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ssullivan 05-30-2020 07:18 PM

Hello, I'm a USA Diesel Owner
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Finally got the Jetta to something postworthy: Main problems were stuck open thermostat and missing factory bellypan. Also, lots of bad rubber, a few electrical things. It had been used and then sat for a while. Has a Malone Stage 1.5 tune.

The open thermostat was hurting me by 4-5mpg. I finally cobbled enough parts to get the factory bellypan back together. Also removed mudflaps. This gave me inspiration to do a significant grill block. Still testing to see if it is adequate in the hot weather. The cooling happens through the emblem and the ~ 1.5" x 2' opening on the lower bumper (not visible in pics). I believe it will be adequate driving like I stole it in 95F weather. For higher temps I will remove the emblem.

Working hard on the driver mod and looking for some 50+mpg numbers. I broke 55 in a stock (small grill block) Beatle TDI which I am in the process of selling. it is in much better shape than the Jetta haha. These are tank-to-tank numbers.

California98Civic 05-30-2020 09:09 PM

Looks good. And with a TDI you will have a high upper maximum MPG as you work on the "driver mod," or the "nut behind the wheel." Is this a manual transmission?;d=1590876879

ssullivan 05-31-2020 01:40 AM

Yep. Auto trans is to be avoided in these years. I understand it injects zero fuel when coasting in gear. I got behind a Model S who was hypermiling on I-80W near Auburn and the engine/regenerative braking were pretty comparable on each short little downhill.

cRiPpLe_rOoStEr 05-31-2020 02:08 AM

Even though a grille block may eventually fool you into believing the thermostat could become somewhat redundant, it's still preferable to have it operating properly.

ssullivan 05-31-2020 03:29 AM

Oops I did it again
Haha, love diesel's low heat rejection efficiency. Looking forward to ABA testing with the intercooler and other lower grille blocks. Upper is "temporary." Also have a gap to fill on the driver side one.

Update: I went to measure for a muffler and before I knew it the sawzall was out and the 19lb behemoth was on the ground :confused: My hypothesis was: based on its excessive size, it was designed to cancel out low frequency more than make it quieter. It now spools even quicker and has the exact sound I was going for. Total volume still about the same inside so I guess I'm done for now! :D Planning to make a high velocity tip to get the vapors out safely since they are dumping around the rear axle.

This was inspired by some work where the author measured pressure drop across the MK4 TDI flow path on the air and exhaust sides. The muffler had the most restriction, and it appears the most weight. I'm really stoked about how this car is coming along. Next step I want to pay Malone to work on the low/mid maps to wring as much mpg as possible. It currently has injectors, injection pump, and the stage 1,5 tune. Because of all the fueling mods I believe there is room to improve.

California98Civic 05-31-2020 02:19 PM

Oh, yeah! Weight reduction, baby!

cRiPpLe_rOoStEr 06-01-2020 12:24 AM


Originally Posted by ssullivan (Post 625429)
I went to measure for a muffler and before I knew it the sawzall was out and the 19lb behemoth was on the ground :confused: My hypothesis was: based on its excessive size, it was designed to cancel out low frequency more than make it quieter. It now spools even quicker and has the exact sound I was going for.

It's usually pointed out that turbocharged engines don't really require further restrictions after the turbine outlet, so a shorter path for the exhaust might be quite desirable. Plus the turbocharger already provides some reasonable levels of noise suppression too.

ssullivan 06-07-2020 02:57 AM

Totally! Glad I didn't buy something before I started cutting. It would have been dead weight.

Another update: The grill block seemed ok testing at 92F. Couldn't get the coolant temp to move. Waiting for the first 100 degree day.

GreenTDI 06-07-2020 05:53 AM

Nice to welcome another TDI owner on this website! TDI's have enormous potential in terms of consumption figures. With cheap adjustments like grille blocking, weight reduction, overinflating tires and a different driving style, you could easily gain 20%. I recently did a 78 MPG trip where I previously got around 60 MPG And meanwhile I know there is even more to it.
Good luck!

skyking 06-08-2020 12:34 AM

Welcome from a fellow TDI enthusiast and all diesel family.

cRiPpLe_rOoStEr 06-10-2020 12:20 AM


Originally Posted by GreenTDI (Post 625884)
overinflating tires

Some folks underestimate the effect of overinflated tyres on fuel savings.

COcyclist 08-08-2020 12:38 PM

Welcome. These diesels are capable of really good mileage with a few basic mods and a patient driver. I am including a shameless plug to direct you to a thread I started after 12 years of hypermiling my TDI. It is a combination of eco-driving tutorial and build thread.

I got a ScanGuage and blocked the upper grill right after I got the car and have never removed it since. It runs warm enough for the fans to turn on during long climbs in the Rockies but it cools right off at the summit. Also, I removed the muffler early on and replaced it with a straight pipe with a turn down to exit in the factory location. With the turbo and the cat in place it is not loud. It makes a cute little spooling sound when you shut the motor down though.

I experimented with blocking the intercooler grill in winter but decided it was not for me. Nothing to be gained there.

ssullivan 08-23-2020 10:20 PM

Nice to meet everyone! Sorry I have not been on in a while. Stoked about the community of diesel owners! I had stalked some of your pages. COCyclist, read your whole writeup, thanks! The numbers these cars can get are are nuts.

I feel like diesels, trucks, MC, EV should at least get top 3 on the front page. Diesels in particular could use the PR. My little rant is that the US govt seems to have received tons of money to kill diesels in the states to sell/burn more petroleum. NOx emissions are not great but I think the reduced CO2 emissions are more important.

Oh and update on the cars: Welded and wired up a hitch receiver, fitted rear airbags and a VR6 rear axle (thicker sway bar, FWD car). Ready to tow, although I do have plans to reinforce the receiver more in the future.

Also had to do some work to my 2003 Beatle TDI which I sold but came back with a bad engine mount. Seems our dry air killed the rubber. I replaced the mount, fromt suspension joints, and found the boost leak that supposedly was created by the engine swinging violently. The woman took it to an ASE certified mechanic who returned it to us with the plastic engine cover unattached. One bolt was missing and the other was not unscrewed, the grommet was just pilled out. Based on the clamp that was missing I suspect he was responsible for the boost leak too but who knows. Poor woman was replacing a Kia that blew the day after a Jiffy Lube. Good examples of why I don't let anyone work on my junk.

ssullivan 08-25-2020 11:43 PM

I almost lumped it into this thread. More TDI discussion here!

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