RX8_Buckeye

Yes, that is incorrect. More throttle = more air/fuel mixture = more torque. It takes much more torque (and thus fuel) to hold 3000 RPM in 6th gear than to hold 3000 RPM in 3rd gear or neutral, because road load and aerodynamic drag increase with vehicle speed.

Think about how far you have to push down the pedal to hold 4000 RPM in neutral. Then think about how far you have to push down the pedal to hold 4000 RPM in 6th gear on the highway. Does that make sense?

guy321

Gotcha,

Thanks!

rotary-convert

Does gear dependent mapping explain why my 8 pulls harder at the same rpms (above 5500) in 1st and 2nd rather then 3rd and 4th? I originally figured it was the difference in gearing.
Granted this is only my butt dyno telling me that.

RX8_Buckeye

That is definitely gearing more than anything, as you suspected. Even IF the mapping were gear-dependent, we're talking about single-digit differences in power and torque.

davefzr

I have the same problem.. if it's a problem.

Someone once told me that I am hitting the rev limiter and my gas is being cut off after I shift..

That doesnt make too much sense to me as my rpm's have already dropped and it shouldnt cut fuel anymore.....

Again.. in 3rd to 4th shift.. as stated.

TybeeRX-8

It hasn't been a problem for me...mine wasa pre-order that has had everthing, including the M Flash done to date. In a quick reading of all this nowhere did i see mentioned whether or not this occurs with the A/C on. Could be that the compressor clutch re-engages on the shift causing a power decrease? just a thought.

ZGlide

i tried the same test several times again today. A/C and DSC were both fully off, i shifted at the beep of 3rd gear (about 86 mph), into 4th fairly quickly without much rpm drop, and still get the dip in power before it starts to pull hard again. I dont think it's the clutch of the syncros since This car is only 3 weeks old with 1200 miles on it, with mostly very conservative driving.

davefzr

I really think it's related to the M flash. This did not happen when I had K.

ZGlide

dave so you experience the exact same thing? after the shift into 4th my rpm is at about 5500~6000. Anyways......is this turbo lag in my non-turbo car something that can be fixed or should I just look the other way?

Gord96BRG

Remember the port transitions in the intake manifold system - somewhere around 6250 rpm, the third intake tract opens (there's a thread here about the s-dais system that describes it's operation). So, when you shift from 3rd to 4th, you're dropping below the point where that tertiary intake tract is used, so it closes, and you have to wait a few hundred rpm for it to open again. It's possible that at lower rpm, there's enough inertia and acceleration that this effect is not as noticeable, but at higher speeds and slower acceleration rates that you notice it then.

The intake ports and manifolding effects are noticeable on dyno graphs - at port/manifold transitions, the airflow is disrupted slightly and momentarily, and can be seen as small dips on the dyno power curves. I'd suggest that it's possible you're just running into those?

Regards,
Gordon

Psylence

Gord.. sounds like a reasonable enough explanation. But the dip occurs and goes away before the revs have really had a chance to increase. At least I'm pretty sure it does. It's a little hard to judge for sure on the roads that I drive regularly, since the 3-4 shift occurs at a much higher speed than the posted limit.

Wish I could datalog it somehow!

LewNutz

I had a similar experience the other day shifting from 3rd to 4th at ~8500 rpm. After the shift to 4th, there was a considerable loss of power accompanied by the check engine light flashing a couple times. This has only happened once, but I have not redlined 3rd gear too many times to know if it is a problem.

Maybe I should go do some testing... :D

Rotarian_SC

I think that someone should volunteer to do the 4-->5 shift at redline to test for aerodynamic drag and such :p. I have done the 3 gear shift and kept accelerating into 4th for a couple more second, and felt no dip. But I don't have any advanced flashes, I have some primitive one before K.

John Corbitt

A friend of mine runs the quarter mile in the 7s with his 7. He just installed a MSD computer that retards the timing in the taller gears to prevent detonation. The gear specific mapping from Mazda could be along the same idea.

All of my shifts were at full throttle with the ac off. I never was able to go fast enough to do a 4th to 5th shift. I am not willing to do that on the street as that may result in a jail sentence. I hit 125mph in fourth at 9300 on the last straight at Sebring in the winter. My summer speeds were slower. Those speeds are just too fast for the street

John