LocostUSA.com

Well, it might not matter after all what we do with the headers, so long as we get the exhaust out away from the motor and driver?

This show examines the question of what happens to HP and torque when you bash a header pipe or two... or four... or 8.

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

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Geek49203 aka
Tim Wohlford
Louisville, KY
Hayes front, S10 +2 rear, Lalo body.

WOW! That video certainly shatters every preconceived notion I've ever had.

This sure opens the door to much more DIY exhaust systems without worries.

Maybe we ought to show this video to the F1 engineers which ought to save them a bunch of $$$$.

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mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

I'd heard from a real honest to God exhaust engineer that larger pipes are overrated. I think I posted those comments here too. So the idea that these headers can be dented and still perform isn't all that shocking to me?

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Geek49203 aka
Tim Wohlford
Louisville, KY
Hayes front, S10 +2 rear, Lalo body.

Resistance is always a function of diameter TIMES distance.

On a side note kiddoes. NEVER strike one hammer head against another, without safety glasses on!

Tom

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Sometimes, I'm as confused as a baby in a topless bar.

My short term memory is absolutely horrible and so is my short term memory.

https://www.youtube.com/watch?v=sG16m2e4O6I

Tim
I do believe that you are right about tube size! If you have over-sized header tubes 1 3/4" Vs 1 5/8 or 1 1/2" Dia. on a SB
You can beat the $hit out of the tubes and have little affect on HP.
I do believe, a local dent in a header tube is not going to kill you. Dave W

I love those Saturday morning shows...

"We removed the 2 1/2" exhaust pipes and installed 4" pipes that were provided by our sponsor..."

"We installed a K&N cold air intake system which replaces all of this stuff (throws OEM intake towards camera)..."

"We installed a lowering kit provided by our sponsor which will make it look really great..." (as if they ever took it out for a handling test before / after??)

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Geek49203 aka
Tim Wohlford
Louisville, KY
Hayes front, S10 +2 rear, Lalo body.

there are two types of car people..

those that modify them for looks and sound

Those that modify them for driving.

All of those shows cater to the same crowd.. the people who want to drive 3 miles to their local cars n coffee every other week and have people look at their car.

Part of the reason I like fast n loud.. there's a smidge of sponsorship in there, but for the most part its doing rad stuff to cars, and burn outs.

And when I'm feeling extra technical, graveyard carz.

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Tucker

Need to start a thread on the Velocity et al TV shows?

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Geek49203 aka
Tim Wohlford
Louisville, KY
Hayes front, S10 +2 rear, Lalo body.

Fun video. As others are mentioning, the header design research I've done points to most headers being oversize (often considerably so) for the majority of engines they'll actually end up on. Especially for off-the-shelf headers on street engines, but even for custom headers on race engines too. Of course, in all of their rambling of specs on that engine, they never actually specified the diameter of the primaries on that set of headers. Based on how much they were able to bash them down beyond just a few minor localized restrictions, I would guess that these too were at least somewhat oversize.

That said, their point of brief restrictions in the flow path not being as big of a deal as many (most?) people would expect, is still a valid lesson. Essentially, as long as flow at the localized restriction doesn't approach the speed of sound, it should still flow through pretty well.

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-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

Another good (but not as entertaining) video on exhaust design:
Interview with experienced exhaust designer:
https://www.youtube.com/watch?v=RWTARjxiqlo

Long story short, header size *should* be same as exhaust port in head.

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Build log: viewtopic.php?t=9291

That first video is surprising how much they could smash the tubes and not affect power, I never would have guessed. As far as tube size, I always thought they were supposed to be slightly bigger than the exhaust port so there's a slight step to help stop exhaust flow from reversing back into the port.
Kristian

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V6 in a book frame build. Now registered.
viewtopic.php?f=35&t=7587
viewtopic.php?f=33&t=18172

...and my buddy's been fretting about having to make a 1/8" shallow dent in one pipe for frame clearance...I think this ought to put his mind at ease.

Kind of gives one pause to ponder at the claims of some of the header manufacturers, doesn't it?

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Scratch building, at continental-drift speed, a custom McSoreley-design framed, dual-Weber 45DCOE carburated, Zetec-engined, ridiculously fast money pit.

http://zetec7.webs.com/

Absolutely. Last project I hand built my headers and went with 1 5/8" primaries which I thought were overkill - but left room for a bigger cam if I chose to do so.

I also custom clearance a downpipe or three for some turbo Subaru swaps into places they weren't supposed to be. nice 5 lb deadblow modifications and didn't lose a single hp over it.

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Tucker

I guess I was surprised that the torque curve wasn't affected more. Smaller primaries (I'd think) would produce a bit more torque early 'cause it would (probably) speed up the velocity, but you'd pay the price in the top end?

But that didn't happen?

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Geek49203 aka
Tim Wohlford
Louisville, KY
Hayes front, S10 +2 rear, Lalo body.

When you put the high-performance "Long Center Branch" type headers on an MGB with left hand drive, the steering shaft interferes with the header. The ancient and accepted way was to "clearance" (Read that as "Beat hell out of") the header tube with a small sledge. Nobody batted an eyelash over it... I sure didn't...

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JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom