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Posted by Drew in Houston [Email] (more from Drew in Houston) on Mon, 13 Dec 2004 00:53:56 Share Post by Email
In Reply to: About the custom HW parts, Vigge, Sat, 11 Dec 2004 03:41:05
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Couple of questions:

1. What exactly are the mechanics behind your statement "The airmass is a value coming from the original (initial) calibration of the Airmassmeter. If you change a hardware part (airfilter, exhaust...) you affect this calibration, therefore the measured value is not "correct" anymore ( 1 is not = 1 but perhaps 0.99 or 1.01 or whatever)."? As far as I know, airmass meters like the ones you're talking-about rely upon the known constant (relatively) of heat absorption from the hot-wire to the surrounding atmosphere--a negative heat transfer that is converted to a voltage difference. The baffles inside of that meter act to normalize the flow around that wire. Please explain further how lessening restrictions before and after the sensor fundamentally affects that heat transfer relationship and the meter output--when the local mechanical passage across that wire remains essentially the same. Is your thought that the response time of the sensor itself is not sufficient due to increased cooling abilty of the increased air flow? Or maybe you're alluding to massive, unknown non-linearalties at some point? Regardless, proportional calibrations of sensor output won't/can't affect that heat transfer relationship--regardless of flow... One issue you didn't mention that could actually matter at some point, and my friend and I calculated it, is that the MAF will run out of span at a certain CFM, but that's not what you're saying.

2. "RICHER MIXTURE=LOWER OUTPUT" Richer than what, perfect mass combustion (14.7:1)? Are you accounting-for increased boost pressures that can be ran due to increased cooling and decreased ping/detonation that results from simply adding more fuel? What if water injection is thrown in the mix? If you're suggesting richer than stoich, you're wrong. Regardless, max power is generally found somewhere around 12.5 to 13.1 (+/- a couple of 10ths).

3. "(the lambda integrator has to add fuel to get lambda 1)" Integrator? Are you talking about fuel or MAP or pressure sensor or all? The "I" in a PID loop stands-for Integral "Integrator"--which effectively acts to dampen the response in a controls system. Analogous to the valving within a mechanical shock absorber system. "P" is proportional, the spring or lever length/points. "D" is derivative and has the ability to regulate steady-state errors (no direct mechanical comparison in a typical mechanical shock absorber). I'm still learning about T7, but my guess is that the Derevative value is what you meant if that's indeed how it's done internally. Or for fuel is the correction more simple than that considering that the output from a narrowband O2 sensor is mostly jibberish and not very useful other than as a too-much, too-little indication? If everything is PID-based, I'm curious to know more about the interface between that PID control and the tables. Are they generated anew based-upon some time-based frequency or refresh rate? Do fuel, timing, boost, etc. tables contain data that's used as feedback and not as real values? Please explain.

4. "Well, I think for the moment its enough and it explains why you "loose" power when you "upgrade" hardware parts on the T7 engines." No it doesn't explain at all. Real-world, dyno-tested power gains, both RMS and peak, from hardware mods without any programming adjustment are possible and my car is documented proof.

Please elaborate more on how increasing the total thermo-mechanical efficiency of a T7 controlled engine directly causes a loss of power, either RMS or peak.

5. "In the future if you decide to tune your car more, no stage sets will mix with the custom HW part." "Stage sets" are mostly bull if an end-user uses their brain and makes informed decisions. Consider the whole picture for a second; more specifically think about the build tolerances between individual cars and their engines. The magnitudes of differences between say, two basically flow-correct performance downpipes of similar diameter from different manufactures is no greater than the differences between individual engines to begin-with. In fact, your statement really suggests that you might personally have something to loose or gain from consumers mixing and matching performance pieces. If you're talking about optimization, custom tuning is essential, regardless of whether you've purchased all of your parts from one manufacturer or not. How much power would I gain in my car if I sold the downpipe that is installed now and I replaced it with a downpipe distributed by the same company that sold me some mail order tuning? I'll answer that one because it's easy, NONE. Why? Because the software wasn't written or optimized for my car in the first place. People do it all of the time with success, but if you install mail order tuning on your car you are taking a chance regardless of the manufacturer because the essence of tuning lies in approaching, but not crossing, the fine line of failure to-closer-than the manufacturer ever intended with respect to manufacturing variances.

Bottom line: If you increase the flow capability and thermo-mechanical efficiency of your engine in a real way you will directly increase that engine's ability to mechanically make power--regardless of where the parts come from. So there isn't any confusion, I'm not saying that all performance parts are created equal, because it's likely that some are better than others, but BETTER and more efficient engine flow (sometimes that means more, somtimes it means faster) will always be a no-lose proposition--even if those gains are ultimately electronically limited.

posted by 67.10.24...
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