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Read this article about a comparison of stock-based heads...

It opened my eyes....

I think I'll hang on to those C9 W heads layin' in the shop a while longer...*G*

IIRC, don't the GT P heads require some tweaking to the headers....?

Pat
http://albums.photopoint.com/j/View?u=1570936&a=11937754&p=42910787.jpg
 

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Usually, flow characteristics are a function of port volume and shape....a larger, more aerodynamically shaped port will flow more...not necessarily better...

Street heads are designed to keep velocity up at low flow volumes to promote efficient mixing and delivery of the air/fuel mixture....that's because street engines spend most of their time at low rpm levels...

Racing heads are designed for maximum flow and velocity at high rpm's and airflows...

Just imagine putting a 1050 Dominator carb on a street 289...that carb would work great on a full tilt big block or screaming 351 C but would give you a gutless 289 because it would mix air and fuel inefficiently at such low velocities because of the enormous throttle and venturi volumes...
Conversely, and we see examples of this in NASCAR, putting a 4100 Autolite on a full race C engine or big block would restrict its performance because the carb wouldn't allow enough air and fuel to pass to develop the full potential of the engine's volumetric efficiency and air/fuel requirements...

Back to heads....it's often been proferred here that the 2V C engine head is more streetable than the 4V head....why? Simply put, because the ports are smaller, thereby promoting higher velocity and better mixing at lower, street, rpms....

The aerodynamic and engineering sides of this question are more the subject of a complete technical article.....you might read through the complete article from the URL I gave you...Joe Mondelo and his staff are much better than me at explaining these things in laymen's terms...

Hope this helps...

Pat
http://albums.photopoint.com/j/View?u=1570936&a=11937754&p=42910787.jpg
 
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