Tas's 2000 Jetta TDI Build Thread - Fuel Economy, Hypermiling, EcoModding News and Forum

tasdrouille · 06-22-2009, 07:49 PM

Ok, I haven't done much yet, but I just want to document what I've done and talk about what I want to do before before I "race" in the AMEC Fuel Economy Run III which I will get to attend this year.

Some of you might remember my previous car, which I was able to push to 79.9 MPG over 1000 km in two days.

So now that I got the following model year, I had to mod it so I can eventually beat my record.

Thanks to the VGT turbo, fuel economy at highway speeds is better even if the frontal area of the car is a bit bigger. The Cd is supposed to be the same.

So, here are's a gimped pic of what I wanted to do aerowise.

But first, I have to talk about the car a bit. I got this car with 200k miles for $3500 CAD last december, which you know is cheap if you are into TDIs. This car had a brand new head and turbo, but it was still a dog off the line and it had a check engine code, and the owner was tired of spending cash on it, hence the price.

So I checked the code and it was an overboost condition which I traced to the a check valve in the vac line to the turbo vacuum actuator, which was backwards on the wrong line, causing the vanes to never move and stay put in max boost condition. So I flipped the valve around on the right vac line and problem solved. But the car was still a dog. The problem was eventually traced to the injector nozzles which were extremely dirty, clogged and not spraying right. So I replaced the stock 0.184 um nozzles with a set of 0.216 um I had bought for my previous car but never got to actually install.

Those nozzles are usually quite a good power upgrade, flowing roughly 37% more fuel than stock nozzles. I thought that since they would allow the end of injection to be closer to TDC, I could get better fuel economy. But that was not counting smaller nozzles atomize fuel better. So at low loads it is a wash at best, and I might very well be penalized over smaller nozzles. But at higher loads I believe larger nozzles are serving me well, especially when pulsing and gliding. My best tank so far was done with P&G 3/4 of the time at speeds varying between 80 and 55 mph. I also tuned the EGR on my car so it is increased at low loads. Not only does it warm up faster, but I believe it increases FE at low loads.

Aerowise here is what I have done so far.

I started by adding a lower grille block and wheel deflectors made of 1/8" abs plastic.

Those are really close to the ground and rubbing at the slightest bump, but they seem to divert the airflow around the wheels and tires quite wheel. You can also see the lower grill block on that pic, although it's taped while the silicone sets.

Next were the mirrors. My driver side mirror base was broken, the cheap white alloy inside had vanished and what was left of it was shattered, and the glass was completely blurred. Since a new mirror on a vw is not cheap, and lets be frank, I had an excuse to buy something else, I decided to get DTM cup style mirrors from ebay UK. Both mirrors with adapter plates cost me less than just an OEM driver side mirror. I only installed the driver side mirror, with a smaller frontal area than stock, and decided to use the adapter plate on the passenger side to make a block off plate.

There's a depression in the adapter plate to accept the cup mirror which I just taped on the passenger side, but eventually I'll cut a piece of abs that cleanly fits the hole.

As far as future mods go, I need to get a belly pan in there, especially considering even the stock belly pan was gone when I got the car. So there's room for improvement there. I also have blocks made for the lower side grilles I need to install. The top grille will also be sealed. Before the fuel economy run I will also get side skirts, rear wheel skirts, and I'm working on a plexiglass kammback.

Daox · 06-22-2009, 09:53 PM

Sounds like you got a ways to go yet. But, its looking very good! Since my sister has the same car I look foreword to seeing what else you do.

ConnClark · 06-22-2009, 10:13 PM

First, Chop off the muffler and replace it with a cherry bomb glass pack.

Upgrade the intercooler to one of these.
TyrolSport UG SMIC Intercooler For VW MK4 Golf/GTI/Jetta TDI
They not only cool better but they also have less boost drop. More air will compliment your larger injectors and increase the percentage of fuel burned. The reduced boost drop will increase the effectiveness of the turbos energy recovery from the exhaust below maximum boost. It will also reduce back pressure on the engine at maximum boost.

tasdrouille · 06-23-2009, 08:34 AM

The muffler will be chopped soon enough and replaced with just a straight pipe exiting in front of the rear driver side wheel. A pipe a clamp and a hanger, that's it, cheap and effective. The turbo, cat and resonator do a good job at muffling already so an additional muffler is not needed. I will just get to enjoy the sweet sound of the turbo spooling up a little more.

I'm too cheap to buy that IC, and I feel there are lower hanging fruits.

SVOboy · 06-23-2009, 09:38 AM

Can't wait to see why you have done by the time the competition rolls around.

Vwbeamer · 06-23-2009, 04:46 PM

I was thinking of putting a set of the old VW's beetles 165 r 15 tires on a stock set of Jetta steel rims.

They are the same height as the TDi stock 195/65/15 tires, but 30mm narrower.

Based on my calculations, this would be worth about 2-4 mpg. based on the 2 mpg I lost going from the stock 195 tire to a 225/45/17 tires and rim on my Jetta Tdi.

The 165's would have less areo drag, less rolling Resistance and be about 3-4 pounds lighter over the stock 195 sized tire.

AS for safety, the old VW buses weighed about as much as the jetta and used similar sized tires. Admittedly, they were much slower.

Also, I have 100% grill block on the upper grill, with no engine over heating, even with recent 100 degree heat we have been having in Georgia.

I feel there is a greater areo advantage to blocking the upper grill, as it smoothes the air going over the hood.

Obviously, you can't block both.

Good luck.

ConnClark · 06-23-2009, 06:49 PM

You could also take a dremel to the air box like Deezler did in his Build thread.

http://ecomodder.com/forum/showthrea...html#post99025

Anything you can do to to increase air pressure in the inlet of the turbo will be an improvement. I once calculated how much more power my ram air intake on my Mercedes gives me. I came up with about 1/3 of a HP at 70 mph.