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Discussion Starter #1 (Edited)
Hey everyone, :coffee:

Id like to start a discussion about ELH sizing/specs. As we know, there are many kinds of ELH out there. One thing i cant seem to find enough info on here or other forums is about the piping size. This can be a big factor in determining the power someone will make when using one over the other. Id like to talk about some of the more common ones and what kind of sizing they are offered in. I was thinking mainly Perrin, Killer B, Tomei, Invidia, HKS, and MAP. If anyone as any more info on these and others that arent discussed on here, then please feel free to add in. If anyone has any data/specs or whatever to contribute, then that would be great too. My purpose of this is to get some more hard numbers to help determin what would be the best ELH for someone.

Perrin ELH:
4-2-1, 2 bolt flange, and offered in a regular sized 1.5" tube header that is good for cars up to 400hp according to them. Idealy they are perfect for a stock turbo sti. Perrin also offers a "big tube" version with the sizing of 1.625" tubing. From my understanding these are mainly benifiical for cars exceeding the 400hp and beyond.

Tomei ELH:
4-2-1 designed with a 3 bolt style flange. What ive seen, 42.7mm, 45.0mm, 60.0mm on certain sites. I believe this is reffering to 1.68" to 1.77" on the runners then to a 2.3" at tubing going to the up pipe. Does that sound about right?? Does anyone have any more info on these?

Invidia ELH
4-2-1 design with a 2 bolt flange. Invidia is offered in a regular size and a big tube size. I cant seem to find any clear measurement as to what the regular size or even the big tube size ELH are. I have even seen some labeled as the "racing" exhaust manifold with a 1.65" but still not clear on if it is the regular or the big tube ELH.

HKS ELH:
4-2-1 design with a 2 bolt flange style header.
2mm (0.079”) SUH 409 SS
Primary Outside diameter = 42.7mm (1.68")
Primary Inside diameter = 38.7mm (1.52")
Secondary Outside diameter = 52mm (2.05")
Secondary Inside diameter = 48mm (1.89")

MAPerformance ELH:
4-1 ELH , 2 bolt flange designed with 1.750" runners and merging to a 2.25" up tube to the uppipe according to the website. This seems to be larger than compared to the others.

Killer B Holy Header:
4-1 design with both a 2 bolt and v-band style flange possibility.
0.065” 321 SS
347 Cast Merg Collector
Primary Runner Outside diameter = 41.5mm
Secondary Runner Outside diameter = 50.6mm
Primary Port Inside diameter= 1.5 inches
Secondary Port Inside diameter = 1.85 inches



SO with all that being said up there, what is it that makes an ELH to be considered a "big tube" header?? There are some people out there that say that the invidia and hks make the most torque. What is it that makes them produce more than let say the perrin unit or any other 4-2-1 design out there? Are there any dyno sheet comparisons out there?

Does anyone have any more info on the Invidia, tomie, and KB headers??

Also what is that makes the Killer B header so much more benificial over other 4-1 designs?

This threads purpose is not to discredit, or trash talk any of the brands or designs. Its just simlply for informative research. Very curious to see what comes out of this.

**Please ignore any spelling/grammatical errors 🤫
 

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Sure, I was struggling to get port sizes and tube sizes when I was shopping for ELH so I made sure I measure them before I install them. Now those photo becomes handy.... hope they will help others

KillerB EL header


58708


Primary runner outside diameter = 41.5mm

58709


Secondary Runner Outside diameter = 50.6mm
58710


Primary port inside diameter = 1.5 inches
58711


Secondary port inside diameter = 1.85 inches

58712
 

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Discussion Starter #3
This up there ^ is excellent information! Good job Lowbee 👊 I wonder why there is a differance in the port sizes. This is not the first ive herd of this on manifolds either. I will update the original post with this as we get more info rolling in.
 

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This up there ^ is excellent information! Good job Lowbee I wonder why there is a differance in the port sizes. This is not the first ive herd of this on manifolds either. I will update the original post with this as we get more info rolling in.
Are you wondering why the exhaust tube from each exhaust port is smaller than the collector-to-uppipe tube?

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Discussion Starter #5
Are you wondering why the exhaust tube from each exhaust port is smaller than the collector-to-uppipe tube?

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Yes that and why the primary inner diameter is at 1.5" compared to the secondary port inner diameter at 1.85"
 

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Yes that and why the primary inner diameter is at 1.5" compared to the secondary port inner diameter at 1.85"
Well secondaries carry flow from four cylinders so not surprising they are larger. To some extend we are limited by what ports and flange sizes are at each end - and they were determined by Subaru long ago.

No?
 

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Well secondaries carry flow from four cylinders so not surprising they are larger. To some extend we are limited by what ports and flange sizes are at each end - and they were determined by Subaru long ago.

No?
Basically, this.

Think, too, of the dynamics that are happening in the exhaust manifold. There isn't just gas with each exhaust event, but there's pressure. The larger diameter section likely helps equilize, or even reduce to an extent, pressure when pressure from all four tubes merge into one area.

After combustion in the cylinders, the cylinder pressure from that event is pretty high. That pressure is ejected on the exhaust stroke. After every positive pressure wave (exhaust stroke event), there's a negative pressure (aka vacuum) right behind it. This negative vaccume is helping to pull the next exhaust event out of the cylinder. This happens withing inches of the heads and the vacuum eventually fades and pressures balance as the gasses flow down the pipe as one continuous stream.

Now down the line you have volume and pressure from the gasses from all cylinders back-to-back. If it was confined to the same space, pressures may increase, pushing back on the next exhaust event, which means that vacuum behind the exhaust event diminishes and isn't able to help pull out the gasses from the next exhaust stoke event.

Exhaust manifold pressure (you could call it Exhaust MAP) increases as cylinder pressures increase. In other words, EMAP goes up during spirited driving because there's more fuel and as a result more boom in the cylinder which increases cylinder pressure and thus EMAP, which causes the turbo to spin faster. It's during this time you want the perfect ingredients to keep pressure flowing in one direction. Too small of a tube and pressure may be too high. Too big of a tube, and pressure may be too low.

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I've been debating on which ELH to purchase for my '19 STI and have also been looking at materials, dimensions, etc.. As of now, I plan to stay at stage 1 or stage 2 levels. I'm considering both ends of the spectrum in terms of price and material quality.. either the HKS header for ~$475 (and then sending it to SwainTech) or the Killer B 2 bolt header (SwainTech coated) for $1670.

HKS 4-2-1 Equal Length Header
409 SS - cheapest, prone to oxidation/surface rust, typically used by OEM for exhaust systems, finite lifespan
Stamped steel collector
High production, hot/fast welds (potential cracking at collector?)
BrenTuning recommends it as the budget alternative to the Killer B header
Can be found for <$500

Dimensions:
2mm (0.079") SUH409 SS
42.7mm (1.68") Primary OD
~38.7mm (1.52") Primary ID? (calculated)
52mm (2.05") Secondary OD
~48mm (1.89") Secondary ID (calculated)

Killer B 4-1 Holy Header (2 Bolt for comparison to HKS)
321 SS - stronger, lower thermal conductivity (less energy lost due to heat transfer), will probably outlast the car, used for aircraft exhaust manifolds
Cast 347 SS merge collector
Symmetrical primary design (tube length & bend geometry) - unique among other non-symmetrical ELH.
Probably the best header on the market.
Killer B is obviously the best in terms of quality, engineering & support for the community. Made in the USA and hand welded. Lifetime warranty.
$1350

Dimensions:
0.065" 321 SS
1.5" Primary ID
1.85" Secondary ID

I know that I should go with the Killer B header.. I just have to rationalize the nearly ~$1,700 price tag for the SwainTech coated version for my daily driver.

Adding the SwainTech White Lightning coating should reduce radiant heat lowering under hood temperatures. Ideally, it will also help retain more heat in the pipes marginally improving spool and boost response, The SwainTech coating is 0.015" thick compared to other ceramic coatings which are typically 0.002". The HKS header should be coated regardless to prevent oxidation/surface rust and hopefully help maintain integrity.

I almost wouldn't want to coat the Killer B header and cover up its beauty.
 

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Discussion Starter #9 (Edited)
I've been debating on which ELH to purchase for my '19 STI and have also been looking at materials, dimensions, etc.. As of now, I plan to stay at stage 1 or stage 2 levels. I'm considering both ends of the spectrum in terms of price and material quality.. either the HKS header for ~$500 (and then sending it to SwainTech) or the Killer B 2 bolt header (SwainTech coated) for $1670.

HKS 4-2-1 Equal Length Header
409 SS - cheapest, prone to oxidation/surface rust, typically used by OEM for exhaust systems, finite lifespan
Stamped steel collector
High production, hot/fast welds (potential cracking at collector?)
BrenTuning recommends it as the budget alternative to the Killer B header
Can be found for ~$500

Dimensions:
2mm (0.079") SUH409 SS
42.7mm (1.68") Primary OD
~38.7mm (1.52") Primary ID? (calculated)
52mm (2.05") Secondary OD
~48mm (1.89") Secondary ID (calculated)

Killer B 4-1 Holy Header (2 Bolt for comparison to HKS)
321 SS - stronger, lower thermal conductivity (less energy lost due to heat transfer), will probably outlast the car, used for aircraft exhaust manifolds
Cast 347 SS merge collector
Symmetrical primary design (tube length & bend geometry) - unique among other non-symmetrical ELH.
Probably the best header on the market.
Killer B is obviously the best in terms of quality, engineering & support for the community. Made in the USA and hand welded. Lifetime warranty.
$1350

Dimensions:
0.065" 321 SS
1.5" Primary ID
1.85" Secondary ID

I know that I should got with the Killer B header.. I just have to rationalize the nearly ~$1,700 price tag for the SwainTech coated version for my daily driver.

Adding the SwainTech White Lightning coating should reduce radiant heat lowering under hood temperatures. Ideally, it will also help retain more heat in the pipes marginally improving spool and boost response, The SwainTech coating is 0.015" thick compared to other ceramic coatings which are typically 0.002". The HKS header should be coated regardless to prevent oxidation/surface rust. I almost wouldn't want to coat the Killer B header and cover up its beauty.
Im not so crazy about the welds on the HKS either also the fact that its basically a raw finish on it. The reason i think the HKS is just so popular is because its price. I wonder why Bren recommends specifically the HKS as an alternative to the KB. Maybe the gains are close to the KB ELH?

You know another option for ELH for you could be the MAP header. With the black thermal coating its around $1200. It seems to be a quality handmade piece. Not alot of guys have it but i believe somewhere on NASIOC it performed really well.
 

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There are lot of things to consider with headers, and everyone has their own priorities. This is why you have different
opinions as to what's 'best'.

With that said, I designed our headers with the purpose of optimizing the EJ's VE (Volumetric Efficiency) and maximizing the energy (pressure, heat, flow, sound) from exhaust port to turbine.

Many assume bigger tubes are better and allow more flow. This is more marketing than truth. Once you transition out of the port to a larger tube, the transition causes a loss in energy and the larger diameter slows gas velocity. Additionally, a larger tube exposes the exhaust gasses to a significantly larger surface area causing more heat loss than a smaller tube.

As far as layout goes, we have intellectual protection of the design for good reason, it works well. We've tried 4-2-1, longer primaries, twin scroll, as well as compared to many other brands. If there were a design that worked better than a symmetrical primary layout like we use, then we'd be doing it :)

As far as the secondary, it too needs to be sized appropriately to reduce losses and maintain ideal flow. The inlet for a 35R turbo capable of +700whp is 2", and where the turbine's volute necks down before opening up to the turbine wheel is even smaller. The most power I've seen pushed through our headers was 1,160whp on a land-speed application.
 

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From BrenTuning:
"As for headers KillerB is the cream of the crop, the best on the market. The HKS is a good budget option, and if the car doesn't see heavy road salt will last a while. Power wise they are about the same, it's just material quality and build quality differences."

"We use the HKS ones all the time, they work great and sound great. Performance is close to KillerB, if you have the money, always go for the KillerB though!"

"Both are very good. I haven't had a back to back with them, but I assume it would be close with the KB making more power. The design is fairly similar. I love the KBHH, and use it all the time. The HKS is a great alternative for those on a budget!"

"The KBHH is much better than Tomei. I would do HKS over Tomei if on a budget, HKS work really well."

Re: HKS reliability
"Have not seen an issue with cracks. I have seen people with 50K+ on these with no issue. I haven't wrapped or coated them, no first hand experience on that."

On the other hand, I believe that Killer B recommends Tomei as a budget option over HKS. I'm not sure if that's based on materials (409 vs 304 SS), build quality, or design.
 

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Discussion Starter #12
Great info so far guys. I think this thread will be helpful to some out there. So does anyone have any more info or specs on any of the other headers out there?
 

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Great info so far guys. I think this thread will be helpful to some out there. So does anyone have any more info or specs on any of the other headers out there?
Like what? Compared to knock-offs, Ebay, materials, coatings, fab, custom, twin scroll, etc...?

I'll share info on our stuff, and we have a lot of info on other products out there, but it would be better for those companies to be involved with sharing their information here, not us. A lot of these companies you'll need to reach out to as they just do not get involved with enthusiasts the way we like to.
 

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While I am a big fan of Killer B products, Full Race should not be ignored, especially if you want twin-scroll.
I have some of the old, heavy, schedule 40, 316 SS one. All have been modified to make then work better.
I believe my primaries are 1.62" ID. I made my own 321 SS twin-scroll up-pipe and make 470 on this tiny ID piping.
What they offer now is tubing. Geoff Racier knows his stuff.
 

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1.62" ID is considered "big tube". FWIW, people have made 700+ whp on Killer B's "tiny" 1.5" ID primaries.
1,160whp is the highest I've seen on our headers. This was +60whp over the competitors "big tube" headers, lol. Flow doesn't help you if you're taking away from the overall energy transmission from port to turbine.
 

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1.62" ID is considered "big tube". FWIW, people have made 700+ whp on Killer B's "tiny" 1.5" ID primaries.
I measured it and got 1.58" ID. Schedule 40 specs say 1.610" nominal. Say what you will but I've never seen anything as small. I am in agreement that you do not want/need bigger. My heads flowed an average of 284 intake/219 exhaust @ .445" lift (Kelford 272's).
 

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58808


BNM also offer both 4-1 and twin scroll options. Really nice looking bit of kit! Waiting on a set fo the 4-1 to arrive and will do so overlays once it's tuned comparing RCM UEL header. Primary ID 1.65"
 

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Discussion Starter #19 (Edited)
Like what? Compared to knock-offs, Ebay, materials, coatings, fab, custom, twin scroll, etc...?

I'll share info on our stuff, and we have a lot of info on other products out there, but it would be better for those companies to be involved with sharing their information here, not us. A lot of these companies you'll need to reach out to as they just do not get involved with enthusiasts the way we like to.
Anything to help serve the purpose of this tread. I feel like when someone is trying to shop around and hunt for the right manifold, there is just so much missing information. I wanted to try and collect as much as possible and put it all in one place (this thread) to help others out down the line. You sir have given us plenty of good educational info on your product and greatly appreciated. I havent seen some of the other brands being active on the forums so i figured we could squeeze some info out of the community rather than calling place to place and being on the phone for awhile.

While I am a big fan of Killer B products, Full Race should not be ignored, especially if you want twin-scroll.
I have some of the old, heavy, schedule 40, 316 SS one. All have been modified to make then work better.
I believe my primaries are 1.62" ID. I made my own 321 SS twin-scroll up-pipe and make 470 on this tiny ID piping.
What they offer now is tubing. Geoff Racier knows his stuff.
I didnt want to ignore Full Race i just couldnt find much info if any on their spec. I know they have a TS ELH option but most of us dont run TS. Although, if i was comparing all TS manifold options then they would have definitly been on the list. Are the specs you have up there for a twin scroll manifold?

1.62" ID is considered "big tube". FWIW, people have made 700+ whp on Killer B's "tiny" 1.5" ID primaries.
So is that 1.62" ID basicially the bench mark number that would make an ELH be considered "big tube" ?


I have updated the thread with the submitted data/specs.
 

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Discussion Starter #20
View attachment 58808

BNM also offer both 4-1 and twin scroll options. Really nice looking bit of kit! Waiting on a set fo the 4-1 to arrive and will do so overlays once it's tuned comparing RCM UEL header. Primary ID 1.65"
This is the first ive herd of this but it looks like a sweet piece right there! Looking forward to your comparisons.
 
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