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Old 04-16-2014, 02:45 PM
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MantisWorx
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Originally Posted by masher81
Yes and no. The more/larger ports you have the less vacuum you produce at lower rpm. This decreases airflow at lower rpm. The more ports you have the more rpm you have to turn to create the same amount of vacuum.

If you compare the same vacuum numbers between a 9 poet and 5 port the 9 port will be making more power, it just takes more rpm to get there.

I am not advocating that less ports is superior, but they do make power fast than more ports. I have no doubt that a properly clutched/geared 9 port is superior in power to a 5 port.

But on a dyno side by side the 5 port will make power sooner than the 9 port.

Ok, so lets get some variables pointed out before we get all crossed up with information

My comparison is for a 7mm restricted 5 port (ROAR legal)
and un restricted 8.5mm 9 port.

now something that i would like to point out is that you get no vacuum once the throttle is wide open you get ambient pressure which is 14.7 ( ie stoichemetric)

I am also not arguing your point IF there is no restriction a 5port may create more power but at a level where it does no good at least not for on road GT racing. Going to the extreme of our sport 1/8 open, those guys clutch and gear so that the engine is in its powerband the entire time. If you take a modded un restricted 5 port and gear it so it can even get close to the 9 port on a heavy GT car its not going to go anywhere, 1 st gear may be ok but its going to suffer on the straight. Case and point the REDS M7 and WC are both 7 port engines but they have HUGE ports. i was sponsored by them last year and going from REDS to TOP, the first thing i notice was that the REDS engines turned really high rpms and had astounding mid and top end . Where as the TOP has a much smoother powerband and not quite as violent as the REDS on the bottom.

You are not wrong on anything you are saying, I am just trying to put it into GT perspective! a 5port is not Torquey by any means at least not enough to out perform a 9 port with the same variables.
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