Ports?
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Junior Member
Joined: Feb 2008
Posts: 16
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From: Grand Cayman, Cayman Islands, B.W.I
Ports?
Can someone help me understand the difference in ports please, i have tried searching the forum to seek more knowledge on the matter but so far no luck.
Small Streetport, Large Streetport, Bridgeport, J-Port, Monster Jport and Peripheral Port.
This would help me out alot
Small Streetport, Large Streetport, Bridgeport, J-Port, Monster Jport and Peripheral Port.
This would help me out alot
Former Moderator. RIP Icemark.
Joined: Apr 2001
Posts: 25,896
Likes: 24
From: Rohnert Park CA
Ports are the equivalent of your camshaft and intake/exhaust valves in a piston engine. Different Port size and shape, changes the intake (and sometimes exhaust) timing (opening and closing times) as well as the velocity of the intake charge. The port closing also is much more pronounced on a rotary engine (similar to a Miller Cycle piston engine) and that shock wave can be exploited to help further increase power with the port design much easier than on a otto cycle piston engine.
Street ports generally allow near stock driving experience as far as engine idle (and and in some cases emissions) with a mild increase in power and usually follow (some what) the stock layout in the side plate.
Bridge ports are just bigger ports with a bridge area of the side plate provided for seal retention. J Ports are also through the side plate, and are typically more J shaped (again for seal retention and port timing).
A peripheral port is a port directly in the housing, and not through a side plate. The Exhaust ports on a RX-7 are always peripheral port (however on a RX-8 Renisis motor, the exhaust ports are through the side plates). The peripheral intake port can make monster power but gas mileage and sometimes driveability will suffer.
Street ports generally allow near stock driving experience as far as engine idle (and and in some cases emissions) with a mild increase in power and usually follow (some what) the stock layout in the side plate.
Bridge ports are just bigger ports with a bridge area of the side plate provided for seal retention. J Ports are also through the side plate, and are typically more J shaped (again for seal retention and port timing).
A peripheral port is a port directly in the housing, and not through a side plate. The Exhaust ports on a RX-7 are always peripheral port (however on a RX-8 Renisis motor, the exhaust ports are through the side plates). The peripheral intake port can make monster power but gas mileage and sometimes driveability will suffer.
To complement Icemark's discussion:
Just like using a larger than stock cam profile on a piston engine.
The larger your port size, the further "to the right" your power band will shift when looking at a dyno chart/sheet.
If you're going to rebuild your motor and want to port it. my recommendation is to sitck with streetporting as they help maintain a stock to near stock idle with a much better driving experience as it will not sacrifice low-end torque for streetability
Just like using a larger than stock cam profile on a piston engine.
The larger your port size, the further "to the right" your power band will shift when looking at a dyno chart/sheet.
If you're going to rebuild your motor and want to port it. my recommendation is to sitck with streetporting as they help maintain a stock to near stock idle with a much better driving experience as it will not sacrifice low-end torque for streetability
Full Member
Joined: Sep 2008
Posts: 180
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From: Newnan, Ga
here is a video of just what Icemark said
<embed id="VideoPlayback" src="http://video.google.com/googleplayer.swf?docid=4519423101109064735&hl=en&f s=true" style="width:400px;height:326px" allowFullScreen="true" allowScriptAccess="always" type="application/x-shockwave-flash"> </embed>
<embed id="VideoPlayback" src="http://video.google.com/googleplayer.swf?docid=4519423101109064735&hl=en&f s=true" style="width:400px;height:326px" allowFullScreen="true" allowScriptAccess="always" type="application/x-shockwave-flash"> </embed>
Ports are the equivalent of your camshaft and intake/exhaust valves in a piston engine. Different Port size and shape, changes the intake (and sometimes exhaust) timing (opening and closing times) as well as the velocity of the intake charge. The port closing also is much more pronounced on a rotary engine (similar to a Miller Cycle piston engine) and that shock wave can be exploited to help further increase power with the port design much easier than on a otto cycle piston engine.
Street ports generally allow near stock driving experience as far as engine idle (and and in some cases emissions) with a mild increase in power and usually follow (some what) the stock layout in the side plate.
Bridge ports are just bigger ports with a bridge area of the side plate provided for seal retention. J Ports are also through the side plate, and are typically more J shaped (again for seal retention and port timing).
A peripheral port is a port directly in the housing, and not through a side plate. The Exhaust ports on a RX-7 are always peripheral port (however on a RX-8 Renisis motor, the exhaust ports are through the side plates). The peripheral intake port can make monster power but gas mileage and sometimes driveability will suffer.
Street ports generally allow near stock driving experience as far as engine idle (and and in some cases emissions) with a mild increase in power and usually follow (some what) the stock layout in the side plate.
Bridge ports are just bigger ports with a bridge area of the side plate provided for seal retention. J Ports are also through the side plate, and are typically more J shaped (again for seal retention and port timing).
A peripheral port is a port directly in the housing, and not through a side plate. The Exhaust ports on a RX-7 are always peripheral port (however on a RX-8 Renisis motor, the exhaust ports are through the side plates). The peripheral intake port can make monster power but gas mileage and sometimes driveability will suffer.
Joined: Feb 2001
Posts: 29,798
Likes: 128
From: London, Ontario, Canada
It totally depends on the purpose of the car, how much power you want to make, and the current setup. A blanket answer is that stock or street ports are adequate for nearly anyone. 400HP on a street port is easily done. After that, it's my opinion that a bridgeport is the next step to keep turbo lag under control when running larger turbos, but a bridgeport is a another realm entirely.
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Junior Member
Joined: Sep 2008
Posts: 16
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From: Seattle
Understanding Porting in Rotarys
First off AC and Icemark hit it on the money... Ok so you have a Four different types of port jobs that can be done... Street Port, 1/2 Bridge Port, Bridge Port, and the infamous Peripheral Port. NOTE: In most cases a port job will make your car not pass or have a really difficult time passing emissions, when planing a port job you must take this into consideration if the county in which you live requires you to pass emmisions. with that said now i will try and break down the different port methods to see which will be best for you... Also remember that you will also impair your fuel mileage with ANY porting job.
Street Port: In many cases this is the port job of choice and is the one that will give you the best chance of passing emissions. With the street port the general idea is to enlarge the intake and exhaust ports. This is the best bang for the buck. I have this on my FC Turbo and i gained the best amount of street power from this.. It has been said that on a stock set-up you can get anywhere between 50-60% Increase in power. result will always vary depending on the condition of the car. If you also intend on adding an exhaust system to your car along with any intake modifications, you may not pass emissions 9 out of 10 times. Here you are allowing the exhaust ports to open earlier and close later.
Bridge Ports: This is the same as the street port but taken a few steps further. When done you actually only leave "bridge" (smaller section) for the corner seal to pass into. Bridge porting also cuts another intake port into the housing itself. (Sounds more confusing than what it really is) When its all said and done you casue the intake ports to open and close later. When done in a small amout you may still have some streetability but you gotta be cautious becasue these pots can be made to large and you can loose alot of lowspeed torque and HP. Torque gain between 5800 - 9000 rpm
1/2 Bridge Port The half bridge port actually has the best of the street port and bridge port. The power gain is more promising with power responding around 3,600 rpm's. This port job work primarly with the intake port being opened up about 15% (street port). But a third port is cut near the end of the housing leaving a bridge (bridge port) Thus getting the name 1/2 bridge port. This is a great port job if you plan on racing your RX7 on the track. I have a friend whos has this and he says its the only port job he will use on the track. I can go with half of that but if you are truly gonna race your car the next port job is for you.
Peripheral Porting Lets start like this
Peripheral: 3. Anatomy. near the surface or outside of; external. (Thanks dictionary.com)
This is why I LOVE rotarys... Mostly everybody loves the sound of a peripheral port job. I think it sounds like a worked boat motor...
Anyhow hear the intake ports are taken out of the side housing and moves them to the periphery side of the motor. LOL somebody got really creative when they thought of this. Thats all I really know about this type of port but i also know that you move you power band way up to about 7800 and takes it to what i think is 10,000 rpm..... yea I just checked my book and it actually says 8000 to 10000 rpm... This is definatly for racing considering you rarley go to lower RPMS.....
Hopefully that hepls.. you could have found this somewhere else on the site but i just like to test my top of head knowledge about rotarys... If I missed anything sorry but Im sure somebody will catch it and correct me.. lol
Street Port: In many cases this is the port job of choice and is the one that will give you the best chance of passing emissions. With the street port the general idea is to enlarge the intake and exhaust ports. This is the best bang for the buck. I have this on my FC Turbo and i gained the best amount of street power from this.. It has been said that on a stock set-up you can get anywhere between 50-60% Increase in power. result will always vary depending on the condition of the car. If you also intend on adding an exhaust system to your car along with any intake modifications, you may not pass emissions 9 out of 10 times. Here you are allowing the exhaust ports to open earlier and close later.
Bridge Ports: This is the same as the street port but taken a few steps further. When done you actually only leave "bridge" (smaller section) for the corner seal to pass into. Bridge porting also cuts another intake port into the housing itself. (Sounds more confusing than what it really is) When its all said and done you casue the intake ports to open and close later. When done in a small amout you may still have some streetability but you gotta be cautious becasue these pots can be made to large and you can loose alot of lowspeed torque and HP. Torque gain between 5800 - 9000 rpm
1/2 Bridge Port The half bridge port actually has the best of the street port and bridge port. The power gain is more promising with power responding around 3,600 rpm's. This port job work primarly with the intake port being opened up about 15% (street port). But a third port is cut near the end of the housing leaving a bridge (bridge port) Thus getting the name 1/2 bridge port. This is a great port job if you plan on racing your RX7 on the track. I have a friend whos has this and he says its the only port job he will use on the track. I can go with half of that but if you are truly gonna race your car the next port job is for you.
Peripheral Porting Lets start like thisPeripheral: 3. Anatomy. near the surface or outside of; external. (Thanks dictionary.com)
This is why I LOVE rotarys... Mostly everybody loves the sound of a peripheral port job. I think it sounds like a worked boat motor...
Anyhow hear the intake ports are taken out of the side housing and moves them to the periphery side of the motor. LOL somebody got really creative when they thought of this. Thats all I really know about this type of port but i also know that you move you power band way up to about 7800 and takes it to what i think is 10,000 rpm..... yea I just checked my book and it actually says 8000 to 10000 rpm... This is definatly for racing considering you rarley go to lower RPMS.....
Hopefully that hepls.. you could have found this somewhere else on the site but i just like to test my top of head knowledge about rotarys... If I missed anything sorry but Im sure somebody will catch it and correct me.. lol
Parker is my homeboy *)
Joined: May 2008
Posts: 759
Likes: 0
From: Houston, Tx
Sooooooo...............
First off AC and Icemark hit it on the money... Ok so you have a Four different types of port jobs that can be done... Street Port, 1/2 Bridge Port, Bridge Port, and the infamous Peripheral Port. NOTE: In most cases a port job will make your car not pass or have a really difficult time passing emissions, when planing a port job you must take this into consideration if the county in which you live requires you to pass emmisions. with that said now i will try and break down the different port methods to see which will be best for you... Also remember that you will also impair your fuel mileage with ANY porting job.
Street Port: In many cases this is the port job of choice and is the one that will give you the best chance of passing emissions. With the street port the general idea is to enlarge the intake and exhaust ports. This is the best bang for the buck. I have this on my FC Turbo and i gained the best amount of street power from this.. It has been said that on a stock set-up you can get anywhere between 50-60% Increase in power. result will always vary depending on the condition of the car. If you also intend on adding an exhaust system to your car along with any intake modifications, you may not pass emissions 9 out of 10 times. Here you are allowing the exhaust ports to open earlier and close later.
Bridge Ports: This is the same as the street port but taken a few steps further. When done you actually only leave "bridge" (smaller section) for the corner seal to pass into. Bridge porting also cuts another intake port into the housing itself. (Sounds more confusing than what it really is) When its all said and done you casue the intake ports to open and close later. When done in a small amout you may still have some streetability but you gotta be cautious becasue these pots can be made to large and you can loose alot of lowspeed torque and HP. Torque gain between 5800 - 9000 rpm
1/2 Bridge Port The half bridge port actually has the best of the street port and bridge port. The power gain is more promising with power responding around 3,600 rpm's. This port job work primarly with the intake port being opened up about 15% (street port). But a third port is cut near the end of the housing leaving a bridge (bridge port) Thus getting the name 1/2 bridge port. This is a great port job if you plan on racing your RX7 on the track. I have a friend whos has this and he says its the only port job he will use on the track. I can go with half of that but if you are truly gonna race your car the next port job is for you.
Peripheral Porting Lets start like this
Peripheral: 3. Anatomy. near the surface or outside of; external. (Thanks dictionary.com)
This is why I LOVE rotarys... Mostly everybody loves the sound of a peripheral port job. I think it sounds like a worked boat motor...
Anyhow hear the intake ports are taken out of the side housing and moves them to the periphery side of the motor. LOL somebody got really creative when they thought of this. Thats all I really know about this type of port but i also know that you move you power band way up to about 7800 and takes it to what i think is 10,000 rpm..... yea I just checked my book and it actually says 8000 to 10000 rpm... This is definatly for racing considering you rarley go to lower RPMS.....
Hopefully that hepls.. you could have found this somewhere else on the site but i just like to test my top of head knowledge about rotarys... If I missed anything sorry but Im sure somebody will catch it and correct me.. lol
Street Port: In many cases this is the port job of choice and is the one that will give you the best chance of passing emissions. With the street port the general idea is to enlarge the intake and exhaust ports. This is the best bang for the buck. I have this on my FC Turbo and i gained the best amount of street power from this.. It has been said that on a stock set-up you can get anywhere between 50-60% Increase in power. result will always vary depending on the condition of the car. If you also intend on adding an exhaust system to your car along with any intake modifications, you may not pass emissions 9 out of 10 times. Here you are allowing the exhaust ports to open earlier and close later.
Bridge Ports: This is the same as the street port but taken a few steps further. When done you actually only leave "bridge" (smaller section) for the corner seal to pass into. Bridge porting also cuts another intake port into the housing itself. (Sounds more confusing than what it really is) When its all said and done you casue the intake ports to open and close later. When done in a small amout you may still have some streetability but you gotta be cautious becasue these pots can be made to large and you can loose alot of lowspeed torque and HP. Torque gain between 5800 - 9000 rpm
1/2 Bridge Port The half bridge port actually has the best of the street port and bridge port. The power gain is more promising with power responding around 3,600 rpm's. This port job work primarly with the intake port being opened up about 15% (street port). But a third port is cut near the end of the housing leaving a bridge (bridge port) Thus getting the name 1/2 bridge port. This is a great port job if you plan on racing your RX7 on the track. I have a friend whos has this and he says its the only port job he will use on the track. I can go with half of that but if you are truly gonna race your car the next port job is for you.
Peripheral Porting Lets start like thisPeripheral: 3. Anatomy. near the surface or outside of; external. (Thanks dictionary.com)
This is why I LOVE rotarys... Mostly everybody loves the sound of a peripheral port job. I think it sounds like a worked boat motor...
Anyhow hear the intake ports are taken out of the side housing and moves them to the periphery side of the motor. LOL somebody got really creative when they thought of this. Thats all I really know about this type of port but i also know that you move you power band way up to about 7800 and takes it to what i think is 10,000 rpm..... yea I just checked my book and it actually says 8000 to 10000 rpm... This is definatly for racing considering you rarley go to lower RPMS.....
Hopefully that hepls.. you could have found this somewhere else on the site but i just like to test my top of head knowledge about rotarys... If I missed anything sorry but Im sure somebody will catch it and correct me.. lol
With that being said a Full Bridgeport would be the middle size of a port job being it is number 3 size out of 5. or am I missing a port size?
I am trying to figure out what the middle size port job would be. Being Street is the lowest and Peripheral is the highest.
Joined: Feb 2001
Posts: 29,798
Likes: 128
From: London, Ontario, Canada
There really is no "middle" sized port.
A number of errors were in that post.
For example, it makes sense to refer to a bridgeport as a "full bridgeport" or "half bridgeport".
A half bridge will bridge the secondary ports only.
A full bridge will bridge both the primary and secondary ports and has the greatest power potential of a typical bridge.
A level farther is a j-port where a massive cut is made into the rotor housing and the eyebrow port from the bridge is extended up into the water jacket. This is really a race only port made to get around rules banning PP engines and should never be considered on a street car.
There are also a load of different levels of street ports. Every builder has their own porting style which will range from just polishing up the ports (virtually useless) to street ports that have nearly the flow and timing of a bridge.
A number of errors were in that post.
For example, it makes sense to refer to a bridgeport as a "full bridgeport" or "half bridgeport".
A half bridge will bridge the secondary ports only.
A full bridge will bridge both the primary and secondary ports and has the greatest power potential of a typical bridge.
A level farther is a j-port where a massive cut is made into the rotor housing and the eyebrow port from the bridge is extended up into the water jacket. This is really a race only port made to get around rules banning PP engines and should never be considered on a street car.
There are also a load of different levels of street ports. Every builder has their own porting style which will range from just polishing up the ports (virtually useless) to street ports that have nearly the flow and timing of a bridge.
http://www.mazdarotary.net/porting.htm helped me alot, hope it helps you!
Choose wisely
guys, there is a lot of good information in this thread. there is also a lot of misinformation in this thread.
let me give this a shot without having to post a paper inlcuding references and footnotes on it. here goes:
generally speaking, think of it as there being 2 types of ports: side ports and peripheral ports. however, you should also keep in mind that they can be used by themselves or in tandem with each other. i will address that part last.
1. your side ports will include stock ports, streetports and bridge ports because the engine inhales through the side housings in all of these types. from the links provided by a few members before me, you can see representative pictures of them all. however, keep in mind that all of them can vary in size (depending on the year and/or the builder). for streetports and bridge ports, you can have terms like mild, small, medium, large, etc. - these are virtually meaningless as it's all relative to person building or describing it. what matters is that you know the fundamental difference between a streetport (which alters the open and close timing of a stock port to a point) and a bridge port (which takes it a step further and opens so early that a bridge is necessary to keep the corner seal in it's place).
2. your peripheral ports are just that. essentially, an intake port is cut in the rotor housing (just like the exhaust ports were) and the intake ports on the side housings are filled with epoxy. these ports will vary in size and timing as well, depending on how much knowledge of the rotor's motion you have or can discern. building one is not easy, but being able to tell it apart from any other ports is.
finally, there are ports that combine more than one port type. this is where you have your half-bridges and semi-peripherals.
1. half bridges usually keep the primaries streetported, while bridge porting the secondaries. of course, you could do it the other way, but i think that defeats the original intention behind this port's inception. i only know of one person that did it that way. i have my personal thoughts, but this is not the place for them.
2. semi-peripherals are basically engines that keep the side ports functioning while utilizing peripherals. generally the peripheral port is physically smaller than a full PP engine, but i know of people that have proposed using a full-sized peripheral. i've never seen or heard of one running though, so i'll leave that there. the side ports can be stock, streetported or bridge ported.
as far as streetability is concerned, all i can offer you are my thoughts. if you're in this, then i'm not going to treat you like children regardless of your numerical age. it's your engines, your monies and your lives. that said, stock ports and streetports are all i would recommend for a car that will spend most of it's time on public roads and highways. do people use other port types on the street? yes. however, many of them curse the day they made the decision. the ones that do and enjoy it are usually people that know what they're in for beforehand because of knowledge and experience. if you have to come here and ask if anything other than a streetport is streetable, YOU probably shouldn't drive it on the street.
i hope this helps clear some things up.
let me give this a shot without having to post a paper inlcuding references and footnotes on it. here goes:
generally speaking, think of it as there being 2 types of ports: side ports and peripheral ports. however, you should also keep in mind that they can be used by themselves or in tandem with each other. i will address that part last.
1. your side ports will include stock ports, streetports and bridge ports because the engine inhales through the side housings in all of these types. from the links provided by a few members before me, you can see representative pictures of them all. however, keep in mind that all of them can vary in size (depending on the year and/or the builder). for streetports and bridge ports, you can have terms like mild, small, medium, large, etc. - these are virtually meaningless as it's all relative to person building or describing it. what matters is that you know the fundamental difference between a streetport (which alters the open and close timing of a stock port to a point) and a bridge port (which takes it a step further and opens so early that a bridge is necessary to keep the corner seal in it's place).
2. your peripheral ports are just that. essentially, an intake port is cut in the rotor housing (just like the exhaust ports were) and the intake ports on the side housings are filled with epoxy. these ports will vary in size and timing as well, depending on how much knowledge of the rotor's motion you have or can discern. building one is not easy, but being able to tell it apart from any other ports is.
finally, there are ports that combine more than one port type. this is where you have your half-bridges and semi-peripherals.
1. half bridges usually keep the primaries streetported, while bridge porting the secondaries. of course, you could do it the other way, but i think that defeats the original intention behind this port's inception. i only know of one person that did it that way. i have my personal thoughts, but this is not the place for them.
2. semi-peripherals are basically engines that keep the side ports functioning while utilizing peripherals. generally the peripheral port is physically smaller than a full PP engine, but i know of people that have proposed using a full-sized peripheral. i've never seen or heard of one running though, so i'll leave that there. the side ports can be stock, streetported or bridge ported.
as far as streetability is concerned, all i can offer you are my thoughts. if you're in this, then i'm not going to treat you like children regardless of your numerical age. it's your engines, your monies and your lives. that said, stock ports and streetports are all i would recommend for a car that will spend most of it's time on public roads and highways. do people use other port types on the street? yes. however, many of them curse the day they made the decision. the ones that do and enjoy it are usually people that know what they're in for beforehand because of knowledge and experience. if you have to come here and ask if anything other than a streetport is streetable, YOU probably shouldn't drive it on the street.
i hope this helps clear some things up.
as far as your turbo question goes, what is your goal and use for the car? you can do well with everything from a 35R to 42R and as we both know, there's a lot in between those two. however it will depend on many factors. you'll probably get better answers in the Single Turbo forum.
Junior Member
Joined: Jun 2009
Posts: 15
Likes: 0
From: Auckland, New Zealand
i think a street/stage 2 port would probably be the best bet for daily driving, extend is just a little bit louder and makes a way better sound and is not too bad for daily driving, a little on the slow side down low revs. it really depends what you are trying to get out of your car. i know a few people that have a bridge ports, j ports and peripheial ports and gets driven alot. they really only have it purely to hear it pusle. they dont care about drivability. so it just depends what you really want.
Mica rx7
Joined: Aug 2009
Posts: 17
Likes: 0
From: Lake Orion, MI.
What kind of numbers in HP would you get to with a street port before you would consider the 1/2 bridgeport or full bridge port? Answer this knowing it's not a daily driver and drivability is not a huge factor.