Dysfnctnl85

So then what's with the lack of aftermarket intake manifolds?

bill shurvinton

No shortage at all. Look at www.japperformance.com.au to name but one.

mazdaspeed7

While the hp gains are there, paying customers arent. Not here at least. Turbo envy runs rampant here.

Drago86

The stock manifolds use both the opening and closing pulse, but because they are both positive pulses and much stronger then a piston motor, we use them in a differnt way with opposed secondary and primary runners so the positive pulse isnt reflected, but just carried to the other rotor during its closing cycle. the opening pulse is positive and not negative like on a piston motor because of the rotarys overlap with the exhaust, which when the exhaust first opens trys to revert the intake charge and creates a positive wave. Stock type manifolds would work much beter than individual throttle bodies. S4, S5 NA, and im pretty sure the s5/s4 turbo use this system. Also the S6 and rx8 use this system of intake manifold tunning, its VERY effective on a rotary.





Documentation: http://www.thecarricos.com/ACRE/Docu...tech90-1-6.pdf

bill shurvinton

Not quite. There is a reversion pulse that can be used outside the tuned frequency of the exhaust, but at higher frequency there are at least 2 negative pulses. One is from the scavenge pulse from exhaust tuning. The other is from the expanding volume in the rotor chamber.



The mode you are referring to is generally used at lower RPM.

mazdaspeed7

A classic example of having just enough knowledge to think you know what youre talking about, but not enough to see the big picture.



The pulse from opening of the chamber is ALWAYS negative, regardless of whether its a piston engine or a rotary. The chamber is expanding as the port is open, hence the negative wave. The air horns on an IR setup invert that pulse back into a positive pulse that arrives back at the port just before closing. The closing of the port traps the high pressure pulse, which results in an increased VE.

Dysfnctnl85

So the performance gained by independent throttle bodies is of no use on a turbo motor?

Drago86

You are a classic example of someone who thinks they know to much, and thus are not open to new (to you) ideas. The SAE paper from Mazda says, and i quote



"A high powerd rotary engine was realized by developing a dynamic supercharging inductions system which uses interference of two kinds of compression wave:



(1) As the intake port begins to be closed, the air pressure risses due to its own inertia as shown in the top of Fig. 9. The high pressure creates pressure wave which moves back up the intake at the speed of sound and down the other intake pipe to feed more air into the other port.



(this is the important part, read carefully)



(2) As shown in the bottom of Fig. 9 the residual exhaust gas, which still has high pressure, is blown up through one of the intake ports and puishes against the intake air momentarily, thus raising the pressure. As a result, a (****) high pressure wave (****) is sent down the other intake pipe cramming more air into the other intake port."



Also if you look down the page, there are nice little figures and graphs showing the same thing. Figure 10, in particular, the two pressure spikes from the the two events described can be seen twards the left of the figure, the first spike is the intake closing even, and the second spike is the intake open event.



I am well aware of how a standard plenum/ air horn system works.



Let me ask you this, where is the pleunum/ expansion chamber/ volume change in ANY of mazdas stock intakes? The rx8 doesnt have one, the 86-88 NA's dont have them, the VDI equiped 89+ NA's dont have one (you can EASILY see this the damn high rpm path is a nice constant volume loop from one secondary port to the other) and the FD doesnt have one. You need a large change in volume to reflect a wave, so where is it on any of the tunned manifolds i mentioned?



This form of wave tunning mazda has found very effective, however it is not the only way to do pressure wave tunning on a rotary. The R26b uses air horns on its variable intake, which work exactly like they would on a piston motor, reflecting the wave back with a revesed sign. I believe the 13b RE and the 20b also use normal plenum tunned systems.



Please, atleast read my documentation before ostracizing me, im am not making things up, only repeating what i have read from reliable sources.

Drago86

http://www.thecarricos.com/ACRE/Documents/...-tech84-1-6.pdf



Qoute is from this SAE paper

Drago86

Also plenum style intake tunning will work fine on a turbo, a turbo motor is just like any other motor, except its sucking in air that is 2-3x more dense (1 bar and 2 bar respectivly) intake tunning still applies as shown by mazda's choice of opposed intake runners (non plenum style) for the fd3s, and there choice of a plenum style for the 13bt



http://my.engr.ucdavis.edu/~pko/13BTvs13BREW.html



This site also backs up my previous thread by stating that the fd3s uses dynamic effect intake, and has opposed runners with no "surge plenum tank".