Frag_dude

When I would be driving my car around in, lets say 3rd gear, while holding the gas peddle steady and fairly lighty, I would feel a little bit more power come from my car as I passed ~4250 rpm. I know that the car has valves that open up at 7250 to allow more air (although I have never really felt them), so this kinda stumps me. I bought my car used, but I haven't really found any ecu upgrade that would mess with th that kind of thing.

I have thrown in the links from two seperate web sites showing dyno charts of a stock rx8 (although I do have a k&n intake, but that shouldn't matter) to show that there is not real change in the horse power or torque curve at that rpm.

http://www.kandn.com/dynocharts/69-6030-1TFK.pdf
http://www.racingbeat.com/FRmazda4.htm

Does anyone experience the same kinda of phenomenon?

Gotian

To correct you a bit on this and to help you out, the last 2 valves only open at above 7k in 1st gear. In 2nd gear the valves open at 5.5k and 3rd they open at about 4.5k (Which is what you were experiencing) It probably just felt weird cause you were paying attention at that moment. That occurance is most noticable in 2nd and 3rd gear as you can hear the tone in the engine change much like a v-tec engine, the car becomes louder and noticeably faster.

You dont see a change in the dynos because the design of the car is continued power all the way to 8.6k where you hit peak power.

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Gotian

Also what k&n system do you have? is it the short ram or the CAI? The short ram causes problems in the car such as rough idle and can also shut the car off, you also lose power since you are sucking in hot engine air.

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Frag_dude

I don't think K&N has a CAI, but i have the revised short ram. The idle is a little ruffer, but nothing really noticeably. I've had it on for almost a year and driven in some rediculously hot climates and have had no ill side effects.

Thanks for the valve info, but to add to that. I was just driving and i heard the exhaust note change again at abour 4.25-4.5k rpm, but in second gear. Weird, but it doesn't really bother me. I was just curious as to what it was.