FD Rotor Housings in N/A 6-port motor
06-03-02, 07:38 PM
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FD Rotor Housings in N/A 6-port motor
For those of you with the FD rotor housings in the N/A motor, is there any advantage to using these over the Turbo II housings? Also any difference from the S4 vs S5 TII housings?
Basically I'm buying new rotor housings for the streetported '90 6-port motor, I want the best. Any suggestions? And anyone who's actually done this without any inchangability problems?
Basically I'm buying new rotor housings for the streetported '90 6-port motor, I want the best. Any suggestions? And anyone who's actually done this without any inchangability problems?
06-03-02, 08:14 PM
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Re: FD Rotor Housings in N/A 6-port motor
Originally posted by SoloIIdrift
For those of you with the FD rotor housings in the N/A motor, is there any advantage to using these over the Turbo II housings? Also any difference from the S4 vs S5 TII housings?
Basically I'm buying new rotor housings for the streetported '90 6-port motor, I want the best. Any suggestions? And anyone who's actually done this without any inchangability problems?
For those of you with the FD rotor housings in the N/A motor, is there any advantage to using these over the Turbo II housings? Also any difference from the S4 vs S5 TII housings?
Basically I'm buying new rotor housings for the streetported '90 6-port motor, I want the best. Any suggestions? And anyone who's actually done this without any inchangability problems?
06-04-02, 11:18 AM
#5
From what I can understand, There is more material around the water jackets in the third gens, so you can safely port them, without risk of hitting the cooling channels. Because of the thin walls around the cooling channels, the 13B was harder to port than the FB's and FD's. You may pay a bit more, but you're getting a newer part, and a safer starting point for porting. Go with the FD's.
I may be wrong, but that's what I've heard.
Nick
I may be wrong, but that's what I've heard.
Nick
06-04-02, 05:21 PM
#6
mad scientist
Thats only for the iron center and end housings. There is no dirrerence in the portable aread of the exhaust on S4/5 and S6(FD). S6 housings are more expensive, but if you can afford it, definately worth it.
I am not completely sure about this, its just what I have heard. The FD rotor housings fit perfect in an S5 block, but will not work in a S4 block. But I dont see why it would work in S5 and not in S6. It might be just a matter of the air ports in the exhaist ports for emissions. So S6 housings on an S4 block would not pass emissions.
I am not completely sure about this, its just what I have heard. The FD rotor housings fit perfect in an S5 block, but will not work in a S4 block. But I dont see why it would work in S5 and not in S6. It might be just a matter of the air ports in the exhaist ports for emissions. So S6 housings on an S4 block would not pass emissions.
11-29-11, 02:12 PM
#7
Thats only for the iron center and end housings. There is no dirrerence in the portable aread of the exhaust on S4/5 and S6(FD). S6 housings are more expensive, but if you can afford it, definately worth it.
I am not completely sure about this, its just what I have heard. The FD rotor housings fit perfect in an S5 block, but will not work in a S4 block. But I dont see why it would work in S5 and not in S6. It might be just a matter of the air ports in the exhaist ports for emissions. So S6 housings on an S4 block would not pass emissions.
I am not completely sure about this, its just what I have heard. The FD rotor housings fit perfect in an S5 block, but will not work in a S4 block. But I dont see why it would work in S5 and not in S6. It might be just a matter of the air ports in the exhaist ports for emissions. So S6 housings on an S4 block would not pass emissions.
im planning to use fd housings with s4 front, intermediate, and rear irons.
which spark plug location from the housings would be better on a 6 port n/a? s4 s5 or s6?
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11-29-11, 02:34 PM
#8
s5 and s6 housings are identical and only vary from s4 housings by having a wider 'split' at the sparkplug ports when compared to s4 housings. fd and na housings dont have the water port drilled on the housings. s4 and s5 t2 housings have those drilled out. all n/a housings have the exhaust baffle diffuser in the exhaust port.
really you can use any housings you want as long as they are within spec.
really you can use any housings you want as long as they are within spec.
11-29-11, 07:45 PM
#10
The FD housings have 32% less Friction Coefficient than the FC housings [according to a pict from Arghx - FC: Fluorocarbon Resin coating, FD: Carbon-Graphite coating].
I'm running FD housings with S4 NA plates and S5 NA rotors/counter weight. Makes for an amazing engine
I'm running FD housings with S4 NA plates and S5 NA rotors/counter weight. Makes for an amazing engine
11-29-11, 07:50 PM
#11
well, his diagram also groups all FC housings together which simply isn't true. the series 5 did have a similar coating, whether identical to the series 6 and later i can't say for sure but they do appear very similar in wear patterns and the layers during cutting down the surfaces. perhaps there was early series 5's that had the simple chrome treatment and then they switched to the more current treatments. at any rate i rarely find series 5 housings nearly as trashed as the series 4's.
Last edited by RotaryEvolution; 11-29-11 at 07:53 PM.
11-29-11, 09:45 PM
#12
well, his diagram also groups all FC housings together which simply isn't true. the series 5 did have a similar coating, whether identical to the series 6 and later i can't say for sure but they do appear very similar in wear patterns and the layers during cutting down the surfaces. perhaps there was early series 5's that had the simple chrome treatment and then they switched to the more current treatments. at any rate i rarely find series 5 housings nearly as trashed as the series 4's.
Sounds like good news for my S5 JDM teardown/build..
11-29-11, 11:19 PM
#13
What exhaust setup are you planning to run? The actual n/a housings have that muffling port insert for a reason... I can speak from personal experience that running without the port insert makes it noticeably harder to contain resonance and droning. It's the kind of thing that gradually wears on you. You might find yourself choosing between a more restrictive exhaust (possibly nullifying most of the preformance gains) or dealing with cops, pissed off neighbors, annoyed passengers, etc.
What I'm saying is, make sure that extra couple horsepower is so important to you that you are willing to pay more for T2/FD housings and then deal with a potential noise/vibration issue.
What I'm saying is, make sure that extra couple horsepower is so important to you that you are willing to pay more for T2/FD housings and then deal with a potential noise/vibration issue.
11-29-11, 11:49 PM
#14
Here's some information about the engineering behind the n/a FC exhaust sleeves, which have the MCPI or "multi-chamber port insert." This comes from the series 4 training manual and Kita, "Noise and Vibration Reduction Technology for Rotary Engine," 1989.
The fundamental issue here is that a pre-Renesis rotary engine's exhaust port opens much faster than a piston engine:
This helps for power but hurts for noise:
The MCPI disperses exhaust energy, which reduces the "exhaust noise at source" (y axis above) and also functions as a muffler. The MCPI was very carefully designed in terms of the size of each chamber and the distance between the insert and the rotor housing wall. Exhaust flows through the MCPI in stages:
Mazda found that if the dimensions of the MCPI were not exactly right it would cause excessive restriction and/or ineffective noise suppression. They also had to figure out the ratio between the diameter of the stock exhaust manifold and the diameter of the MCPI. There's a bunch of math involved that I won't get into.
One thing that is interesting here are some charts that confirm what we all suspect--the MCPI built into the n/a housings reduces obnoxious high frequencies in the exhaust.
So before you ditch your n/a exhaust port inserts think long and hard whether you want to increase the high frequencies in the exhaust for the sake of a few horsepower. On my '88 GTU the previous owner had built the engine with T2 housings and after enough time passed I ended up wishing he hadn't. I changed out parts of the exhaust system a bunch of times and had to decide whether to add more restriction or put up with the hassles of excessive NVH (noise/vibration/harashness).
The fundamental issue here is that a pre-Renesis rotary engine's exhaust port opens much faster than a piston engine:
This helps for power but hurts for noise:
The MCPI disperses exhaust energy, which reduces the "exhaust noise at source" (y axis above) and also functions as a muffler. The MCPI was very carefully designed in terms of the size of each chamber and the distance between the insert and the rotor housing wall. Exhaust flows through the MCPI in stages:
Mazda found that if the dimensions of the MCPI were not exactly right it would cause excessive restriction and/or ineffective noise suppression. They also had to figure out the ratio between the diameter of the stock exhaust manifold and the diameter of the MCPI. There's a bunch of math involved that I won't get into.
One thing that is interesting here are some charts that confirm what we all suspect--the MCPI built into the n/a housings reduces obnoxious high frequencies in the exhaust.
So before you ditch your n/a exhaust port inserts think long and hard whether you want to increase the high frequencies in the exhaust for the sake of a few horsepower. On my '88 GTU the previous owner had built the engine with T2 housings and after enough time passed I ended up wishing he hadn't. I changed out parts of the exhaust system a bunch of times and had to decide whether to add more restriction or put up with the hassles of excessive NVH (noise/vibration/harashness).
11-30-11, 12:11 AM
#15
well, his diagram also groups all FC housings together which simply isn't true. the series 5 did have a similar coating, whether identical to the series 6 and later i can't say for sure but they do appear very similar in wear patterns and the layers during cutting down the surfaces. perhaps there was early series 5's that had the simple chrome treatment and then they switched to the more current treatments. at any rate i rarely find series 5 housings nearly as trashed as the series 4's.
Also, for S4s at least, the TII had a harder surface then the N/A. Also the TII housings had a anti-friction coating compared to the N/A housings that did not.
11-30-11, 02:58 AM
#17
Here's some information about the engineering behind the n/a FC exhaust sleeves, which have the MCPI or "multi-chamber port insert." This comes from the series 4 training manual and Kita, "Noise and Vibration Reduction Technology for Rotary Engine," 1989.
The fundamental issue here is that a pre-Renesis rotary engine's exhaust port opens much faster than a piston engine:
(image)
This helps for power but hurts for noise:
(image)
The MCPI disperses exhaust energy, which reduces the "exhaust noise at source" (y axis above) and also functions as a muffler. The MCPI was very carefully designed in terms of the size of each chamber and the distance between the insert and the rotor housing wall. Exhaust flows through the MCPI in stages:
(image)
Mazda found that if the dimensions of the MCPI were not exactly right it would cause excessive restriction and/or ineffective noise suppression. They also had to figure out the ratio between the diameter of the stock exhaust manifold and the diameter of the MCPI. There's a bunch of math involved that I won't get into.
One thing that is interesting here are some charts that confirm what we all suspect--the MCPI built into the n/a housings reduces obnoxious high frequencies in the exhaust.
(image)
So before you ditch your n/a exhaust port inserts think long and hard whether you want to increase the high frequencies in the exhaust for the sake of a few horsepower. On my '88 GTU the previous owner had built the engine with T2 housings and after enough time passed I ended up wishing he hadn't. I changed out parts of the exhaust system a bunch of times and had to decide whether to add more restriction or put up with the hassles of excessive NVH (noise/vibration/harashness).
The fundamental issue here is that a pre-Renesis rotary engine's exhaust port opens much faster than a piston engine:
(image)
This helps for power but hurts for noise:
(image)
The MCPI disperses exhaust energy, which reduces the "exhaust noise at source" (y axis above) and also functions as a muffler. The MCPI was very carefully designed in terms of the size of each chamber and the distance between the insert and the rotor housing wall. Exhaust flows through the MCPI in stages:
(image)
Mazda found that if the dimensions of the MCPI were not exactly right it would cause excessive restriction and/or ineffective noise suppression. They also had to figure out the ratio between the diameter of the stock exhaust manifold and the diameter of the MCPI. There's a bunch of math involved that I won't get into.
One thing that is interesting here are some charts that confirm what we all suspect--the MCPI built into the n/a housings reduces obnoxious high frequencies in the exhaust.
(image)
So before you ditch your n/a exhaust port inserts think long and hard whether you want to increase the high frequencies in the exhaust for the sake of a few horsepower. On my '88 GTU the previous owner had built the engine with T2 housings and after enough time passed I ended up wishing he hadn't. I changed out parts of the exhaust system a bunch of times and had to decide whether to add more restriction or put up with the hassles of excessive NVH (noise/vibration/harashness).
11-30-11, 06:11 PM
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using FD rotor housings and S4 irons *might* block off the air injection, it should be checked.
if passing smog doesn't matter, then it doesn't matter.
every other 81-2003 US engine has the air injection thru the center iron, and so if you're using an S4 TURBO, FD or S5 center iron, than it is compatible
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