sharperedgeengines Auto Parts

1-866-651-2992

Over 15 Million Engines and Transmissions

sharperedgeengines Used Engines , Transmissions Why the Manual-Transmission Porsche 911 GT3 Fails Californias Noise Test

Why the Manual-Transmission Porsche 911 GT3 Fails Californias Noise Test

Why the Manual-Transmission Porsche 911 GT3 Fails Californias Noise Test

porsche revealed the 2022 911 gt3 touring this week—a comfier, more subtle version of the razor-sharp new gt3 that was introduced earlier this year. buried at the bottom of porsche's press release was a jarring, disappointing admission: "the seven-speed pdk gearbox will be the only transmission offered in california with the 911 gt3." that's right: the six-speed manual, a no-cost option that would seem to be ideal in the raw, visceral, naturally aspirated gt3, can't be sold in california, the state where you'd expect to see the greatest number of this sports cars sold.

it all comes down to noise. according to a porsche spokesperson, the gt3 passes california's drive-by noise test when equipped with the pdk seven-speed dual-clutch automatic; with the six-speed stick, it fails. it's a factor of the way the test is performed—and which testing method california chooses to employ.

the california code of regulations specifies that highway vehicles must pass a drive-by noise test designed by sae international, formerly known as the society of automotive engineers—specifically, sae j1470, "measurement of noise emitted by accelerating highway vehicles." this sae paper goes into extreme detail explaining the design and layout of the ideal testing environment, the proper arrangement of the measuring equipment, the exact condition of the vehicle to be tested, and on and on. but basically, the test boils down to this: a vehicle accelerates past a microphone, and the sound pressure level, in decibels, is recorded.

sae j1470 aims to measure "the highest noise level consistent with urban driving." the exact testing method varies based on vehicle size, power output, peak acceleration rate, and gearing, but generally, it involves a full-throttle run starting at 50 km/h (31 mph) and continuing until the engine reaches its peak-power rpm. manual-transmission vehicles are tested in either second or third gear; given the gt3's curb weight and power output, the procedure calls for third.

here's the thing: automatic-transmission vehicles aren't necessarily tested at wide-open throttle. the method specified in j1470 states that "the throttle shall, as rapidly as possible, be opened as fully as will ensure maximum acceleration without operating kickdown" (emphasis added), and held at that position until the car reaches the end of the testing area. "kickdown," as defined by the sae, means "a forced downshift to the lowest possible gear (first or low gear)."

you see the problem here. the pdk-equipped gt3 can do nearly 80 km/h in first. certainly, flooring the accelerator in an automatic gt3 would trigger a multi-gear downshift all the way to first. so while the procedure calls for the manual gt3 to run full-throttle nearly to redline in third, the same procedure prohibits full-throttle acceleration in the automatic version of the very same car. hence, the pdk passes the test, while the manual fails.

porsche's spokesperson would not answer any specific questions about how the manual or automatic gt3 performed in california's noise tests. but the porsche representative did highlight something notable: sae j1470 is no longer the most up-to-date testing method when it comes to measuring drive-by noise.

see, sae j1470 was first published in late 1984. the paper reveals itself to be relatively out of date when it comes to automotive drivetrain technology: the standard test procedure assumes that the typical stick-shift vehicle is "equipped with a manually operated gearbox having not more than four forward gear ratios." there are alternative testing parameters for vehicles with highfalutin gearboxes with more than four forward ratios, and sae has published updated versions of the test method since 1984. but the basic framework of j1470 seems insufficient for testing modern vehicles in 2021.

sae international addressed this with an entirely new vehicle standard: sae j2805, published in 2008 and updated as recently as may 2020. j2805 completely revamps the drive-by test procedure. rather than a full-throttle (or nearly full-throttle) drive-by, j2805 lays out a hugely complex method of calculating the appropriate rate of acceleration for each individual vehicle being tested. as the very first paragraph of j2805 states, this updated procedure "is based on extensive statistical investigations of vehicle operation in real traffic." j2805 includes techniques appropriate for hybrid vehicles and other advanced drivetrain designs that did not exist when j1470 method was published. long story short, j2805 more accurately simulates "acceleration at a partial throttle condition in urban traffic."

here's the problem: california doesn't use j2805. vehicle noise testing is performed by the california highway patrol, as defined by california code of regulations title 13, section 1046. that regulation specifies sae j1470 as the official testing procedure. so while porsche assumedly engineered the gt3 to pass the updated j2805 test with both available transmissions, in california, the old method is still the law of the land. (porsche's spokesperson indicated that chp has been planning to update its testing regulations to incorporate the new sae procedure; road & track reached out to chp for comment but did not receive a reply at publication time.)

so for now, porsche can't sell you a 502-horsepower 911 gt3 with a six-speed manual in california—despite the fact that the pdk-equipped gt3 has the same engine, the same exact exhaust system, and, as far as we can tell, makes the same amount of noise.

"we don't know when the new sae j2805 procedure will be adopted by california, therefore we can't guarantee the sale of the manual gearbox on the 911 gt3—and where there's doubt, we're always cautious," porsche's spokesperson told road & track via email.

our contact at porsche was eager to point out that the noise regulation issue does not affect any other 911 variant, nor does it apply to the 718 boxster or cayman. so if you want a brand-new porsche sports car with a manual transmission, and you want to put a california license plate on it, you've got every model available to you—except the one you really, really want.

this content is created and maintained by a third party, and imported onto this page to help users provide their email addresses. you may be able to find more information about this and similar content at piano.io

source:caranddriver.com