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Old 02-04-2008, 03:25 AM   #1
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Default GT2871RS and IWG vs EWG

So I am currently running a 2871RS with an external gate on a tubular manifold. For a couple reasons, I am considering switching to a cast manifold without an external waste gate port. (FM's) I have heard they have had some issues with boost creep but have not run this turbo before. Anyone have any input on this? I know most people graduate to an external gate rather than the other way around, but if I can make it work, it will simplify the system in the car as well as take some weight out.

Any thoughts?
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Old 02-04-2008, 10:21 AM   #2
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https://www.miataturbo.net/forum/showthread.php?t=16588

should know soon enough: internal with 3" turboback.
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Old 02-04-2008, 10:31 AM   #3
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...on a 1.6
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Old 02-04-2008, 11:13 AM   #4
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I think (anecdotally at least) that turbo has been on the borderline between OK and not OK with its internal wg.

At best you'll get away with using the internal gate and porting it out, but at worst you'll spike all over at low boost levels.

What PSI are you planning to run? remember the WG works harder the less boost you run.

datapoint: my 2876R never spiked at 4 psi with an external wg.

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Old 02-04-2008, 11:49 AM   #5
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more details would be good I guess.

I have a 2.0L stroker in the car. I've been running between 7 and 12 psi on the track with the turbo simply because the suspension on the car hasn't been able to hold more than 250-290hp effectively. Once the car is set up a little better, and the ecu has a better tune, I'll probably turn it up a little more.

This is pretty much a track only car. So it will suck to have to waste a tow and a track day to discover that the thing creeps all over the place...
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Old 02-04-2008, 12:06 PM   #6
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Then go External WG just for the peace of mind. 38mm tials cost less than a track day.
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Old 02-04-2008, 12:08 PM   #7
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What is your reason for wanting a cast mani?
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Old 02-04-2008, 12:11 PM   #8
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I've already got the wastegate. its a manifold that it will bolt to that I am having trouble with.

I'm looking for cast for added reliability. I'd prefer to spend race days passing cars, not swapping manifolds in the pits...

Are there people here who are using tubular manifolds on the roadcourse that aren't suffering issues with cracking? Street use is extremely different IMO, and I am loosing faith in the tubular manifold I have. Others have run it with no problems on the street or light track duty, but I have not had success with it.

Matt

Last edited by Matt [exz3owner]; 02-04-2008 at 12:22 PM.
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Old 02-04-2008, 12:14 PM   #9
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Quote:
Originally Posted by Matt [exz3owner] View Post
I've already got the wastegate. its a manifold that it will bolt to that I am having trouble with.

Are there people here who are using tubular manifolds on the roadcourse that aren't suffering issues with cracking? Street use is extremely different IMO, and I am loosing faith in the tubular manifold I have. Others have run it with no problems on the street or light track duty, but I have not had success with it.

Matt
Sounds like you need a BEGi S5 Mani..

Cast and EWG
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Old 02-04-2008, 12:25 PM   #10
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Old 02-04-2008, 12:29 PM   #11
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Quote:
Originally Posted by Matt [exz3owner] View Post
I've already got the wastegate. its a manifold that it will bolt to that I am having trouble with.

I'm looking for cast for added reliability. I'd prefer to spend race days passing cars, not swapping manifolds in the pits...

Are there people here who are using tubular manifolds on the roadcourse that aren't suffering issues with cracking? Street use is extremely different IMO, and I am loosing faith in the tubular manifold I have. Others have run it with no problems on the street or light track duty, but I have not had success with it.

Matt
all manifolds crack. expansion and contraction and thermal stresses are a fact of heat cycling from ambient to red hot. but I still believe in mild steel thick tube shorty headers as the least likely of the tubular to crack.

my long tube has been on the car many miles (15k+) with a track day and some autox and it's been rock solid. it's an ETD made of mild steel sch40 weld els.

If I were to do it again, I'd get this: http://etdracing.com/miata3.html
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Old 02-04-2008, 12:34 PM   #12
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Quote:
Originally Posted by y8s View Post
all manifolds crack. expansion and contraction and thermal stresses are a fact of heat cycling from ambient to red hot. but I still believe in mild steel thick tube shorty headers as the least likely of the tubular to crack.

my long tube has been on the car many miles (15k+) with a track day and some autox and it's been rock solid. it's an ETD made of mild steel sch40 weld els.

If I were to do it again, I'd get this: http://etdracing.com/miata3.html
That is pretty much the same price as a BEGi S5 when you add the EWG flange. What in your mind is the benifit of the ETD mani over the Cast BEGi S5 for his application?
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Old 02-04-2008, 02:04 PM   #13
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Quote:
Originally Posted by MX5-4me View Post
That is pretty much the same price as a BEGi S5 when you add the EWG flange. What in your mind is the benifit of the ETD mani over the Cast BEGi S5 for his application?
flow path. both the BEGi and FM manifolds (BEGi being slightly better) flow into either each other or a wall. the ETD has smooth turns into the turbo.






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Old 02-04-2008, 05:11 PM   #14
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Nice CAD model Matt. Pro-E? Did you do that yourself?

I think this one would flow more, but I am biased


Mild steel manifold should last longer than a stainless because stainless grows much more than mild steel when it gets hot.
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Old 02-04-2008, 05:22 PM   #15
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i cant wait to complete my mani, i really want to hear what everyone thinks and also to point out my flawzz
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Old 02-04-2008, 07:41 PM   #16
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Quote:
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Nice CAD model Matt. Pro-E? Did you do that yourself?
Looks like the Flyin Miata CAD picture of their manifold - IIRC they posted it some time ago when they were still in preprod.
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Old 02-04-2008, 09:24 PM   #17
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Quote:
Originally Posted by TurboTim View Post
Nice CAD model Matt. Pro-E? Did you do that yourself?

I think this one would flow more, but I am biased (big *** pic)

Mild steel manifold should last longer than a stainless because stainless grows much more than mild steel when it gets hot.
yeah that CAD doodad is off FM's site.

I agree yours is better than all of the above, but I bet it would put my turbo into the chassis. as it is I have about 1/2" before bad juju.

see, tim knows where its at with mild steel! you should build OP matt a manifold and get your **** published in SCC.
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Old 02-05-2008, 09:43 AM   #18
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Quote:
Originally Posted by y8s View Post
yeah that CAD doodad is off FM's site.
ahh ok. I don't really like the #1 & #4 primaries pointing at each other, like a standard log style manifold. It's not "bad" but not as nice as it could be especially if you are doing a casting and can model whatever shape you want...like BEGI's.

Quote:
I agree yours is better than all of the above, but I bet it would put my turbo into the chassis. as it is I have about 1/2" before bad juju.
The GT2871 fits with plenty of clearance, you may be surprised, even with your huge compressor housing. You can see from this pic that there's a decent amount of room around the housing before it'd run into something. But that manifold it's a no-go with A/C and P/S.

Quote:
see, tim knows where its at with mild steel! you should build OP matt a manifold and get your **** published in SCC.
Who? I'd build whomever whatever they want It'd be nice to be in a magazine too I guess.

If I could get a nice stainless head flange I would seriously consider building my manifold in stainless. Even though it grows more and therefore be more prone to cracking, I like the lower thermal conductivity. I guess it really depends on the application. True, you can ceramic coat mild steel, but for some unknown reason I don't. I think I can't decide on coating just the outside or both the inside and outside.
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Old 02-05-2008, 11:05 AM   #19
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Matt the original poster = who.

I see your mani hangs under the pinch seam. my turbo is just above centered on it.
http://gallery.y8s.com/miata/turbo/D...geViewsIndex=1

you should build a manifold that's 1/2 stainless and 1/2 ceramic coated mild steel. Just cut two flanges down the middle. I'd be curious which looks better and outlasts the other.


oh.... and I have PS and AC so ...
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Old 02-05-2008, 11:44 AM   #20
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thanks for the input guys. I haven't spent a lot of time here in the past. Lots of good information here and lots of options.

I had another conversation with my manifold manufacture, and we are going to have another go at it. we've made some design changes, so hopefully we'll have something that will take the abuse I subject to it. Oddly, they've built a couple miata manifolds, and I am the only one who has managed to crack it. could have just been a bad header, or it could simply be I'm harder on parts than the other guys.

As a side conversation - what do you guys think about the damper pulley that FM sells? They say they can add a lot more timing on boosted applications because of how smooth it makes the car run. I assume this is because it isn't rattling the crap out of the knock sensor? If it is removing vibration, I wonder if it would help make the manifolds live longer...

Matt
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