Long trip ahead; 70mpg tank goal with Helga (Jetta TDI)

[NachtRitter]

Hi folks,

Going to see if I can turn this into a success story.

At the end of this month, I will once again be traveling to St. Louis from Central California with Helga, my Jetta TDI. I did this last year (see http://ecomodder.com/forum/showthrea...ero-21172.html) and was able to get a 68mpg tank (875 miles) with a 65mph average speed. Of course, that was helped by having an end point 5000 ft lower than the begin point, but the FE after nearly 4,500 miles of driving at mostly freeway speeds was still a pretty impressive 61mpg, without any special hypermiling other than staying in the wind shadow of larger vehicles if possible... the trip even included some AC when necessary.

In preparation for last year's trip, I added a Home Depot air dam and an axle-back belly pan. The axle-back belly pan came off the first day of driving and the air dam didn't seem to help much so I removed it after I returned. Since then, I have not added much in the way of aero mods, though when I'm the primary driver I can still get at or near 60mpg tanks. Goal for this trip is to get one tank over 70mpg. I'll be happy with that even if I get a gravity assist.

Before I go on this trip, I have planned to do the following things:
- Drop ride height of Helga by about 1" using aftermarket springs. Needed new shocks anyway, and I found a set of used springs for cheap.
- Replace thermostat with a higher-temp t'stat. I haven't been able to keep the temp above 188* summer or winter, even with the grill blocked as much as it is. I'll be putting in the 205* t'stat as described here: Modified Thermostat for higher MPG's... - TDIClub Forums
- Cover up a few under-body gaps. Ideally, I'd do the whole underneath of the car, but I don't think I'll have time
- Remove muffler. No, I don't expect that to improve my FE.
- Make smooth wheel covers. If I have time.
- Add spats in front of the tires
- EDIT: Change to lower viscosity oil (5w-40 to 0w-30)

Things I will not do:
- Remove passenger mirror: Since my wife drives it too
- Add quickie wheel skirts: Has to pass wife approval, so they need to be relatively nice looking. Won't have time to make two nice skirts.
- Change wheels/tires. Currently I have LRRs on there and I may go for taller tires once these wear out. But that'll be after I get back.

Will try to keep you up to date on my progress.

[NachtRitter]

Today, got the t'stat replaced and the rear shocks & springs replaced.

Not too exciting, but here is the finished shot of the t'stat replacement effort...

No pic of the new t'stat, but there isn't anything special about it anyway.

Unfortunately, it seems like a good 1/4 of the coolant ended up on the ground...

Soaked up by the towel.

Rear shocks & springs, new (inside) vs old (outside)...

The old shocks might have been on there since new... here we are at 340K miles later!

Here they are installed...

Looking forward to trying them out! In the background, you can see the replacement exhaust pipe... needs a bit more welding before I put it on.

Started on the front struts & springs and I can already tell they're going to be a bugger to get off and replaced....

[AndrzejM]

Nice! I'm sure you'll achieve your goal. So I'll have to fight more to get Berta up the list ;-)

Good luck and I'll keep my fingers crossed for 70+

[NachtRitter]

Thanks Andrzej! At least, it will be a good challenge!

Today, I was able to get the front struts done. A real challenge with the original springs since they do not provide much space to lift the strut out of the spindle. The trick is to 1) put spring compressors on the springs when the springs are fully extended (no weight on them), then put full weight of the car on the springs (I used a jack to lift the spindle until the full weight of the car was on it), tightening the spring compressors along the way, then release the weight... this gives some room to move the strut upwards and out of the spindle without fighting against the spring; and 2) remove the steering knuckle (it helps _a lot_ to have an impact wrench for removing the nut)... this allows the spindle to move around in a way that makes it easier to remove the strut. Even employing these tricks, the front struts were still a bugger to get off... The spindles did not want to give up the struts at all!

Obviously, it's important to be careful when the spring is compressed... there is a lot of potential energy there!!

Here is the comparison of the front strut and spring, old (left) vs new (right):

Supposedly one way to tell a strut (or shock) is toast is if they do not fully extend on their own. None of the old shocks or struts extended on their own. I still marvel at the thought that these might have been on the car since new...

Here is a shot of the new strut & spring installed on one side:

Last time they'll be as clean as that, I'm sure!

Muffler removal is done (whups, forgot to take a pic... tomorrow) and once I get a bit of welding done I'll put the replacement pipe on there... prolly Tuesday.

Adding an oil change to the list... Realized that I'd changed it last about 10K miles ago, which is the recommended interval. It's already spec'd to use full synthetic, so no additional gain possible by going from dino-oil to synthetic oil. But I will try going to a slightly thinner oil to see if that make any difference.

[AndrzejM]

I have to change oil as well... Thanks for reminding me!

[NachtRitter]

Yay! Post #1000!! Almost feels as good as getting a 1000 mile tank.

As a local pedant correctly pointed out, improving FE from 60mpg to 70mpg is only saving ~0.2381 gallons per 100 miles, which is the same as improving FE from 20mpg to 21mpg. Yes, that is true, but I believe that simplifies it too much.

With a 16 gal tank, for me the improvement means a 'free' trip to South Lake Tahoe or to Napa Valley each tank (not counting the gambling or the wine ). For someone that improves from 20mpg to 21mpg it might mean an extra trip to the local shopping mall (assuming the same tank size). For me, it means I can get to St. Louis with only 2 fillups (2,146 miles one way) rather than needing 3. For someone improving from 20 to 21, it makes no difference... 7 fillups either way.

And of course there are the bragging rights. Even though the savings are the same, telling someone that I have improved from 20 to 21mpg simply does not have the same impact as telling someone I have improved from 60 to 70mpg.

OK, done rationalizing the desire to mod for FE. I am fully aware it's not a money-maker, but it is a lot of fun!

[AndrzejM]

Congrats! #445 of mine

And I fully agree with what you've said... I like to think that I can fill up and drive to Sofia on one tank. That's just awesome and to be honest I like it more than driving like a maniac. You're right it'a a lot of fun

[ausias]

My Ecotxec is a Skoda Octavia 1.9 Tdi the same car as a Jetta TDi (VW Bora in Europe) and I'm very impressed with my >50 us mpg last fuel fill up.
Both are made with the same engeenering using A4 platfromf PQ34
Volkswagen Group A platform - Wikipedia, the free encyclopedia
I have an airdam , upper and lower partial grill block. I have tried lexan smooth wheelcovers but they are ot fitted now because they are ugly compared with my alloy wheels or steel wheels i used to have with aero hubcaps. They gve me around +3 us mpg.
But I'm very impressed with your 60 mpg at more speed than me.
Next week I'm trying the 5th gear swap to 0.681 because I have 0.769 in my 1.9 TDI AHF 110 cv VGT engine.
I'm using Michelin Energy SAver+ Tires 205 55 16 rated B rolling resistance (rr 6.5 to 7.7 kg force per Tonne) and A wet grip (about 1.35 G lateral grip). Using European Tire Label.

I think I'm able to raise fuel economy to 60 mpg when I swap 5th gear, is it right?
Coasting it's far better now with airdam, front grill partial block (I can't block full grick because Valencia's weather it's like California's).

Volkswagen Jetta - Wikipedia, the free encyclopedia
is helga a A4 typ 1J with 90 bhp?
my Octavia is a A4 typ 1U Å*koda Octavia - Wikipedia, the free encyclopedia
I lowered also my ride 2 cm (0.79 in) using Skoda Octavia vRS spring and shocks (the same as Seat Leon Cupra ones, same VW platform spanish automaker), I dont have 1.8 Turbo petrol engine with 180 bhp but drives the same, ahahah. Also I fitted upper and lower front strut bars from an Audi S3 (same A4 VW platform). If they are good for a 1.8 T with 225 bhp, they are good for ecodriving, ahahaha.
My car has only VW original parts inside but in a custom way.

[NachtRitter]

Hi Ausias!

Yes, the 5th gear swap was pretty helpful in improving my FE at reasonable speeds on long trips. There are many options for the gear ratio on that 5th gear... I didn't go too tall, only .681 but of course there are also .622 and .588 available. There is even a kit now that can add a 6th gear to the standard 5-speed manual transmission (cheaper than doing a complete change to a standard 6-speed... ). It is something that I may consider doing because then I can have a slightly tall 5th speed and a very tall 6th for the long flat drives.

As described in my Helga description, I've also replaced the stock injector nozzles with larger T4 nozzles and had a little bit of a tune to adjust for the larger nozzles... this has helped improve the 'driving enjoyment' quite a bit while also giving Helga the extra grunt that she needs to shift much sooner (usually around 1500rpm or so). So yes, originally I started with the 90hp 1.9L TDI, but now I think it is a little more than that.

One of my (non-FE related) tasks in preparation for this long trip was to replace the driver's side axle... it was making a bit of a grinding noise possibly related to the bolts being loose after some service... one of the reasons I prefer to do my own work when I can. So while I had the front struts out anyway, I removed the axle. Here is the missing appendage:

Can't help but think of the Boston Marathon victims when looking at Helga without the axle. Thankfully not as traumatic.

I got a brand new axle.

The inner CV joint was not pre-greased; the little tube in between the two axles is the grease. Unfortunately, I made a mistake when greasing up the joint... I rotated the outside of the joint so I could grease the ball bearings but I went too far... the whole CV joint came apart and the ball bearings popped out. It took one day, two buckets of sweat, and three languages of swearing to get everything back together again, made doubly difficult because everything was covered in grease. Now that it is finally all back together again, I'm fairly certain the ball bearings are well greased.

Pics of it all assembled next time.

Earlier this week, I worked some more on the replacement exhaust pipe. Here is a comparison shot between the old muffler and the new pipe.

I welded together 2 18" extensions plus a 45 degree tip and also welded on a hanger. Then did some grinding to hide my mistakes and painted. Came out about half-way decent, plus it'll be under the car anyway. Should be able to get it fully installed this weekend.

Now that the hardest parts are done, I'll be finishing up the rest tomorrow (Saturday). Exhaust, oil change, spats, and probably another attempt at an axle-back under-tray (as noted before, last year's attempt failed pretty quick, but I think I have some ideas). As well, a triple (or more) check on the important nuts and bolts that hold the suspension together.

Monday, I'll bring Helga in to get an alignment done, just to ensure that it's correct again after all that mucking around with the suspension.

Then Tuesday, we start the trek and I'll be trying to hit that magic 70mpg tank!

[ausias]

It's is very interesting the 5th to 6th gear conversion kit
Index | Eurotuning s.r.o.

1180€ + shipping + several workshop hours it seems very much compared with
337€ + workshop time on the 5th swap.

I did some fast calculation (my engine has Bosch VE rotary pump VP37, it's not a PD, cd lowered from 0.31 to 0.25) and 0.588 to 0.622 F.E. figures differences at constant speed are about -0.1 to -0.2 L/100km (best results in my car in mid range because of VGT) saving 0.1 L/100 kms at 90 km/h or at 180 km/h it'not very useful as an improvement.
Improvement of getting taller ratio
(0.769/0.588)*(44.5 km/h)/1000 rpm = 58.2 km/h looks very good and Seat Ibiza/Cordoba PD 131 Sport, Fabia Vrs <2004, Polo GT PD130 used to have 59 to 62 km/h/1000 rpm 6th gear ratio in firts versions (lasted with 50 to 54 km/h/1000rpm, so if you have lots of BHP it is very good to know and far easier than changing lots of things (inside or outside de gearbox, included or not).

But talking about my car, almost the same car as yours. Using Matlab i get this figures.

Comparing 0.622 (or 0.625) with standard 0.769 it's a very good improvement as an additional 6th gear, but not as a swap becasue of big gap on rpm. It saves 0.6 L/100kms at 90 km/h, 1 L/100kms at 120 kmh and 2.7 L/100kmh at 180 kph.

Swapping 0.681 (cd 0.25) into 0.769 (cd 0.31) gear will give to me with my current drags and improvement of -0.5L/100 kms at 90 kph, -0.7 L/100km at 120 kmh and
-2.14 L/100 km at 180 kmh.

I discarded 0.658 swap because at constant speed differences where 0.05 L/100km at low speeds between 0.681.

In Spain max speed is 120 kph (130 kph in project) so german Auutobahn drivers or very tuned 1.9 engines will notice a big improvement in fuel economy, top speed (if lowered drag it will be big improvement) and drivebaility
PD with more than 131 bhp also have 6 speed gearboxes.

But it is a very good alternative to full 6th gearbox swap as explained in spanish here Instalación de la caja de cambio de 6 Velocidades en motores TDI 110cv o 90cv | www.fullcustom.es

that will cost almost 1200€ + workshiop time (1500$ on junk yard/ some news parts + workshop cost) or far more if using a refurbished gearbox or new one.

Click on the following almost white thumbs to get big images:


LEFT: Fuel Economy (in L/100km/h) at Full Load and at constant speed (in km/h), standard car vs aeromoded and 5th swap. Theoretical (but fuel consumption in standard car at ctt speed it is predicted +-1% error). Using BSFC map to convert torque in fuel mas per kilowatthour and diesel specs and data. RIGHT: efficiency at ctt speed no units 0 to 1 (not g/kWh, or us, uk units, 0 means 0% -fuel energy converted in heat- and 1 means 100% - fuel energy converted in work-)


Theoretical Power (in W,). at Full Load and at constant speed (in km/h), standard car vs aeromoded and 5th swap. Remmeber 1 kW = 1.36 bhp, so 81000 W are 110 bhp.