Smaller or Bigger? 2

From another post on Yellow Bullet, November 2015.   “You mentioned in a blog on another site that you worked with different lengths of primary tubes on cup engines, and found one length gained in power AND torque, yet another length not so much. Since those guys race at different tracks, and drag racers are ...

Match that port area? 2

Copied from a post on Yellow Bullet  November 2015 Well this is a good place to hopefully help with some clarification on this issue. Anyone having dealt with me knows the first thing I do is measure accurately the AREA of the port. This requires a bit of work and it is surprising at least ...

Merge Collectors and stuff 2

Ok, so this is easy but thought the following copies of my posts recently can help. Originally from “Class Racer.com” Originally Posted by Alan Nyhus Calvin, a couple of questions. I’ve got a set of your 4-2-1 headers on my 327/275 stocker motor and want to spend some time on the dyno this winter doing ...

Can we define “Blowdown Length”?

I suppose it’s debatable but I think I am the one the one using the term in discussion with customers and on several blogs for quite a while now. I think it is time to discuss how I define the term and how it affects my thinking about headers and what goes on. “Exhausting 101′,… ...

AR or Anti-Reversion Dams mismatched flanges

August 2015 Speed Talk Forum thread a reader “Flinstone” posted this question:   “slightly off topic but still relevant, what ever happened to having an anti reverversion step at the flange face ? this used to be accepted practice some time back but i hav’nt seen it done any time recently. the usual place was ...

Out with it…. 4

Ok, I’ll just say it… When I first started running into this stuff, choking the exhaust port area on a “cup” engine??? and making more power, everywhere??… I at first used to believe that I was looking at momentum and velocity “pulling” a depression behind it that was lasting through overlap at the end of ...

What tube size off the head? 23

Ok, easily one of the most common questions, so lets dive in. This subject is right off the bat too broad a question as it matters who is asking. It is one level above the question, “What size header…”, but both questions show the general lack of understanding available about exhaust systems. This is important: ...

A Fly on the wall…

Can we go back to say the year I was born, 1950?  Our much loved “small block” Chevrolet was a gleam in the eye of at least several engineers at Chevrolet, maybe giddy with reports of new casting processes or something they knew was gonna allow them to design a better engine for their own ...

Diving in… 8

I first want to address a issue that is fundamental in my approach to my work and headers in general. It didn’t take long for me to learn that there was a lot more going on in an exhaust header than “tuned” lengths and diameters. These two variables are of course critical to any application ...