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Twin scroll hx35 spool results.

Posted by bastarddsm, Aug 8, 2011

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  1. boostdawd

    boostdawd Supporting Member

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    What type do u use on your masterpieces?
     

    Street Build 774  1

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    1991 Eagle Talon TSi AWD
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  2. Archer Fabrications

    Archer Fabrications Supporting Vendor

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    I use 1.5" sch40
     

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  3. Kapok6

    Kapok6 Proven Member

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    I'll be using 1.25" runners when I have my divided manifold built.
     
    Kapok6

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  4. lasthope05

    lasthope05 Proven Member

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    Im more inclined to believe smaller, 1.25", runners are more ideal for small/mid framed turbo. The smaller runners will definitely help increased exhaust gas velocity and spool times without limiting overall exhaust flow up to a certain point. I believe there are diminishing gains with manifold pipe size as there is with exhaust systems. Being able to tailor that one part for you application is hard because, like you, many manufacturers just stick to the standard 1.5 els.

    Ron Shearer offers a small diameter 1.25" manifold for our cars. His prices are higher than most but he actually has lots of testings and data on his products.
     
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  5. bastarddsm

    bastarddsm Proven Member

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    What has lead you to this conclusion? When I made this statement I was referring to 1.25 and 1.5" schd 10 I believe. I still stand by this, and my argument comes from a thorough survey of the field, as well as both simple geometrical calculations, and complex thermo-fluid science simulations.

    If you do some searching on the right forums you'll see that buschur and shearer have worked together on some header testing. As best as I can tell, buschur is about the most thorough and fair person you will see dyno testing parts. They found small primaries, around the size of 1.25 sched 10 was good for a 200rpm improvement in spool over 1.5, and it did not show any power loss on a 35r setup making 600whp on bushcher's dyno. That's more than 95% of dsm'ers will ever make. Next they turned up the boost and made like 675, the small runner didn't cost power, but buscher thought it was unhappy or something, as the curve was lumpy. Perhaps playing with cam timing could have fixed that.

    If you look at any real race car, the headers are made from 321 mandrel bends not pipe fittings, and the primary's are smaller than 1.5" schd 10 or 40. That abrupt transition from the oval port to round that everyone does on a dsm/evo header is garbage too. The only thing worse is the sharp 90* that a top mount header has there, plus the 6' of tubing they have to loose all that exhaust energy.
     

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  6. Devilsfutbol17

    Devilsfutbol17 Proven Member

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    Does this come into play with manifold construction? It looks like it could make a difference to me. Found this video on facebook. I tested my T3 TS manifold and it did not pass this test.

     

    606  3

    1991 Mitsubishi Galant VR-4
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  7. Archer Fabrications

    Archer Fabrications Supporting Vendor

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    My point is that a 1.5" sch40 will spool quicker then the 1.5" sch10. Because it has a smaller ID by a few MM, thus not needing to sacrifice FLOW of which a 1.25 would. The same thing applys to sch10 & sch40 in 1.25" in which case id say the sch10 varient is better for flow then its sch40 counterpart. I didn't say 1.25 was bad or that it cost power, it's just not as optimal as a 1.5" sch40 where you sort of get the best of both worlds, in my opinion. Each choice has it's place
     
    Last edited: Dec 7, 2016

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  8. ThunderChild

    ThunderChild Supporting VIP

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    I'm out of most of this discussion, but the video caught my eye.

    This is a good example of a designed manifold with good collector angle. granted I want to express on a scavenging effect, but remember, we have turbines impeding flow to a certain point. at optimal flow, id expect this test to show some similar results in a practical test, but it mostly comes down to the cheap manifold collector design and ramming all the exhaust into a common area, vs directed flow to the collector and into the volute like the better made manifild.

    Just an observation, but pretty easy to see the difference.
     
    Last edited: Dec 7, 2016

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  9. GSXftw

    GSXftw Proven Member

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    Thank you for this. Im researching to build my first TS mani and was wondering about this vid I had seen as well. I didn't know what the real difference was but the collector angles make total sense.
     

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  10. ErikTande

    ErikTande Supporting Member

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    Can anyone explain the significance of this test? The pitch of the air changes on the first manifold which I would assume means the runners aren't all the same size. Which I assume is bad. I don't understand the vacuum on the second manifold.
     

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  11. GSXftw

    GSXftw Proven Member

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    They are the same size, it has to do with the collector and the angle they meet.
     

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  12. lasthope05

    lasthope05 Proven Member

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    The test shows what a properly built TS manifold should do. The second manifold is built to where the flow of one runner scavenges exhaust flow from the other which helps with cylinder filling. The first manifold does the opposite where it causes reversion of the exhaust gases back up the runner. Thought I dont know how much this would effect a boosted car. Either way, I'll take a properly built scavenging manifold any day.
     
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  13. ThunderChild

    ThunderChild Supporting VIP

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    More so, this type of design consideration is going to focus on maintaining velocity and helping guide (scavenge) the other exhaust pulses into the turbine housing, vs just ramming all the exhaust through any opening like so many factory and log manifolds do.

    You should see reduced drive pressure/egts/spool times and better top end flow theoretically, but there are alot of other factors that play into that like: runner size/length, turbine housing size/type, tune, etc. Basically you are trying to increase flow potential and make your exhaust ports work in unison, vs fighting to get out first and causing a buildup of pressure.
     

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