header primary size

I have done a search and not really found a specific answer to my question. I'm in the planning stages of building a 557,A429's ported with unknown flow numbers , around 14-1 and a custom ground cam (unknown specs yet, but will be an all out roller deal)victor 460 with a 1050 dom bigger if I can come across one. This is in a mudtruck and I want to do away with the up-draft headers and go with a fender well/side  exit header. Dynatech has a side exit kit that is 2 1/4" to 2 3/8" step to a 4" collector. This kit has bbc flanges and I plan on using Shoenfeld flanges and short 2 1/8" stubs into the 2 1/4". From what I find a 2 1/4" would be ideal , will the 2 1/4" to 2 3/8" be to big?

mudtrucker wrote:I have done a search and not really found a specific answer to my question. I'm in the planning stages of building a 557,A429's ported with unknown flow numbers , around 14-1 and a custom ground cam (unknown specs yet, but will be an all out roller deal)victor 460 with a 1050 dom bigger if I can come across one. This is in a mudtruck and I want to do away with the up-draft headers and go with a fender well/side  exit header. Dynatech has a side exit kit that is 2 1/4" to 2 3/8" step to a 4" collector. This kit has bbc flanges and I plan on using Shoenfeld flanges and short 2 1/8" stubs  into the 2 1/4". From what I find a 2 1/4" would be ideal , will the 2 1/4" to 2 3/8" be to big?

That all depends upon how high in the RPM range you intend for it to run.

rmcomprandy wrote:

mudtrucker wrote:I have done a search and not really found a specific answer to my question. I'm in the planning stages of building a 557,A429's ported with unknown flow numbers , around 14-1 and a custom ground cam (unknown specs yet, but will be an all out roller deal)victor 460 with a 1050 dom bigger if I can come across one. This is in a mudtruck and I want to do away with the up-draft headers and go with a fender well/side  exit header. Dynatech has a side exit kit that is 2 1/4" to 2 3/8" step to a 4" collector. This kit has bbc flanges and I plan on using Shoenfeld flanges and short 2 1/8" stubs  into the 2 1/4". From what I find a 2 1/4" would be ideal , will the 2 1/4" to 2 3/8" be to big?

That all depends upon how high in the RPM range you intend for it to run.

I would say 68-7000 rpm would be the upper limits with my A429's.

Personally I would use 2" to 2 1/8" with those heads, engine size and RPM limit. A 4" collector about 20" long.

I used 2" Mad Dog fenderwells on our truck with nearly an identical combination. I just don't think a 2.25" header does anything for an A429, because of the poor exhaust port

Get with a header designer with a good reputation like Calvin Elston or Wes @ Pro Header. There are a number of factors you need to take into consideration. Mostly is how much power you're going to make, not necessarily rpm. What's your ex port exit opening size?

dfree383 wrote:From my experience bigger is better.

That is almost never true in just about any aspect of building an engine.

mudtrucker wrote:I have done a search and not really found a specific answer to my question. I'm in the planning stages of building a 557,A429's ported with unknown flow numbers , around 14-1 and a custom ground cam (unknown specs yet, but will be an all out roller deal)victor 460 with a 1050 dom bigger if I can come across one. This is in a mudtruck and I want to do away with the up-draft headers and go with a fender well/side  exit header. Dynatech has a side exit kit that is 2 1/4" to 2 3/8" step to a 4" collector. This kit has bbc flanges and I plan on using Shoenfeld flanges and short 2 1/8" stubs  into the 2 1/4". From what I find a 2 1/4" would be ideal , will the 2 1/4" to 2 3/8" be to big?

It'd depend on how low rpm you leave at and how high you are going to turn it. At any rate, I don't think the 2-3/8" has a seat at the table. Primary tube length is a consideration also.

dfree383 wrote:

Scott Foxwell wrote:

dfree383 wrote:From my experience bigger is better.

That is almost never true in just about any aspect of building an engine.

BBF stock style heads like big tubes, seen it a number of times.

I know it goes against conventional wisdom.

Yeah, 'cause they're "special" I guess. It doesn't go against conventional wisdom, it goes against conventional physics. Wisdom has nothing to do with it.

WTF ever.....not every head likes the same primary tubes. In this case it's just observation.

mudtrucker wrote:I have done a search and not really found a specific answer to my question. I'm in the planning stages of building a 557,A429's ported with unknown flow numbers , around 14-1 and a custom ground cam (unknown specs yet, but will be an all out roller deal)victor 460 with a 1050 dom bigger if I can come across one. This is in a mudtruck and I want to do away with the up-draft headers and go with a fender well/side  exit header. Dynatech has a side exit kit that is 2 1/4" to 2 3/8" step to a 4" collector. This kit has bbc flanges and I plan on using Shoenfeld flanges and short 2 1/8" stubs  into the 2 1/4". From what I find a 2 1/4" would be ideal , will the 2 1/4" to 2 3/8" be to big?

My combo is very similar to what you plan on building. I'm 14.1 521 vid decent size solid roller and well worked A429 heads. Under a port matched victor intake with some plenum work also. When we dyno'd the enginge we ran the Dyno guys headers because He had egt bungs welded in each cylinder. They were just a cheap 1 7/8 truck header that he bought because he knew they would clear the Dyno and not get in the way of the oir filter. We made 782 with his headers. After we were done tuning I asked if I can try my headers and see if they would clear his Dyno. They are 2 1/8 primaries with a 4" collectors. Made to fin in a fox body, long story short they made nearly 30 HP less then the small tube truck headers. We figured it was either way to large of primaries or the tight turn the headers make to clear the engine bay of the mustang.

I went home sweating my head, I'll pro try building a new set of step headers this winter and try to keep the bends as far away from the head flange as possible.

dfree383 wrote:

Scott Foxwell wrote:

dfree383 wrote:

Scott Foxwell wrote:

dfree383 wrote:From my experience bigger is better.

That is almost never true in just about any aspect of building an engine.

BBF stock style heads like big tubes, seen it a number of times.

I know it goes against conventional wisdom.

Yeah, 'cause they're "special" I guess.  It doesn't go against conventional wisdom, it goes against conventional physics. Wisdom has nothing to do with it.

I'll take real results over theory anytime, but that's just me. Calculate on oh wise one.

And please I hope the site can forgive my unscientific wrenching, results and observation. I'll do better next time and do the math to prove the results

Your first statement was "from my experience bigger is better". VERY general statement. Bigger and better than what? So, what, go ahead and put a 2-1/2" primary on a "stock style" head (whatever that is)? Why stop there? How about 3"?
Sorry...I deal with this kind of nonsense on a daily basis...general statements that do go against basic experience and knowledge. Has nothing to do with calculations or math (well, it does to some extent), has everything to do with the physics and there are SO many variables that most of the time, and this is a perfect example, you simply can't make a general statement like you did. Especially with heads and cams; the whole "bigger is better" thing very, very seldom is true but because of mass marketing, when a lie gets repeated enough times, it becomes truth...till you get to the track.
Where's your testing? What heads, what engine, what headers? Back up your statement with some examples and facts.

fe50stang wrote:

mudtrucker wrote:I have done a search and not really found a specific answer to my question. I'm in the planning stages of building a 557,A429's ported with unknown flow numbers , around 14-1 and a custom ground cam (unknown specs yet, but will be an all out roller deal)victor 460 with a 1050 dom bigger if I can come across one. This is in a mudtruck and I want to do away with the up-draft headers and go with a fender well/side  exit header. Dynatech has a side exit kit that is 2 1/4" to 2 3/8" step to a 4" collector. This kit has bbc flanges and I plan on using Shoenfeld flanges and short 2 1/8" stubs  into the 2 1/4". From what I find a 2 1/4" would be ideal , will the 2 1/4" to 2 3/8" be to big?

My combo is very similar to what you plan on building. I'm 14.1  521 vid decent size solid roller and well worked A429 heads. Under a port matched victor intake with some plenum work also.  When we dyno'd the enginge we ran the Dyno guys headers because He had egt bungs welded in each cylinder. They were just a cheap 1 7/8  truck header that he bought because he knew they would clear the Dyno and not get in the way of the oir filter.  We made 782 with his headers.   After we were done tuning I asked if I can try my headers and see if they would clear his Dyno. They are 2 1/8 primaries with a 4" collectors. Made to fin in a fox body, long story short they made nearly 30 HP less then the small tube truck headers.  We figured it was either way to large of primaries or the tight turn the headers make to clear the engine bay of the mustang.  

I went home sweating my head, I'll pro try building a new set of step headers this winter and try to keep the bends as far away from the head flange as possible.

Actually, those RESULTS are a pretty common happening.

dfree383 wrote:Simple Engine

14:1 466 with Eddy RPM heads ported by me

Home built tunnel ram and 2x1050s again home built from old junk cores

Base 2" dyno headers

Rpm TQ HP
5500 607 646
7500 536 765
Peak TQ 5800  628
Peak HP 7300 777

Switch to 2 3/8 dyno headers

5500 626 655
7500 555 792
Peak TQ 5900 643
Peak HP 7300 800

Observed similar results with P-51 heads on bigger inches too, not theory dyno'd observations

Again...one engine, two sets of headers we know nothing about except one dimension, and a hundred other variables. You can't make a general statement like you did based on this. That doesn't help anyone.

dfree383 wrote:

Scott Foxwell wrote:

dfree383 wrote:Simple Engine

14:1 466 with Eddy RPM heads ported by me

Home built tunnel ram and 2x1050s again home built from old junk cores

Base 2" dyno headers

Rpm TQ HP
5500 607 646
7500 536 765
Peak TQ 5800  628
Peak HP 7300 777

Switch to 2 3/8 dyno headers

5500 626 655
7500 555 792
Peak TQ 5900 643
Peak HP 7300 800

Observed similar results with P-51 heads on bigger inches too, not theory dyno'd observations

Again...one engine, two sets of headers we know nothing about except one dimension, and a hundred other variables. You can't make a general statement like you did based on this. That doesn't help anyone.

Have at it and post your dyno findings on a stock type Ford head please, Im waiting for your real world data..... Proceed and contribute something other than an argument.

My argument is, and will always be, against misleading general statements from almost zero information. One engine, one dyno session, two sets of headers, does not make a consensus. All you found was that bigger headers than 2" made more power on an 800hp engine. Well duh. Did you try 2-1/8? Did you try 2-1/4? How do you know one of those might have not made even more power? Your torque is down for the combination, and that's usually a sign of too big a primary pipe when it comes to headers, regardless of peak power. When you try 10 sets of headers on the same engine, record all the tube and collector diameters and lengths, distance from the port of the bend, collector style, etc. and it proves that the biggest header made the best power, THEN, MAYBE you can make such a general statement. I don't have a problem with your findings and not arguing against them at all. They're just no where near conclusive.

dfree383 wrote:When you going to post some real data? How about you spend some time testing 6-10 sets of headers on your time and dime? And post up the results? Your a big time builder show us what you got.

I didn't make the statement and I have tested many sets of headers on many different engines over the years. Funny... not one set ever asked if it was on a Ford or Chevy. How bout we keep this technical and not get personal. Can you explain why the "'stock style" BBF head is so different?
Or, just let it go.

Im not a real good internet forum guy but I feel like Im a pretty good engine guy! If you need someone to tell you why a Ford Head needs or deserves a different header maybe you should not be giving advice. Next most of those dyno numbers were done at my shop! We dont serve up the Bs here like several of you guys do!

I would give all READERS some advice PAY attention to who is getting it done in REAL world situations and not get caught up in alot of these so called facts!

Oakley Motorsports wrote:Im not a real good internet forum guy but I feel like Im a pretty good engine guy! If you need someone to tell you why a Ford Head needs or deserves a different header maybe you should not be giving advice. Next most of those dyno numbers were done at my shop! We dont serve up the Bs here like several of you guys do!

I would give all READERS some advice PAY attention to who is getting it done in REAL world situations and not get caught up in alot of these so called facts!

Not pretty good, "Damn Good"!