Ft Liquordale

Point taken on the cone filters. Another volume vs tuning affect. I have read in other posts the turbulence may affect the MAF (which entirely is another story)

I am going to read up on exhausts (I noticed it is a long thread) while I drop this last question on you.

If tuning via ECU is done, should there be adjustments made on intake and exhaust? (Airflow tuning is adjusted according to engine tuning according to wakeech's last post)

rotarygod

ECU tuning is making what you have now work it's best. Any changes that you do whether intake or exhaust will also require an amount of fine tuning to see its full potential.

What Wakeech is referring to is a different form of tuning. The tuning he is referring to is what powerband do we want the intake and exhaust to "tune" to. This is more of an acoustic tuning since the lengths of the intake and exhaust will determine where the engine can make its best power. Computer tuning is making sure we have the proper air/fuel ratio and timing so that we can get the most potential power and take advantage of what we have. If we changed the intake and exhaust we would change where the powerband lies and it would require ecu tuning changes. 2 different uses for the word tuning.

Broke_Apex_Seal

Yup I will be there

Ft Liquordale

Don't you people have email?

Okay, I am going to try and sum up what I have learned.

Engine intakes need lower frequency tuning at low RPMs and higher tuning for the converse regardless of volume. This helps for air velocity through the valves or rotary chamber. Tuning is acheived through width and length of the port pipes as well as the area diplacement of the intake box (or other device). If the port pipes are widened, then it produces a higher frequency (more air volume/velocity) While the volume is ideal, the pipe needs to be lengthened to reduce the frequency. Cone filters, while allowing more air into the filter through filtered area, creates turbulence which hinders the flow into the engine (as well as other problems).

So the modifications that can be made are
1. Super Charger
2. Widening/Lengthening Intake Ports
3. Increasing flow/Decreasing turbulence through the filter box/cone.
4. A combination of the above stated.

Now back to the valve. If left open, the frequency is raised and at lower rpms will create disturbance on the intake chambers. This will hinder the velocity at which the air may enter.

My question now is, why wait until 7250 RPM to open the valve? Would the volume/turbulence ratio be more in favor for the volume at around 5000 RPM?

What would the affect be to eliminate the short pipe and increase airflow from the long pipe? Would the volume cancel out the need for a higher frequency?

wakeech

so when you're designing and building the intake and exaust manifolds to go with your ports, and other things like your throttle body size, fuel system beefiness, etc etc, you're designing and building the "piano".

the adjusting the way the ECU runs the motor is like actually tuning the piano.

starting and running the motor to it's fullest potential is just playing the instrument

Ft Liquordale

now we are speaking the same language.

though they are different tuning, they are codependent. Adding that Greddy Intake would require some ECU adjustments as well.

wakeech

yeah, something like that.

i like to think of it in stages: you design the hardware with certain performance targets and characteristics in mind, and then tune everything to work as well together as possible (primary and secondary sorts of things).

rotarygod

Mazda designed this system to work at 2 different locations. It doesn't just give a gain there but also tapers off above and below these points. It isn't like the system won't work without them tuned where they are. They just won't get the gain in those spots. Mazda apparently felt that 7250 was a good crossover point. Previous rotaries had 7000-7500 rpm redlines but the Renesis doesn't. It redlines at 9000 and fuel cutoff will kick in somewhere around 10000 rpm depending on the car. That is much higher than before. You could design a system that can transfer over at a lower rpm. It's just where they chose to do it.

If you eliminate the short pipe altogether and give it a long pipe, you are still only tuning around a certain zone rather than around two of them. The problem is that every system that is tuned for a certain range will hurt in others. You have to trade something. Depending on the acoustic effects, it is possible to have less air flowing through the pipe even though there is more area. Acoustics do some weird things. If I were to redesign the system, I would still utilize a flat plate filter but a much larger one. This would probably force the battery to relocate. I would then use 2 closer to equal pipes and then tune them to where I want them. When it comes to Helmholtz resonant tuning there is another thing to worry about when designing intake size. You do not want the airflow through the pipe to ever exceed 122.74 mph. It's a formula so don't ask! This will determine optimum inlet size.

Wakeech: I love the piano analogy. So simple yet so true.