Stepped headers

[AZlb5.0]

@91gt331sc are you going to tune your car?

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[91gt331sc]

The car is currently running the ford performance tune. Will be tuned for e-85 shortly!

 

[Decible]

They only make RHD ones. I already reached out. If ARH doesn’t have any options I’m going to go with lethal performance. They sell a set of Pypes stepped headers. Right now it seems they are the only ones with a set for 5.0s. Then it’s all about tuning and seeing how they work out. I’ll be making a thread once I get the car set up completely with nitrous and see how it all works together.

Kooks makes a set of 1 3/4 to 1 7/8 for the s550

 

[AZlb5.0]

Kooks makes a set of 1 3/4 to 1 7/8 for the s550

I saw they made them I don’t know if they still do. I’ll reach out and see if they are still manufacturing them for our cars. Thanks

 

[K4fxd]

I think I'd listen to @GregO and go with 2 inch.

 

[GregO]

I saw they made them I don’t know if they still do. I’ll reach out and see if they are still manufacturing them for our cars. Thanks

There’s a great Kooks write up about why they didn’t bother with 4-2-1 and step tube at the production level. The Kooks step tube mentioned in this thread are a unicorn.
If I find the article I’ll post it here.

 

[GregO]

I doubt we can be of much help to you, even though we have built more step headers than we could ever recall over a few+ decades.
Started building them in early '90s for our clients. I say we can not likely be of much help, because we were doing them for V8, NA, 2 valve, cam in block stuff, w/62.5+ cubic inches per cylinder, & occasionally something smaller in the 50" per cyl range.
(So no real experience with 4v EFI....& that does matter at least a bit, based on what we learned w/EFI vs carb signals, since step headers signal the intake tract harder)

Steps make more power in our experience. Never seen a set make less power, but on rare occasion, the gains were a bit close to negligible. Perhaps they were slightly sized wrong on rare occasion to net measurable gains. We are prof car builders. Our area of expertise is largely drag racing. We are Not professional eng builders. So we had to rely on our clients feedback from the pump (waterbrake dyno).
There is no real down side to them in a NA car, or an eng w/sniff on it, like you said you planned to run. On supercharged stuff we usually built headers, as large as what worked end to end- so No cross sectional area changes thru out the primary. Steps showed no gains in big boost programs.
We played around with 4-2-1 collectors for a few yrs,
(4-2-1's are not the same as a merge collector, & rarely used nowadays as I can tell. They add quitea bit of lengthto the pkg, & many cars justdon'thave the space nowadays)
as those usually made more mid range torque than a standard collector, & not as peaky as a merge collector output design.

Usually per the clients request, we built steps, in most cases. Custom racecars required custom headers, & building a set of headers is quite easy compared to the car itself. So we were in the business by default, until specialty header builders became much more prevalent in the industry. Freeing us up to do other things I suppose. We always had more work than the qualified man power to do it. So subcontracting anything usually benefited us.

Step headers signal a bit harder than straight primaries, so they may not be quite as beneficial (to your EFI situation) as it was for the bulk of our clients, who ran very high quality carbs, & just a handful of them running EFI, by comparison.
The EFI guys benefited more on power output, once they realized they needed something closer to batch fire EFI, when dealing w/cycle speeds well above 8000Rpm,
(vs a true sequential injection) which was eventually discovered to be needed to get the most out of everything. Carbs lay fuel on the back side of the valve when the intake ( or intakes) closes, by nature. This proved critical to understand, once we didn't have it with properly timed EFI, since you needed that rich fatty mixture when the valve 1st opened for the Combustion event, to give you a rich, stochiometric clump of air/fuel, to start & spread the flame front of a leaner mixture, of around 0.31 to 0.35 BSFC. Why is the EFI stuff relevant to a header? Because your increasing the signal with a step header. So understanding your fuel distribution/metering may be effected differently, than a closed loop 02 metering.
I say "may". Because I am not by any means an expert in this area-- 'Not our wheelhouse'.

We always thought sequential fuel injection ( before we had it in a hi quality system) was gonna give us something carbs never could, & we needed to get to the high resolution EFI systems that we knew technology would eventually bring to us, only to then find out that carbs were quicker than EFI, initially.
NHRA Pro Stock even proved that, as it took awhile for mandated EFI technology to run as qwik, & as much mph, as the carburetor stuff did. We didn't know how good the csrb experts had gotten at metering fuel, even with low, intermediate, & high speed circuitry. We gained even more respect for there skills in fuel distribution & homogeneous mixture control.

As for the actual header construction itself, we dont mind building step headers, because they go together a bit qwiker, (thus easier) & the only down side is there can be a small amount of increased waste from mandated cuts every so many inches as you travel down all 8 primary tubes.
Not really relevant, (the waste) since you can often use the drop pcs in the future on another set at some point. We kept bins if every size in scraps/drops, to use in future.
Our standard formula was close to (no exactly-just a example)
of a 1/3, - 1/3, & a 1/3, when doing a 3 step.
Some guys only do 2 steps. As to where to place the steps, in our area of eng types, ( nothing close to yours) we usually did ~8" out from the flange, on say, a ~28" long primary. The last length on a 3 step us usually the longest of the 3, obviously.

I have no way to quantify the actual hp/Torque gains on a 4 valve EFI, with less than 40 cubic inches per cylinder, like a 5.0L

As we said, we never saw a NA or a nitrous eng that made LESS power w/a step header, vs a straight cross section primary. May not make much more, but less is rather unlikely, unless boosted perhaps. Boosted to us means over ~38lbs thou, & closer to ~50+lbs.

So as I said in the beginning, this may be of no help to you. Good luck in what you decide. If I were building a set of headers for my own GT500, & staying under 20-25lbs of boost, Id be building step headers myself. We have our own 'Indian Tricks' to do near the collector, to fool the collector into thinking its a merge collector...
....vs the cost to buy, or the labor to build a full merge. They are labor intensive.
I dont even know if anyone in the "production header arena"
even builds a 4-2-1 collector these days?? or not,-- but they did make more power that a straight collector in our experience, on our clients stuff.
Well, more Torque I should say. Not necessarily much more peak hp. Pesk hp is overated in nearly everything that needs a reasonably wide/broad Torque curve.
Torque accelerates a vehicle, not hp. We just get an artificial Torque gains nowadays with these 7spd trannys like our 500, & the 10spd in the GTs & Mock. Torque multiplication by gear ratio, as opposed to being largely from the bk flange of the crank arm itself.

The ring & pinion doesn't really care how the LbFt of Torque got there. Packaging a 4-2-1 collector on 1 of these cars may prove to be prohibitive by space constraints.
& a good merge design will likely get you close enough. Yet, doubtful it will ever produce the midrange Torque of the 4-2-1, though, that we seen via the dyno. Again, our eng design/size experience are vastly different thsn a 5.0L eng. So take this info w/grain of salt.

None of the gains between everything discussed above are all so vast, that you must have any 1 design in particular, or your fate will be catastrophic. They all work. Even a straight header.
Regards,

Some insightful stuff here !
Your NHRA Pro Stock comments has my attention.
Whose headers are you referencing in your post ?

 

[AZlb5.0]

There’s a great Kooks write up about why they didn’t bother with 4-2-1 and step tube at the production level. The Kooks step tube mentioned in this thread are a unicorn.
If I find the article I’ll post it here.

That would be great if you could find that. I’ll search on the net also. Thanks for the post.

 

[GregO]

That would be great if you could find that. I’ll search on the net also. Thanks for the post.

https://www.enginelabs.com/engine-tech/exhaust/determining-header-design-affects-output-coyote-5-0/

 

[AZlb5.0]

https://www.enginelabs.com/engine-tech/exhaust/determining-header-design-affects-output-coyote-5-0/

Great read. A lot of good info. These engines are a breed all of their own though and that is shown by how much hp can be made even with small primary headers. There was little to no difference between the 1 3/4 and the 1 7/8 headers. It was impressive that they were able to make 700hp with the smallest of the headers. Which I agreed with the writer. Coming from the LS family it would be impossible to accomplish with an LS engine. Also the torque numbers were impressive with the 1 5/8 and they were only down 4hp at peak. I guess I’m just the nut chasing tq over peak hp.

 

[GregO]

Great read. A lot of good info. These engines are a breed all of their own though and that is shown by how much hp can be made even with small primary headers. There was little to no difference between the 1 3/4 and the 1 7/8 headers. It was impressive that they were able to make 700hp with the smallest of the headers. Which I agreed with the writer. Coming from the LS family it would be impossible to accomplish with an LS engine. Also the torque numbers were impressive with the 1 5/8 and they were only down 4hp at peak. I guess I’m just the nut chasing tq over peak hp.

Chasing a unicorn will grind you down.
OEM Ford primary’s are a touch smaller than 1.75” (44mm)
Just go 1.875” or 2.0”, it really is that simple.
Now your cam timing, that’s the unicorn to chase. Pick your tuner wisely.

 

[AZlb5.0]

Chasing a unicorn will grind you down.
OEM Ford primary’s are a touch smaller than 1.75” (44mm)
Just go 1.875” or 2.0”, it really is that simple.
Now your cam timing, that’s the unicorn to chase. Pick your tuner wisely.

Seriously I’m chasing ghost
Thanks

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