Mazda RX8 horsepower controversy

Since its launch, the Mazda RX8 has been the focus of enthusiasts. The high level of attention is due not only to the car’s stunning driving dynamics, but also to some early reports of unpredictable performance. Specifically, the wheel horsepower measured by running several chassis dynamometers was well below the expected 17% to 20% drivetrain parasitic loss. And it runs 1/4 mile anywhere between 0.5 and 1.5 seconds from the pre-production vehicle produced by the magazine.

In connection with the RX8’s horsepower rating: The original marketing material from Mazda North American (MNAO) advertised the 6-speed manual transmission RX8 at 247hp @ 8,500rpm. Assuming a 17% to 20% loss of parasitic drivetrain (common in modern rear-wheel drive vehicles), the Stock RX8 will be 205 on the rear wheels, depending on altitude, pressure, temperature, and correction factors applied. ~ 197 horsepower (rwhp) needs to be measured. Instead, the Stock RX8 chassis dynamometer shows results in the range from medium to high to 160 to 185 rwhp. Such readings indicate that the loss of the parasitic drivetrain is over 25%. Needless to say, experiencing such a high level of loss in a “sports car” drivetrain with a carbon fiber drive shaft is an understatement.

To further solidify doubts about the actual output of the new Renesis, some owners were unable to reproduce the mid-low 14-second quarter mile pass, as published by the well-known US car magazine. The slow trap speed was another hint to the apparent lack of output.

Shortly thereafter, several discussions on online enthusiast forums and bulletin boards became fierce about the causes of this “linear performance” decline. Many former Miata owners recalled earlier “snuffs” in Mazda’s history when manufacturers clearly exaggerated their redesigned Mazda Miata horsepower figures.

A few months later, MNAO explained that he had come forward and misrepresented the output of Renesis. The modified number was now 238hp @ 8,500rpm. However, according to MNAO, this revision did not change the results of previously achieved track performance.

There was a lot of speculation about the reason for the sudden lack of output. However, there are currently two ways of thinking.

• First, it supports the idea that the RX-8’s engine management unit (ECU) cannot get accurate readings from the chassis dynamometer in combination with many “nanny” devices such as ABS and TCS. .. For simplicity, only the driving wheels are spinning when the car is running on the chassis dynamometer. The RX-8’s ECU detects abnormal driving conditions, delays timing and applies other safety measures to protect either the “driver” or “engine” or both from damage (read: A skid situation or a road where a car goes out.)
• Second, we believe future federal emission regulations have forced MNAO to redesign the software that performs engine management, even before the first batch of RX-8 arrives on the US coast. I especially read those that require a catalytic converter life of about 100,000 miles. The greatest enemy of catalytic converters in any vehicle is heat (and heat is the greatest attribute of rotary engine exhaust).

MNAO has offered two options to those who pre-ordered the RX-8 or who purchased it by September 2003.

• They would buy back the car, no questions were asked.
• They offer a $ 500 “gift card” to those who choose to keep their car, in addition to free regular maintenance during the warranty period.

I was among the people who chose to keep the RX-8. After all, the driving experience hasn’t changed since the test drive before purchase. Since August 2003, I’ve measured well over 20,000 miles-as of January 18, 2005-and I regret only an ounce of my decision. If you would like to know more about the owner’s opinion, please visit this thread at @ RX8Club.com.

Numerous ECU “updates” have been released in the last two years. As far as I know, all the early samples of the ’04 RX-8 were from engine management software level “J” ports. Since then, it has escalated from the alphabet to “M”. It was released in a TSB campaign by Mazda North American (MSP04) to have Service @ Authorized Dealers flash all vehicles to “M” calibration. ..