieve, so power should be in the Hot Rod range with a car this light.

 

My 26 T with a Nova (Toyota) 4-age weighs in at 1480 wet.

 

Hi from merry England ,
I `ve a English Ford Anglia based alluminium bodied hot rod / special that weighes in at 500kg thats about 1000 Ibs .
Powered by 1950`s flathead four of 1172cc with alloy head , 18 inch wheels on rear to get gearing so it will cruise between 65 - 70 mph all day on highway.Did have it up to 90 once but a bit hairy !
Best fun is round our English country lanes with no screen. Been on road over 12 years now , as you can see in photo its quite small at only 9 feet long tyre to tyre. a friend built the chassis and body ,I did the rest .

NEVER GROW UP ,NEVER GROW OLD !
Dave

 

You'll have no trouble attaining 1500 pounds or less. Mine has a 4.3 V6 Chevy, T5, and Toyota pickup rear end and it weighs 1350 lbs.

Bob

 

My Lotus 7 weighed in at 950 lbs. including the steel wheels and heavy rear axle. With aluminum wheels and a Speedway quickchange it would have weighed in under 900. It's not exactly street legal, or a "traditional" rod, despite coming from the '50s. And the carbon fiber is just sticker. It's steel tubing, aluminum sheet, and fiberglass fenders and nose.

 

My Old Roadster, a 23 T Bucket, weighs 1750# with 283/aluminum PowerGlide and 57 Chevy rearend, CAE Sprint axle and hairpins, F100 steering box, 10 gallons of gas.
With me in it it just topped 2K# and was like a rocket sled to me.

 

Great thread ..... I wonder if anyone built any of these car projects?

 

A couple of questions about plywood monocoques - Marcos was the british manufacturer, Frank Costin was the designer. The brits were leaders in lightweight cars/cyclecars...

 

There was another post today? doubtless deleted for being incontrovertably OT.

Tangentially relevant to this seven-year-old thread, I was only last week thinking about a strategy for estimating the CG height of a car without resorting to scales or other empirical devices. Basically, you identify heavy components, whose mass you can look up somewhere, and make an educated guess as to the height of their respective centres of gravity. Adding the product of mass and CG height of all those components together and then dividing by their combined mass will give you the combined CG height of all those components. If you've done this right the total mass will be less than the actual mass of the car. If you then assume that the balance of the mass has a pretty much uniform density, as it'll comprise bodywork and such, you can place the CG of the balance of the mass at its geometric centre. Now you repeat the exercise but include the balance as if it were a single component.

Don't forget to include your own weight and a passenger or two. The US military reckons the CG of a seated person is about at their belly button, and even conducted extensive research to ascertain this. By definition this applies regardless of how the person is oriented in space.

In the course of figuring all this out I came across some data gathered by NHTSA, according to which the CG of a typical modern sedan is somewhere around 22" above the ground. This is true of things like BMW M3s and the like, too. Only obvious sports cars manage a CG height of less than 20", and many don't.

When I finally got to doing the math the first thing which struck me was how easy it is to place much of the heavy stuff in a hot rod at or below axle height. I did a not-unrealistic exercise for an open car and got a CG height of 17" with two people on board – two people with their belly buttons a good bit higher above the road than is the modern norm.

The thing I was after was: Modern cars are getting wider and wider, and surely derive some of their lateral acceleration ability from their width as measured over the outer edges of the tyres. I nevertheless has a suspicion that our narrower '30s cars might have an advantage overall, if built right. And my suspicion was correct: from CG height and width the geometric limit to lateral acceleration of a modern performance sedan – i.e. the point at which adding more adhesion doesn't result in greater lateral acceleration but in the car falling over – lies at around 1.60-1.65g. For my above open-bodied example it's 2.02g, much narrower track notwithstanding. And it didn't involve a lot of cleverness, just a body with a level of flimsiness which is illegal for any OEM.

Interesting to know.

 

They were good at it in the 30's/40's too. The de Havilland Mosquito comes to mind.

 

Exactly.

 

A modern Chevy V8 engine is lighter than iron block GM 3.8 or 4.3 V-6s.

 

135 pounds. 1922 Briggs & Stratton Flyer

 

This is an old thread, resurrected.

@rottenleonard that no-frameModel A roadster, I wonder how much that weighed?
@rusty rocket built that cool flathead 4 banger single seater on a T frame, I wonder how much that weighed?

Ducati did well competing against the Japanese motorcycle manufactures aluminum perimeter frames using chrome moly tubing in a trellis like structure, with lot's of triangulation throughout for strength without a lot of weight. That might make a good way to go about building a lightweight hot rod chassis, though not very traditional.

 

Ancient thread but still an interesting one. I was looking at my post from 2009 and interestingly I have a dohc 4 banger out of a car that was my daily driver for a few years that got totaled a few years ago and a pretty stout 5 speed to go behind it. With some clean up the engine kind of looks like a baby Offy if you squint right. That little bugger should allow me to build a rather spartan T Modified with some other pieces I have sitting around and that light weight stick of tubing. The engine was headed to an engine swap in a small British sporty car but a T modified sounds a lot simpler.

 

My single seater has a dodge flathead six and not a four so that bumped the pounds up . I weighed it after I had got it running with about 5 gallons of fuel in the tank and it was 1490 pounds. I’ve taken off the stock head and replaced it with an Edmunds aluminum head so I just about bet I’ve taken off another 20 pounds.

 

I think this was built by Coddington?

 

I think my hot rod fits in this category. It's probably between 1400 and 1500 lbs.

 

Looks like a HOT ROD to me! Weren’t Seven’s Pre-1965?