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'Kirk Racing Headers' need feedback

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M

myspitfire

Jedi Warrior
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Gentlemen!I won an auction for a set of headers i believe are/is a Kirk Racing'brand which is endorsed by Grassroots racing.I believe i have a 4 to 1(4 straight pipes curve into one)I plan to replace my stock factory exhaust manifold/cat converter(which is gutted).Does anyone have some input feedback on the issue?I plan on keeping the stock muffler/tailpipe on a 1980 1500 Spitfire.TIA:smile: /ubbthreads/images/graemlins/driving.gif
 
The 4-1 design is just what the ad said...a racing header. The 4-1 is designed to produce more horsepower at the very peak RPM's and in most cases will lower power in the low and mid ranges where we most often run our engines.

Using the stock muffler with any header setup is just defeating the whole idea.

The reason to change over to a header system is go gain more power. To do that the exhaust must be able to get rid of the waste fumes as quickly and completely as possible. A 4-2-1 header such as the one designed by Bell does this very well at normal engine speeds. It is designed to make power at lower RPM's. Combined with a less restrictive exhaust system such as a sport exhaust it can realize you up to 15 extra brake hp.

However (did you see that coming?) No exhaust system by itself will gain you much. In order to gain maximum benefit you also must increase airflow at the intake with less restrictive air filters, such as K&N's, jetting must be modified to allow for the increased flow, larger valves would be a plus, as would a cam with a more agressive camshaft.

Having the head milled to increase compression is also something to consider. If you live in an area where there are emission standards you may not be able to do any of these and remain legal.

Once you begin modifying an engine it becomes a slippery slope. One thing just leads to another.
 
what are the primary pipe lengths (measure each one-they usually vary) and od of the pipes, diameter of collector and length? then we can evaluate what you have.
rob
 
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