i've never had a n/a rx7 and don't know if this is normal or not but when i hit 5k rpm i have a sudden gain in power i guess i can compare it to vtec in a honda my exhuast note changes and i can feel it pull a lot more. i recently just fixed my aux. ports but they open at 3800 when reving the car in nuetral. i don't know if it did it before the aux. port fix but the car is all stock. so is it normal?

 

Ha ha, funny to have an N/A owner question a bit of power from their car. If it's S5, its the VDI kicking in, which in short changes the intake geometry to get a natural supercharging effect.

 

model year and mod list

 

If you have a 89 or up...

That would be the VDI ports (secondary butterflies in the LIM like an Integra GSR) it’s all a part of the LIM where the AUX ports are, you most likely figured that both actuators on the LIM are for the AUX ports and fixed them both, but one is for AUX and one for VDI. You get one boost of power at 3800rpm and another at 5000rpm.

 

88 vert the engine has been changed but it has all the s4 intakes and omp so i'm assuming its a s4.

car is stock

 

The auxiliary intake ports are pretty much the same as VTEC except they're for rotaries and they were invented 5 years before the piston version . AFAIK it's a seamless, unnoticeable transition around 4000 rpm (3800 is something unrelated btw). Maybe yours are sticking a little so you get the power all of the sudden at 5000 rpm? Who knows. I do know that on the RX-8 at least both the auxiliary ports and VDI are totally seamless. Mazda knows how to make their stuff smoooth. Maybe too smooth to make money off of all the Civic, American, etc. car punks who think a slow shaky engine jerking them around is power :P.

 

as I've pointed out, the VDI system (a similar version of which may have been on older 80s Ferraris or something before Mazda had it) is equivalent to the variable intake runner system on the NSX and the Integra GS-R. The nonturbo 3000GT DOHC also had a similar system, and so did the non turbo Skyline engines.

 

VDI has no butterflys but a rotating valve. Engines with VDI have 3 vaccume pots, Two for the Aux ports on the LIM and one in the middle passenger side of the middle intake manifold for the VDI

Dont get to ahead of your self, I had a late 1970's Alfa Romeo with VVT and i think Fiat started this in the 60's

 

just throwing this out there, could this sudden power gain be caused by the engine leaning out?
like from the secondaries turning off.
stick a wideband on it just to make sure, cause, not saying it is the case, but if it is, that could really suck!

im not trying to be a pessimist, or make u go on a wild goose chase, but u may just wanna be cautious anyway, so it doesnt cost you

 

If the secondaries don't switch on, the engine will hit a wall at WOT around 5-6k RPM. The primaries top out, and there's just no fuel to support the airflow. It'd be lean alright, but excessively so.