Results 1 to 10 of 10

Thread: Difference between 4 port-6 port 13b's

  1. #1
    Senior Member
    Join Date
    Nov 28, 2007
    Location
    ft. collins, co
    Posts
    1,111

    Default Difference between 4 port-6 port 13b's

    This is a quick right up about the difference in a 4 port 13b and a 6 port.
    Let me know what yall think. Good for motor swap info if you wanted to go with a NA 13b.

    S4's use exhaust pressure to activate the ports. Usually the activation occurs when the exhaust pressure reaches around 2psi or so. This means that it could activate at any RPM on the Tach, however most common occurances appear to happen around 3200-3800 rpm when under load. Remember it's exhaust pressure that does the activating. The reason for the opening of the ports is to maintain torque at low RPM's that that you don't suffer in the topend RPM's.

    On the S5's they are activated using an either an electric pnumatic system or the airpump (I can not exactly remember--I think it's the Electric though). The pressure of activation remains the same and is again around 2psi. This however is usually set to activate at a specific RPM regardless of load conditions.

    These ports are used as previously stated to maintain low end torque without suffering for it at top end. It's a similiar if not the exact theory behind VTEC, ECO-TEC, and every other variable valve timing out there. It's a way to have more torque at low end while not suffering at the highend of the RPM range.

    As for not having a 6PI on the turbo models there would be no real advantage to it as far as I could fathom. By the time the activation would occur of the 6PI the turbo would already be making boost. Low end torque would be less of an issue since the turbo would be making boost lower than the activation point. Granted the torque wouldn't be there at idle to boost, but that distance is extremely small. The 4 port setup also is about the same size if not just a little smaller than a fully opened 6 port setup. This is primarily the reason why those who do N/A conversions usually either tie open the 6PI or remove the sleeves.

    There are others that use the 6pi on turbo setups, however you would have to remove the actuators and the ACV to make the turbo fit (Not to mention the airpump). Which would mean another form of activation would need to be put in place.

    all N/A engines are 6 port only the 84-85 gslse engines are N/A 4 port. All turbo engines from 87 to 95 are all 4 port. And all 12A engines are 4 port
    Last edited by eg8dude; Feb 10, 2008 at 08:31:24 AM.
    Driving a Honda is like being in the Special Olympics, Even if you win, Your still retarded.

  2. #2
    Senior Member lovmyrx7's Avatar
    Join Date
    Dec 19, 2007
    Location
    Abilene, TX
    Posts
    792

    Default

    [/QUOTE]all N/A engines are 6 port only the 84-85 gslse engines are N/A 4 port. All turbo engines from 87 to 95 are all 4 port. And all 12A engines are 4 port[/QUOTE]

    Might want to check your info more on the GSL-SE, they are 6 port sir. And the 89-91 N/A's use the Airpump to open the 5/6 ports

  3. #3
    Shake and Bake
    Join Date
    Jan 13, 2008
    Location
    Lubbock,Texas
    Posts
    91

    Default

    All NA 13b motors after '84 came with a 6 port design. The 84-88's were activated by the exhaust backpressure (mufflers/cats) while the 89-91 13b's were activated by the airpump pressure. They open by pressure but yes, the typical RPM range is 3500 to 4000. The main purpose of the 6 ports is to improve mid range and top end power.
    87 RX7 Turbo
    90 Camaro RS
    94 Camaro Z28
    66 Ford F-100
    66 Mustang
    72 VW Beetle
    47 Chevy 3100

  4. #4
    Senior Member lovmyrx7's Avatar
    Join Date
    Dec 19, 2007
    Location
    Abilene, TX
    Posts
    792

    Default

    Quote Originally Posted by 87Turbo2 View Post
    All NA 13b motors after '84 came with a 6 port design. The 84-88's were activated by the exhaust backpressure (mufflers/cats) while the 89-91 13b's were activated by the airpump pressure. They open by pressure but yes, the typical RPM range is 3500 to 4000. The main purpose of the 6 ports is to improve mid range and top end power.
    So i guess your agreeing with what I/he said? Lol

  5. #5
    Senior Member
    Join Date
    Nov 28, 2007
    Location
    ft. collins, co
    Posts
    1,111

    Default

    yeah i just realized what i put. But yeah what they said is right.
    Driving a Honda is like being in the Special Olympics, Even if you win, Your still retarded.

  6. #6
    Senior Member
    Join Date
    Nov 28, 2007
    Location
    ft. collins, co
    Posts
    1,111

    Default

    So pretty much this is just saying that every na rotary in the rx7 series, is a 6 port after 1984, So This is still some motor swap info. So let me know how i did.
    Driving a Honda is like being in the Special Olympics, Even if you win, Your still retarded.

  7. #7
    Shake and Bake
    Join Date
    Jan 13, 2008
    Location
    Lubbock,Texas
    Posts
    91

    Default

    Yeah, basically from 84 to 91 you would have all 6 ports for NA 13b's. Only difference is how they are activated. However I wouldn't say this is motor swap info. There are alot of larger factors that would come in to someone doing a motor swap than the actuators. In all honesty the actuators don't even have to function for the car to still run and most 5/6 ports do not work when buying a used NA anyways.

    Good job on the topic and some of the info as not alot of people would be aware of the port difference though.
    87 RX7 Turbo
    90 Camaro RS
    94 Camaro Z28
    66 Ford F-100
    66 Mustang
    72 VW Beetle
    47 Chevy 3100

  8. #8
    Senior Member
    Join Date
    Nov 28, 2007
    Location
    ft. collins, co
    Posts
    1,111

    Default

    Thanks, just trying to help our little community.
    Driving a Honda is like being in the Special Olympics, Even if you win, Your still retarded.

  9. #9
    Senior Member
    Join Date
    Nov 28, 2007
    Location
    ft. collins, co
    Posts
    1,111

    Default

    But how can you say that. What if i wanted to do a NA 13b, and i knew that there was a 4 port 13b and a 6 port 13b but i did not know what the difference is. That is why i wrote this up.
    Driving a Honda is like being in the Special Olympics, Even if you win, Your still retarded.

  10. #10
    Shake and Bake
    Join Date
    Jan 13, 2008
    Location
    Lubbock,Texas
    Posts
    91

    Default

    Well because most people wont do to many NA swaps and if so then you have other issues to worry about besides those actuators simply because the 13b wasn't put out until 84. If you are going to swap a 13B NA into something you can pretty well say it will be a 6 port.

    This info helps as far as telling someone how they are activated between the years but some people may opt for the electric conversion as well.
    87 RX7 Turbo
    90 Camaro RS
    94 Camaro Z28
    66 Ford F-100
    66 Mustang
    72 VW Beetle
    47 Chevy 3100

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •