like most of you guys I read thru the magazine articles that do the engine builds and compare parts.
like many of you I understand that those results tend to be lets say, "SUSPECT" and more than once Ive found myself, uttering (BULL $%$%) under my breath after reading thru a dyno test. but on occasion I find what they are not pointing out just as telling.
now they did admit that a 700hp plus rated big block they built previously would more than likely have about 550hp once installed in and measured from the cars rear wheels so thats some progress.
I won,t mention the magazine, responsible. but recently one compared some DART 215cc heads to some dart 227CC heads and an wieand dual plane, with a Keith darton single plane intake,the wieand dual plane, is almost an exact match in port size to the 215cc heads now they acted surprised when the dual plane made almost as much power and more torque than the single plane intake on the engine with the 215cc heads,and acted surprised again when the larger port Keith darton single plane intake on the larger 227cc heads worked rather well. now anyone who has carefully compared both those heads and intake manifold knows that the port size on the 227cc heads and a Keith darton single plane intake, are both significantly larger and flow better than the smaller dual plane and 215cc head ports,. now the the larger port Keith darton single plane intake, can be a good upgrade on the smaller heads if your using a plate nitrous system and you've got the cam to match, so what they are ignoring in the intake comparison on the heads is that no matter what the heads or intakes flow your limited by the most restrictive components that are matched, and that the cam timing must allow full flow potential of both components for both components to reach their full power potential..
example
if lets say the heads you select, reach their max flow at a .670 valve lift, your rather obviously restricting their potential if the cam, your using only reaches a .530 lift. if thats the case it would be foolish to use the larger heads designed to max flow at an even greater , lets say .740 lift, or use the larger head on a combo that will never see rpms that can use near their full potential flow.
everything's a compromise,
you can design a combo to make killer peak hp, or a milder combo to get good mileage, or a responsive street performance combo thats between the two extremes and the components used will be different in all three engines
if the 215cc heads flow 270cfm and the single plane intake flows 310cfm, then the combo flows a max flow rate that will be at or less than 270cfm, if the 227cc heads flow 310cc and the dual plane intake flows 270cfm , same deal, max flow will be at or less than 270cfm., making the high flow heads or intake look pathetic, compared to their TRUE potential, when properly matched.
whats the difference?
well, if
Potential HP based on Airflow (Hot Rod, Jun '99, p74):
Airflow at 28" of water x 0.257 x number of cylinders = potential HP
or required airflow based on HP:
HP / 0.257 / cylinders = required airflow, that 270cfm equals a max potential power of about 555hp, the higher 310cc=637 hp a calculated potential difference of 82 hp now I would never assume the calculations provide a true indication of potential power potential, but it does show that matching components has a huge potential to make a difference in the combos results, even if the true numbers are bogus the 12%-13% increase thru use of matched components with the significantly higher flow rates IS potentially valid in most combos
related info
WATCH VIDEO
https://www.youtube.com/watch?annotatio ... v3ZkqZiMjI
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