Okay, so maybe it's not that technical. But my brother told me headers are actually bad for engines because they are supposed to have certain amount of back pressure. Is this true? If so, how do I correct this?
it all depends on the set up of the engine, any engine, not just a 302. alot of times you'll loose low end at the expense of higher end power. the exhaust set up can also make a big diffrence too. to say that headers are bad in all situations is totally false though.
Headers are not bad for your engine.OPEN headers are bad for your engine as they allow no back pressure(he's right there)and in cold weather I've seen warped valves on initial startup.Just make sure you've got some exhaust piping/mufflers on there.
Hell, I have a header on my 250 6 cylinder (totally stock 250,000 mile long block). I am very pleased with the header. The car runs all around better, and it seems to have helped the fuel economy a little also.
I actually had a 1988 Escort GT that came with a 1.9 L High Output engine that came fromt he Factory with Headers
Your brother is mistaken. No engine "needs" back-pressure. The idea is to get as much velocity (speed of exhaust flow) as possible, especially for a high performance engine. Headers always flow better than regular exhaust manifolds. In a V-8, the benefit really isn't realized until the engine reaches around 3000 RPM. Having too large of header primary tubes for the heads that are being used, can cause sluggishness in the lower and middle RPM range, as well as having too large of exhaust pipe tubing can cause the same thing. The key is to have all of the engine's components (Intake, heads, ignition, cam, & exhaust system) matched to work well together. Headers come with their own set of problems, such as radiating extreme amounts of heat, and being less durable than stock exhaust manifolds (unless they have a ceramic or "Jet Hot" coating). Installation can be tricky (especially on Mavericks) as well...
It's not that an engine needs back pressure. You can't have your exhaust so big that you loose velocity and pressure to the point that the exhaust has less than atmospheric pressure. Makes it more difficult to get the exhaust gasses out. Race engines get away with open headers because they run at a high rpm and produce a large amount of exhaust.
Your brother is wrong. Headers do so many beneficial things for an engine. They take heat from the engine that cast iron holds in, allowing slightly more compression or ignition timing. The added flow effiency gains fuel economy. The added flow gains HP and TQ. Your engine combo is best served by tayloring the primary tube diameter, primary tube length, collector diameter, and collector length to the purpose your engine is built for. If you don't get these sizes/lengths right for your engine, then you can not gain as much as you otherwise would. You won't lose when going from cast iron to headers, but you can skew the gain somewhere you don't really need it by using the wrong specs.
If that were true, people would hose up intake valve all the time!! How much pressure do you think is in the intake manifold?
This should set you right.... http://www.uucmotorwerks.com/html_product/sue462/backpressuretorquemyth.htm it provides insight on the subject. so i dont have to.
Inexperienced with the headers obviously...he may have heard or read something that was confusing or missinterped. This issue may be somewhat critical in a professional racing bracket, which most of us are not in. So the last one to the finish line has a rotten egg of a brother J/K Certainly hope you find the answer your looking for...
AN engine is basically an air pump . The more air and fuel you can sqeeze in the more you will get out of it. volumetric efficiency . pure and simple. matched components get the job done!
