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depends if youre in the northern hemisphere or southern hemisphere....
I know that was answer was coming right after I hit submit.
 

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Calvin,

we have seen your thoughts on headers with few bends and therefore straighter, making them relatively short i.e. certainly not adding a bunch of bends and such to make achieve a certain length. At what point do you worry about not having enough length and the tradeoff from achieving the length.
So you get a length recommendation from burns of 28" if you need a bunch of bends 120-180* to get them from 20" to 28" (just random example) do you ever do it even though its going to hurt upstairs? i gather it depends how wide the power needs to be which comes down to the application?
or do you believe if you make it fast enough and with enough anti reversion the shorter can act close enough to a longer? i just see the F1 headers from >5 years ago and they are deliberately making them longer than what would produce the most upstairs.
I always work to get as close to the same length as possible. Some cars lend themselves to easily get equal length so next on list of priorities is smoothness and the smoother it can get the smaller the tubes can be for longer. At that point it is experience as to how small I think I can go.

It is not uncommon to see unequal length as much as 6 inches. I would have to call that cross tuning. It was common in Cup 4into1 headers in the 90's. I am able to get a SB early camaro to within a inch on a 4into1 in a stocker or SS, but 421's are a lot trickier and there are some secrets in those I won't mention.

Bottom line answer is experience is a big player. A lot of my headers get copied.

Now F1 is a entirely different animal. They have to give up on any velocity and do not need it. You are just looking at flow. They do play with large steps as tuned length does operate even though the tubes are really big. They are equal length and incredible pieces.
:eek:
 

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The master has spoken.... Calvin is at the top of the food chain in the header game.... I will say this about stocker headers..... we have found, with dyno testing and track proven that we dont really care about equal length and there are a couple reasons why.... the first is why would I want to make an equal length header when the stock intake manifold is not equal in length in its runners?? A big player in that is packaging in the early 69 camaro can be tough..... I worry more bout collector pulse timing than I do anything else and firing order rotation is a big player in that..... everybody gets their chance to exit the collector and pull the following pulse with it......
 

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Can A header or Exhaust system over scavenge, and what are the results of it, if it does?
 

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Tough to say, but I imagine 5-25+, depending on how "fairly good" they were!
We see 1-3 between a perfect set, and a more perfecter set! Lol
Cool, easy to show pics now. Looking for opinions on these new 2" for my next 408c build. These are for cleveland A3 heads on 9.2 deck in a fox mustang. Just a street strip car.
 

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BOSS, looks good to me, but what do I know? 🤷‍♂️ What RPM are you going to turn?

Can A header or Exhaust system over scavenge, and what are the results of it, if it does?
My not very well educated guess is no, because then you could shorten up overlap which would be a win.
 

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BOSS, looks good to me, but what do I know? 🤷‍♂️ What RPM are you going to turn?

My not very well educated guess is no, because then you could shorten up overlap which would be a win.
Darin said to shift it at 8600, I'm hoping to stay below 8200 but... A couple tubes turn downwards close to the port exit and the last pic with the pipe wrapping around the other concerns me a bit as far as flow goes but other than that they seem to have nice smooth bends to me, but I have no idea
 

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As far as turning right at the port exit, yeah #5 doesn't look so great, but you either move the header out of the way of the chassis or vice versa, and moving the chassis out of the way isn't always feasible.
 

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As far as turning right at the port exit, yeah #5 doesn't look so great, but you either move the header out of the way of the chassis or vice versa, and moving the chassis out of the way isn't always feasible.
Yeah, #4 and #5 are similar, but beggars can't be choosers, lol. Hopefully the 2" size helps with the poor turn. Seem to be clocked to me, 1-3-7-2-6-5-4-8 and a thick wall header also, 3.5" collector and close to equal length
 

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heh Blake who's monte in the shop? never pictured you a closet chevy guy lol
Hey Rick, how ya been. That's my race car, you chevy guys keep putting 350's in fords so I put my cleveland in an SS, best part is it's slow as shit and everyone thinks it's a 350, lol. No, that's my dads monte and his garage, I'm still building mine. Car is mint, he has 355 in it, ran 12.8 at 112 with slicks, he still has original 305. You get that motor of yours together?
 

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fuk thats pretty funny ya had me going for a sec sound like a nice ride for a chev . I'm good ,negative on the clevor being back together still going my usual 3 different directions at any given time . good to see your getting closer with yours .
 

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Now F1 is a entirely different animal. They have to give up on any velocity and do not need it. You are just looking at flow. They do play with large steps as tuned length does operate even though the tubes are really big. They are equal length and incredible pieces.
:eek:
can you elaborate why they dont need veloicity?
 

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