Header Design Theory & Turbo EJ Headers

[Rhitter]

Something I think is interesting, I read a lot "replacing headers will delay spool because they are bigger."

 

It's interesting that the primary's are basically the same across most after-market headers. The Perrin Big-tube are the same as OEM...

 

Do you think the secondary / tertially have that much of an impact on boost threshold? Do you expect your area under the curve to be shifted right with the Tomei?

EJ Headers

This is not a definite list and might contain errors, finding this information took a lot of web searching.

 

Primary Internal Diameters

Exhaust Port Sizes: 39mm

USDM OEM: 39mm

Full Race: ~35.3mm (Educated guess based on tube thickness of 3.68mm, from Geoff's forum posts, and guessing 1.5" OD SCH10 pipe.)

Invidia: 39mm

Killer Bee Holy: 36.56mm

Perrin E-4 Regular: ~36.6mm

Perrin E-4 Big Tube: ~39mm

Tomei EL & UEL: 39mm

MAPerformance EL 4-1: 42.98mm

 

Secondary Internal Diameters

In this section I will list the secondary and tertiary (4-2-1 headers) diameters that I've found, calculated, or measured. While secondary diameters are less important, the do also contribute to overall responsiveness. Only two companies listed their secondary diameters, rest are based on my best judgement

 

OEM (4-2-1): 40.7mm Secondary, 41.7mm Tertiary

Full Race (4-2-1): Same as Primary

Invidia (4-2-1)- About same as Primary

Killer Bee Holy (4-1): Unknown: Best guess: ~50mm

Perrin E-4 Regular (4-2-1): About same as Primary

Perrin E-4 Big Tube (4-2-1): About same as primary

Tomei EL (4-2-1): 42.5mm Secondary, 57.5mm Tertiary

Tomei UEL (4-1): 57.5mm Secondary

MAPerformance EL (4-1): 55.68mm

[covertrussian]

To be fair, I think calling the OEM header 39mm is a bit generous. It's really an oval with maximum diameter at 39mm and minimum around 36-37mm.

 

I can also see where the lag comments are coming from... having individual 39mm primaries while OEM crams two adjacently firing cylinders only 2" away from the head into a 40.7mm secondary. Since EL headers and even aftermarket UEL headers have much longer primaries I can see why some manufactures choose to be smaller then oem diameter and they still gain plenty of power. If Tomei offered a smaller diameter header or Perrin was made out of thicker 304, had an up pipe, and was cheaper, I would go with that instead.

 

I personally am worried about the lag, but I think I might be able to use timing and AVCS to help reduce the lag with a more efficient header. I still have 700 city miles to do on my new clutch and then I'll start doing the header testing.

[dga]

Dang it, just saw this or I would have given you some measurements and pictures from the Full-Race header I installed last night.

 

Will have it tuned in couple of weeks, but first thing I noticed last night is a quieter and smoother engine. The car has a downpipe, but a stock cat back. Waiting on a larger TurboXS mid and Y-pipe and will run it with stock cans.

[Gigs]

Equal length makes the car feel silky smooth

[covertrussian]

Dang it, just saw this or I would have given you some measurements and pictures from the Full-Race header I installed last night.

 

Will have it tuned in couple of weeks, but first thing I noticed last night is a quieter and smoother engine. The car has a downpipe, but a stock cat back. Waiting on a larger TurboXS mid and Y-pipe and will run it with stock cans.

 

That would have been awesome, oh well! Next time your under the car if you want to grab the outer diameter of the primaries and secondaries I think that would be sufficient since we know how thick schedule piping Full Race uses.

[dga]

That would have been awesome, oh well! Next time your under the car if you want to grab the outer diameter of the primaries and secondaries I think that would be sufficient since we know how thick schedule piping Full Race uses.

 

Poop...it's fully wrapped, but I'll see what I can do.

 

http://i303.photobucket.com/albums/nn141/Drazengalic/Mobile%20Uploads/20170123_190718.jpg

[covertrussian]

Oh no worries then!

 

Does Full Race not void the warranty if you wrap them? Maybe I should add that as a new information point, who voids warranty from wrapping.

[dga]

Oh no worries then!

 

Does Full Race not void the warranty if you wrap them? Maybe I should add that as a new information point, who voids warranty from wrapping.

 

One of the reasons I went with them, lifetime warranty to the original purchaser whether it's wrapped or coated.

 

It's a beefy sucker that (strictly by feel) weighs in at more than the stock cast manifold. Very thick mating flanges too, roughly 1/2 inch.

 

To me it was between Full-Race and Killer B for that very reason, lifetime warranty regardless if you decide to wrap or coat it. Reason I finally decided to go with Full Race vs Killer B is thickness of the material, even though it's not 321 SS.

 

If I remember right Full-Race has the pipe made to their specification and thickness. I was certainly not able to find that thick of a pipe in mandrel bends by any shop, or straight sections at that.

[covertrussian]

I definitely considered Full Race myself for the thickness and durability, it was just hard to justify the 2x cost + up pipe cost on top of that. While I like the idea of 321 SS, the thinness is definitely negative for durability. But it is slightly thicker then most other 304 headers still.

 

Oh about lifetime warranties, I don't know about Full-Race but Killer B's lifetime warranty only applies to the original purchaser. So if you get one used and it cracks (which the old non cast merge collectors did do), your on your own.

 

Full-Race uses schedule piping, that's basically cast to shape. I once bought a bunch of schedule 10 bends/pipes to build my own header too (but gave up and switched setup). Full-Race's pipe is someplace between schedule 10 and schedule 15 piping. Very thick and durable as long as you get proper burn through on the welds (which they do with robotic welders).

[dga]

I definitely considered Full Race myself for the thickness and durability, it was just hard to justify the 2x cost + up pipe cost on top of that. While I like the idea of 321 SS, the thinness is definitely negative for durability. But it is slightly thicker then most other 304 headers still.

 

Oh about lifetime warranties, I don't know about Full-Race but Killer B's lifetime warranty only applies to the original purchaser. So if you get one used and it cracks (which the old non cast merge collectors did do), your on your own.

 

Full-Race uses schedule piping, that's basically cast to shape. I once bought a bunch of schedule 10 bends/pipes to build my own header too (but gave up and switched setup). Full-Race's pipe is someplace between schedule 10 and schedule 15 piping. Very thick and durable as long as you get proper burn through on the welds (which they do with robotic welders).

 

Full-Race warranty is only extended to the original purchaser as well. I also went with their lower manifold only and run the stock up pipe. For couple of reasons really, I want to end up with an EFR7163 that I can fabricate up and down pipes for and the flow of the stock up is not that much lower than aftermarket ones, according to the Grimmspeed data.

 

I do like their pipe thickness and if it ends up cracking (do we know of any?) I can send it back, or worse come to worse I can patch it with my MIG, back purge and all.

[covertrussian]

Good to know on the warranty too, that's unfortunate too.

 

I would have went with the same manifold myself, for one it takes less space then the 1.5 scroll setups, but second reason is flexibility to go rotated down the road.

 

Agreed on being able to weld it if anything, I got a MIG myself so if the Tomei cracks I can patch it up as needed.

 

Man, now I really want to install my header, but I must resist and do proper tuning with the stock manifold now that my clutch is not slipping. I am also half tempted to P&P a spare STI header that I have to see how well it compares...

[Rhitter]

This thread made me want an ELH. I picked up Battelready's used Tomei. That looks like it has some sort of DIY (maybe?) ceramic coating in okay condition. It was wrapped though. I pulled off the wrap (most of it was rotted) and the pipes look to be in decent condition.

 

My plan is to wrap it back up with DEI TI, if it cracks I'll have a reason to go KillerB or Fullrace .

 

Debating on HVAC tape or HD aluminum foil to help protect the header wrap from any leaks.

http://i.imgur.com/4UcF1RR.jpg

[covertrussian]

HVAC aluminum tape should be be the best option, glue will burn off but it should retain it's shape. I'm not sure aluminum foil will be as strong.

[Rhitter]

There is also this -

https://www.kaptontape.com/1_Mil_Kapton_Tapes.php

 

which seems to have a higher temp range than the HVAC tape.

[covertrussian]

That doesn't look to have any metal in it, I would worry about it melting away. HVAC tape (the foil backed one) is used because the thick foil will retain it's shape even though the glue will melt off.

[utc_pyro]

 

Man, now I really want to install my header, but I must resist and do proper tuning with the stock manifold now that my clutch is not slipping. I am also half tempted to P&P a spare STI header that I have to see how well it compares...

 

I still have that Grinspeed PNP set in storage. If you'll test it vs stock vs tomei you're welcome to borrrow it.

[covertrussian]

I still have that Grinspeed PNP set in storage. If you'll test it vs stock vs tomei you're welcome to borrrow it.

 

Would love to take you up on that offer, I just don't know if it's worth the $50 in shipping fees . I have the tools to P&P my own, but crosspipe would still be the stock suck

[utc_pyro]

Would love to take you up on that offer, I just don't know if it's worth the $50 in shipping fees . I have the tools to P&P my own, but crosspipe would still be the stock suck

 

Understood there! The ackward shape and weight is part of the reason i haven't gone through the effort to sell them yet. If you change your mind PM me. They'll come with an up pipe and EGT probe as well so you can try the "whole set" they used to offer.

[dga]

...

My plan is to wrap it back up with DEI TI, if it cracks I'll have a reason to go KillerB or Fullrace .

 

Debating on HVAC tape or HD aluminum foil to help protect the header wrap from any leaks.

 

I went with one inch DEI and overlapped at least 50% and it turned out great. Steel band zip ties and a lot of tedious wrapping did the job.

 

Not sure I'm following you on protecting the header wrap from any leaks...

[Rhitter]

I went with one inch DEI and overlapped at least 50% and it turned out great. Steel band zip ties and a lot of tedious wrapping did the job.

 

Not sure I'm following you on protecting the header wrap from any leaks...

 

I am going with one inch wrap also, I'll overlap it less though because of the thinner metal.

 

Oil leaks / coolant leaks etc. I currently don't have any, but I am a little afraid of turning it into a wick.

 

Really it's protecting the wrap from me pouring oil onto it when I am doing an oil change.

[covertrussian]

It's a very good idea to protect the wrap, while material is not flammable on it's own, it will wick oil and become flammable. Soaking water, oil, coolant down to the header could also do some long term damage to the header it self.

 

Another hidden benefit is not having an engine bay full of fiberglass, since the radiator fans will be blowing it all the time.

[dga]

Oh, I got ya. Good idea. I'm curios to hear how it works out.

[Rhitter]

Installed my Tomei headers. I am getting a vibration around 3k RPM. Unsure if I left a bolt loose somewhere or if that's just how they are (I suspect downpipe to transmission might be loose)

 

Haven't noticed a difference in spool by feel. As soon as my Tactrix is fixed (they are fixing it for free), I'll get tuned for it and see what it gives me (beyond just a happier engine)

[xtea]

Installed my Tomei headers. I am getting a vibration around 3k RPM. Unsure if I left a bolt loose somewhere or if that's just how they are (I suspect downpipe to transmission might be loose)

 

Haven't noticed a difference in spool by feel. As soon as my Tactrix is fixed (they are fixing it for free), I'll get tuned for it and see what it gives me (beyond just a happier engine)

 

You should see an earlier and higher peak torque after the tune. Might need to be wot to notice it also.

[LatentWagen]

Just picked up a Synic EL header, this is the old Fujitsubo design that was later copied endlessly on eBay with poor quality welds and materials. The Synic version seems well built. The Swaintech coating has help up decently over the last decade, too:

 

http://legacygt.com/forums/attachment.php?attachmentid=244869&d=1486956923

 

In doing some research on the other site, Boostjunkie was going to do a batch of them but he was less than impressed with the gains when paired with large turbos (500WHP setups). The stock and stockish sized gains were sizable, with a good bump in the mid-range.

 

Think I'll put them on the car and see how they feel. Interested to hear the EL sound paired with my exhaust (full Cobb setup with catted DP, added Vibrant UQ resonator).