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From TOV:



The K-series Strikes Again
The 2006 Civic Si's K20Z3 engine is one more member of the highly exalted K-series lineup. Combining elements from a variety of other K-series engines (K20A2 style head, Euro-R RBC intake manifold, K20A3 style balance shaft, K20Z1 style camshafts, etc.), it exhibits a smooth, refined demeanor along with a typical Honda high rpm rush of power, and a typical Honda VTEC dip as well.

While nothing leads us to believe that the K20Z3 won't be just as capable in the aftermarket as other K-series engines, it does face the hurdle of a completely new ECU and drivebywire, so modifications may be a little more difficult (we'll be the first to tell you in our project car chronicles).

In the case of our particular example, the gains may be even tougher still. Take a look at the dyno results.



The lowest curve, 197.9 hub hp, was recorded in completely stock trim after a few runs. We think this is more representative of what our car will do. The next run, 204 hub hp, was recorded with a little cool down. Note that the biggest difference occurs from 7500 rpm on up. The final run of 209 hp was recorded with the airbox cover off (note the bottom end losses). While the car gets much noisier and loses the refined growl of the stock intake system, the 5+ hp gain indicates that an intake system will probably be able to pick up some noticeable power (do not drive with the cover off, with the hood closed, you'll kill power by ingesting hot air from the engine bay).

Now take a look at the AF ratios. Note how smooth they are. Also note that they are relatively close to the optimal range of 12.5-13:1. Finally, note that on most runs, with the exception of our stock 204 hp run, that the AFR goes very rich after 7000-7500 rpm.



We think there are a couple factors at play here. First of all, either Honda has underrated the new K20Z3, or we have a ringer. On the same dyno, a stock 05 RSX (rated at 210 hp on the old system) will put down around 185 hub hp. The best one we ever did (another preproduction car) put down 190 hub hp. Given how strict the new ratings systems are, we suspect we have a ringer, but we'll wait to see what other gains we get, and what production cars do. If you live in SoCal, we'll do free dynos for the first 3 production Si's that come in (310-518-4966).

The fact that the AF ratio goes rich at high rpm on virtually all runs tells us that the K20Z3 is either very temp sensitive, very knock sensitive, or both. The very flat AF curve is also unusual for a factory car (Honda or otherwise), which is one reason why we suspect a little tweaking.

Stay tuned as we begin pulling the car apart and looking for more power.
 

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drive by wire can't be THAT bad if Honda is starting to use it in their cars.

Anyways, VERY impressive #s on the Z3. Looks like this one isn't a ringer as they posted an update on the site where another Si got similar #s.
 

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Acorns!
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chibianh said:
drive by wire can't be THAT bad if Honda is starting to use it in their cars.

Anyways, VERY impressive #s on the Z3. Looks like this one isn't a ringer as they posted an update on the site where another Si got similar #s.
it's not just honda that is using this technology. A lot of companies are going to drive by wire, and the car industry claims that all cars will be using it within a few years. I just remember people on the TSX boards having problems modding their cars because of the drive by wire setup. Hopefully they can overcome it and still produce excellent numbers.
 

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webby said:
it's not just honda that is using this technology. A lot of companies are going to drive by wire, and the car industry claims that all cars will be using it within a few years. I just remember people on the TSX boards having problems modding their cars because of the drive by wire setup. Hopefully they can overcome it and still produce excellent numbers.
The only problem experienced is the throttle lag. The vtec.net guys said it was still there but less noticeable than in the TSX and you could still hold rpms running through the gears quickly. They said it was better than the TSX but could still use some improvement. I think the drive by wire will <3 my driving style :)
 

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Besides throttle lag, what other issues may come up from this drive by wire technology?
What exactly does it do and why are so many companies doing it if supposedly it affects the car's performance?
 

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Acorns!
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here is an explantion from honda on the TSX's drive by wire -


DRIVE-BY-WIRE THROTTLE CONTROL SYSTEM

An electronic drive-by-wire system helps enhance the driving character of the TSX. With smart electronics connecting the throttle pedal to the throttle butterfly in the intake tract, the engine response can be optimized to suit the driving conditions and to better match the driver's expectations. By eliminating the direct throttle cable connection to the engine, the ratio between pedal movement and throttle butterfly movement can be continuously optimized. This adjustable "gain" between throttle and engine is a significant step forward in drivability.

To establish the current driving conditions, the system monitors pedal position, throttle position, vehicle speed, engine speed, calculated road slope and corner radius and engine vacuum. This information is then used to define the throttle control sensitivity.

From the driver's standpoint (because the drive-by-wire system is combined with other functions such as VSA and Traction Control) this means that the way the TSX responds to throttle pedal movements is tailored to the driving conditions. In stop-and-go driving, the pedal response has low gain and is smooth and progressive for easy driving. A similar low-gain response makes starting out on snowy or icy roads more predictable. In low- to medium-speed driving conditions, the gain increases to improve response and acceleration. In high speed driving, the gain increases further still, so that there's ample response for passing. The system also alters response based on the road slope, providing more throttle gain on uphills, and less on downhills, and also reduces changes in gain on curvy roads to make the car easy to control.

The throttle system works with the available SportShift 5-speed automatic transmission to make shifts faster and smoother than has been possible before. By coordinating the throttle opening with the transmission's shifting functions, engine power can be precisely tailored to the needs of the transmission at every point during the shifting process. That means less shift shock and delay, no matter the driving situation.

The TSX uses a DC motor to control the throttle butterfly position in the intake tract. Large bearings and internal upgrades give the motor greater resistance to vibration.
 

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From what I have heard Honda's implementation of DBW is much better than that of Toyota. I have never driven a Toyota with DBW so I can't say personally. My Accord has it and it really is pretty transparent. There really isn't much lag, but it can make shifting in lower gears a little tricky until you get used to it. Also, my Accord (6MT) will automatically match revs on upshifts, which is pretty useless unless you are granny shifting.
 
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