The DUNGBTL Build

[DUNGBTL]

[DUNGBTL]

[Rome]

The Beetle rear fender front curvature air intake which I remember was shown here on tS, about 3 years ago. He cut a thin, tall section into the fender either with louvers, or metal screen. Fabricated a channel on the quarter panel to guide the air into the engine compartment. It was a very good effort and outcome. I just did a quick search here but could not find it, despite remembering that I posted a comment.

[VolksRodT]

You're welcome, hoped I wasn't stepping on toes - not my intention...

FWIW;
I'm doing this from memory.
The guy that did the lower-front-fender air-intake, made a sealed duct that went along the inside edge of the fender, over the top of the tire & dumped into the engine compartment right alongside the webers(iirc). Enough airflow that he decided a divertor was needed to help even-out the flow into/across the carb inlets. Did engine, compartment, etc temp tests to see if it was worth anything. It was!.
They were not just slots or a hole in the fender. & the opening wasn't all that big, but iirc, he did do some rough calcs on sq" area(s).

& while I can't lay my finger(s) on it, awhile back before the funny cars got blob-looking, sharp folks figured out that a fairly large fender-lip-extension(inward towards & near/around the tires' outer edge, also included moving the tires' edge to near - or at least closer to - the outer edge of the body.) drastically reduced turbulence & cleaned-up the front wheel-well area. Don't think it'd be of great use on a bug, but might be worth playing with, as it might be surprising. Decades ago(very early 80s), in a "former" life, I got to listen to an aero-seminar from a couple Ford engineers, relating to mpg-gains from airflow at ~ 55mph. Turns out small things matter. .
Marcus...

[VolksRodT]

Found one of the threads:

https://www.thesamba.com/vw/forum/viewtopic.php?t=742109&highlight=engine+compartment+venting

Marcus...

[DUNGBTL]

[VolksRodT]

More than a few rambling thoughts... ... Which have morphed just a little... .
Keep in mind here, inspiration(s) come from the Dodge Winged Daytona, Shelby GT350 & Shelby Daytona coupe, Bonneville, some IMCA, GTP, Indy & F1 ideas. Oh, & Jim Halls' Chaparrals. Can-Am. . & even abit from the hi-mileage groups.

No, I didn't figure you needed "more air-cooling"... ;D . W/o going back into thread, not sure how much venting you have for engine intake, probably enough. Hopefully enough if you ever decide on super/turbo-charging, too?

So, this'll get abit word-y, since I don't post pics, much less "w/circles & arrows & a paragraph on the back explaining what each one is(in 3-part harmony)"... . Ahem.. Sorry... ''


Where the fender-trick(s) could come into play, esp for you & your cars' style, would be to use that hi-pressure area to:
a) reduce drag & turbulence there,
b) reduce(change) the low-pressure area behind the rear window/deck-lid area,
c) possibly use a little air there for rear brake cooling possibilities,
d) possibly(again, hopefully) use the airflow for other(idk, engine, trans, ??? eventually intercooler ?) cooling effects. (Making the "cold" air now "hot - or at least warm & thus more volume-y" [sorta like this thread-comment '' ], & in this case, more *is* better + useful for "back-filling" behind the bug).
e) Mostly moving hi-pressure to(wards) low-pressure areas. Hopefully doing at least 2 things at once. If you're gonna expend energy moving the lazy air, may as well force something useful outta it at the same time.

Some amusing(& useful) trickery can come into play here, & the effort would be worth the onlookers' head-scratching-comments, not to mention from all the mouth-breathing "wuffo's" too. ''.

So, it's somewhat well-known(or, so I've read) that the acvw bug suffers from suck-lousy aerodynamics(coke-bottle-shape it ain't), esp from the leading edge of the rear glass back. The little spoiler that fits on top of the rear window helps by creating a Kamm-back effect. Good start.

Remember the GT350 rear window? ;D ... ??? The top inwards-deflection is to reduce turbulence & low(er) pressure there by allowing airflow thru that gets into the body(like to drive w/your - or the, window(s) open much, esp if it's hot? ) to exit into the low(er) pressure area, which lowers the drag-suction(& subsequent lift) at the cars' rear. & should, in theory anyways, alter the cars' pressure-balance(I forget the proper term here '' ), even if only a little bit. I'll postulate "anything useful" helps". .

Ya, yah, yaahh, uhuh. So we know this already - & the same thing can be applied to a bug. I've long thought about it, & occasionally doodled it, but you're one of the 1st guys(other than FJCamper) I've seen to seriously propose it.

I'd also experiment w/an outward vent - including a lip-like spoiler at the bottom of the rear-glass(think Merkur or SVO Mustang effect here[sorta]), as an extra outlet. Like say, from near the tops of the rear fenders thru the body (hopefully) ducted directly to the lower-part of that rear-glass? You should be careful w/the sq"-area(s), so's at least the outlet is larger than the combined two inlets.

Theoretically, & w/o yarn-testing idk, but - it should work to use the rear side windows popped open to vent from the hi-pressure fender area. I think the lower rear window exit would work best.

Or you could duct the air thru the engine compartment letting the mill take what it wants, & then duct it out of the decklid into that low(er) pressure area.

Making a quick-plug for an experimental window isn't hard, nor expensive, just takes time. & can be later used, after the tuft-testing, et-al(I'd include at least one homemade cheap manometer here), to make a plug for a plastic window. That's abit ,more involved, but can wait. If you're careful, you could make an interim-"window" using clear resin(maybe even the glue-version you mentioned) & the white 'glass cloth/mat. Not see-thru, but not black either. & easily modifiable...

Now, about the lower & tops of the fenders...

I don't think just opening up the front lower fender area & dumping it into the tire will help much, other than acting as a parachute fill. IDK, maybe...

I suppose you could reverse-scoop the tops of the rear fenders, but, iirc, there isn't much room there. & I'd bet at the bottom-rear-window/top-of-the-decklid area would show a lower depression, but that's just a guess.

On the front fenders, a reverse-scoop should work well to help reduce inside-fender pressure & also fill the turbulent low(er)-pressure area behind those too. (Jeez, I hope I'm remembering this correctly... '' ).

To get the venting to work better, or at least "more correctly", an inner-fender partition should be utilized, shaped so's it's ~ 1-2" away from the tires'-edge travel. Doesn't need to be complicated, flat or near-flat will work. It could follow the fender-lips' curve to the body, ending near the back ~1/3ds' top surface. & the bottom portion should be sealed w/a flat piece, I'd put a nice radius where the two join instead of a sharp edge. The rear-facing-scoop will vent the tire & fenders' front area. & the front bottom of the fender should also have a flat plate closing off that area up to near the tire, I'd add a small lip(mini-spoiler) for strength & to help direct air movement.

At this point, you could also choose(hey, it's *just a little more* work - right??? ) to use the rear portion of the front fender + another(maybe) top-fender-vent to empty the hot radiator air, instead of behind the bumper. & could utilize abit of the flat-under-panel to duct hot air out too. So's you'd split the radiator exits 'twixt into the front fenders. This'd be sorta-IMCA-inspired, but w/o the radical fender extensions. The whole point here is almost-kinda-sophisticated-trickery that still functions. Would(should) calculate the exit areas to get a decent spread. Final exit larger than entrance, taking into account hot-air-expansion.

Btw; the same inner-fender(aka: splash-guards/etc) panel & bottom-plates should be done to the rear fender. Stops the "parachute" effect - or at least slows it down.

So's we also have a hi-pressure area at the bottom of the windscreen, some of which could be moved to the rear via a small(variable) opening, using hinges & locks(or electric motors if you wanna be trick) to keep it in place. Like the Samba kits, or the late 20's->early 30's cars. There's at least ~ a half-dozen ways to do this nicely. We're only talking about opening it ~1", maybe 2". & at this time, now we need to also open the rear windows. All Oem, since VW did offer pop-opening rear windows, right??? . Depending on how much air we're moving, might want to make "bubble-shaped" rear windows for better air-flow. Might find that the front-door-post-mounted "wind-deflectors"(oem option?) may also help... Again, need to figure out sq" area exit(s) vs the other openings...

To help manage airflow under/around the bug, I'd also use thin, say maybe 3/8" thick or less(possibly as thin as ~1/8"?), conveyor belting as skirts, almost touching the ground. Hopefully the bug isn't too low already, as really thin skirting would be flexible for bumps & suspension working, but it'd allow a low(er) pressure area under the bug the faster it goes. Across the front behind the spoiler, alongside & inside the tires, & also alongside the body. Essentially following the htr-channels & continuing to the ends of the rear fender.

"& now for something completely different..."
'' '' '' '' .
*If* you want to close off the area starting at the under rear torsion-bars, the little back-seat & pkg-tray area would be perfect to mount a small 2-stoke & a prop on it. Or stupid cheap = adapting an available-area-sized lawnmower & blade(+ the guard = a must), ducting all that out the rear window. Are you sure you *need* a rear window... . Viola, a Sucker-Bug. .

If you don't want the skirts &/or the sucker-fan, dispense w/the side & rear skirts, & run a box-section in front of the firewall & torsion tubes out thru the rear window. Or preferably, duct it out thru the catwalk under the rear window. It'll pull a lot of air there. The inspiration for this is the '53/'54 Studebaker coupes & hardtops at Bonneville. While being one of the slickest cars made, there is a low-pressure area behind the rear window that is dangerous at speed(severe lifting), to the point that, iirc, SCTA has allowed the modification to stock-bodied classes, strictly in the name of Safety. The mod is a box-shaped "tube" that opens in the floorpan ahead of the rear axle, goes behind the rear seat back, & exits thru the catwalk between the rear window edge & the trunk edge. Nothing trick, just an open box for air to travel thru to reduce the low-pressure area, thus reducing lift at the rear of the car. Works unbelievably well. Could also make a decent place to mount that spare tire to the front of the box, & maybe some other things too.

Or, there's always the Dodge Daytona Wing... '' .
"The H w/all this" ??? Ya, I don't blame you... . Well, then, at least use some homemade Vortex-Generators to alter the boundary-layer-flow where needed. Easy to make. Just 2"->4" circle of al, w/two edges bent up at ~45*, ~ 1/4" in from the outer-radius, maybe 1/4" high, & the bends placed forward. Space them ~ 3"->6" apart. Temporarily tape them to the body for tuft-testing, dbl-stick tape, glue, or small bolts to hold them in place permanently.

If you can't tell, I really like your project. I'm also guessing that by about now, you're wishing I liked it a *whole* lot less... .

I'll quit now, since I've dug myself quite a hole...

Marcus...

[DUNGBTL]

Marcus…
WOW…that’s a lot to think about! Thanks for taking the time to jot them down!

Lots of cool ideas there. I’ll admit I’m not ambitious enough to implement most of them! I’m trying to accomplish my build goals by implementing the KISS method, although I may appear to fail a lot.

I have read a lot of FJ Campers’ STF posts and blog. He seems to be a SME on making Beetles and KG’s go fast around a track. My build is more a street car that I could take to a local AX or club track session and have fun and not be too embarrassed by the big bangers…and take to Car ‘n Coffee and VW meets and perhaps raise some eyebrows and/or created conversations.

I’m striving to strike a balance between styling and AX/Track performance…with perhaps a tad more on the aesthetics side. Styling being mainly vintage Porsche 356/911 production based racer inspired. So things like ‘skirts’ and ‘vortex generators’ are out. I have a strong vision in my mind on how I’d like this thing to look and I don’t want to stray too far away from that (think Rod Emory “Outlaw” Porsche meets early Super Beetle).

Things like shaving the rain gutters are possibilities though! Likewise, venting the fenders seems to be in the realm of what Porsche did back in the days of the vintage 911 racers. Esp if one did it “tastefully” using louvers or cutouts w/stainless mesh behind.

For engine air intake, I reversed the TB (from Subie oem position) and modified the OEM air box. Happy accident that it landed directly behind the decklid vents…

Not going to turbo or SC…my style is NA with performance through light weight with modest HP.

Really cool ideas though! If I was building a Time Attack or track only car, I’d definitely consider implementing a lot of them. However, I will keep them in mind (and now they’re part of the DUNGBTL documentation! ).

Thanks,
J.

[VolksRodT]

Hey, Dungbtl;

I kinda figured most ideas would be out of bounds. & most not useable.

I dropped them, mostly due to the pics of the other beetles you posted. Since they seemed to not fall into any class, but "fantasy" or "could be" ? IDK. Only partially familiar w/the various classes the modified 911s ran in. You know way more than me. Part of the reason I got wordy, was to try & describe possibilities of "almost hidden" mods. Think like: Smokey was hired by Porsche. . These weren't for actual track use, although they'd help - thus the "justification(s)", & would work on the street also. Albeit "potentially" radical. Maybe. .

If I could have a beetle, I'd like those mods...

I'll watch...

Marcus...

[bruceo98]

For engine air intake, I reversed the TB (from Subie oem position) and modified the OEM air box. Happy accident that it landed directly behind the decklid vents…

Will air enter the lower rear window vents being its a low pressure area? Will the rear window spoiler help that? I’m just looking to get air into that area for the intercooler on my car. Someone told me to put a fan on the intercooler blowing the air out of those vents and I was hoping to be-able to draw air from there . That’s something I never looked into and don’t know much about.
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I may not be the best, but when the top 10 get together, they all talk about me.

[DUNGBTL]

[DUNGBTL]

[bruceo98]

Yes .a2a and I will probably have more like 450 fwhp.
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I may not be the best, but when the top 10 get together, they all talk about me.

[DUNGBTL]

Started working on refreshing the ‘03 Subaru EJ25. Started from the top.

Removed the intake manifold which contains a myriad of tubes, hoses, the fuel injectors and the engine wiring harness.

All the fuel lines and vacuum lines are baked. They’ll be replaced. I sent the fuel injectors to RC Engineering for cleaning and flow balancing.

I always use RC for injector service…quick turn around and injectors come back complete w/seals and o-rings ready to go!

Cleaned the outside of the intake manifold first with a wire brush on a drill…

…then the inside from 180K miles of baked on oil vapor with brake cleaner followed by a scrub down with Simple Green HD Aircraft cleaner (safe for aluminum).

Got all the ports and runners pretty clean…

…did the same for the coolant crossover…

Did the same to all the spaghetti tubing. Coated everything with VHT clear brake caliper paint…

…and heat cured per instructions (200F for 1 hr…heat and chemical resistant after heat curing).

Intake wouldn’t fit in oven…it’ll have to heat cure in operation.

Spent a lot of time unwrapping, inspecting and cleaning the wire harness. All wires and connectors were in good shape except for the cam position sensor. Its wires at the connector were toasted to the point that the insulation had cracked away. I bought a new connector w/pig tail and spliced it in.

I also spiced in a Speedhut water temperature gauge sending unit. This required drilling and tapping the water crossover manifold for a 1/8” NPT fitting. The OEM Subaru water temp sensor has to remain in place. It’s signal goes to the ECM which triggers the cooling fan to go on. It appears that Subaru may have anticipated another sending unit being installed. There’s another fitting ‘boss’ adjacent to the OEM sending unit…

Once drilled and tapped, the Speedhut sending unit moved in next door…

I’m using Speedhut programable gauges. I was going to use vintage Porsche ‘silver-dot’ gauges in my ‘custom’ dash…

However, I decided I didn’t want to monkey around with the typical fuel gauge issues…making the tachometer work with the Subaru engine signal…or the typical speedometer error when using the mechanical speedometer with different diameter tires. Can be done, for sure, however for me this is the path of least resistance…modern digital programable gauges that you can actually read at night!

I’ll eventually restore the Porsche gauges and sell them online.

So along with the temp gauge, I bought the Speedhut oil pressure sender and their adapter for Subie motors.

Also bought their wiring harness that match their sensors and gauges…of course they don’t come with their gauges. I integrated the the new temp and oil psi harnesses into the engine harness…

Now just waiting for OEM Subie parts to arrive to reassemble the intake manifold. Then it’s “OFF WITH THEIR HEADS!”…the #2 & #4 head has definite head gasket issues as it is wet w/oil all around the parting line (tell-tale EJ25 head gasket failure sign)…#1 & 3 is dry. I’m getting rebuilt heads w/slightly hotter cams and using these as cores.

Slowly but surely!
J.

[bruceo98]

I really like those gauges. Nice job cleaning up everything. Hope the cams have a rump to them . Love the sound of NA car with cams . I stayed with stock cams but may change them out later.
_________________
I may not be the best, but when the top 10 get together, they all talk about me.

[DUNGBTL]

[DUNGBTL]

All race cars (and wanna bees) need tow straps.

Came up with an idea for the rear using my bumper slots.

Took the right side oem bumper bracket and cut a slot thru the aft face.

Cut out some 1/8” gussets…

…and welded them in to make a double shear tow strap mounting bracket…

Strap attaches with hi-strength M12 bolt and nut…

Stowed away for ‘street’ driving…

J.

[H2OSB]

Genius! You should do the front as well.

You have no idea how many ideas I plan to steal from you.

H2OSB
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(o\_i_/o) I'm not a vegetarian because I love animals, I'm a vegetarian because I hate plants.

[bruceo98]

[DUNGBTL]