TopGear.com America high mpg project (regeared, aeromodded diesel Rabbit)

[MetroMPG]

Neil: check the video; I didn't spot it in the stills posted with the articles.

[eyesoreracing]

Originally Posted by Daox

Using a scangauge as gospel for MPG... yeah, thats not gonna work. Its not even calibrated.

Good catch guys.

The lack of calibration is exactly why we never said what mileage we got on those tests, only what the difference was. You can still measure differences without calibration, but you can't believe the absolute values. Besides, the absolute fuel economy at cruise at 60 mph doesn't mean much anyway.

We've run plenty of fuel through this thing, but sometime during each tankfull we have to either unplug the Scan Gauge to plug in the aligator, or we have to change a fuel filter and lose all the fuel that was in it, so calibration was never possible.

Plus, changing the injectors changes the calibration, which is why we couldn't say whether the injector change helped our FE.

Just so you know, we have been filling the tank all the way up the filler neck so we know exactly how much fuel we have. Just going until the pump shuts off isn't very precise (we put in 2.5 gallons after shutoff once), so if you're calibrating your scan gauge that way, you're fooling yourself.

-Dave Coleman

[Daox]

Good to know Dave. Thanks for the clarification.

[tasdrouille]

Originally Posted by FTA

Two shifts and a lot of wheelspin are dramatic but not fast. Refining launch technique for less wheelspin, and keeping the go-pedal flat to maintain boost between shifts, Jared finally knocks the time down to 7.5, but no less.

Then, the epiphany: We have 240 lb-ft of torque — why don't we launch in second gear? It'll save the time normally wasted shifting from first to second, and it might even waste less time smoking the tires. Success! First try and the time drops to 7.09 seconds.

Told ya launching in 2nd was faster

Turns out we didn't order the larger nozzles (Bosio PP520) used on the 140-hp dyno charts we'd spotted on the Internet, but less aggressive ones (Bosio PP357) that Malone recommends for people trying to do crazy things like squeeze 70 mpg out of TDI-powered Rabbits.

That's too bad you didn't get the PP520. With proper tuning you would have gotten at least the same fuel economy as the PP357. I personally run PP502 in my car, bigger than the PP520 and can still get as good fuel economy as with stock nozzles, with a kind of ghetto diy tuning no one does. Since you have a scangauge, can you tell us what the timing with the tune is at 2000 rpm when cruising down the highway.

If it's below 5 BTDC, a quick fix for the fuel economy run would be to just cut the wire for the IAT sensor and put a 18k ohms resistor in there, look up the IAT on the scangauge, it'll read around -15 F with the resistor in place. That'll give tou an additional 2 degrees of advance at part load only, good for you FE run and won't change a thing to your pedal to the metal 7 secs goal.

[NeilBlanchard]

Hi,

Are you referring to the single wiper; positioned up the center of the windshield?

They introduce their aerodynamic designer, but I see very scant evidence that they did anything to improve very much? I wonder how fancy suspension helps towards their goals?

[MetroMPG]

Nope, not the wiper (that was mentioned a bit earlier up this thread).

[MetroMPG]

Originally Posted by NeilBlanchard

They introduce their aerodynamic designer, but I see very scant evidence that they did anything to improve very much? I wonder how fancy suspension helps towards their goals?

There was this hint:

Look for some slick aerodynamic tweaks - designed with help from UCLA aerodynamics professor John McNulty - that will include vortex generators and a flat undertray.

Source

[giff]

Hey guys, 55 days later and we're done. I'm going to let the video and feature speak for themselves

Video;
Watch TopGear.com's Project Sipster - A Top Gear Car Video - Top Gear US

Feature;
http://www.topgear.com/us/features/more/project-sipster-sipster-indeed/

[Deezler]

Whoo-hoo!

Congrats guys. Love the shots of the rabbit drifting sideways across the desert at the end.

One serious question: You filled up until the neck was full. Is there a vent-tube that runs along side the main filler neck though (to allow for expansion)? If you didn't "vent" the tank, you could still be off quite a bit.... hope that doesn't ruin your day.

Who gets to keep the rabbit now?

[MetroMPG]

Originally Posted by jamesqf

You folks are working in the US, right? Didn't anyone tell you we drive on the other side of the road?

We've been had! Look for the location of the original (driver's side) windshield wiper arm pivot in the pic. Oh! How did it get over on that side?