HOW TO SIZE HEADERS

摘要

In the world of engine hop-up components, headers are truly a win-win-win deal. They can deliver measurably better torque, horsepower, and mileage. When swapping out factory iron manifolds for headers, a typical peak-to-peak gain (even for a smog-laden motor) is about 25 hp, and roughly the same for Ib-ft of torque. Having said that, the low-speed torque can go up as much as 40 Ib-ft with headers that are optimized for the engine. For the average hot rodder there is no downside, and for the racer they are essential. What they are not, though, is foolproof. Headers can deliver a great deal in terms of return on investment-if the headers are spec'd out properly. When it comes to the right spec, it's all about dimensions.