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Old 04-19-2007, 04:35 PM
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Default square port heads round port intake

anybody have any experiance with this? i had that thread going a few weeks ago about squeezing a few more ponies out of my stock 365 mags while they are out and came up with a few odds an ends to bolt on. so far i have

crane gold roller rockers (thanks Mr.Patriyacht )
crane crn-134242 cam and lifters
Gil exhaust and risers
Air gap intakes (gonna try stock Q jets first before new carbs)

now heres my question. the intakes are oval port and the heads are square port. i have been told on good athority that using this combo increases the velocity of the flow into the head giving a slight increase in performance over using the square port manifold. anybody done this before? I am willing to give it a try and thought i'de see if anyone on here has heard of this. thanks all
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Old 04-19-2007, 07:15 PM
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Yes it works well, but will not perform well in the upper RPM range.
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Old 04-19-2007, 09:29 PM
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I am running an oval port intake on rectangular port heads. I started this thread about it. You may find it interesting.

http://www.offshoreonly.com/forums/s...angular+intake


This is the thread I started soon after with the dyno results.

http://www.offshoreonly.com/forums/s...540+dyno+today

This was a few years ago. I have run this engine for about 150 hours. It pulls well through out the rpm range. I wish I could have tried a rectangular intake while on the dyno, but it just wasnt feasible.
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Old 04-19-2007, 11:31 PM
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Originally Posted by HighPriority View Post
Yes it works well, but will not perform well in the upper RPM range.

was that your P5 secret?


Great info guys, i also spoke to Dean Gellner on the subject and he gave me some tips on doing this. he basically told me to blend the roof of the round port intake to meet the roof of the square port head but leave the floors alone. that will maximize the effect. I am looking to optimize the lower part of my rpm range because i am puting them on basically stock 365 Mags. want to stay in the max rpm range of this engine

great link CM454mag thanks. thats what i was lookin for real world results
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Last edited by glassdave; 04-19-2007 at 11:37 PM.
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