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Old 04-27-2009, 10:40 PM   #21 (permalink)
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Bio Deezler (sold) - '03 Volkswagen Jetta GLS TDI
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Yep Cd, we definitely think alike. Thanks! I was actually just down in my garage pondering a decklid extension.

The car is already super low though dude. Probably about 3" of ground clearance under the skid plate.

I agree on the VGs too. Worth a try for 20 bucks and the cool look, imo. I think the reason you (and me) are confused is that while they often tuft test well, showing better attached flow right behind them, or on rear glass, etc, we still have no idea what is going on above the boundary layer or further downstream. And in those cases where they do add frontal area, well, that might be more explainable. One thing I don't get is how people recommend to place them on the rear slope of the car such that they don't add frontal area. This makes sense in general, but if the air flow over your car is still attached where you place them, don't they still present drag on a nearly full speed air flow and thus add "apparent" frontal area? Ok, so not full speed air flow, but the same boundary layer conditions as you have further forward on the car in area that would add frontal area....?

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Old 05-24-2009, 07:51 AM   #22 (permalink)
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I am curious about the change in coolant temp with the grill blocks you have.

I need to do blocks on mine very soon.

Pete
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Old 05-24-2009, 02:13 PM   #23 (permalink)
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I think the air is likely to be disturbed enough without the VGs.

You're car's surface is not a nearly perfectly smooth object like a solid golfball without indents. IMO I doubt they'll work and they would have to add frontal area. . .so its a small frontal add and an unlikey cd boost. . .

If you're doing it for the look I can't say anything lol. Go for it ^_^.
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Old 05-29-2009, 11:42 AM   #24 (permalink)
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Bio Deezler (sold) - '03 Volkswagen Jetta GLS TDI
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Repete, the grill blocks have almost no effect on coolant temps until ambient air temps rise over 75 deg F. Then things start heating up. If you notice, I left open the lowest valence slot and also a small slot of the lower grill opening. These were critical to keeping things stable for most of the year. In the summer time I have to remove the lower block sometimes.

Also, I swapped out my original thermostat that was opening at around 180 F for one that was supposed to be 195 F, however it runs at 206F. Kinda hot. So now when the grill blocks become a cooling limiting factor I get a little more nervous. I don't want to see coolant temps over 215, ever. It would probably be safe to 230, but I just don't like the idea of all that additional thermal stress on all my engine components.

Well, I decided to throw on some vortex generators and see what happens to my mileage. BAD NEWS! I lost at least 3-4 mpg. Even with slower driving to boot. In retrospect I think I may have chosen too large of VGs, since small children and motorcycles were getting sucked into my wake....



Mileage be damned! Kayaking is so freakin awesome. Off to do some more now.
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Old 06-01-2009, 01:44 PM   #25 (permalink)
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Ok, finally some actual progress to show. The kayak rack is back off the car for a little while also.

Car is currently in the shop getting a new timing belt, clutch, and 5th gear swap! New gear ratio should give ~13% lower rpms.

Before she went in to the shop, I managed to get started on some more aero mods.

Found a local plastic supplier and picked up some ABS and polycarbonate sheet. This stuff blows coroplast away for material properties, but yes, it does cost money. The ABS is pretty cheap though at ~$3 per sq ft. I have another 1/8" thick half sheet (4' x 4') on order.



I had already ordered some "custom" side mirror delete panels a while back. Now I wish I'd just made them myself though, as I ended up trimming off this much just to get them to fit:



First, pull the mirror off. This requires removing the inside door panel, so that you can remove the tweeter cover on the sail panel, to then finally unbolt the mirror. I would call only breaking one door clip a success! ha.





The small convex mirror is just foam taped to the dash with a simple L-bracket. View from Driver's perspective:



vs the actual view to the rear in my garage:



First impressions are that its really not too bad! Nearly complete blind spot coverage. Once a car in the next lane disappears completely in the mirror, its headlights come into view in my interior rear view mirror. I was planning to add one of the small sit-on-top safety mirrors that everyone else has been using, but I'm not sure its necessary yet.
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Old 06-01-2009, 09:56 PM   #26 (permalink)
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Quote:
Originally Posted by Deezler View Post
Yep Cd, we definitely think alike. Thanks! I was actually just down in my garage pondering a decklid extension.

The car is already super low though dude. Probably about 3" of ground clearance under the skid plate.

I agree on the VGs too. Worth a try for 20 bucks and the cool look, imo. I think the reason you (and me) are confused is that while they often tuft test well, showing better attached flow right behind them, or on rear glass, etc, we still have no idea what is going on above the boundary layer or further downstream. And in those cases where they do add frontal area, well, that might be more explainable. One thing I don't get is how people recommend to place them on the rear slope of the car such that they don't add frontal area. This makes sense in general, but if the air flow over your car is still attached where you place them, don't they still present drag on a nearly full speed air flow and thus add "apparent" frontal area? Ok, so not full speed air flow, but the same boundary layer conditions as you have further forward on the car in area that would add frontal area....?
I'm not the sharpest tool in the shed, as the saying goes. I like to hang out on this forum and pretend I can hang with the smart guys, and I see your point about the frontal area problem. What I had imagined was that the VGs would 'somehow' reattach the airflow like you see here Browser Warning without adding to the frontal area of the car by mounting them low and in the turbulent flow.

Who knows where the airflow is detached !
It may be attached all the way down the back window. ( Air does strange things sometimes ! )
It would be really interesting and useful to several folks here , as well as yourself, if you ( or anyone else ) could do a simple tuft test on the back glass of your particular car.

I really like what you have done with the mirror blockoff. That is by far the most professional looking job I have seen. I can't wait to see what you come up with next.

I want to clone your car
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Old 06-12-2009, 07:32 PM   #27 (permalink)
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Got a little more work done on the car. Had some incentive as the annual company car show was today. Not like anyone cared about fuel efficiency though..... Just a bunch of guzzlers and yours truly.



Re-did the front grill blocks with some ABS plastic:



Also sealed in the passenger side mirror delete with some silicon:



I don't think I posted an interior shot yet. Keen observers will note the added boost and oil temp gauges, scan gauge, and ipod integration.



One more out back at work:

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Old 06-12-2009, 07:36 PM   #28 (permalink)
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We can't observe keenly if you tell us what to observe...
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Old 06-13-2009, 12:26 AM   #29 (permalink)
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Quote:
Originally Posted by Christ View Post
We can't observe keenly if you tell us what to observe...
lol

Im liking the car too

Dont know how you manage to drive so smart

I mean... boost? cmon....
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Old 06-15-2009, 05:50 PM   #30 (permalink)
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Geez, calm down.

Aloha... : huh? A boost gauge on a diesel is comparable to a vacuum gauge on a gasser, fueling still roughly corresponds to intake manifold pressure. In a turbocharged engine you want to minimize your boost for the additional pumping losses created by accumulating exhaust manifold pressure to attain that boost, too.

But I suppose it's mostly for turbo safety when driving like an idiot. Is that what you meant?

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