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Old 09-25-2012, 07:37 PM   #12 (permalink)
aerohead
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component mods

Quote:
Originally Posted by freebeard View Post
And so we come to the driver. I won't say daily driver because I divide my travel needs between the bicycle (Schwinn Collegiate with a banana seat), city bus (I'm of an age where I can ride for free) and the 1971 SuperBeetle.

It was pretty much stock when I got it, It is 40 years old and has less than 100,000 miles. Since then I've made the following modifications:
• Renewed front suspension with adjustable MacPherson struts (we lowered it until it looked *good* and then raised it until it clears most traffic control bump strips)
• Rebuilt brakes (although I now question converting the front to disks) with the drums and rotors cryogenically processed to extend the part life.
• CB Performance electronic distributor (this is a billet housing full of Ford parts, the spark curve is programmable by swapping out springs) that possibly got 4—5 mpg increase in the first car I had it in.
• AM antenna delete
• Driver side mirror delete — this is temporary (honest, officer)
• Tire pressure maintained at 40 psi
• Nut behind the wheel lightly torqued

What works against me:
• Low miles travelled. The only time I would be able to gather data is on sporadic trips out of town.
• Incomplete data. No Onboard Diagnostic Port, no MAF sensor, no GPS
• Screwy data. The gas gauge is way out of calibration. Because the front tires are 165-45/15 the speedometer, which reads off the left front wheel, it wildly optimist. I can bury the speedometer needle at normal freeway traffic speeds.
• Eh, that's enough

What works for me:
• It doesn't look shabby, at least to start (it's a 5' car, get 2' away and you can start to nitpick chips in the paint and rust in the door hinges) so anything I do will reflect favorably on my fellow ecomodders.
• I'm familiar with the platform. Ferinstance, from hanging out on thesamba.com I learned you can get the correct kind of activated charcoal to repack the gas vapor recovery system by buying a $14 Cadillac part.
• The Bug Bearer bike rack. It is mounted with some custom brackets added to the stock bumper brackets. It peaks at the Template line and is 34" wide. I could make a K-back out of 2 or 3 layers of the plastic the use to wrap palletized freight.

What I'd like to do:
• Better instrumentation. The panel van had a head temperature gauge with sending units on the #1 and #3 spark plugs on a toggle switch. I could use the AM radio antenna mounting hole to install a pitot tube for (barometrically sensitive) air speed. maybe a MAF sensor in the bottom of the air cleaner to measure intake air. Using the Airflow Meter as a Dyno I'd like an engine vacuum gauge but I'm not sure about running a vacuum line the length of the car.
• Engine modifications. A Gene Berg Jet-A-Vator. Hot VWs got xx% improvement with this. Water/methanol injection so I don't have to run Premium grade gas for the octane rating. The H2O Way Part 2 Maybe electrical tape wrapped around the intake manifold runner for heat.
• Aerodynamics. Eventually a boat tail or Template-shaped single wheel trailer. But also front and side air dams. When I repaint, move the turn signals down off the top of the fenders, unless I start liking them after I chop them down to half height and put in LEDs.
• Replace the stock rear bumper brackets with a custom built class-1 trailer hitch. This would incorporate heavy-duty sockets for the bike rack that could double as mounting points for a single wheel trailer and tabs to mount the rear bumper. This would give me three options in back. Otherwise, I think I could build a boat tail that weighs little more than the stock bumper. I have no problem with driving around without bumpers or spare tires.
• Judicious torquing on the nut behind the wheel.

But enough jibber-jabber; let's talk boat tails.

Back when I first started seriously reading Ecomodder.com, I whipped up a Template primitive .obj object and held it up against a commercial VW model to see what's what. I was kind of dismayed that the boat tail is as long as the car's wheelbase. I also looked at messing with the Template by giving it a parabolic cross section and using three for that 1930s look.


The single aeroform is maximal, I held it as far forward as I could. The interesting part to me there was the area ahead of the rear wheels. Instead of fade-away front fenders, this might offer a solution that doesn't affect the doors.

The triple aeroform in minimal. If reducing the volume of the wake is beneficial, accepting a dirtier flow off the body might be acceptable.

For purposes of this post I prepared some side views with the template:

We begin

The Template

Ground clearance

What if we only do the rear fenders?

Move the same cross-section to the roof

Truncate the lower aeroform

I think I could live with this
If you want to consider component mods,'Aerodynamic Drag',by Sighard Hoerner is your friend.Hoerner worked for Messerschmitt during WW-II and was brought over to the U.S.A. under Operation Paper Clip.Hoerner personaly did full,automobile body discard and Jaray body replacement aero comparisons.His book is a treasure trove of streamlining.Complete breakdowns of every component on an aircraft is covered as well as cars and trains.His tables will show you how to best streamline any part of the Super Beetle.The 'Template' won't be applicable for all of that.
Ask a local librarian to find the nearest library which has a volume.If you make the trip with enough cash for the copy machine,you'll end up with one of the best reference books ever written on streamlining.I found mine at U.T.Arlington,Texas.Typically,these books cannot be checked out.
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freebeard (09-25-2012), slowmover (09-30-2012), Sven7 (10-04-2012)