Aeromodability of a VW Bug?

[gtkid2002]

Howdy everyone. I probably should have posted this question before I went out and got myself a Bug to tear apart and redo, but I felt it still possible. Still do though.

Anyhow.

I'm going to try and strip down my VW bug I just got down to the chassis, and put an aeromodded body on it. I read somewhere that the reason why the VW Bug gets such limited gas mileage**(Mom's informed me that her 68 got 30-40mpg, current non project 69 gets 14, current project 75 doesnt run yet) because of the aerodynamics, the Cd of .41.

Would it even be worthwhile to try and continue this project and make a custom aeromodded 1975 VW Bug designed for fuel economy (As in try and get a Cd of say.. .18 or lower for a beginning goal), or should I just rebuild the carb that's on it an enjoy it as the baja it currently is (29's up front, 32's in rear, haha)?

I can post a basic outline of what I was planning on trying to make if anybody is interested, but it's nothing fixed yet. Right now I've got the bug set aside, and I'm trying to sell the tires to fund the project, but if it's best to keep it bajaed, I'll take down my ad and have some fun. Or just fix it and sell it or something.

[Joenavy85]

I would say that there are a lot of different things you could do to an "old-school" Bug. I think .18 Cd is a little on the optimistic side, i would set a beginning goal of .25-.30 Cd. Then again if you look at basjoos's Aerocivic, you can drop it down quite a bit. i would drop the ride height for starters; depending on how tall you/your passengers are you might want to chop the top down a couple inches. a boat-tail is pretty much a given, maybe you could extend the wheelbase back a little to help weight distribution(though that could take quite a bit of work)

[Joenavy85]

go to The-Blueprints.com - Frontpage and you can get a profile view of an old Bug, they might not have a '69 though. then use paint or some other photo editor and draw up some ideas.

[botsapper]

Here's one an applicable analog with another ambitious plan. >150 mph on only 36hp!
Bonneville VW Challenge - Page 9 - The VolksRodders Forum

[elhigh]

I'm glad you asked this question.

I don't have a Beetle myself, but I wouldn't say no to one. Kids' tuition, house payments - you get the idea. No time or money just yet.

But: Hot VWs magazine picked up the idea of building an engine, optimized for fuel economy. The project dropped off the radar a couple of years ago when fuel prices dropped, but prices are heading back up - maybe they'll get back into it, hey?

Anyway. Their stocker racked up a dismal 22mpg as found. With a chassis tune and a fresh alignment, they got up to about 27-29mpg. Big improvement!

Then came the engine. Contrary to what you might think, the motor they built is no slug. It makes good torque, it gets a big power bump. A little more stroke makes for good twist. Their assessment was that the car with the new motor was downright fun to drive.

Hot VWs' project was almost exclusively engine mods, and a "Freeway Flyer" tranny swap. They added a small spoiler to aid airflow separation, which was good for 2mpg, this after having already gotten solidly into the 30s. But bellypans, rear wheel skirts, smoothie wheel discs? None of that was ever done.

At its best combination, with a CBPerformance throttle body injector, the Freeway Flyer and the spoiler, the Beetle would tool down the highway at 65mph, delivering 36mpg. That's pretty good by any measure.

Do all the aero mods you can think of, and I bet you could get it into the 40s and keep it there.

CBPerformance has the entire run of articles archived on their site. I used to have them all in the mag, but needed to make room for more comic books.

[RobertSmalls]

http://ecomodder.com/forum/showthrea...why-12732.html

This thread has some good information on the Beetle's unimpressive aerodynamics. The basic body shape isn't great, and an air cooled rear engine is far from ideal from a FE perspective. So I would say an aero rebody is a great place to start. I would also make it a point to get modern, LRR tires and an efficient engine.

An aero rebody is a very ambitious endeavour. I can only think of a handful of people on EcoModder who have attempted it. How far along into the process of planning and allocating resources are you?

[gtkid2002]

Well I'll be using a 1975 chassis. I got it specifically for this purpose. I plan on using only the chassis and engine, not the body. I want something with a suPer low Cd. Since I won't be using a bug body, a Cd of .18 should be possible. Not adding onto it, just a one peice body. I'll post up an idea of what I was thinking when I get home.

[Joenavy85]

i would say .18 Cd is definitely achievable since you're ditching the stock body

[gtkid2002]

Ah, to be able to type on something that doesn't have a touch screen.
Anyhow.

Robert- So far I have the bug. Picked it up for 50 bucks and some of my junk, so I got it for a steal. It's been bajaed, so I get to undo that. I'm selling the tires, shell, and some other minor stuff off of it to help fund the body parts. I've got a standard arc stick welder, and a tiny little oxy-mapp welder I can use if I need to. I've done fiberglassing before, and I don't think working with rivets should be too hard. Right now I'm at the planning phase, but I at least have the car. Soon as I get a solid idea, I'm going to start selling things and dumping funds into this. I think the hardest thing for me to get ahold of will be the steel tubing for the roll cage.

As for the engine, right now it is nowhere near FE goodness. I have to dump raw gas down the carb, rev the crap out of it, and feather the clutch to move it. I found some stock wiring I'm pretty sure went to a stock fuel pump for the stock FI engine, so somebody swapped engines in this thing along the line. So I plan on switching back if I can, or just seeing if I can get this one running well enough to use it for a start engine.

Although if you know of a more FE engine that'll bolt straight up to a standard VW Bug transmission (I -really- want the Freeway Flier), let me know so I can look into it.

Elhigh - The freeway flier is the trans I want to end up using. 3500rpm @ 75mph would be better than most cars I drive now (that data is on the mid-america motorworks website I think). I think for the first phase of the project I'm going to just stick with a carb, mostly because it's cheaper to work with, and I kind of already have one installed. The stock engine was supposedly FI, which I love (I did injector cutoffs in the car that's my avatar, that was awesome). I was actually trying to find a small single cylinder diesel engine to use like the single seater VW concept (I forget the name) used, but I remember two things:
A: I live up 600 feet. I have to commute to sea-level, and back up. I don't think that would work for me, unless I want to get hit.

B: I want to retain the haulability of four passengers. I figure for the rear "seating"/cargo area, I would leave the basic lap belts in, but remove majority of the comfort factors back there. No padded seats, more like a hard dense plasticy foam, or just plastic seats. Nothing fancy, more like something you'd find in the back of an old school classroom.

I somehow doubt that a 10hp diesel engine could putt me and three passengers, a full tank of gas, and say a 50 lbs guitar amp up a rather steep grade, at least at 20mph, with all the lights on. So I kinda said forget that.

Botsapper - Is it just me, or does it seem at least slightly impressive that a 36hp engine can hit such high speeds? Interesting link at least.

JoeNavy - Aerocivic has had a huge impression on me. I kept a tab of that open for months, just drooling over that car. That's just about the main driving reason behind this. I want to drive a car that costs pennies to run distances in. Granted he did an engine swap, but 80mpg at 60mph?! I've got no problems driving in the slow lane. And where I'm at, If I had 20 bucks to burn, I could get bored and almost do a 600 mile road trip. I could do it comfortably on 50 bucks (Granted that's if gas goes back down to 3.27 a gallon when I calculated that).

I'm still toying with body designs, but one of the popular threads up was the one about the pillbug car? Seated seven, but dissapeared to england after WWII from what I got. The prototype had a Cd of .117 I think? I'd have to rearead the thread to find out for sure.

[botsapper]

Here's an American-designed version. http://blog.hemmings.com/wp-content/...liner_1000.jpg

...design to your heart's ($ and fab capabilities) desire.