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Old 11-28-2016, 10:44 PM   #1
I--RIDE--BIKES
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Default Header design

Im a huge DIY sort of guy and am taking a stab a making my own header right away here to work with my BW s362sx-e and fully built engine. Goals are 500 whp roughly on pump 94 oct and meth, and 700 whp on e85 with quick spool around 4500 rpm.

Now I think I've settled on the usual 4-2-1 design over the 4-1 due to its lower merge angles and more symmetrical design. I will obviously be making it equal length unlike my Tomei "EL" headers (2 primary runners are a full 4" longer than the others).

So essentially this is the plan:
-Fully back purged and tig welded
-1/2" flanges manifold and turbo
-304 stainless pipe and weld els
-4-2-1 design
-Single scroll
-vband at up-pipe connection
-as of now i think ill use Schedule 10 (can easily be persuaded to sch40)
-Turbo uses a T4 flange

However, I am having an issue in choosing my primary, secondary, and up-pipe sizes.

Primary
-My stock heads have an exhaust port size of 1.5". Now my choices are either 1.25" or 1.5" nominal pipe size, which have an ID of 1.442" and 1.682" respectively in schedule 10. For reference, shedule 40 1.5" has an ID of 1.610"

-Now my gut says that you wouldn't want to restrict the exhaust gases right out of the head by running 1.25" pipe, and that it would be better to have the 1.5" for the primaries (which would be 0.182" oversized compared to the head port). However, I believe I read that Full Race uses 1.25" pipe for the primaries and 1.5" for at least the secondaries in schedule 40. Can anyone confirm that? Anyways, whats everyones opinion on this?

-I measured my tomei EL headers and the primary is also 1.5" ID like the head exhaust ports.

Secondary
-Say we choose 1.5" pipe (so 1.682" ID for Sch10 and 1.610" for Sch40) for the primaries, Should I still use that for the 8-12" of secondary before merging into the up-pipe Vband? Since it will be equal length, the exhaust pulses should merge smoothly instead of smashing into each other right? Therefore 1.5" pipe would be adequate?

-Or the other option would be to use 1.25" pipe for primaries, then 1.5" pipe for secondaries, but that initial restriction at the head to manifold connection still bothers me.

Up-pipe/final merge
-So now we have 2 x 1.5" pipe (presumably) secondaries merging at the up-pipe vband. Seems like having the 2 x 1.5" pipes merging into 2" pipe for the vband to nicely mate to makes sense. i was using a custom 2.25" tube up-pipe on my last setup and was going to make another out of that same material. Seems to be a size that is common for this type of build. Opinions?

-So basically its a pipe manifold and tube up-pipe as of now. Or could easily run the Sch10 or 40 2" pipe right to the T4 turbo flange.



Any and all info/suggestions would be greatly appreciated!
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Old 11-29-2016, 08:53 AM   #2
Titter
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there are alot of factors to consider. things like pipe volume can diectly affect air velocity. if your looking for low end streetability then skinnier pipes will benefit you since the air velocity will be greater and the air will be hotter the turbo will spool quicker. if doing a big hp drag setup, a huge 2.5" up pipe for massive air volume could benefit you then.

also this all changes with the size of your turbo. if you have a giant turbo then i wouldnt consider skinny runners at all. a good rule of thumb is to increase each connection by 1/4". so an example would be 2" head collectors into a 2.25" crossover collector into a 2.5" uppipe. (dont go that big. numbers for example only)

i think 4 -2 - 1 @ 1.5" - 1.75" - 2.0" would be a good setup for that turbo. if you went bigger you would lose streetability.
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Old 11-29-2016, 09:55 AM   #3
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That is somewhat what I had in mind but they don't offer 1.75" nominal pipe sch10. So then it would either be 1.5-1.5-2.0 or 1.25-1.5-2.0.

The car is a fun street car that only gets driven spiritedly and every once in a while sees track use. So I don't want it to be a overly laggy beast.
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Old 11-29-2016, 10:57 AM   #4
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how you are going to do your "2" collector. is the merge in the uppipe or is the merge in the crossover.

i have seen the 2 - 1 merge been done in the up-pipe. except i would make the single tube up the uppipe be a bigger diameter. it looks like lachute uses the same length the whole way, but its is also for a stock turbo, your going big so you want a bigger uppipe.

http://www.lachuteperformance.com/co...up-pipe-v2.jpg

or you can do the merge before the flange like most companies

http://perrinperformance.com/images/M142538383

as for size, i would go with 1.5 - 1.5 - 2.0 if i had to choose between those 2 choices.

Last edited by Titter; 11-29-2016 at 11:02 AM.
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Old 11-29-2016, 11:20 AM   #5
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I will be doing the merge before the up pipe flange for sure. By the "2" collector" I just mean I'll be running the 2 secondaries into a collector that will exit into either 2" pipe or 2.25" tube for the uppipe. The flange will be a 2.25" vband at the header to up-pipe connection.
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Old 11-29-2016, 12:35 PM   #6
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Mine is a 4-1 design with 1.625 primary's v-band up 321ss ceramic coated. have yet to run it in since my engine needs to be rebuilt.
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Old 11-29-2016, 12:45 PM   #7
Titter
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Default Header design

are you a 2.0L or 2.5L motor?

im no turbo expert but personally i cant see a 2.0L moving enough air to justify bigger than a 2" up pipe.

Last edited by Titter; 11-29-2016 at 12:54 PM.
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Old 11-29-2016, 12:46 PM   #8
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Quote:
Originally Posted by Titter View Post
are you a 2.0L or 2.5L motor?

im no turbo expert but personally i cant see a 2.0L moving enough air to justify bigger than a 2" up pipe.
2.5L Motor.
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Old 11-29-2016, 12:46 PM   #9
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Is that pipe or tube? what's the ID of the up-pipe and merge pipe? Looks great.
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Old 11-29-2016, 12:53 PM   #10
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Yes I'm on a 2.5. I was running a 2.25" I'd up-pipe with tomei header on my last setup and it spooled my hx35 nicely.
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Old 11-29-2016, 12:54 PM   #11
Titter
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ya for 2.5L that'll do nicely
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Old 11-30-2016, 11:56 AM   #12
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Here's another data point from Lachute. "The actual ID of the headers is 1''5/8 while the up pipe is 1''7/8".

Seems like a small up-pipe to me.
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Old 11-30-2016, 12:59 PM   #13
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schedule 10 is prolly going to add a decent amount of weight to the header. I would def make a brace and gusset the pipes to the flanges etc.
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Old 11-30-2016, 01:19 PM   #14
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Quote:
Originally Posted by I--RIDE--BIKES View Post
Here's another data point from Lachute. "The actual ID of the headers is 1''5/8 while the up pipe is 1''7/8".

Seems like a small up-pipe to me.
ya that would be a little small for your setup. the lachute headers are made more to oem spec than big hp aftermarket spec. was more using the pic for example of the merge in the uppipe.

Quote:
Originally Posted by insaneimpreza View Post
schedule 10 is prolly going to add a decent amount of weight to the header. I would def make a brace and gusset the pipes to the flanges etc.
regardless of the material, it is always a good idea to support/brace the turbo with more than just the headers.
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Old 11-30-2016, 01:27 PM   #15
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I will most definitely be bracing it.
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Old 11-30-2016, 10:12 PM   #16
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If you want a proper header, ditch the idea of making it from pipe, and use correctly sized tube. If done right, pipe only makes for a super heavy setup and possibly gasket issues.

Unless you're going to a T4 turbine housing, a 2" up-pipe is ideal for any T3, and that will run you well into 1,000whp territory.

Another thing to consider, is equal length has more to do with the actual centerline of the tubing. In other words, a tube with a bend vs a straight tube, of the same length, will not 'merge' at the same time. Calculating losses from a bend means the tubes will NOT be equal length, but will provide equal pulse spacing, which is what provides best scavenging and transmission of the most energy from port to turbine.

Good luck on your journey. Read lots of books from experts in this field, and much less from forums. This is a topic where there is a LOT of misinformation.
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Old 11-30-2016, 10:33 PM   #17
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Thx for the advice KillerB.

I will indeed be feeding a T4 flange and not a T3.

Can you elaborate on why tube is better to use than pipe? Is weight the only concern between the two?

Also, can you point me towards any books/literature on the subject that I can read/purchase?
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Old 12-01-2016, 07:54 AM   #18
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No problem.

Are you running a T4 because it's an EFR or it's just a monster turbo? Curious.

While there is more thermal mass with pipe, tube will retain more heat. Your selection of bends with pipe is very limited, and most are tight 1D or smaller bends which are the least flowing bends you can get.

What I think is most important, is the limited selection of sizes in pipe; tubing will allow you to match IDs to port and turbine housing ID. When you have aggressive transitions you loose energy in the form of flow, and create thermal concentrations. The most efficient transfer of energy will be where there are no transitions.

One of the benefits of pipe is that it's really easy to make look pretty... on the outside. With tube, it's easier to make a weld that penetrates through to the inside that's smooth, but it does take skill to accomplish this and make it look pretty on the outside. It short, tube is less forgiving from a welding standpoint.

If you've got a big bookstore nearby you'll likely find a few books on the shelf that are specific to turbocharger setups that will detail manifold design. Some written by some reputable people, and turbo manufacturers. Beyond that, you're looking at undergrad or graduate level books, which contain a wealth of knowledge once you have a good grasp on the basics. Shop used on those, or expect to pay a couple hundred per book.
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Old 12-01-2016, 08:15 AM   #19
Titter
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Quote:
Originally Posted by KillerBMotorsport View Post
If you've got a big bookstore nearby you'll likely find a few books on the shelf that are specific to turbocharger setups that will detail manifold design. Some written by some reputable people, and turbo manufacturers.

who needs a bookstore when drones can deliver it to your doorstep lol...

https://www.amazon.com/Scientific-Ex.../dp/0837603099
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Old 12-01-2016, 09:08 AM   #20
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I was thinking this one, which is part of a 2-book series, but I'm all for drones!

https://www.amazon.com/Design-Techni...9MAN5EA6W6TSDX
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Old 12-01-2016, 10:14 AM   #21
I--RIDE--BIKES
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Default Header design

That all makes perfect sense. The reason it's T4 flanged is because it's an Airwerks series s300sx-e (62mm) and not the EFR. It is only offered in the T4 flange.

Unfortunately our closest large bookstore is 2.5 hours away. Can you maybe point me towards some reasonably priced options that would be available on Amazon or similar? I already have Maximum Boost by Corky Bell which is great but doesn't go that deep into manifold design.

With the tube, what wall thickness would be recommended for this application? Is the typical 16ga enough?
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Old 12-01-2016, 10:42 AM   #22
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Quote:
Originally Posted by KillerBMotorsport View Post
I was thinking this one, which is part of a 2-book series, but I'm all for drones!

https://www.amazon.com/Design-Techni...9MAN5EA6W6TSDX

even better!
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Old 12-01-2016, 10:43 AM   #23
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Old 12-01-2016, 12:59 PM   #24
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2D is the minimum we use on bends where we have to. The straighter the bend, the higher the flow capacity, and the shorter the length of the full runner.

If you're in a budget Acerace parts is a good place to shop, but it does = made in China

those are good intro level books too. I think Borg Warner has one as well.

16 ga is what we use. Unless you're making racecar parts, there's no reason to go any thinner. If you can find the bends you need in surplus 321 stainless all the better!
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Old 12-01-2016, 01:13 PM   #25
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Great I'll look into those books and search for the Borg Warner one.

KillerB if you had to comment on runner, secondary and up-pipe size for the turbo I'm running and my "good spool characteristics but still make 500 whp on pump/meth and 700whp on e85 needs", what kind of sizing would you recommend based off of your experiences?

Should the size always step up slightly after each merge, such as primary to secondary?

Thx for the info. Very appreciated. I'll be ordering those books today.
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