The best header discussion ever....

[garickman]

I am trying to educate myself on vehicle exhaust systems, mainly in the header department. I have searched the internet and various threads but have not found all the answers I am looking for. Most threads are specific to one question and I have several questions. I was thinking a lot of people have some of the same questions I do so I thought I could start a discussion which might address multiple concerns.

How important is the primary tube size?

How do you determine the primary tube size?

How important is it that primary tubes are all the exact same length?

Are stainless steel headers really that much better than mild steel?

If stainless steel headers really are better, would ceramic coated mild steel headers be just as good?

Can you ceramic coat stainless steel headers?

How come it seems some headers use gaskets and some don't?

Is it a good idea to safety wire header bolts?



Do headers effect you torque as well as your horsepower?

How important is the size and length of the merge collectors?

Should the o2 sensors be located in merge collectors?

[Rod]

these questions are assuming that there's one style header for all things, and there's not, A drag racer needs top end, so a long tube big primary big exhaust pipes works, no bottom end at all but when you launch off the trans brake at 4000 grand you don't need bottom end or ground clearance the 1320 is fairly flat, autocross needs all bottom end HP and torque, and road track needs mid HP and torque, so you must decide the use of you're car realistically, and were can you make up for exhaust deficiency elsewhere on the build (I.E. more top end can be added with carb spacers or taller intake)

[garickman]

these questions are assuming that there's one style header for all things, and there's not, A drag racer needs top end, so a long tube big primary big exhaust pipes works, no bottom end at all but when you launch off the trans brake at 4000 grand you don't need bottom end or ground clearance the 1320 is fairly flat, autocross needs all bottom end HP and torque, and road track needs mid HP and torque, so you must decide the use of you're car realistically, and were can you make up for exhaust deficiency elsewhere on the build (I.E. more top end can be added with carb spacers or taller intake)

AAAHHH! My application would be more for a street car with the occasional autocross/road race type of event.

[Yelcamino]

For more header info than you probably want, check out the "Header Design Comments" page from Headers by Ed.

[bbcc]

Both Speedtalk and Yellowbullet have had some excellent threads regarding header and exhaust system design. You'll see a program called Pipemax being talked about a lot. It's one of the best and cheapest algorithms out there specifically tailored to performance engines. With good data input, it will give you all the criteria to build an ideal exhaust system (among other things).