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L28ET custom exhaust manifold experiment

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I haven't seen many L-Series manifolds that are designed for prolonged boost usage. Those that are, generally have slip joints, expansion joints, or expansion loops. This goes for the stock cast iron units as well. The US and JDM were not expected to see more than occasional boost, and didn't have joints. Their maladies with warpage and stud breakage are well known.

 

The Nissan Eurospec Turbo Manifold, however, had expansion joints as described and does not suffer from the warpage, stud breakage, etc when subjected to constant or sustained boost usage.

 

You will see Mercedes TD's also have similar joints. Inline sixes usually have some expansion device incorporated on the longest of the runners. It's physics and engineering, same reason you see "Omega Loops" on a wellfield...thermal expansion on a hot summer day would lift the anchor blocks if there wasn't a device were that expansion could be taken up without adding undue stress and strain to other components.

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I think I'll do just that for now. I'm more curious to see what kind of, if any, performance gains I can get with this particular design.

Slip joints will work just fine for this application and don't take up that much space.  Burns has single and double slips for this.  I've been using single slips on my manifold for several years now with no leakage issues - the inner tube tends to heat and expand more than the outer so it seals just fine once hot.  You are at a point now where you could implement this and not have to f*** with fixing it later, and you will almost certainly have to fix it later if you don't address it now...

 

http://www.burnsstainless.com/Slips.aspx

Edited by TimZ

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Could I get away with making my own slip joints, or do I have to buy specially made ones from Burns? Do they have to  be an interference fit, or should they be able to move freely? Would a single slip be adequate, or is a double slip joint required? Suppose I put them just off the flanges where they bolt to the head? Or would they pull too far away and cause leaks? I'm new to slip joints on a turbo manifold - Only ones I've seen are leaky ones on N/A headers. Sorry for the gratuitous questions - I'd rather this stuff didn't fail at all, and some mechanic friends are telling me I'm thinking too much about this.

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Could I get away with making my own slip joints, or do I have to buy specially made ones from Burns? Do they have to  be an interference fit, or should they be able to move freely? Would a single slip be adequate, or is a double slip joint required? Suppose I put them just off the flanges where they bolt to the head? Or would they pull too far away and cause leaks? I'm new to slip joints on a turbo manifold - Only ones I've seen are leaky ones on N/A headers. Sorry for the gratuitous questions - I'd rather this stuff didn't fail at all, and some mechanic friends are telling me I'm thinking too much about this.

 

You want the slip joints to be able to expand in the direction that the manifold is going to grow as it heats up.  I'm thinking I would put single slips in the following locations:

 

DSC_0598_1.jpg

 

You'll also likely want to support the turbo but that's a separate issue.

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We're working on a support bracket for the turbo, most likely going to hang it off the intake manifold, since that seems strong enough. When I get in touch with my friend who TIG'd it together for me, I'll ask him about putting in some slip joints. Like I said, it's gotta come off for ceramic coating, anyway.

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Could I get away with making my own slip joints, or do I have to buy specially made ones from Burns? Do they have to  be an interference fit, or should they be able to move freely? Would a single slip be adequate, or is a double slip joint required? Suppose I put them just off the flanges where they bolt to the head? Or would they pull too far away and cause leaks? I'm new to slip joints on a turbo manifold - Only ones I've seen are leaky ones on N/A headers. Sorry for the gratuitous questions - I'd rather this stuff didn't fail at all, and some mechanic friends are telling me I'm thinking too much about this.

 

Sweet looking manifold and the design is unique.  As others have stated put the slips on the straight legs after the 1-2 merge and 5-6 merge.  A single slip can have leakage, but it is not typically audible and more so that you can see carbon blow-by over time.  I personally prefer a double slip over single just because and that is what I use on manifolds I fabricate. (sorry Tim :huh: )  As a note, the welds look hot so if you didn't use a flux paste or purge you could end up with cracking regardless of slip joints.  Also, if this is 0.065" it should be 321SS and not 304SS or it will likely crack.

 

FYI, this was the first 0.065" 304SS twinturbo manifold I made back in 2002, which ended up cracking.  So we all learn from our experiences over time.

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This is a manifold I made for my EVO in 2012 and it is still going strong after 40K miles.  Thick walled 316SS twinscroll with double slip joint.

ts19.JPG

ts18.JPG

ts21.JPG

Edited by 240Z Turbo

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That stuff looks almost like the sch-10 stuff that vibrant makes, which I once used on an experimental J-pipe that mounted on a stock late L28 manifold. I welded it with just my MIG, and used 1/2" mild steel for the main flange, and a reused turbo flange from a Subaru up-pipe. I didn't like how close the downpipe was to the firewall, though, so I made the full manifold in question, but that was TIG'd together by a retiree from the airforce. He says it shouldn't crack, but we'll see.

post-5105-0-06069900-1473552452_thumb.jpg

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post-5105-0-08807400-1473552552_thumb.jpg

post-5105-0-60697400-1473552608_thumb.jpg

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That stuff looks almost like the sch-10 stuff that vibrant makes, which I once used on an experimental J-pipe that mounted on a stock late L28 manifold. I welded it with just my MIG, and used 1/2" mild steel for the main flange, and a reused turbo flange from a Subaru up-pipe. I didn't like how close the downpipe was to the firewall, though, so I made the full manifold in question, but that was TIG'd together by a retiree from the airforce. He says it shouldn't crack, but we'll see.

 

Yes, the EVO manifold is sch10 from Treadstone.  The advantage is that you have the ability to get tight radius bends that are not otherwise available with standard 0.065" stainless.  For an L28 manifold it would be more suitable since there are space constraints.  I also found that short runner manifolds do hella-good for spool on a street car where response is critical.  I may suffer on the topend vs a long runner manifold, but I really like the boost response.

 

On my 2L I make 27.3psi @ 3848rpm with a GTX3576r and 27.4 @4351rpm with a GTX3582r both logged in 3rd gear.

 

GTX3576R_vs_GTX3582R.jpg

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1.06 a/r T4 TS from ATP on the current setup.  Keep in mind that ideally you should pair it with a TS header with dual (separate) gates.  You would need to measure exhaust back pressure (EBP) to understand if the housing is sized appropriately for a 2.8L, but for sub 600hp I think it would be a good option.  I think ideally you want to see 1.5x boost pressure when measuring EBP.

 

As a note, the new TS turbine housings from Honeywell are actually sized to have equivalent cross sectional area to an open scroll.  So a 1.01 a/r T3 TS would have the same flow as a 1.01 a/r T3 OS.

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Holy Resemblances, Bruce!

 

It's the BATMANIFOLD!

What? Did I do something wrong? I'll admit I was going for a similar trick to the crown kits from way back, but sadly, the way I was making it with the sch-10 bends, it would be less than 1/2" from the steering shaft. The only way I could figure it out was to run the J-pipe back, instead of outwards.

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Heh... Now that I look at it, it kinda does. Might have to make one look like that on purpose, next time. Might even play with J-pipes on other low-boost turbo experiments in the future. You know, for those engines that don't have an obtainable turbo manifold available for them...

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