Jerry wrote,
>>Hello,
>>I am about to install a rebuilt Ser. V 1725. I have dual DCOE 40
Webers
>>and would like to use a set of header exhaust pipes. Could anyone
>>recommend a reputable source? Also, any suggestions for the
>>installation? Also, any ideas for remedying the knocking noise I get
>>from the exhaust pipe as it passes through the opening in the
underframe
>>and knocks against the car, especially at idle?
>>Thank you very much,
>>Jerry
Jay answered,
>The problem with exhaust headers is not wasting your money. First,
larger
>headers really only help at the top end, and if done right maybe only
get
>you 3 hp max.
S N I P.
I agree with Jay, but....
I would say that a propperly designed header COULD net significantly more that 3BHP, BUT there exists no MFGR that has mass produced a properly designed header for any of the alpine engines.
The factory and aftermarket headers use short length Tri Y headers, that breath better than a conventional iron manifold, but do not perform the basic function that makes a header a header.
Equal runner lengths, long runner lengths, and mandel bends without ugly weld restrictions are important to allow resonance, and at the proper frequecies. The alpine headers that are available would seemingly like to run most effieciently at about 10 grand with their short lengths. Runner length and camming are inter-related, so the best header for a given cam profile is not the same as that for another.
The Iron maniold used on SIV and SV engines is actually quite good, and I would make (and have made) only one minor tweak inside the #1 and #4 exhaust ports, there is a "D" shape instead of an "O" shape becuase of the mounting on the outsides of the manifold. A dremel tool and some patience will fix that.
The DCOE carbs will net you far better performance per dollar or hour than the available headers will.
Jarrid Gross