The Rabbit TDI Project
Appendix 1: Dyno Results
or: Who needs a VR6?
I've had two oportunities to dyno the little TDI pickup.
Round 1: Baseline, Sept 2003
specs: base install, stock injectors, stock chip
So for an essentially stock engine, it put down 101HP to the wheels.
Not too bad for an engine rated 90hp at the crank.
A bone stock A4/mk4 2.0 ran 96hp earlier that day.
Figuring that car is rated 115 crank, that should put my TDI at
about 120hp at the crank.
Round 2: Chip & injectors, April 2004
specs: base install, .205 injectors, ASV ECU, Rocketchip 3.1
So, change to a different ECU, add a chip, install injectors, and we're laughing. 149HP at the wheels, 276ft-lb torque.
Using our same drivetrain loss as before, that should put the TDI
to about 168hp at the crank.
So, it's now worthwhile to look at an A4/mk4 VR6 dyno plot:
So here's an engine rated at 174hp crank, putting out 148hp to the wheels.
Compared to my TDI which is putting out about the same power to the wheels, plus my TDI is running about 100 ftlbs more torque, AND I'm getting 50+ MPG.
Why would anyone bother with a VR6?
Keep in mind, my pickup is probably 800lbs ligher than an A4/mk4....
Now the disclaimer bit:
my two tests were done at the same location, but different weather conditions. My tests were obviously done at a different altitude and whatnot from where the VR6 was dyno'd. Plus, many people have issues
about the validity of the DynoJet results, and so on and whatever.
My first dyno was run in 4th, the second was run in 3rd gear. I had slightly
larger tires for my chipped run. If one wants to get technical, we could
talk about all this for hours. Let's not, but say we did.
So where can we go from here?
The next logical steps for improvement to the TDI would be larger injector
pump, a fuel cooler, and different nozzles for the injectors. After that, we
get into a different turbo, custom ECU programming, larger injectors (.216)
headstuds, improved boost piping, larger exhaust and downpipe, and on
and on, and that's just on the engine side.
One would also have to get that power and torque to the ground, so we're talking about a big strong clutch, LSD, and perhaps Syncro or 4-motion.
So where do I go from here?
It's my daily driver, so it carries me to work and back...
My injectors are a bit off balance, so I'll mess with that eventually.
Currently, my next task is to install a stronger 02A tranny.
150hp and 275ft-lb of torque, how long do you think the 020 will last?
Part 1: Introduction
Part 2: Installing the Engine
Part 3: Transmission
Part 4: Wiring 1
Part 5: Speedometer and Cluster
Part 6: ImmobilizerIII
Part 7: Drive By Wire
Part 8: Intercooler
Part 9: Intake and Exhaust
part 10: MFA and Cruise Control
Part 11: The Dash
Part 12: The Little Things
Part 13: The End (for now)
Part 14: 6spd transmission and brake upgrades
One Year Later
Who Needs a VR6