02 TDI Jetta grille block
 

i am hitting between 55-59 inst mpg(ultragauge) compared to 49-53, no drafting, flat concrete interstate(conditions were the same, as best as i could get them). stop n go, ac on, rain, temp climbed to 210 but fell to 197, where it stays while cruising. fill up yesterday but forgot to clear trip odo so will have to wait till next tank bc i can get over 900 mpt.
using silicone, placed 3 larger than opening pieces of coroplast together, held down with cans on flat surface.
removed grille.
http://i110.photobucket.com/albums/n...ps9a9df23f.jpg
marked areas to remove, using grinder with cut off wheel, removed/beveled sections to fit.
http://i110.photobucket.com/albums/n...psf36cf7b1.jpg
added salvaged wiper strands into slots and added a rear support to prevent deformation.
http://i110.photobucket.com/albums/n...ps4a1b2e5a.jpg
http://i110.photobucket.com/albums/n...psc30ea803.jpg
added 2 more pieces to bring it close to flush, adding spacer to form curve.
http://i110.photobucket.com/albums/n...psad6d0dd6.jpg
http://i110.photobucket.com/albums/n...ps3d286a52.jpg
http://i110.photobucket.com/albums/n...psf5f72a66.jpg
silicone/tape was used to attach/seal/hold edges.
http://i110.photobucket.com/albums/n...psfb5073eb.jpg
bent plate , relocated to center bumper, held on with silicone after this pic.
http://i110.photobucket.com/albums/n...ps9280b941.jpg
needs some fine tuning around edges of last layer.
so far so good.
no finished pic but will get one later to show contour of leading edge.

A lot of the TDI guys cut out the upper corner of their grill blocks for the intake. But if this is working for you, great.

i thought about that but the whole area in front/below the rad is open as well as the lower opening. so far it's working but i will see. i have an open(ed) mind.

Did you monitor intake temps before and after, just out of curiosity?

nothing wrote down but ultragauge read 70's in the morn, low 100's evenings. i will check on the way home today.

Cool! errr... Hot! I like the license plate over the driver's side grill.

Mine for reference (a little dirty from a trip):

https://lh5.googleusercontent.com/-i...llBlocks-2.jpg

Used foam between the slats to do the block... yours looks better though.

thank you. i moved the plate to the bumper after that pic, attached with silicone after it was bent to shape. i have the mounting hardware if you want it. stainless and copper.
this is in the "68 vehicle mods for better fuel economy ...'
'Grill blocks come in many forms, though most often they are made to be flush with the outside of the bumper for greatest benefit. Simply inserting a piece of cardboard in front of the radiator does not provide the same aerodynamic benefit.'
65+ Vehicle modifications for better fuel economy - EcoModder.com

IAT on the way home, between 4 and 5 pm, was 91* so there is no impact on that.

EDIT:
between 6:30-7:30 this morn IAT was 73*.

ended up blocking the 2 lower openings a few weeks ago and today put in the HID's and added some covers for the openings between the skid plate/front dam to smooth the flow some. will see tomorror on the way to work if it makes a difference. plastic came from a mud flap that i picked up off the side of the road.
here's the pieces installed on the bumper cover:
http://i110.photobucket.com/albums/n...ps4c4c0f93.jpg
http://i110.photobucket.com/albums/n...ps1d29be3a.jpg
best shots i could get:
http://i110.photobucket.com/albums/n...psf7b07514.jpg
need to get it on ramps, drill a hole and bolt both of the corners to the skid plate so they won't be hanging so low.
http://i110.photobucket.com/albums/n...ps6ddc30d0.jpg
openings closed:
http://i110.photobucket.com/albums/n...psf87a466c.jpg
i reinstalled the rear flat deck fin, boxed the rear somewhat.
this is the best i could do at the moment but i will try to make the transformation a little better when i get the chance:
http://i110.photobucket.com/albums/n...ps53d6d34e.jpg
http://i110.photobucket.com/albums/n...ps38280de9.jpg
http://i110.photobucket.com/albums/n...psa550d8a0.jpg
http://i110.photobucket.com/albums/n...pse5fdf635.jpg

Thanks for the pics! I did something similar to what you did with the bumper-to-skidplate transition, though with a bit more coverage... will have to get some pics of that the next time I take off the front bumper. And I've been trying to figure out the rear too... had ideas similar to what you did, but seeing how you did it is awesome! Think that helped FE?

Edit: Oh look, I'd already taken a pic:
https://lh6.googleusercontent.com/-L...0/P4130013.JPG

(Hope you don't mind me adding pics of my mods in your Jetta mods thread)

Note that you may want to keep the passenger side duct open to give the intercooler some cooling air... not sure about yours, but on mine there is a duct that guides the incoming air directly through the intercooler. Actually, it wasn't there when I bought the car used, but I've added it since... I understand that getting the compressed air cooled down helps both power and FE.

1)no problem.
2)same here. lots of weird pockets, exhaust, hitch, nothing to attach anything to.
3)as of this morn, FE was the same as before, pushing 57-63 inst on the flats. will be filling up either today, after i drive 60 miles home, or i might push it and wait till tomorrow, after 120 more miles. i'm at 800 miles for this tank, which is about normal.
4)don't mind at all. would be nice if there was a sub forum just for the MK4 Jetta/Golf/Variants.
i will leave it be for now until the end of the next tank, then i will add/get supplies for the rear skirts and wheel covers and put them on. the 15" wheels will need a 15 3/4" cover that i will tap the lugs for threads to mount them.

I usually don't like to say Subscribed as a post, but I am interested in following this!

When I finish my plan I will be trying a flat rear plate out of the rear.

i know what you mean and i'm guilty too.
i keep up with YOUR post 'cause i am interested too.
my speeds are, to say the least, slow, compared to "normal" drivers on the road. i do pass someone, at least once a month, am able to draft if the traffic is thick enough to create a 'tunnel', i am guilty of hitting my brakes/slowing down when a vehicle gets a little too personal to my rear.

one thing i noticed today after adding the under skirts, IAT reads 105 F now. still not bad considering my latest fuel entry. contemplating deleting the IC to see if there are any differences.

Looking at your picture it appears you do not have the side skirts to you belly pan.
Belly Pan & Sideskirts Underbody Set w/ Hardware (A4) - IDParts.com
I think they help close up the belly pan better.
I would remove the cover over the intercooler also.

i see $229.00 listed for the comolete kit, i don't need the plate.
why remove the IC cover? it's not hurting anything.

They sell just the side skirts too. That was just the full set I posted.

So it can do its job and cool.
I do not know off the top of my head but does the TDI have an intake air temp sensor? If so it would be interesting to know how much covering the IC would affect it.

lots of talk here about warm air intakes.

Yes on GAS engines this is a DIESEL

Better answer is test it both ways and see what works for you.

Diesel's like air, the more the better and cold air is denser so more air per unit of volume.
The other points are that cooling the air in intercooler causes a small pressure drop, so less backpressure for the turbo compressor, this means less exhaust back pressure on the turbo side and higher efficiency.
What you might want to consider is a RAM air cold intake.

The other point anyone running a diesel should have both boost and EGT gauges and understand what they mean, they should guide your driving behaviour.
High EGT's is what kills diesel engines, the hotter the air intake the higher the EGT's, running the engine hotter may yield a small benefit in FE, but it's false economy when engine longevity is compromised.

it's working for me.

PS: i didn't know this was a quiz.

for some reason, VW didn't add a volt meter in the Jetta, so i will be adding this one. $5.00 off the bay. thing is small!
http://i110.photobucket.com/albums/n...psb54c2dca.jpg
http://i110.photobucket.com/albums/n...ps0919f6e7.jpg
http://i110.photobucket.com/albums/n...ps59751038.jpg

I love the build of your rear cavity- it mixes my love (and large quantity) of polycarbonate with someone who has [the] passion to make it look good. (Random, but why I often stop by lol)

My plan was to do this as a rear tail on my Insight, but I have since made a new plan. Look forward to seeing it installed.

deejaaa, Did you do any testing before and after with the rear end mods? Would love to know if they helped at all.

no ABA but i was getting 50 before the grille bolck, front flaps and rear mods. when i get more time, i will remove one at a time to test but i want to get the wheel skirts and smooth wheel covers on first.

Your mods look good. Funny, I sealed the bottom front corners on my Mk IV with coroplast. We think alike.If you hypermile slow and easy on the flat land of Texas you may be fine with such extensive grill blocking, especially if you are not using A/C. I monitor Intake Air Temperature (IAT) on my ScanGuage and it can go to over 200 F on long climbs in the Rockies. IIRC I read somewhere that a degree of intake temp increase is like 3 degrees of Exhaust Gas Temperature. I have the top left grill block open to feed cool high pressure air to the factory ram air intake. I have the intercooler grill open except in winter when I block part of it.

I have a full belly pan from the front to the back bumper. Check my album. I have loaded some pics. I only screwed into plastic- body plugs, bumper edge etc. There is a wind deflector plastic ahead of the fuel tank of the Golf. I pulled it off so I didn't drill into the tank but I have a couple of screws into that plastic.

Have you ever looked real close under your Jetta or Golf?
VW did a lot of work under there to streamline it. There are a lot of little plastic pieces that deflect air over/around parts.
There is one in front of the rear axle and a few others.
I think a full belly pan is better.

Agreed. I was able to tuck brake cables up and really smooth the underside if my car.

I have noticed that little spoiler ahead of the rear axle on my wife's 2011 A3 TDI. I have wondered if removing it and installing a belly pan to the rear of her car would be better. FWIW the Mk IV doesn't have that same plastic deflector. The newer VW/Audis have a lip that turns down just before the rear axle. In the pic Ron posted you can see that on the Mk IV it is flush with the axle.

Ron, what year is your TDI?

Mine is a 2002 built 2/02
Here is a picture of the side shields on the belly pan
http://i304.photobucket.com/albums/n...IMG_0452-1.jpg
Red arrow points to side shield. Yellow arrow the aluminum belly pan. Blue arrow is the inner fender liner.
I do not like how inner fender liner is open to the bumper cover. Need to add shield like you guys did.

I have the plastic piece before the rear axel
http://i304.photobucket.com/albums/n...IMG_0456-1.jpg
Red arrow points to the plastic piece
Yellow arrow points to rear axel

Yep, I have the same plastic shields in the rear of mine. Ron didn't point it out in the pic, but there is also a plastic deflector in front of the rear spring & shock area... can kind of see in his pic on the right towards the bottom.

Yea I forgot about the plastic on the springs.
Car was not in the air I just stuck cam under and took pictures so not the best :)

I suspect that may be for rocks and debris as much as for managing airflow but that is just my opinion. My raingutter diffuser starts flush with the spring shield to guide the air out the back of the car to help fill the wake.

Does this thread need a new title?

Good idea! "MkIV Jetta aerodynamics" or something to that effect...

EDIT: Oops, didn't mean to leave out the Golf! "MKIV VW aeromods" maybe... :D

i would like to see this thread read "MKIV VW aeromods" if possible.

Turning into a nice build sheet.

did this today. resting voltage after sitting 4 days. this would have been useful when i was having battery problems. purchased from the bay for $5.00, installed in an empty slot, tied into a key on fuse.
key off, flash on,
http://i110.photobucket.com/albums/n...ps3d7c7baa.jpg
key on, flash on,
http://i110.photobucket.com/albums/n...ps82a892de.jpg
key on, flash off,
http://i110.photobucket.com/albums/n...psb2f9aa0a.jpg
little closer,
http://i110.photobucket.com/albums/n...psa9a26402.jpg
haven't turned on the engine yet but will see in the morning.

gauge is working great. had the idea for as long as ive had the car and im glad it worked.
my next tank is going to be measured driving 55 mph and speed will not adjusted for road conditions. i want to get a baseline at that speed. after i get this stretch of work days over with i will be concentrating on getting the rear wheel skirts, LED DRL's and smooth wheel covers installed.
my mods are paying off so far, being a government employee and not knowing when i will get paid, the mileage im getting and the cost of fuel has not been that big of an impact on us compared to others ive talked to.