Turbo II 4 port Irons with s5 na rotors
Turbo II 4 port Irons with s5 na rotors
Hi all. Im looking for someone who has built an engine using turboII irons and s5 na rotors. Im building it to run in my FB with a lightweight flywheel and a 12a tranny. I know with the 12a tranny and GSL rear i will gain low end and lose top. But, after a fellow club member and I spoke today I'm a little afraid with the 4 port irons, it will really lack in bottom end, especially with the aluminum flywheel. Ill be powering it with a Weber 48 sidedraft. Anyone experience in the seat behind this particular setup would be helpful
Thanks !
Dave
Thanks !
Dave
Joined: Mar 2001
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From: https://www2.mazda.com/en/100th/
[quote]But, after a fellow club member and I spoke today I'm a little afraid with the 4 port irons, it will really lack in bottom end,[/quote[
a longer porting explanation will follow, but the 12A is a 4 port, and it does ok, yes?
especially with the aluminum flywheel. Ill be powering it with a Weber 48 sidedraft. Anyone experience in the seat behind this particular setup would be helpful
Thanks !
Dave
Thanks !
Dave
porting: Mazda has used 2 different intake porting styles over the years in the street cars. the 4 port and the 6 port.
the 4 port is used in all the early cars up to 1986, and then the FC and FD turbo are 4 port. the 6 port was introduced in the GSL-SE in the US, and was used in all the NA cars from 1984-2012.
the 6 port system came about because the 4 port system becomes a compromise, if you size/time it for high rpm power, than you loose low end power, and if you size it for low rpm power, you loose high rpm power.
so the 6 port has 4 ports sized for low rpm power, with 2 additional ports that open at high rpm and load to keep the top end they had with the 4 port system.
notice how that's worded, the 6 port is sized to keep the top end of the 4 port and add low end.
in real life, when you go to modify the engine the 4 port ports are nicely sized, while the 6 port stuff has poorly flowing runners, and crazy port timing, so the 6 port engines don't make much power, and its usually at a really high rpm.
the 4 port engines tend to make the same or more power, and at a lower rpm.
compared to what? the trans/diff make no difference in engine power. and the GSL, was a 12A, so you have a stock combination. once your foot is off the clutch, the aluminum flywheel will have more response. i did have a combo something like this and it was very nice, lots of midrange. porting: Mazda has used 2 different intake porting styles over the years in the street cars. the 4 port and the 6 port. the 4 port is used in all the early cars up to 1986, and then the FC and FD turbo are 4 port. the 6 port was introduced in the GSL-SE in the US, and was used in all the NA cars from 1984-2012. the 6 port system came about because the 4 port system becomes a compromise, if you size/time it for high rpm power, than you loose low end power, and if you size it for low rpm power, you loose high rpm power. so the 6 port has 4 ports sized for low rpm power, with 2 additional ports that open at high rpm and load to keep the top end they had with the 4 port system. notice how that's worded, the 6 port is sized to keep the top end of the 4 port and add low end. in real life, when you go to modify the engine the 4 port ports are nicely sized, while the 6 port stuff has poorly flowing runners, and crazy port timing, so the 6 port engines don't make much power, and its usually at a really high rpm. the 4 port engines tend to make the same or more power, and at a lower rpm.
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