Hey guys!! I have a 62 Bel Air with a small block that I plan on doing a little bracket racing with. I have been driving this car on the street some and plan on dragracing it off and on. Anyway, I currently have the typical "shorty" headers and have been thinking about getting full length headers. After looking at similar cars with full length headers, I noticed they are routed very similar to my shortys except where my shortys end at the colector flange these continue down and out towards the bottom, THEN come to the colector. When I go racing I plan on removing the exhaust and running open headers. So I got to thinking, why not make an extenion on to my shortys, say 2.5 to 3 in about 2 ft long and run that open. Would this acomplish the same thing? Would I be better off just getting the full lengths? I hope that all makes scence?? Thanks!!!
There is a formula they use to determine tube size and length. Shorty headers won't give you the power long tube headers will. If you want the most power out of your engine you'll want the long tubes.
I was told that each tube has to hold just over the volume of the combustion charge from each cylinder. Just a bit of math and you'll have your length for each tube.
It's a little more complicated than that. It has to do with engine size, power, rpm's, etc. Shorty headers are barely better than 2 1/2" ram horn manifolds on a Chevy small block, for power--long tubes.
Back in the late '70's or early '80's, Car Craft of Hot Rod magazine ran a bunch of good tech articles, including a series on determining the header size you need. Thanks to the Internet, all that kind of information is available at our fingertips, more or less. Here are a few links I found by searching for "exhaust header size calculator": http://www.ehow.com/info-tip_8428151_exhaust-header-length-calculation.html http://www.wallaceracing.com/header_length.php http://www.bgsoflex.com/bestheader.html http://www.ehow.com/how_7942410_calculate-exhaust-header.html http://horsepowercalculators.net/headerdesign/header-design http://www.speed-wiz.com/calculations/engine/header-1.htm http://www.thedirtforum.com/headercalc.htm Hope this helps!
There's a reason why they're called "tuned" headers. The longer tube aids in more torque while the equal length helps horsepower. Go with the full tube headers and add cutouts at the collector. When you're racing pop the caps and make some noise (and power).
that site certainly gets you in the ballpark - but nothing is that easy. You will note that it calculates longer headers than you can usually buy if you are honest about RPM range. Tube diameter has an even larger effect on the scavenging abilities of the header - usually smaller than you would think.
My point exactly! Some people do this strange math based on the size of the exhaust port to figure tube size - it should be figured based on HP output and displacement.
Dolmetsch had some discussion on this subject a while back on this board. 40 years of building engines, drag racing and experimenting taught him that headers as bought are usually too short. He found if he lengthened them he picked up a noticeable increase in power and performance. It varies with different engines but usually about 9".
Hey, thanks alot for al the replies!!!! Guess i'll start looking into a set of long tube headers. Any one know of a decent set for a resonable price? I have a hard time finding them for a 62 chevy.
Only when XY is equal to Z. Here is something that is not too scientific, most off the shelf small block chevy long tube headers have tube that run between 30 and 32 inches in length. Collectors are normally 3" and range in length from 4-8" unless you are buying the real modern headers that don't seem to have much collector length at all. Now if your headers actually scavenge properly and not just make noise you will need to jet up when you uncork them to take advantage of them unless you are already running fat through your exhaust pipes. By the way if you are a machinist worth your salt trig is you best friend and it doesn't hurt to be at least aquainted with caclulus.
It will really come down to cost. for what it sounds like what you want to do and with the choices for off the shelf headers for your car, you are pretty limited. A good old cheap 1 5/8 header will do you just fine for $100+ish dollars. to get any better than that you will spend 3 times that, or to get REAL tuned race headers it will be 8 to 10 times that. Hans
To answer your questions at the end there - NO, putting extensions on the end your shorty's will NOT do the same thing, not even close. In fact it won't be any different that running a 2 1/2" exhaust system. YES, you will be better of getting long tubes, they will make a noticeable difference IF your motor is strong enough to matter, otherwise the difference will be smaller. The X Frame cars like yours are a little different when designing headers (It is what I do for a living) and the BEST on the market is probably the Doug's D358 - Ceramic coated they are going to cost you about $622 from a place like Summit, or $450 Raw for you to paint. It might seem expensive, but they are good quality with 3/8" flanges and thick tubes, premium gaskets, bolts and reducers. And it sure beats the Two Grand plus that I charge for custom headers! http://www.summitracing.com/search/?keyword=d358&dds=1
I personally like step tube headders for a street/strip car ...1 1/2 to 1 5/8 about 10-14" of 1.5 " tube and the rest 1.625 for an overall length of 32-34" and a 4" diam collector 10-12" long.....has worked pretty good for me on the SBC I have run....Shawn
4" collector is WAY to big for a header that is only 1 1/2 to 1 5/8. A 1 1/2" header is for a pretty small, low HP motor and a 4" collector is for a monster sized small block. In my Professional Opinion, this is Not a good combination.
Benno and Wadday are too much! Laurel and Hardy? A book worth its weight, is titled "A mathematician's Lament" by Paul Lockhart He writes that math needs the connective tissue of intuition, to remain a tool in the memory. (My best sense of his efforts) A Stamford math Prof, he went back to teaching high school math. And yes, rodders use Calculus every durn day. Stoplight or sign, you just completed a critically-damped-stop in Eng-speak. Your foot was as clever as...Newton? Benno? OK, we'll take Benno, he's stayed at a Holiday Inn at least once.
Dynomation5 does a decent job simulating header options but for me what's always worked best is to just ask burns stainless what they recommend then do what they said.
I would have made a good laurel. I got the build and the looks. Hey lets be the marks brothers, I got grouchos eyebrows and harpos hair.
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