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Go Back   TDIClub Forums > VW TDI Discussion Areas > Upgrades (non TDI Engine related)

Upgrades (non TDI Engine related) The place of handling, lighting and other upgrades that do not relate to the performance or economy of the TDI engine. In other words upgrades to your TDI that don't fit into TDI Fuel Economy & TDI Engine Enhancements.Please note the Performance Disclaimer

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Old October 20th, 2019, 15:54   #1
Andyinchville1
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Default //// anybody here doing aero ?.... some ideas ////

Hi All,

Car is back to running well so i thought i'd take the opportunity to start some aero mods ...

I know the Eco modders site has a lot of discussions concerning this but I was hoping to see if anybody's here was doing anything and what their results were on actual Volkswagens as opposed to cars generically..

1) I've noticed that a lot of modern SUVs have a small extension past the roof line ... I'm wondering if that more of a looks things or an actual partial kamm back which could be functional for better fuel mileage.....

The size on many of these Factory pieces is somewhat less than 4 inche long so I'm not sure how much that actually helps and I was wondering if anybody has done anything like that here as an addition to a car not normally equipped with one.

2) I know there are a lot of body kits available off of eBay for side skirts and modified front air dams etc. ..has anybody here tried any of those? if so which ones and how have they affected fuel mileage?

3) I thought about doing the shark fin antenna mod but after reading a lot on it I'm not willing to lose a lot of radio signals so I probably won't do that mod for aerodynamics.

4) since I recently hit a deer with my car and one of the mirrors got damaged I thought about going back with some really small mirrors ... side mirrors that is.... has anybody here done that? I think I saw somewhere a company was selling stubby mirrors for our cars specifically the Jetta Mark fours.... the smaller size ought to be more aerodynamic but I thought about going seriously small has anybody done that and or deleted side mirrors all together in their quest for better fuel economy?

I would probably have to put some rudimentary side mirrors on just to satisfy the 300 feet sight distance law but I would add a large wink style 5 panel interior interior mirror so that basically everything can be seen on the sides and to the rear of the car.

5) I'm seriously thinking of deleting my roof rack since it's never use anyways I'm wondering how much I can expect as a game from doing that?


If anybody else on here has been experimenting with aerodynamics I would be interested in hearing and seeing what you've done and what types of fuel mileage increase as you've gotten with it...

Thanks in advance for any and all help
Andrew
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Last edited by Andyinchville1; October 21st, 2019 at 18:12.
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Old October 21st, 2019, 05:05   #2
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if there are no cross bars on your roof rails, I doubt the gains would even be noticeable. and then you have holes in your roof to deal with.
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Old October 21st, 2019, 10:30   #3
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Admittedly, I had typed up a tongue in cheek reply about weight reduction as a way to potentially increase your FE ... but I'm sure it would have come across as mean, and that was not the intent. That said ..

I googled hyper-miling Jetta TDI and got some good links (some to TDIClub, so to other forums). There were also some good images. One even showed a passenger side view mirror that was inside the car.

Good luck.
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Old October 21st, 2019, 12:29   #4
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lowering. reduce drag under the car.
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Old October 21st, 2019, 14:45   #5
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Not sure but I plan to try a bunch of things....

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Old October 21st, 2019, 15:52   #6
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The BlueMotion TDI is a good place to start when thinking about aero changes to improve FE. I'm not sure what body items will directly translate, but I think the MkIV GW did have BM counterpart. I know the BM Mk7 Golf has a full underbody tray to reduce drag, and the e-Golf and BM grills do the same. Also, you may be interested in reviewing the old experiments by Ernie Rogers, whose MkIV Beetle was a real-world testing ground. Lowering doesn't guarantee gains, and (IIRC), Ernie did better with narrow LRR tires, despite these raising the height, than he did with other options.

The roof rails can be deleted, but, as said, you'll have to fill holes to fully realize gains. As with most aero mods, the FE improvement might be too small to track on its own.

VW did sell stubby SVM's that will fit the MkIV. Some were made for both RH and LH drive cars, so you could do this on both sides if you find one of each. If VA doesn't require a PS mirror, just delete altogether. From memory, the SVM are one of easiest ways of reducing drag. If you delete and replace these with a camera system, you'll certainly see some gains, but VA may frown on your solution.

Aero mods are interesting, especially if you've already focused on easier, quicker gains: Your right foot, FE tunes, LRR tires, lowering RPM, reducing weight, etc. My guess is deleting the rear seat and full size spare alone would raise city FE, equal to any aero gains on the highway.

The challenge after modding is reliably documenting gains in connection to specific mods. Unless you're using a wind tunnel, the variables in everyday driving are so difficult to control that results are easily skewed and difficult to interpret.
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Old October 22nd, 2019, 05:39   #7
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Hi

Thanks for the replies so far.

Since I got my car back to running I haven't had a tank less than 50 miles per gallon over the last 4,500 miles.

Most of my driving is at night requiring few if any real stops ... many times at night I don't even do the speed limit because of the number of deer out.

I don't employ any real hypermiling techniques like engine off coasting pulse and glide Etc because most of the things I have to drive to have to be done based on 50 miles per hour.

Admittedly I probably don't accelerate as hard as normal and I tend to coast up to stop signs and stop lights as opposed to running up to them and putting on the brakes.

As far as aerodynamic modifications I have done in the past I have done grill blocks (upper grill, driver side lower grill, half of passenger side lower grill and up to half of the lower center grill).

Having done grill blocks before the biggest benefit I noticed from that was quicker engine warm up temperatures as indicated by the ScanGauge.... the car never really ran hot although intake air temperatures were somewhat higher when partially blocking the intercooler Grill...

As far as the aerodynamic Pizza Pan wheel covers ... I'm not sure if I had any measurable difference in fuel mileage as a result of them but I sure got a lot of interesting looks..

Although my initial attempts at aerodynamics we're done with the intent of getting vastly improved fuel mileage , I'm not sure I was able to actually come up with a numerical value for that but I think part of that might have been due to my injection pump and injectors failing around the same time therefore possibly negating any of the benefits from Aero ( in effect the improvements made by the arrow may have been supporting my fuel economy numbers in the past because of impending mechanical failures ... ie my injection pump eventually failed and after changing out the injectors it was found that one of the injectors had been leaking and I'm also assuming the spray patterns weren't optimal).

Of course after I got the car back to running and averaging over 50 miles per gallon without Aero aids I want to try to establish a new Baseline for fuel economy and then reapply the aerodynamic aides to see if more mileage can be gotten....

One thing that is a little unfortunate though is that my driving is not necessarily on the same route as it was often before .... having to do dedicated runs was really great for mileage tests because the route would be the same over and over again but now they're just a series of Random one-offs so changes in fuel mileage may be hard to determine but if all of a sudden my fuel mileage hovers above an establish Baseline I suppose that could be an indication that things are working out for the better when i reimplement my aero improvements....

Fwiw some of the other none Aero improvements I've made to the car were ....

11 mm injection pump and DLC 520 injectors, Malone stage 1 tune with Dynamic EGR, avus Wheels to replace steelies, ecopia tires P 205 70 R15 upsize, ceramic tint to reduce need to run air conditioner, remove rear seat lower cushions so when seats are folded down I gained a little more space while still retaining a flat floor the weight Savings in this was a little negligible. LED Lights.

I suppose if I were hardcore trying to get fuel mileage I would gut out the interior and leave the spare tire at home.... but admittedly I'm not quite that hardcore yet although I did go to the junkyard and bought a Avus wheel
To replace the steel spare yesterday....

I do carry a plug kit with me and thought about just simply adding a compressor to eliminate the spare tire altogether because I have never actually had a flat on the road....

Anyways for now I think I need to establish another 5,000 miles or so worth of base line fuel economy and then I'll start doing some Aero aids.
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Old October 22nd, 2019, 09:04   #8
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For the rear seat, yes, the bottoms are negligible- It's the seat backs that are quite hefty. If you want to maintain the flat floor, you could mimic some of the vortex owners who built a cover (some are carpeted, with storage) which creates one continuous trunkspace.

From memory of old threads, fuel use measured by VCDS on the MkIV: coasting in 5th uses less fuel than neutral, and coasting in neutral uses less fuel than engine off and starting back up (except obviously where there is an unusually long coast time).

Having the same roads/route certainly helps establish a baseline, but you'd also want to establish a base over the same seasons, temps, wind conditions, etc. Where the aero gains are small, it will still be hard to narrow down the cause. As you know, just that 10,000 miles will have worn the tire tread, slightly changing the circumference, which slightly changes the odo recording, which impacts calculated FE. You can record miles traveled by GPS, but GPS is not perfect for recording distance. If you account for any error in the odo (which you may already be doing with 205/70/15's), it may still be nearly impossible to determine if a FE bump was due to a specific aero mod, or the improved FE of a tire as it wears in (and becomes more fuel efficient than when new).

A different 5th gear might not fit your current route, but will provide some highway gains (or a 6 speed swap). A donut spare would save some weight. Somewhere there is a thread on vortex generators (or whatever they are called), I'm not sure if that thread ever did Club testing.
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Old October 23rd, 2019, 20:33   #9
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The e-Golf got the extension past the roof line along the top of the hatch, along with some side fairings up the rear window along the sides to connect to the roof extension at the top. It also got "Pizza pan" style wheels (Astana style). Under the e-Golf the aerodynamic goodie panels stop where the fuel tank would have stopped, and the rear axle and under body behind the rear axle are open to any wind drag where a typical Golf would have it's rear muffler... In the e-Golf forums, we've been debating what gains are possible if this area of the under body had something like a custom skid plate in reverse?
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Old October 23rd, 2019, 21:04   #10
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where- Do you still have your Astana wheels, and do you know how much they weigh?
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Old October 27th, 2019, 21:35   #11
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Astana has part # 5GE601025 which has a weight of 9 KG which is 20 pounds, which is heavy as ****: https://www.online-teile.com/volkswa...ml?language=en

you'd be better off buying Enkei RPF1s and putting pizza pans on them. honestly, the money you would spend would not be worth it.
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Old October 27th, 2019, 23:43   #12
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Quote:
Originally Posted by jerrymander View Post
Astana has part # 5GE601025 which has a weight of 9 KG which is 20 pounds, which is heavy as ****: https://www.online-teile.com/volkswa...ml?language=en

you'd be better off buying Enkei RPF1s and putting pizza pans on them. honestly, the money you would spend would not be worth it.

Hmmm. That site also says the part number is 44x19 (17"x7"), so I'm not sure about the precision / accuracy of their measurements. No matter, my guess would have been about 20lbs, which despite being heavier than many lightweight aftermarket wheels, is still decent compared to other VW choices. Plus, the RPF1 costs, what, $200 each? A set of Astanas can be found as used/low miles for less than half that. There was a set of 4 new take-offs Astanas on CL for $300 last month- with stock tires. I'm not a fan of aftermarket wheels, so I don't know if the RPF1 can be found in a 15 or 16 inch wheel with 5x112, but I'm sure there are other options that meet those specs. While the light weight of the Enkei or others will certainly help in city driving, the aero advantage of low Cd wheels and LRR tires will have a bigger impact at sustained highway speeds. Pizza pan caps not withstanding, of course.
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Old November 7th, 2019, 11:11   #13
Andyinchville1
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Hi all,

I recently had some work done to my car suspension wise...new (beefier) front Springs and struts all around.

The mechanic said the front of the car sits noticeably higher now ....

I know by reading posts on suspension replacement it takes a while for the front end to settle down after replacing Springs I think it would be interesting to see how that affects fuel mileage so I'm not going to do anything to the car for a bit to see how the new higher front ride height affects fuel mileage ...

My original goal for the new suspension parts up front was to increase handling and also get a little bit of more ground clearance because I drive sometimes on gravel roads ungraded driveways Etc ...

I'm hoping after the Smoke Clears and everything settles in the front of the car will be level with the back of the car.... I really don't haul a lot of weight and most of the time it's just myself so I don't need the car to be raked forward and then be flat when I load it because I never really load it ...

I did take measurements to the fender well before and I'll get some measurements after the modifications and see what the ride height change does to fuel mileage...

Once I establish what the changes are if any I'll start doing Aero mods and if it's a few inches higher than stock most likely I'll have to do something air dam wise or under the car tray wise for starters ....

Has anybody else raise the height of their car and had changes to fuel economy because of aerodynamic changes? If so what changes did you have?
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