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Old 07-02-2015, 04:52 PM   #1
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Default Twinscroll worth it?

Im thinking about designing a twinscroll cast manifold. Do you think this is worth it and would you buy it?

When the complete kit is finished it would be for sale at a MX-5 specialist.



I was thinking about a similar design like this




What are your toughts? Worth it or not and is there any interest?
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Old 07-02-2015, 05:11 PM   #2
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Not enough information to determine if it's worth "it."

What is "it?"
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Old 07-02-2015, 05:25 PM   #3
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Pro tip: actually get any sort of proper cast manifold designed, built, and in production for a 1.8 miata for a reasonable price, that fits t2's and t3's, plays nice with the rest of the bay, and has a decent angle for a downpipe, and you will already "have a market".
You know why? Cause it's not easy. There's a reason only approx 2 companies make them now, with hopefully a 3rd competing in the near future. Learn to walk before you run.

also, iirc that picture won't work with the bp firing order
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Old 07-02-2015, 05:27 PM   #4
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Quote:
Originally Posted by concealer404 View Post
Not enough information to determine if it's worth "it."

What is "it?"

Worth the extra time to design and possibly the extra money for the turbo


Quote:
Pro tip: actually get any sort of proper cast manifold designed, built, and in production for a 1.8 miata for a reasonable price, that fits t2's and t3's, and you will already "have a market".
You know why? Cause it's not easy. There's a reason only approx 2 companies make them now, with hopefully a 3rd competing in the near future. Learn to walk before you run.

In 2 weeks we have a new meeting for the next parts we are going to make. I think a 1.8 turbokit will be on the planning. Oh and i need a bigger turbo so thats a plus.

I like to create the impossible.
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Old 07-02-2015, 05:30 PM   #5
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What IS the extra time and money?
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Old 07-02-2015, 05:31 PM   #6
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Developing and testing will cost some extra time. And the twinscroll turbo's are more expensive than singlescroll
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Old 07-02-2015, 06:23 PM   #7
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Well with that answer, i'll say that the answer to your original question is a rock solid "potentially."
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Old 07-02-2015, 06:39 PM   #8
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Quote:
Originally Posted by Vincentmiata View Post
Developing and testing will cost some extra time. And the twinscroll turbo's are more expensive than singlescroll
There's 2 companies that offer cast manifolds right now. If you came out with a generic, nothing-revolutionary, but good (not perfect, just good) quality manifold and could undercut the competition, you would sell them.

Miata market is like this:
1. Price
2. How much it cost
3. Quality
3. Everything else

I used to rock a GT3271 twin scroll turbo, and I wouldn't have bought the manifold you're discussing building. I wanted a manifold that actually closed-off a valve and forced all the air into one side of the turbine for better spoolage. If you built that, and I had the GT3271, I prob would have bought it.
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Old 07-02-2015, 06:42 PM   #9
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Go for it, I was considering a twinscroll 7163 but the overall cost was looking closer to 3000 for everything assuming I could find someone to fab up the manifold which was my only complication. I've read good things on those that do run twinscroll, though. Add a TS setup with a VVT head and you have a recipe for radically entertaining response.
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Old 07-02-2015, 06:45 PM   #10
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Quote:
Originally Posted by patsmx5 View Post
There's 2 companies that offer cast manifolds right now. If you came out with a generic, nothing-revolutionary, but good (not perfect, just good) quality manifold and could undercut the competition, you would sell them.

Miata market is like this:
1. Price
2. How much it cost
3. Quality
3. Everything else

I used to rock a GT3271 twin scroll turbo, and I wouldn't have bought the manifold you're discussing building. I wanted a manifold that actually closed-off a valve and forced all the air into one side of the turbine for better spoolage. If you built that, and I had the GT3271, I prob would have bought it.


Like this?

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Old 07-02-2015, 06:47 PM   #11
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Yes, like that. But in my case, with a cast iron manifold, I couldn't bolt that between my manifold and turbo without my turbo hitting the car in ways I could not trim-to-fit for. I always wanted to build that valve into the turbo itself... I even bought the stuff to do it, but when I pulled the turbo I discovered it was toast and ended up replacing it with a non-twin scroll.
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Old 07-02-2015, 06:49 PM   #12
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Will this non divided manifold with valve spool better than a fully divided manifold?
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Old 07-02-2015, 06:50 PM   #13
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Not quite apples to apples as it were.

This is my old Evo 3

Built bottom end 2.0L 9.3:1 CR, HKS 272/280 cams, 24x12x3.5 AGP bar and plate, short route 2.5" piping TD05-20G with a 12.5cm^2 twin scroll housing on a short runner unequal length exhaust manifold & full 3" exhaust


And wouldn't you know it. I cannot find the boost curve for when I had the stock motor/turbo in my photobucket. I do not have the data but for what little it's worth without proof I would make 14psi at 3400-3500rpm on a stock 8.8:1 bottom end, stock TD05-16G 7cm^2 turbo, stock intercooler with stock long route hard piping, HKS 272/264 cams & 3" exhaust

spool negatives : larger intercooler, bigger exhaust cam
spool positives : shorter intercooler piping, 0.5 points of static compression


The increase in transient response between gears was noticeable but again I don't have any data. I am a firm advocate of twin scroll for anything but a drag setup.
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Old 07-02-2015, 06:50 PM   #14
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Quote:
Originally Posted by Vincentmiata View Post
Will this non divided manifold with valve spool better than a fully divided manifold?
Yes it would.
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Old 07-02-2015, 06:56 PM   #15
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So it basically makes the turbo variable, for example like an 1.0 AR to a 0.5 AR with the valve closed right?
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Old 07-02-2015, 06:58 PM   #16
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Quote:
Originally Posted by Vincentmiata View Post
So it basically makes the turbo variable, for example like an 1.0 AR to a 0.5 AR with the valve closed right?
Yeah something like that. The valve shuts and now all 4 cylinders worth of exhaust have to go through one port, exhaust velocity goes up A BUNCH and this super fast exhaust hitting the turbine helps spin it up very quickly. Upside of this is great response, downside is turbo will choke if it stays like this. So the valve needs open once boost target is reached so turbine inlet pressure will drop and everything can breathe.
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Old 07-02-2015, 07:26 PM   #17
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Eh let me think. The small scroll is for the spool. And the bigger scroll is for the horsepower. If you only have the small scroll it will choke.

You want a valve to open up the big scroll at certain boost level.

Those valves only open up both scrolls.

And what about a divider. Low boost everything goes to to small scroll for quick spool. And after a certain boost level the valve switches from the small scroll to the big scroll. So instead of both scroll opened.. al the air goes only to the big scroll
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Old 07-02-2015, 07:30 PM   #18
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All that valve does is block one scroll. There is no big scroll, small scroll, just 2 equally sized ports. The valve can open/close one of those ports, effectively making the turbine housing bigger/smaller on demand. There are variable-geometry turbines that take a different approach and accomplish the same things.
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Old 07-02-2015, 07:33 PM   #19
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Quote:
Originally Posted by patsmx5 View Post
Yes it would.
Would like to see this test because on most vehicles a fully divided manifold coupled with a fully divided turbine housing will perform better than a non-divided manifold with a quick spool valve.
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Old 07-02-2015, 07:35 PM   #20
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Quote:
Originally Posted by Arca_ex View Post
Would like to see this test because on most vehicles a fully divided manifold coupled with a fully divided turbine housing will perform better than a non-divided manifold with a quick spool valve.
Hmm. I'd like to see that test too. I'm speculating on my post, I've tested nothing. Do you have any examples of what you're referring to?
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