Homebrew Engineering

[sdkrc]

I recently came across this photo and this thread on the ecomodder forum and it's blown my socks off. I really like reading homebrew engineering stories, anyone got anything similar?

https://ecomodder.com/forum/showthread.php/what-spotted-rear-engine-tdi-custom-aero-body-26074-12.html

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Anyway, the car is mine, I designed and built it back in 1985-1987 and it's only purpose was to get great fuel mileage. It was originally powered by a 1980 VW diesel that I added a Rajay turbo to and ran about 9 psi of boost. It got about 65mpg at 65 mph back then. Now it has a 1.9 TDI AFN motor in it and gets 74 mpg at 60 mph. The tune that was in it was more performance oriented and dumped a lot of fuel during hard acceleration. Fun, but not as efficient. The newest tune is much cleaner, albeit not as fast. Engineering tradeoffs....
I made the body out of poly isocyanate foam board and covered it in glass and epoxy resin. The frame is a space frame made from 316l stainless steel. I know, what was he thinking! (I hate rust!) Front suspension is modeled after the Ford Mustang II/ Pinto set up, just copied it out of stainless.
The rear suspension is made up of the strut and brake/spindles from a 1972 Datsun 240Z. Front and rear have coil-overs. The engine/transaxle is in the rear as a mid engine layout. DLC PP520 injectors, VNT-17 turbo, water cooled intercooler, fabricated intake, 2.5 exhaust with Magnaflow muffler, tune,
thinnest head gasket, port clean up, unshrouded valves, air/oil separator, and I forget what else!
The windshield is from a McLaren, the door frames, hinges, and latches are from a 1967 Corvette, taillights are 1982 aftermarket Corvette, side markers are Ford truck, front directional are 1972 Camaro.
I designed this car on paper after being hit broad side on my motorcycle at an intersection by a drunk chic. Cops never figured that part out....my friend did.
I had plenty of time to do this as I was laying in a bed for a good part of a year with a couple casts on.
Hope that helps.

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I was 23 years old and working out of my parents two car garage. I had next to no money but lots of ideas...The whole thing was done by one guy with no help of any kind and went from idea to a finished car in 2.5 years. Looking back on it, I have no idea how I did that. The shape of the car just sort of evolved as I watched how snow drifted, the shapes of animals, airplanes and race cars. No computer, degree or any of the like.

The car is a bit heavy, weighing in at 2600 lbs. The gearing is custom, with first being as low as VW ever made and 5th being as high as I could buy in the aftermarket. The final drive is from a VW trans that had the highest they offered. I forget what it is, but 3.14:1 sounds right. It was from a CTN code tranny.

I didn't have any of the major tools required, like a TIG welder, lathe, band saw, drill press, etc. so I traded things like putting an engine in my friends dads Monza for an OLD Lincoln stick welder which I then modified to a TIG machine complete with pre and post feed Argon, internal back purge Argon timer, foot controlled amperage and start, high freq. start, and vent fan control. The little South bend lathe was borrowed from another friend that owned an airport. And on and on....

The headlight covers are made from vacuum formed polycarbonate, but I didn't have a vacuum forming machine....so I made one. It had 3 foot square electric heaters with resistance wire made from 316l stainless TIG filler rod, an old electric stove thermostat, two shopvac motors to pull a vacuum. It was the size of a minivan!

I needed a paint booth to paint it so I made that too. It was really nice, all made from OSB board, I had 4 feet of room all the way around the car to maneuver, second hand fluorescent lighting, old whole house fan and a ton of furnace filters. I even made an air supplied mask that piped in fresh air directly to my face mask from the great outdoors.

Had some quirky handling issue in the beginning but it turned out that the spring rate up front was to low, all better now.

There are many more stories to tell, just can't think of them all right now!

 

[sdkrc]

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About the windshield, it was purchased from McLaren in England for about $1000 back in 1987. It has the AS1 designation which relates to laminated safety glass, the correct material for a FRONT window. The car was a race car and I forget which model. The same window was used in the "Hard Castle McCormick" TV show car, I think it was called the Coyote. (1985?)
The body was made from urethane foam sheets from an industrial insulation company and then covered with glass and epoxy resin. (not polyester) Sanded and filled with epoxy fillers, primed with high solids epoxy primers, did I mention ,SANDED !, (forever!)
Painted with base coat cleat coat automotive paints.(DuPont)

The final drive is all set, it's the fifth gear that might change. Will be a little taller. If I go to far, it gets a bit funny in the shifting, the "spacing" between ratios goes out the window. Really needs a 10 speed, but that's going too crazy...It's all about keeping the antiquated internal combustion engine in it's "sweet Spot" in regards to rpm and load.

As for registering it in NY., it was easy. Just filled out a form that was titled "Homebuilt" and took it for a stolen parts inspection after I finished it. I know, sounds crazy! But that was it. Maybe things have changed since 1987, don't know. Go to your DMV and ask....

About he radiator, yes it is in the front for weight distribution reasons. It was originally in the back, but I realized that I made a mistake and changed that. Air flow was a *****, always needed a fan and the back was tail happy. Now, the fan NEVER turns on, what a waste of a really nice PWM fan motor control!

As for tuft testing, funny you should mention that. Just a few months ago my friend said, "remember when you covered this thing in yarn pieces and I drove it and you followed with a camera?" Man, I hardly recall that but, yea, we did do that! People in town had no idea what we were up to. The underside of the rear was a bit turbulent, but hey, what do you want from a 22 year old kid with no money?

[sdkrc]

Another good one from ecomodders. Bonus points if you can guess the base car without Google lens

12 forward gears 🤝

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• Engine: the original engine was replaced with a 1600cc engine from a Ford Pinto
• Engine modifications: the camshaft was retarded 2 notches (making a poor man’s Atkinson cycle); electronic ignition was substituted for the original system (in combination with a wider spark plug gap this permitted running a slightly leaner air/fuel ratio); adjustable on-the-fly carburetor from a Briggs & Stratton lawnmower; belt driven cooling fan removed.  Tom says it never overheated, even in summer.  He could run cabin heater fan if the coolant temperature started to climb.
• Tires: new for the time radial tires with lower rolling resistance

• Transmission(s):  a big portion of the mpg improvement came from adding a manual 3-speed Buick transmission inline (but reversed) with the Pinto 4-speed manual, providing 12 forward gears and up to a 2.5 overdrive.  The engine ticked over at just 1100 rpm @ 55 MPH (Nixon speed limit days). Excellent for economy, but requiring more from the driver: “a slight incline required downshifting.”

 

[Jim Bell]

"the camshaft was retarded"

 

Can't say things like that anymore. Can't say nowt.