I've seen many video's of people in rx7's that are staging on a track and when they bring their revs up it makes the BIG rotary POP POP POP POP POP. I was just wondering what that was. Is it because they're to rich or lean. Or is it the rev limiter?

 

It's called a two-step rev limiter. It's not just rotaries, piston engines do it, too. Like this Supra, for instance: http://www.youtube.com/watch?v=Aeh4AIaS3dw

 

How does a two-step rev limiter work?

 

can't be good for any engine to bounce it off the limiter like that.

 

like this??????

http://www.youtube.com/watch?v=tQ9zaqTfNTk

 

I always thought the pops were the way the exhaust pulsated or something (not the limiter bounce ones).

 

It's a button or switch (often a clutch switch) that, when triggered, limits engine speed to a preset level by cutting or severely retarding the ignition. This allows the user to launch at a consistent RPM. It's particularly beneficial for turbocharged cars, as keeping the throttle fully open allows the turbo to build boost prior to launch. It's called a "two-step" because there are two RPM limits: the normal one that prevents excessive engine speed, and one at a lower RPM used for launching. The loud popping is caused by unburnt air and fuel igniting in the exhaust system.

 

As long as it is a ignition cut rather than fuel cut limiter all goes well.

-billy

 

My Rx8 had the ECU reflashed and revs up to 10,200

Sweet on a tunnel

🤤

 

I bet, but doesn't power fall off right after 9000 stock?

 

Oh no! Not stock!

Bridged and Ported, idle is around at 1300/1400
Pushes all the way up! Except the middle range, it's a bit lazy there

 

Seen a lot on RX8club about introducing overlap on MSP engines and it usually doesn't tend to be good, have you dyno'd it? Curious to see how the mods perform.

 

Sure thing!

210hps and Air/fuel was set around 11.5/12

The HP curve shows power up to 9.8... more or less

I want to go again to the Dyno since it was reprogrammed and feels even better now
​​​​​

 

What is funny is my bridge port does not pop on the two step.

My friend's MSM swapped Miata, on the other hand, does all sorts of pops and bangs

 

Try pressing the clutch a bit when deceleration

 

Sounds like an F1 since it has BHR exhaust.

Sweet sweet sound

 

210 to the wheel is pretty nice for a renesis. People have done 220whp with a ported renesis + a long list of other mods, maybe your bridge can top it. Gonna take a lot of time and $$$ tho lol

 

huh? We're talking about hitting a two step. Clutch is fully depressed.

 

Maybe!

😂

 

a properly built and blueprinted Renesis 6-port engine on factory ports will be 225 - 235 bhp at around 8600 rpm.

porting will only gain a few hp at the expense of longevity and is not recommended beyond basic cleanup and edge smoothing

In 20 years I’ve never seen any BP Renesis get close to those numbers, ever. In fact I’ve never even see a dyno graph for one as high as claimed here. Most often it’s verbal bragging and carrying on about idle brap nonsense. So immagonna challenge you to post up the proof.

I banged on the 10k limiter plenty for competition purposes, but knowing full well that anything beyond 9k kills the keystone shaped side seals in short order. Even the Mazda STAR/Pro Formula race series cars using the afore mentioned built/blueprinted Renesis engines and a locked-spec MoTeC ecu specifically had an 8,600 rpm rev limiter for that reason. They made ~240 whp due to the lower friction loss transaxle drivetrain - not ported at 13:1 afr.

Why anyone thinks that higher rpm with less power makes sense is beyond my understanding.
.

 

This is the first I've heard of the RPM limitation of the RX-8 side seals. Very interesting! I wonder what the mechanism is. Possibly twisting and warping so they don't sit flat to the side housing?

 

You can believe what you decide to and I will always respect that, it's your right.

I don't feel the need to demonstrate anything to anyone and that's my right.

Since that what forums are for, I shared my experience with my car. You may enjoy it as another "mission impossible" sequel or try to find out what my Puerto Rican mechanic did to my engine...

Cuz I won't share it.

I do encourage you to dig more on what has been possible by the rénesis engines. It's very interesting what can be found about it.

Wish you to have a good one 😊🫶🏽