Header Primary Pipe Size

Enginerd

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I'm still a newbie on this thread. And to these trucks. I'm loving my 93 extended cab f250hd. I just swapped to a 5 speed, and I'm super happy I did. I just think a 5 speed is natural behind these engines. I've put in a good exhaust, a few gauges, fixed lots of odds and ends, and it's serving well as a daily driver.
Anyways, I've been absorbing all I can off this forum. Like watching the current performance overhaul Project Big Blue by Thewespaul and learning from that. Boy there's a lot to learn!

I want to use this 93 truck as my NA platform. I have a 91 "diamond in the rough" that I picked up and it will be my turbo platform because it has the nice banks sidewinder kit already on it.
I'm keeping this 93 naturally aspirated. I understand boost is the way to go for power, economy, etc. But I think I may have something up my sleeve...

I've been working hard to develop a new algorithm for header design. I think I've nailed it - this set of formulas I've built up should create a perfectly rhythmic pulse through the collector and provide the foundation for maximized scavenging.

The advantage to applying it to these engines is that I have a baseline of dyno'd trucks to reference. If I can come even close to a 10 psi turbo, it would be completely worth it to me. The disadvantage is there is almost no valve overlap, so scavenging may not help as much as with other engines. But I still want to try it out.

My plan is to build
1. a set of equal length 40" primary headers as the control
2. a set of headers applying my algorithm
3. and a set of headers applying my algorithm that follow the tri-y design.
One hour on the dyno cost $150 just 20 miles down the road from me. I want to dyno manifolds, equal length, my algorithm, and my tri-y algorithm and see the comparison. It should cost me about $800 to do this experiment if it all goes according to my plans.

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I want to hear your thoughts on my primary pipe diameter because I am still hesitant. I'm thinking a 1 1/2" will be good because that should allow enough flow for this diesel staying below 3,200 and making 200-250 flywheel hp, while still maintaining velocity. It won't choke it though right? Or be too big? What is the diameter on those Stans headers?
What are your thoughts? Or votes? Or experiences? Thanks for the help. It's $150-$200 for materials to build a set of headers and I want to do good on the first try.

And sorry for being so long-winded, I guess I get too excited sometimes :)
Plus I have to explain why I'm not just putting a turbo on it haha!
 

IDIBRONCO

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What is the diameter on those Stans headers?
It was dark and I was using a flashlight the best that I could. The outside diameter appears to be 1 3/4" so I'd guess that the inside diameter would be about 1 5/8".

Plus I have to explain why I'm not just putting a turbo on it haha!
I remember that you've had a post or two about this in the past. You're wanting to experiment with your own ideas.
What are your thoughts?
As Wes and I said before, go for it! Even if it doesn't meet everyone's approval. Who cares? It's your truck, your time, and your money. Do with it whatever you want and don't listen to any naysayers. I enjoy hearing about the experiences of those who are willing to think (and do) outside the box. Even if it doesn't produce the results that you're hoping for. Most of us can't say that we've tried something completely different (me included). I can remember reading about one or two who experimented with mounting a blower on their IDIs. IIRC, they just couldn't find small enough pulleys to get much boost due ti the low RPM of our engines.
 

Enginerd

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Alright thanks. I'll go with the 1 1/2" OD. I would lean towards 1 3/4" being too big for the low rpm and low hp, and maybe that's why no one feels like they do too much.
Hopefully within a month or two I'll be able to post up some results. I just wanted to get all the issues sorted out first with the truck before fooling with headers. Now that I feel like I'm on top of it (knock on wood) I'll get to crackin
 

Thewespaul

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Sounds cool! I've gone down the na performance route a bit but never got as far as building some good headers, I mostly focused on the fueling part and cylinder heads. I haven't ported a million idis, but the best performing set I've done had a 1 3/4" diameter, with the stock port size being about 1 5/8". If you're using a smaller diameter header than the port, then make sure there isn't a step, and that the exhaust is funneled into the pipe, otherwise there is going to be some significant turbulence that will hurt exhaust flow. What I found really makes the biggest difference on an na engine is the fuel system especially the calibration of the injection pump's governor.
 

Enginerd

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I want to dyno manifolds, equal length, my algorithm, and my tri-y algorithm and see the comparison.

Yeah I had mentioned that as THE baseline in the middle of the long winded post. The equal length would be the baseline as far as performance headers go since those are typically regarded as the best.
 
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Enginerd

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What I found really makes the biggest difference on an na engine is the fuel system especially the calibration of the injection pump's governor.

Is there some word I can search to bring up more info on this? I'd like to know what exactly you mean by this. And how to do it.
 

Thewespaul

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I have a thread called “building a better db2” that has some good pump info, and the db2 tuning guide has some good info for getting more performance from a stock pump, but it’s no replacement for a built and calibrated pump. With turbocharged engines you get the most performance from increasing the fuel output which is straight forward on a stock pump, however on an na application you’re pretty limited in the fuel it can burn, so you get the most improvement in performance by dialing in how that fuel is delivered and maximizing the efficiency of the fueling you can burn. Unlike just increasing fueling across the board, that fine dialing is something you’re only going to achieve setting the pump up on a test stand, where you can see the temp of the fluid, the injection quantity, the injection timing and duration all in real time.
 

Enginerd

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Ah, okay I'll check into that. Thanks.

All I've done fuelwise is turn it down from when I got the truck. It still is getting more than plenty of fuel because it can dump black smoke and send the egt's to 1100 quickly.
Just last week someone gave me (for free) a spare injection pump that I should probably try to learn from.
 

IDIBRONCO

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and maybe that's why no one feels like they do too much.
I think it's mostly people confusing "flow" and "pressure" (from a turbo). With little pressure, there's only so much that our engines can flow.
I've gone down the na performance route a bit but never got as far as building some good headers,
You've still got mine spoken for if I can ever get the freaking turbo put on this thing! That is if you still want to trade.
 

Clb

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Yeah I had mentioned that as THE baseline in the middle of the long winded post. The equal length would be the baseline as far as performance headers go since those are typically regarded as the best.


SLIPPED right by ... nice bit of tech.
 

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