FlyinTomato

I recently picked up a set of used headers. They are B&Bs. I didn't know there was a dent until I received them. I was wondering what this might do to performance, not that I will notice if there is any effect from the dent anyway, but I was intrigued.

So I went on searching for an answer to this, and I came across this video. Just to put this to rest. the answer is "it doesn't matter!" besides cosmetic.

The video is interesting. Hosts did a base line dyno with smooth header, went on smashing the tubes, then performed a few more dynos.

HDA

Interesting.

So you bought the ones I saw on eBay last week for $500 obo ?
I was tempted to get them too but the "box" at the headers' exit just looks too much against physics to me.

Keep on searching...ok if dented

rkwfxd

Fill it with water a freeze it. Might take a couple of times but the dent should come out.

-nick

Interesting video. Truly seems hard to believe. Possibly the header tubes were already too big, so squeezing them down made no difference? Weird all the same

FlyinTomato

Thanks for the idea. The dent is at the collector near the flange. It might be difficult.

JohnK964

I think there would also be a good chance of the freezing water to cause more damage to the headers

Porschenut_Lee

I would think that it would have to have an effect. Maybe on that particular car with those headers it had no effect, but reducing the cross section and disrupting the laminar flow defeats the purpose of having headers.

Porschenut_Lee

Does engine design and displacement make one engine more sensitive than others to header effects? In other words, does a 3.6 flat six vs a large displacement V8 require more attention to flow characteristics?

ilko

I would just return them. Ebay has a pretty good return policy these days. Life is too short to install crappy parts on your car, Ken.

A914MAN

I call them Bernoulli bumps but I'd prefer not to have them.

rkwfxd

Has never been a problem with motorcycle headers. Pretty common fix.