STEPPED HEADERS

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STEPPED HEADERS

Post  stanger68 on April 15th 2018, 8:38 pm

I'm building a A headed 557. I'm considering building my own headers and was just wondering if its worth the effort to try and step 2 1/4 to 2 3/8" or just take the easy route and do straight 2 1/4" out the side?

Dynatech has a kit for this but I think they're stretched at the joints like muffler pipe looks kinda cheesy to me. So if I do it it'll probably be done the hard way. plus I don't have TIG machine just a MIG.

How much power is going to be worth in the end?

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Re: STEPPED HEADERS

Post  BBFTorino on April 15th 2018, 8:46 pm

A lot depends on the whole combo. Some engines respond better with a stepped header, while others don't.

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Re: STEPPED HEADERS

Post  rmcomprandy on April 15th 2018, 11:16 pm

Getting them the correct length and also the collector size and length correct will be a whole lot more important

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Re: STEPPED HEADERS

Post  TravisRice on April 16th 2018, 5:05 am

Calculating the length and collector size is the hard part. I just built a set of 2-1/8 to 2-1/4 into 4inch for a 535 Pontiac. Bulter built the engine and provided the spec on the header for the application as they are Pontiac gurus and assemble these engines daily.

The 2-1/8 slides inside the 2-1/4 and created the step without having a bell on the pipe. Likewise in your case. The header total length and the steps are calculated off the valve.

I would take the time to have someone tig weld them though. If you decide to tack them together with the mig and take them somewhere to get tigged you really need to make sure you clean the inside and outside of the tubing well. Buff with scotchbrite the outside joints and make sure the fits are gapless. Lacquer thinner works well on a saturated rag that you can pull through the inside. DONT use chlorinated brake cleaner. The fumes will take your breath away once you start welding on them and is quite deadly, so think of the next guy before you do this.


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Re: STEPPED HEADERS

Post  dfree383 on April 16th 2018, 6:04 am

Correct inductions and headers are what most engines lack.

And it makes a lot of potential hero’s just another build
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Re: STEPPED HEADERS

Post  stanger68 on April 16th 2018, 10:59 pm

rmcomprandy wrote:Getting them the correct length and also the collector size and length correct will be a whole lot more important

That's exactly what I was thinking. Is there a formula for sizing the primaries?

TravisRice wrote:Calculating the length and collector size is the hard part. I just built a set of 2-1/8 to 2-1/4 into 4inch for a 535 Pontiac. Bulter built the engine and provided the spec on the header for the application as they are Pontiac gurus and assemble these engines daily.

The 2-1/8 slides inside the 2-1/4 and created the step without having a bell on the pipe. Likewise in your case. The header total length and the steps are calculated off the valve.

I would take the time to have someone tig weld them though. If you decide to tack them together with the mig and take them somewhere to get tigged you really need to make sure you clean the inside and outside of the tubing well. Buff with scotchbrite the outside joints and make sure the fits are gapless. Lacquer thinner works well on a saturated rag that you can pull through the inside. DONT use chlorinated brake cleaner. The fumes will take your breath away once you start welding on them and is quite deadly, so think of the next guy before you do this.


Is there a minimum length that will yield any measurable increase when stepping them up? What I mean is If I did step them up, at what point is considered the ideal location for a step? middle of the run, first 25%, last 30% ?? I haven't been able to find any books on header fabrication that address these questions.


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Re: STEPPED HEADERS

Post  rmcomprandy on April 16th 2018, 11:32 pm

stanger68 wrote:
rmcomprandy wrote:Getting them the correct length and also the collector size and length correct will be a whole lot more important

That's exactly what I was thinking. Is there a formula for sizing the primaries?

TravisRice wrote:Calculating the length and collector size is the hard part. I just built a set of 2-1/8 to 2-1/4 into 4inch for a 535 Pontiac. Bulter built the engine and provided the spec on the header for the application as they are Pontiac gurus and assemble these engines daily.

The 2-1/8 slides inside the 2-1/4 and created the step without having a bell on the pipe. Likewise in your case. The header total length and the steps are calculated off the valve.

I would take the time to have someone tig weld them though. If you decide to tack them together with the mig and take them somewhere to get tigged you really need to make sure you clean the inside and outside of the tubing well. Buff with scotchbrite the outside joints and make sure the fits are gapless. Lacquer thinner works well on a saturated rag that you can pull through the inside. DONT use chlorinated brake cleaner. The fumes will take your breath away once you start welding on them and is quite deadly, so think of the next guy before you do this.


Is there a minimum length that will yield any measurable increase when stepping them up? What I mean is If I did step them up, at what point is considered the ideal location for a step? middle of the run, first 25%, last 30%  ?? I haven't been able to find any books on header fabrication that address these questions.


The diameters are all about air speed and heat expansion at a certain RPM.
The lengths are all about sound wave tuning at a certain RPM
At the moment ... the "Pipemax" program predicts the closest results I have witnessed..

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