We've been waiting anxiously to once again try out Acura's TSX, which is the recipient of several upgrades. Of course the most significant change to us are the revisions to the motor, which are described as follows:
|On the intake side of the TSX engine, the diameter of both the throttle body and the intake duct were enlarged to increase induction flow rate from 95 liters per second to 110 liters per second. In addition the diameter and shape of the intake valve were enhanced to help increase intake flow by 16 percent and the high RPM cam profile for the intake cam was modified to provide increased intake valve lift and duration. In addition, a ventilation passage was machined into the engine block to reduce pumping friction by increasing air flow between cylinders.|
Engine code remains K24A2
All this is said to result in only a 5hp increase, but don't forget that due to the recent revisions to the SAE J1349 testing standard, almost all Acura and Honda motors horspower and torque have been revised downward for 2006 so the actual improvement over last year's motor is said to be actually 10hp.
The first 2006 TSX press loaner just became available here in Atlanta, so I jumped at the opportunity to check it out. Unfortunately, this is also the first 5AT TSX that's been in the press fleet here, so we don't have any basis for comparison on our dyno run. There are currently no 6-speed '06s here yet, but we're going to try to get our hands on one in the next month or so.
I took the car over to Dynolab in Marietta, GA, where Arthur strapped it to the rollers which we subsequently spun to 145mph.
Click for full-size
We're pretty sure that the strange loop shown in the dyno plot is the point where the torque converter finally locked up. It's a little strange that it didn't happen until nearly redline, and you can see that below that point the slippage of the torque converter was costing the car some power and torque. Inside the car, it was strange as well because I've never felt a car lose rpms at full throttle on a dynojet before. Perhaps there's some trickery going on with the drive by wire which momentarily cuts the throttle as the torque converter locks, in an effort to disguise that event to the driver and passengers. Obviously, the false peak of 180hp must be thrown away as it's clearly an artifact of this step, but after the torque converter locked up this car put down a pretty healthy peak power of 175hp. On the road it feels quite nice - much better than the '05 TSX, which had a very subtle benefit from VTEC. On my own '04 TSX baseline dyno, if you compare the difference in the power level at 6000 rpms (just as the VTEC switches over) and at the car's peak (in VTEC), it's only about 20hp. On this '06, the difference is roughly double that, at a little over 40hp! This can very obviously be felt on the road and it gives the '06 that sense of urgency and a bit of an added high-rpm thrill that's lacking on the '04 and '05 TSX. The rev limiter remains at 7300 rpms on the '06, and it's still not enough - particularly since the car now pulls more strongly up top, it feels like it could use another 500 or so rpms.
Overall, I like the improvements to the K24A2 (it's still labeled that, by the way) for '06 and I can't wait to try out the 6MT version. We're hoping it puts down 10-15 more hp at the wheels than the 5AT version. With a few bolt on mods such as a 4-2-1 header (the '06 appears to use the same design as the '04 and '05) and a cold air intake, it wouldn't surprise me if the '06 is capable of over 200whp. And if Hondata can successfully reprogram the '06's ECU, then we might even see another 10hp or so of peak power and a healthy dose of added midrange.