Crunched/crushed primary Header tubes and the effect on power

[Qikbbstang]

This could make for an interesting addendum to TGFEIC's Header Tests:


David Freiburger does a "smashing" exposé on headers....


https://www.youtube.com/watch?v=azPKIjxmmdU

[57 lima bean]

Maybe the primary tubes were to big in the first place.

[Chrisss31]

It's just like the age old finger at the end of a garden hose!  It's a common discussion in the heating/plumbing industry, the idea is that if there is a restriction in the pipe (dent, valve, smaller ID fitting etc.), fluid or air in this case will move the same volume but at a higher velocity at that restriction.  Some people think that if you have a 1" pipe with a 1/2" hole at one end, the pipe will only flow as much as a 1/2" pipe.  It's untrue.

[Autoholic]

Kinda surprising it didn't matter but then again, it wasn't a uniform restriction of consequence. The insides are still smooth. Ideally, the least amount of restriction is the best way to go and even if denting it didn't impact performance, it looks like crap. This does make me wonder about using a sonic orifice (choked flow) at the beginning of the primaries as a way of preventing reversion due to sonic waves. If designed properly, it might even increase power. Really well designed merge collectors already use a converging-diverging nozzle to improve flow, now that I think of it. The critical part to focus on would be the velocity across the restriction, ensuring that it is fast enough to prevent unnecessary back pressure.

[thatdarncat]

I dug this out of the attic of shame. Drivers side Hooker Super Comp from my Mustang. I was backing the race car off the trailer one Sunday morning at the dragstrip when the lower edge of the collector caught on the trailer and shoved the whole header toward the front of the car. I had raced the car Saturday but at the time there were no time trials Sunday morning - right into eliminations. I didn't go back here and dig out my log book, this was quite a few years ago, but it probably wouldn't matter, I certainly didn't do any A-B-A testing, and there may have been other variables that day, I just remember guessing the car would slow down and it really didn't. The results Freiburger found don't surprise me. I will guess you would probably see more of a difference on something like a NHRA Pro Stock car where a lot of testing has been done to optimize the best possible header design. And as we've seen, on our shock tower Fords the header design is already compromised by turning the tubes down sharply right after the port.

[mygasser]

seeing those pics made me chuckle. i did the same on a low kerb on an industrial estate near me in a 66 fairlane gta i used to own. the hookers were quite old and it wrapped itself round the steering, not good.