Exhaust manifold fab advice, head port to 1.5"

[Sirnixalot]

I am building a short runner, unequal length manifold for my Evo3 for use with an Evo X turbo.

Everything is carbon steel because i cannot weld stainless. I am not in the US so it's not so easy for me to "just buy a new flange", shipping a $70, 5lb flange will be more than double what its worth on top of the 25% import duty.

Most of the DIY flanges i have seen come with ports slightly smaller than the stock head ports so you can butt weld the pipe/elbows to the face of the flange and port them accordingly. The head flange i got is from RRE which is basically an exact replica of the exhaust manifold gasket. This of course means the ports are about 2-3mm larger all the way around.

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This is what i am working with.

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Ovaled 1.5" sch40 straight

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Does anyone see any issues i might run into if i were to have the oval transition welded so it sits inside the flange about half way in (centered better than in the picture of course). I would get this part done by someone with far more experience and a better welder than myself.

Basically weld the transition and fill in the sides from the turbo side of the flange. On the inside do a pass or 2 between the face of the flange and the oval transition so that i can port match it to the head.

I realize the flange will need resurfacing after that but that is no big issue.

 

[imagine-02]

This video might be of some help
YouTube - Custom Headers Part(4 of 6).wmv

 

[Sirnixalot]

Thanks

I went ahead and welded the transitions to the inside of the flange

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I have gotten this far with the manifold, i hope to have at least one of the collectors done tomorrow

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[MY1GDSM]

I am building a unequal length manifold

Hope you don't mind me... Asking but why?

Wouldn't that kinda of negate the point of having a divided turbine housing?

Or at least since your building it make some attempt to make them close to proportionate in length?

 

[Sirnixalot]

I am emulating the stock manifold design on both the Evo 4-9 and the Evo 10. Short runners are less volume to fill which is inline with my goals

 

[nitrouskris]

This video might be of some help
YouTube - Custom Headers Part(4 of 6).wmv

great post

 

[ViciousLord]

Hope you don't mind me... Asking but why?

Wouldn't that kinda of negate the point of having a divided turbine housing?

Or at least since your building it make some attempt to make them close to proportionate in length?

Stock evo manifolds are all unequal.

 

[MY1GDSM]

I understand that But thanks for pointing out what someone just said Lol

I was just asking why not make or attemt to make it an equal length manifold since he's fabricating it him self...

 

[Ppayer38]

This works out good for what I am about to do with an Evo turbo onto my GSX...

SUBSCRIBED!

 

[ViciousLord]

forgive me for not reading every post before posting, I just read your post and decided to answer your question.

I was just asking why not make or attemt to make it an equal length manifold since he's fabricating it him self...

less work or maybe because the length of the runners aren't hugely different it may be just as effective as an equal length mani.

 

[mitsu-luver]

It looks good, great welding if you wanted to do it "by the book" they say to weld the inside ( which you already did) and put 1/2" welds all the way around the out side of the flange using some triangulated pieces on the under side of each runner for support. as for the unequal length i do not think that matters the divided turbine housing will help with the spool a lot as i am sure you already know. looks good, finish!

 

[tkelly27]

Looking good. One piece of advice I can give is to make a divider for the two sets of tubes, weld the divider to the flange, then weld the tubes to the divider. Getting in between the two sets of tubes is a total pain in the ass.

 

[Sirnixalot]

Just a small update. I managed to get the inner runners/collector done. I will be attempting to tackle the other collector this weekend. Then i can get to porting the turbine inlet flange and collectors

The pictures i have look like ass so i will put up some better ones tomorrow.

 

[Sirnixalot]

It's no show piece but I finished the manifold! Now it just needs to be pressure checked and the flanges resurfaced

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Once over with a knotted wire brush wheel

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Soon

 

[Ppayer38]

So why did you decided to not worry about equal length tubes?
I'm in the middle of making my manifold now and my design is based off the full race pro stock mani for the Evo just to fit a DSM and it isnt equal length but yours has huge differences...

Look good though let us know how it performs

 

[DSMReviver]

i see a massive turbulence coming out of the exhaust ports. MASSIVE TURBULENCE.

 

[Sirnixalot]

Probably but i haven't really started porting/cleaning it up. It's not a perfect manifold by any means but not too shabby for my first time.

A few more pictures of everything mounted up!

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I am thinking of adapting a DSM O2 housing as with the bottom bolt in it pivots and lines up perfectly with the turbine outlet. The wastegate passage will need some covering but it looks feasible.

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I don't have it rotated properly but trust me it lines up. Seeing as i have the turbo ALMOST in the stock location i shouldn't have to do to much to my down pipe.

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All mounted up. Clears the power steering pump with about 10mm to spare.

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Awful picture showing the stock oil feed and water lines lined up with a little bending. There is a spot on the Evo X compressor where they engraved the part number that was a little in the way. I need a longer rubber hose for the lower line as a result.

So why did you decided to not worry about equal length tubes?
I'm in the middle of making my manifold now and my design is based off the full race pro stock mani for the Evo just to fit a DSM and it isnt equal length but yours has huge differences...

Look good though let us know how it performs

Missed this post. Sorry about that. I wasn't too concerned with the equal length as my aim is to keep the runner volume low and runner length's down to try and give me a little quicker spool. I realize I could have gotten some more torque out of it in the midrange but with a 2.3 feeding it i am not so sure i will be missing the 10-20lb/ft. Virtual dyno had me at 333whp and 289wtq the last time i got to log the car, if i can pull anything near 350whp and 320wtq i will be happy (will have a much better intercooler setup as well)

I will not know what it does until i get the car back together in January. I still have the intercooler piping, O2 housing, engine rebuild and seam welding to do.