Quote:
Originally Posted by mwebb
"EDIT: We didn't attach an OBD reader to the car... but there was little need and no time to do a comprehensive test... it's a relatively simple car with a single cat that doesn't meet US or Euro emissions standards, so any computer chicanery is happening due to what's going on at the MAP and not the O2 sensor... especially since we weren't running it in closed-loop on the dyno (all WOT runs).
"
very pretty
but you have not attributed any values to any of the pretty little lines on your graphs which may or may not be related to the blarney you are posting -
so
you follow the
if you can not dazzle them with brilliance , baffle them with BS .
the alleged test mule is not in "closed loop" and meets no EOBD or OBD2 standards as such - how do you suppose this has anything at all to do with what you imply ?
it does not .
try again
no more BS
you do not need a dyno in fact for real cars driven on the street
dynos do not and cannot reflect real conditions - like this - see calculated load
if you do something / anything to improve this exact system on this exact car - the calculated load value will increase when driven under the same conditions shown in this screen cap
you claim x% at wot
- your claim would be reflected or disproved by calculated load
show me
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I try to be nice...
I don't know what you
think I am saying, but what I am saying is that these are power gains and losses shown on a car at full throttle
under load on a Dynapack dyno.
Under load means it is pushing against the brakes of the dyno, which measure the force exerted against them.
That the car is at WOT and not in closed loop is important because somebody said the computer would readjust itself in milliseconds. Which is both true and not true.
Some computers adjust right away (again... turbodiesel, cone filter... no gain)... some don't. Those that don't adjust can still adjust if the AFRs at the O2 sensor wander far enough to cause the computer to adjust... but that won't happen at WOT, it will happen in closed-loop at part throttle. Which we were not testing... And it takes time for LTFT to wander. Also, taking OBD readings off the stock narrowband is nowhere near as accurate as using a wideband. Yes, there are issues with using a wideband shoved up the tailpipe as opposed to plugged into the exhaust manifold (my exhaust, for example, throws off tailpipe readings), but it will still be more sensitive than the stock narrowband O2.
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A dyno is not real world conditions... I absolutely agree. But a dyno is a repeatable, stable test wherein you can control load, speed, temperature (if you've got enough fans) and other variables. You still can't control for humidity given our settings, and SAE correction factors are often inadequate when testing out modern cars that actually adjust themselves for ambient temperature and air pressure (see the brouhaha over the R35 Nissan GT-R dyno-tests when it first came out, non-SAE corrected, it often made the same HP in various conditions on similar dynos... apply SAE corrections, you got wildly different outputs... because the GT-R ECU alters boost levels based on atmospheric conditions, as can be seen by the boost traces on those dynos).
There are no headwinds or tailwinds on the dyno. Throttle position and how aggressively you start your "sweep" are still an issue, but you can control that by doing braked point tests instead of a sweep. There is no tire slippage on a Dynapack, no effects of tire pressure or rolling resistance.
It's just a simple measure of how much torque an engine can transfer through the driveaxles into the brake. There is some argument as to how accurate each dyno is, as they all read differently, and endless arguments over best gear-ratios to use when dyno-ing (should get as close as possible to 1:1, but that's not always possible), but here, we're only interested in the difference caused by the part being tested.
If all cars responded to all air intakes in the same way, and if all aftermarket air intakes were bogus, companies wouldn't be spending thousands of dollars researching new intakes and trying to find ways to make more "bogus" power with them.
As for values:
The steady blue line trace is stock power and torque measured on the brake via a sweep test at full throttle. No SAE correction or Torque Correction Factor applied. (TCF is bull, anyway... since it's an assumed, operator entered number).
Ratio and roadspeed are operator entered and not accurate. Again... this was done as a "before and after" preliminary test to see if it was worth building an intake for the car, so we weren't concerned with actual road speed or gear ratios, just the before and after traces for power. The incorrect gear ratio doesn't mess up the torque-to-hp calculations, since the dyno reads rpm off the ECU and does those calculations internally. Besides... again... we were only interested in before and after traces.
The three sweep lines with the irregular peaks are with the intake.. and show obvious gains at low rpm and high rpm, with an obvious dip in the middle.
Again, not shown are where we bolted the stock box back on and did a few sweeps. The gains and losses in each area were exactly halfway between stock and modified. The operator didn't think to save those traces at the time.
Would it have been instructive to attach an OBD reader to see this phenomenon happen on the road? Of course. Was it my job to do so and did I have time to do so? No.
I'm honestly baffled by what your issue is. All I've said previously is that intake modifications nowadays are voodoo simply because the computers seem to either adapt to them or not according to their own whim, and that this particular car gained power in some places and lost power in others, seemingly due to some weird intervention by the computer. And that I've seen some MAP-equipped cars that could dial back power completely from an air-filter change... Could it be very specific resonance tuning involving the intake resonator? Maybe. Would more testing tell us for sure? Probably.
I don't see how this, in any way, is bull. I'm not selling any snake oil here, just sharing what I've seen. Intakes are weird. They sometimes work and sometimes don't, and not always for the reasons you think they will or won't. And that's all there is to it.
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Perhaps your issue is where I said a fuel economy change was believable with a MAF-equipped car (which the car in the dyno doesn't have). I say that because MAF-equipped cars are sensitive to turbulence or tubing or positioning changing the senor readings, and what we've noticed is that air filter position can play a role in gaining or losing power. some guys have even resorted to putting small mesh filters in front of the MAF to smooth out the air at the sensor... and in testing, the shop will sometimes try out multiple MAF positions to find out what works best.
While I say this is believable, I am
not a believer in changing out your air filter to increase fuel economy. It could just as easily make it worse. Or not do anything at all except give you less filtration than stock for no increase in power or economy. And if there is an increase in economy, it may eventually get lost if the ECU readjusts. It would be much better to retune the car simply so that the usually overly rich fuel tables in the ECU are dialed back to more realistic levels.
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Oh... and... please be nice.