Flowmeter dyno testing
Here is dyno proof that the RX-7 flowmeter gives a 4.1 HP improvement over the OEM unit on a stock 1.6 engine. Since June of 1996 when I discovered that the 1986-88 RX-7 flowmeter was a larger plug-in replacement for the Miata 1.6 unit I have been preaching that it offers a huge improvement above 6000 rpm. I even dyno’d it back then with my then new 1.8 motor as proof and it gained 5.5 additional HP.
The pessimists insisted that I only got that much of an improvement then because the larger air requirements of the 1.8 motor needed it and that the OEM unit is correctly sized for the 1.6. I was told that I could expect minimal gains on an otherwise stock 1.6. Additionally they said that I had other breathing enhancements done to the motor such as a performance header and muffler that discounted the dyno results. This time the dyno run was done on my wife's bone stock 1992. The only mod done to the car was the RX-7 meter, even the muffler was stock. This was a true isolated test.
You will however notice that the dyno graph shows a loss of torque from 4500 - 5000 rpm. That is because I just threw my old hand-me-down RX-7 flowmeter from my CSP car on and I had tuned it for the requirements of my old 1.8 to eliminate the same dip. The torque curve can easily be restored with adjusting the spring tension of the flapper door, fuel ratio adjustment and resonance chambers.
I’m here to say that other than the free timing advance mod the RX-7 flowmeter interchange is the most cost effective performance improvement you can make to a 1.6 Miata.