I have a bbf 71 block dove heads 180h magnum cam lifters 850 holley and lightning headers I run a dual plane intake now just wondering if a single plane would be better seems like  thats all I see on jet boats any info would help

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Any good recommendation on a  single plane manifold for my set up

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Alot of my ford friends run the trick flow one
http://www.trickflow.com/partdetail.asp?part=TFS-53400112

i run a stealth on my sisters 460 , changing it out in the winter

Its not a race boat it runs 5200 rpm now.. with the rpm air gap manifold I have on it... I just see a lot of single plane manifolds thats why im curious to see what everyone thinks

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That's a pretty good intake, I'd keep it.  Are you looking for more power or speed? 


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Or just mill the divider down a bit...

Milling the divider is difficult to go back, it is difficult to put the material back in.  The AirGap RPM already has part of the divider milled down.

Be careful milling the divider, it is actually possible to lose power or not achieve the desired results.  Typically, the divider will be milled down anywhere from .200 to .500-inches.  The cut could also be biased towards the rear of the plenum and not centered.  I have seen a lot of manifolds that have had the entire divider removed, but I have read a lot about that being a bad idea and actually hurting power.  I have not found any documentation on modifying an AirGap RPM and I didn’t have the resources to develop mine before changing directions.

You might also consider trying a 2-hole and a 4-hole spacer.  You might see some benefits from increased plenum size while keeping the two planes isolated as it will keep the velocity of the air and fuel up, promoting better atomization and therefore a more complete burn with increased power and efficiency.  To do so, you will need to fill in the portion of the divider that has already been removed.

If you do feel the need to modify your divider, either leave the remainder of the divider square or put as large a radius as possible.  DO NOT sharpen it to a point, it causes shearing of the air and reduces flow.  A large radius will help airflow transition around the sharp bends.

Hope you enjoy the attached reading, I think it is a good start to understanding induction science.  You may find that porting your existing manifold would be a better option for your particular usage.  Keep in mind that runner length (relative to cam timing) and cross-sectional area (relative to cylinder volume and RPM) are key to having a good performing engine.  Shorter runners as well as larger cross-sectionals area favor higher RPM.

Just be advised that each change you make will probably require rejetting the carb to see any real benefits.  Each configuration will require “developing a tune” and evaluation to see if there is a gain or a loss.  Take good notes so that you can go back to what worked.

Cheers,

Joe