Exhaust System.
03-16-2003, 02:24 AM
#26
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Originally posted by Jeff20B
Well, the side plates actually contain both primary and secondary intake ports. On the GSL-SE engine, all three side plates flow primaries. In the case of the front and rear plates, it's just the lower ones.
Well, the side plates actually contain both primary and secondary intake ports. On the GSL-SE engine, all three side plates flow primaries. In the case of the front and rear plates, it's just the lower ones.
uh, i think at least one of us has some terminology problems... and i'm not sure who!! :D
what i think you're saying is that the two ports on either side of teh motor (one in side housing, other in inter. housing) are both primary... as i understand it, the side housing port is the "primary" port for each rotor, and the intake port in the inter. housing is the "secondary" port for each rotor... i'm getting this from the 13BREW stuff, 'cause they only have 4 ports to maximize velocity of the intake charge from the turbos (as the 13BT's before it did).
Originally posted by Jeff20B
The secondaries are the 5th and 6th ports.
The secondaries are the 5th and 6th ports.
the 5+6 ports are what i was referring to as the "tertiary" ports, as they're the third ones which open (when active)...
... something smells a little fishy here, and it might be my brain going bad... can we get a third opinion here??
03-17-2003, 08:12 PM
#27
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The shared port means no true duals. It isn't "close enough" if true duals are what you want for tuning purposes. But, that doesn't mean you can't make a good exhaust system. I am sure that there will be some new variations on old tricks or entirely new tricks to maximize exhaust flow on the RENESIS.
I suspect the port is shared because there isn't enough room for two ports. The intermediate housing would have to be rather large to fit two substantial exhaust ports. As mentioned, there may acutally be some useful scavenging stuff that makes the shared port a good idea. So, each rotor has two exhaust ports, and the exhaust ports in the intermediate housing are joined in that housing. There are three spots to hook an exhaust pipe to the engine.
Each rotor fires exactly once per eccentric shaft revolution, so an exhaust port opens to the shared port every 180 degrees of eccentric shaft revolution since they are equally spaced. I am not sure of the duration, but that also means the ports close 180 degrees opposite of each other. It is possible that the two exhaust ports for a given rotor have different opening and closing times, but I would expect the times to be the same (but 180 degrees out of phase) for the two ports that share the exhaust port in the intermediate housing.
On the 13B-REW, the smaller primary intake ports are in the intermediate housing. The larger secondaries are in the side housings. 20B engines have one intermediate housing with two primaries and one with both a primary and a secondary. Both side housings have secondaries. Primaries are just smaller ports that have good velocity at low flow levels for idle and low-RPM power. They secondaries on a 4-port are not switched like the two extra ports on the 6-port engines. The secondaries just don't flow that great at low RPM and they do flow well at high RPM.
I am not sure of the terminology for the 6 port engines (though Jeff20B's post sounds reasonble), but each rotor has one small port in the intermediate housing like the 4-port engines do, and the other two ports for each rotor are in the side housings. The high-power RENESIS is like the older 6-ports, I think, and the lower power version is like the older 4-ports, I think.
The 13B-REW has one 45mm throttle plate for the primary ports and two 50mm throttle plates for the secondaries. Or at least that is how they are lined up and how they open when you press the pedal down. They all actually feed a common area in the manifold, IIRC.
-Max
I suspect the port is shared because there isn't enough room for two ports. The intermediate housing would have to be rather large to fit two substantial exhaust ports. As mentioned, there may acutally be some useful scavenging stuff that makes the shared port a good idea. So, each rotor has two exhaust ports, and the exhaust ports in the intermediate housing are joined in that housing. There are three spots to hook an exhaust pipe to the engine.
Each rotor fires exactly once per eccentric shaft revolution, so an exhaust port opens to the shared port every 180 degrees of eccentric shaft revolution since they are equally spaced. I am not sure of the duration, but that also means the ports close 180 degrees opposite of each other. It is possible that the two exhaust ports for a given rotor have different opening and closing times, but I would expect the times to be the same (but 180 degrees out of phase) for the two ports that share the exhaust port in the intermediate housing.
On the 13B-REW, the smaller primary intake ports are in the intermediate housing. The larger secondaries are in the side housings. 20B engines have one intermediate housing with two primaries and one with both a primary and a secondary. Both side housings have secondaries. Primaries are just smaller ports that have good velocity at low flow levels for idle and low-RPM power. They secondaries on a 4-port are not switched like the two extra ports on the 6-port engines. The secondaries just don't flow that great at low RPM and they do flow well at high RPM.
I am not sure of the terminology for the 6 port engines (though Jeff20B's post sounds reasonble), but each rotor has one small port in the intermediate housing like the 4-port engines do, and the other two ports for each rotor are in the side housings. The high-power RENESIS is like the older 6-ports, I think, and the lower power version is like the older 4-ports, I think.
The 13B-REW has one 45mm throttle plate for the primary ports and two 50mm throttle plates for the secondaries. Or at least that is how they are lined up and how they open when you press the pedal down. They all actually feed a common area in the manifold, IIRC.
-Max
03-17-2003, 09:09 PM
#28
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Originally posted by wakeech
the 5+6 ports are what i was referring to as the "tertiary" ports, as they're the third ones which open (when active)...
the 5+6 ports are what i was referring to as the "tertiary" ports, as they're the third ones which open (when active)...
Primary = 1st
Secondary = 2nd
Tertiary = 3rd
ter·ti·ar·y ( P ) Pronunciation Key (tûrsh-r)
adj.
1. Third in place, order, degree, or rank.
Jeff20B says there is no Tertiary ports, Wakeech says there is Tertiary ports (opening at 7,200 RPM?)
03-18-2003, 01:57 PM
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YAY!! 1st post!
Anyway, everything I've ever seen about the RENESIS indicates that there are three ports per rotor, with the 2nd and 3rd ports "opening" at prescribed RPM levels. This not only makes more sense from an induction point of view, but is also visible on the dyno graph. There are three distinct humps in the torque curve.
On the issue of the exhaust port, this type of port is referred to as a "siamesed" exhaust port. It is generally considered a Bad Thing(tm). There are ways to work with the design, but it is (again, generally) thought that the best modification is to get rid of it. On piston engine, this usually means a head swap. On a RENESIS it would entail ALOT of welding and grinding, but shouldn't be altogether impossible. It would most likely be out of the reach of your typical street enthusiast, though. I thought I read somewhere that this port makes exhaust pulse tuning impossible, which is why the RENESIS comes with a log style manifold. Log style manifolds suck, especially on high RPM engines.
Not all hope is lost, though, the Star Mazda guys are getting about 300HP out of these things with nothing but bolt-ons. And they are doing it with a lower rev limit (7300?)!!!
Anyway, everything I've ever seen about the RENESIS indicates that there are three ports per rotor, with the 2nd and 3rd ports "opening" at prescribed RPM levels. This not only makes more sense from an induction point of view, but is also visible on the dyno graph. There are three distinct humps in the torque curve.
On the issue of the exhaust port, this type of port is referred to as a "siamesed" exhaust port. It is generally considered a Bad Thing(tm). There are ways to work with the design, but it is (again, generally) thought that the best modification is to get rid of it. On piston engine, this usually means a head swap. On a RENESIS it would entail ALOT of welding and grinding, but shouldn't be altogether impossible. It would most likely be out of the reach of your typical street enthusiast, though. I thought I read somewhere that this port makes exhaust pulse tuning impossible, which is why the RENESIS comes with a log style manifold. Log style manifolds suck, especially on high RPM engines.
Not all hope is lost, though, the Star Mazda guys are getting about 300HP out of these things with nothing but bolt-ons. And they are doing it with a lower rev limit (7300?)!!!
03-18-2003, 02:07 PM
#30
Prodigal Wankler
Originally posted by Cylo
Jeff20B says there is no Tertiary ports, Wakeech says there is Tertiary ports (opening at 7,200 RPM?)
Jeff20B says there is no Tertiary ports, Wakeech says there is Tertiary ports (opening at 7,200 RPM?)
The Standard Power engine (seen only with the automatic trans in the US) has only the primary and secondary ports. The tertiaries are only on the Hi Power variant of the Renesis.
03-18-2003, 02:20 PM
#31
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Welcome CNinja
:o whoops, you're right eccles, i forgot about the low-power one
yeah CNinja, the thing with the three ports is (i'm guessing) that they'll work like the primary and secondary will ALWAYS be open, whilst the tertiary (the 5+6 ports... the dinky ones above the primary ports) will be activated for high rpm breathing (although i'd not put a specific number on it: during hard acceleration, they'd open much earlier than if you were slowly accelerating) the same way as the Series 5 13B motors worked (as they're the closest thing i can think of to compare to...)... the three lobes come from the ECU switching the length of the intake path AND actuating that tertiary port.
... i'd really love to learn more about the detriments/advantages of these "siamesed" exhaust ports... do you have any ideas how this would affect operation in a wankel motor??
Star Mazda engines aren't turboed??? i suppose the SPEED channel guys just didn't think an all-motor engine could spit flames like that (13B with p-port exhaust does)... anyhoo, just what i'd heard.
but to get 300hp at 7300 rpm, that'd be uhhhhh... 215.8 lbft. of torque??? WTF???
are you SUUUURE that they aren't turboed?? wow... :D
:o whoops, you're right eccles, i forgot about the low-power one
yeah CNinja, the thing with the three ports is (i'm guessing) that they'll work like the primary and secondary will ALWAYS be open, whilst the tertiary (the 5+6 ports... the dinky ones above the primary ports) will be activated for high rpm breathing (although i'd not put a specific number on it: during hard acceleration, they'd open much earlier than if you were slowly accelerating) the same way as the Series 5 13B motors worked (as they're the closest thing i can think of to compare to...)... the three lobes come from the ECU switching the length of the intake path AND actuating that tertiary port.
... i'd really love to learn more about the detriments/advantages of these "siamesed" exhaust ports... do you have any ideas how this would affect operation in a wankel motor??
Star Mazda engines aren't turboed??? i suppose the SPEED channel guys just didn't think an all-motor engine could spit flames like that (13B with p-port exhaust does)... anyhoo, just what i'd heard.
but to get 300hp at 7300 rpm, that'd be uhhhhh... 215.8 lbft. of torque??? WTF???
are you SUUUURE that they aren't turboed?? wow... :D
03-18-2003, 03:49 PM
#32
Prodigal Wankler
Originally posted by wakeech
the thing with the three ports is (i'm guessing) that they'll work like the primary and secondary will ALWAYS be open, whilst the tertiary (the 5+6 ports... the dinky ones above the primary ports) will be activated for high rpm breathing (although i'd not put a specific number on it: during hard acceleration, they'd open much earlier than if you were slowly accelerating) the same way as the Series 5 13B motors worked
the thing with the three ports is (i'm guessing) that they'll work like the primary and secondary will ALWAYS be open, whilst the tertiary (the 5+6 ports... the dinky ones above the primary ports) will be activated for high rpm breathing (although i'd not put a specific number on it: during hard acceleration, they'd open much earlier than if you were slowly accelerating) the same way as the Series 5 13B motors worked
Here's the relevant section:
technologies for higher output
synthetic intake system for variable valves: The
side-intake/side-exhaust port RENESIS gains 30%
in intake port area over the previous engine, and
this, combined with the delayed intake port close
timing, makes for a sizable increase in charging
volume resulting in greater power output. The
engine also incorporates innovative technology
designed to boost filling efficiency.
The High Power specification engine has
three intake ports per rotor chamber: primary,
secondary and auxiliary (giving a total of six intake
ports for the twin rotor RENESIS engine), with each
subject to different timing. The variable intake
control system operates opening/closing of the
secondary and auxiliary intake ports. RENESIS also
takes full advantage of the incoming air’s dynamic
charge effect to boost charging for more substantial
low-to-mid range torque, as well as increased
torque and power output at higher engine speeds.
The intake system on the Standard Power unit,
which is tuned for the superb driveability at regular
rpm, has two intake ports per rotor, for a total of four
intake ports are controlled by the opening/closing of
a variable intake valve governing use of the
secondary intake port. For even more accurate
control, RENESIS incorporates an electronic throttle
control system that optimizes intake control in
response to feedback of sensors monitoring the
degree and speed of accelerator pedal operation.
variable fresh air duct (FAD): The High Power
specification engine incorporates a variable fresh
air duct in addition to a large, low resistance air
cleaner. At around 7250 rpm, a shutter valve
opens to shorten the intake manifold upstream of
the air cleaner. The shutter valve works in tandem
with the variable intake valve to boost torque and
power at high engine speeds. The fresh air duct
is partially inserted into the air cleaner and enables
an optimal length intake system by valve
opening/closing.
synthetic intake system for variable valves (High Power unit):
secondary shutter valve: opens at 3750rpm
auxiliary port valve: opens at 6250rpm
variable intake valve: opens at 7250rpm
variable fresh air duct: opens at 7250rpm
03-18-2003, 07:21 PM
#33
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Originally posted by eccles
The tertiary ports are officially called "auxilliary" ports, and they open at 6250rpm.
The tertiary ports are officially called "auxilliary" ports, and they open at 6250rpm.
well, i eat my words: the ports DO open at a specific rpm... well, maybe that's just at full throttle?? in any case, a good number to know for guys with FC's who've converted from the stock system (exhaust back-pressure actuation) to a different one (like the really trick electronic 3-way valve one that uses air-pump pressure) :D nice.
6250, i won't forget this time
03-18-2003, 08:00 PM
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Ok, I found the link about the Star Mazda's.... it was just something posted in another forum, so its not exactlly reliable, but here's how I got the idea into my head.
http://www.nopistons.com/forums/inde...T&f=11&t=14191
BTW, current Star Mazda cars are sealed NA 13b's, so I think they will remain NA with the new RENESIS motors.
http://www.starmazda.com/y2k/carmain.htm
Siamesed ports are bad because they screw up pulse tuning in the exhaust. This only really affects headers, which make full use of it. The log style manifolds don't make any use of pulse tuning. Again, if you were to add headers, you could work with the port, but it would still be less than ideal. If you know welder with like 100 man-hours to burn you could probably relocate the port by welding and grinding. :D
http://www.nopistons.com/forums/inde...T&f=11&t=14191
BTW, current Star Mazda cars are sealed NA 13b's, so I think they will remain NA with the new RENESIS motors.
http://www.starmazda.com/y2k/carmain.htm
Siamesed ports are bad because they screw up pulse tuning in the exhaust. This only really affects headers, which make full use of it. The log style manifolds don't make any use of pulse tuning. Again, if you were to add headers, you could work with the port, but it would still be less than ideal. If you know welder with like 100 man-hours to burn you could probably relocate the port by welding and grinding. :D
03-18-2003, 10:15 PM
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Originally posted by CypherNinja
If you know welder with like 100 man-hours to burn you could probably relocate the port by welding and grinding. :D
If you know welder with like 100 man-hours to burn you could probably relocate the port by welding and grinding. :D
03-18-2003, 11:41 PM
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Originally posted by wakeech
... would you have to relocate it?? or could you just make more room for both ports together on the side, and wall them off (to separate them) completely??
... would you have to relocate it?? or could you just make more room for both ports together on the side, and wall them off (to separate them) completely??
03-19-2003, 10:47 AM
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Siamesed ports are bad because they screw up pulse tuning in the exhaust.
03-20-2003, 09:20 PM
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The siamesed exhaust ports should not cause a problem opperationally as there would be no overlap of the exhaust ports from each chamber, so they won't be using the exhaust port runner at the same time.
You cannot lengthen the septum (wall between the two exhaust ports in the centre housing) out towards the outer edge as this will decrease the effective area of the exhaust port and will create a substantial loss in flow.
As far as building extractors or headers for the Renesis engine it will be possible. The outer exhaust ports will have a pipe off each one and will merge at a predetermined length. Another pipe will come from the centre exhaust port and will also merge, potentially in between the two other pipes, and will not disturb the flow of exhaust.
Because the exhaust will be flowing from one chamber at a time, you will have pulses in the outer pipes from the front and rear ports, and a more constant flow of exhaust from the centre port pipe so when they merge it will opperate like a good collected header should.
Quite simple really.
You cannot lengthen the septum (wall between the two exhaust ports in the centre housing) out towards the outer edge as this will decrease the effective area of the exhaust port and will create a substantial loss in flow.
As far as building extractors or headers for the Renesis engine it will be possible. The outer exhaust ports will have a pipe off each one and will merge at a predetermined length. Another pipe will come from the centre exhaust port and will also merge, potentially in between the two other pipes, and will not disturb the flow of exhaust.
Because the exhaust will be flowing from one chamber at a time, you will have pulses in the outer pipes from the front and rear ports, and a more constant flow of exhaust from the centre port pipe so when they merge it will opperate like a good collected header should.
Quite simple really.
Last edited by Dazz; 03-20-2003 at 09:23 PM.
03-20-2003, 09:51 PM
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Originally posted by Dazz
The siamesed exhaust ports should not cause a problem opperationally as there would be no overlap of the exhaust ports from each chamber, so they won't be using the exhaust port runner at the same time.
You cannot lengthen the septum (wall between the two exhaust ports in the centre housing) out towards the outer edge as this will decrease the effective area of the exhaust port and will create a substantial loss in flow.
As far as building extractors or headers for the Renesis engine it will be possible. The outer exhaust ports will have a pipe off each one and will merge at a predetermined length. Another pipe will come from the centre exhaust port and will also merge, potentially in between the two other pipes, and will not disturb the flow of exhaust.
Because the exhaust will be flowing from one chamber at a time, you will have pulses in the outer pipes from the front and rear ports, and a more constant flow of exhaust from the centre port pipe so when they merge it will opperate like a good collected header should.
Quite simple really.
The siamesed exhaust ports should not cause a problem opperationally as there would be no overlap of the exhaust ports from each chamber, so they won't be using the exhaust port runner at the same time.
You cannot lengthen the septum (wall between the two exhaust ports in the centre housing) out towards the outer edge as this will decrease the effective area of the exhaust port and will create a substantial loss in flow.
As far as building extractors or headers for the Renesis engine it will be possible. The outer exhaust ports will have a pipe off each one and will merge at a predetermined length. Another pipe will come from the centre exhaust port and will also merge, potentially in between the two other pipes, and will not disturb the flow of exhaust.
Because the exhaust will be flowing from one chamber at a time, you will have pulses in the outer pipes from the front and rear ports, and a more constant flow of exhaust from the centre port pipe so when they merge it will opperate like a good collected header should.
Quite simple really.
Another thing I've just thought of: I can't imagine the interior shape of that port being very good for exhaust gas velocity at all.
Also, I'm know that that proper exhaust port area will have to be maintained if the septum is extended. Thats why sufficient porting would have to accompany it. This is what wakeech and I meant 4/3 posts up. I'm not saying anybody's wrong, just that we have to wait and see. :D
BTW green, yes, each rotor has two exhaust ports. But if one is not flowing optimally, this may be hurting power at the top end. But, hell, it could also actually be helping the low-end.
LOL, I love this stuff......
Last edited by CypherNinja; 03-20-2003 at 09:53 PM.
03-20-2003, 10:20 PM
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I think that you would want to keep the septum there as it guides the exhaust gas neatly towards the runner. Without it being there, the exhaust would travell straight towards the opposite port and then have to turn through 90 degrees to head out the runner. It would also be exposing the side of the rotor of the opposite chamber to the extremely hot exhaust gasses directly which would not be desirable.
03-22-2003, 12:32 AM
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Originally posted by Dazz
I think that you would want to keep the septum there as it guides the exhaust gas neatly towards the runner. Without it being there, the exhaust would travell straight towards the opposite port and then have to turn through 90 degrees to head out the runner. It would also be exposing the side of the rotor of the opposite chamber to the extremely hot exhaust gasses directly which would not be desirable.
I think that you would want to keep the septum there as it guides the exhaust gas neatly towards the runner. Without it being there, the exhaust would travell straight towards the opposite port and then have to turn through 90 degrees to head out the runner. It would also be exposing the side of the rotor of the opposite chamber to the extremely hot exhaust gasses directly which would not be desirable.
What I meant was to build two seperate, proper exhaust ports by welding in metal in some areas and grinding out in others.
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