749 Variations With DP Power Kit
The 749S for model year ’04 is a bit different to last years. It has the hottest cams of any Testastretta model (see the updated cam report), bigger valves, more compression and a lighter crank. The ’04 non 749S the 749Dark and 749 run the same engine as the ’03 749 and 749S. I haven’t got to dyno more than one of the ’04 749S so far, but as far as I can tell the changes take away performance for most of the rev range without really giving anything back. Pity.
But, I have only dyno’d one ’04 and two ’03 models so far, so it’s not much of a sample. As time goes on I’ll update this report.
To some curves. First up is a ’03 model, std and with DP asymmetrical power kit. The cheap one. Green is all std, red is power kit fitted. No air/fuel as the traces look a bit off to me it can be hard to get a good trace with the std mufflers on these things I’m finding. Not sure why it loses power in the midrange, but that’s what I got. Nice smooth, flat curve though.
Next another ’03 model with the same power kit. The main focus of these runs are the air/fuel curves. The asymmetrical DP systems have no x-over or balance pipe between the exhaust for each cylinder, so you can just stick the probe into the muffler and go from there. This gives a very clear idea of what each cylinder is getting. And, for people who have access to such equipment and experience as Ducati Performance do, the result is fairly poor. Lots of variation between cylinders and in overall fuelling. Really annoys me actually. They have all the right stuff and this is what they do. It’ll be interesting to see how much better they ride with a well mapped ECU. Duane currently has one of our customer’s bikes with this exhaust system for mapping testing/development with his U59 ECU. This graph shows torque and air/fuel red is vertical cylinder, green is horizontal.
Now a ’04 model 749S. This bike originally was fitted with a ’03 power kit as no one told the sales guys they needed different ECU to the ’03 models. Once we sorted that out we also did the cam timing check/reset to new specs that is a service information solution to some stalling at idle issues this model is having. It’s only about a 6 degree change in lobe separation (less overlap) but it makes quite an amazing difference on the bikes we’ve done so far. The std ‘installed’ cam timing also appears to be quite good, with variations of only a couple of degrees from spec. Once we’d done this we dyno’d it to see how much it made. It looked pretty good in isolation, although the cylinder to cylinder fuelling shows very similar trends to the ’03 graph above. First up is power before and after cam timing, although there is also the ECU change here as well. Green is before, red is after.
The variation in air/fuel is shown with torque in the next graph. Both these runs are after cam timing with the correct ’04 ECU, and are vertical cylinder in red and horizontal cylinder in green.
Finally we’ll put them together. As I said above, I haven’t dyno’d enough of each to get a good feel for them yet, so this will be updated as I get to do more.
Green is the first bike all std. Red is that bike with the DP power kit. Blue is the second bike with the DP power kit. The runs with power kit fitted (red and blue) are both quite consistant so it would appear they are quite representative. Yellow is the third bike (’04 749S) with the correct ’04 DP power kit. You can see how the ’04 model trails the others pretty much all through the RPM range. How they feel side by side is another thing though. Something we’ll get a feel for as we have two brothers who own one of each.