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Old 09-08-2020, 07:16 AM   #1
snow_bound26
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Default Decisions decisions (IWG vs EWG)

2005 9-2x
v7 207 w/S20V big port heads and AVCS
Process West TMIC
KS 73mm big MAF intake
Cobb EBCS
Phenolic spacers
3" TBE
OEM ex manifold (keeping for now)
ID 1050x
Walbro 255
Perrin fuel rails
Perrin 2.4" inlet (debating on 3")
06 STi oil pan w/Killer B pickup and baffle

Right now I'm stuck between 20gXTR and the Dom 1.5XTR. My gut tells me Dom 1.5 w/3" inlet and 10cm housing. All info I've found supports that this spools basically the same as the 20g but has a wider power band. Either way, they are both very similar overall. So thinking in terms of wide power band and transient response how much would a Tial 38mm MV-S EWG make? I know regulating boost pressure is easier with an external but I'm not looking at high pressure or tuning with E85. It's not available where I live. I'm guessing I'll end up in the low 20psi on a 91 tune. How much of a difference would this make on initial spool, transient response and should I consider an 8cm housing since those seem popular with an EWG? Personally I lean toward the 10cm no matter which route I go as it doesn't seem to make a huge difference down low and helps the turbo flow easier up top.

And lastly, I'd route the dump pipe back into the down pipe because I'm not a fan of the extra noise and don't want any issues at tracks that really monitor decibels. Is an EWG going to be a hassle that's just not worth it if I move to UT where some of the counties have emissions inspection similar to CA? I currently split my time between NY and UT but may make the move permanent.
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Old 09-08-2020, 09:11 AM   #2
KillerBMotorsport
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There's no doubt that an EWG is going to enhance performance, but that does scale up with power level as well. If track time is in your future, stick with the larger turbine housing. It will reduce EGTs and turbulent pre-turbine exhaust flow as you will be bypassing less exhaust gasses through the WG with the larger turbine.

At your power level, doing a recirc setup will still yield good benefits to the EWG. Heck, I run them on bigger turbos just because I don't like attracting every cop in a 5 mile radius. Maybe I'm just getting old, lol.

If you're worried about future emissions, you can follow the same path I do. High quality high flow cat in the DP, with the EWG recirc going around the cat. Running the cat as far down the DP as you can will also improve performance vs up close to the turbine. I don't know specifics about NY and UT, but unless the car is on a loaded dyno (again, with a high quality cat), you should be fine. Pic for reference...

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Old 09-08-2020, 01:13 PM   #3
subaru_gc8
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Location: Orange County CA
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Quote:
Originally Posted by snow_bound26 View Post
2005 9-2x
v7 207 w/S20V big port heads and AVCS
Process West TMIC
KS 73mm big MAF intake
Cobb EBCS
Phenolic spacers
3" TBE
OEM ex manifold (keeping for now)
ID 1050x
Walbro 255
Perrin fuel rails
Perrin 2.4" inlet (debating on 3")
06 STi oil pan w/Killer B pickup and baffle

Right now I'm stuck between 20gXTR and the Dom 1.5XTR. My gut tells me Dom 1.5 w/3" inlet and 10cm housing. All info I've found supports that this spools basically the same as the 20g but has a wider power band. Either way, they are both very similar overall. So thinking in terms of wide power band and transient response how much would a Tial 38mm MV-S EWG make? I know regulating boost pressure is easier with an external but I'm not looking at high pressure or tuning with E85. It's not available where I live. I'm guessing I'll end up in the low 20psi on a 91 tune. How much of a difference would this make on initial spool, transient response and should I consider an 8cm housing since those seem popular with an EWG? Personally I lean toward the 10cm no matter which route I go as it doesn't seem to make a huge difference down low and helps the turbo flow easier up top.

And lastly, I'd route the dump pipe back into the down pipe because I'm not a fan of the extra noise and don't want any issues at tracks that really monitor decibels. Is an EWG going to be a hassle that's just not worth it if I move to UT where some of the counties have emissions inspection similar to CA? I currently split my time between NY and UT but may make the move permanent.
if you ware worried about emmissions testing, I wouldnt go ewg. on that turbo its not going to make a big difference anwways. Personally I had a 16g with a iwg and a ewg, and it didnt make a bit of difference at 22psi. BUt here is my 2 cents about he way the 207 makes power. It makes power way up to. so you want to match a turbo that will get you up there not some small turbo thats going to choke and screw your power band up. the 207 really start to make power ast the 4000 mark so trying to make power below that is really not going to happen. So with that said I would go with somehting bigger than the 1.5 at least a 2.5 if not bigger or a gtx gen2 3076. but that is my opinion right now I have a 2.1 with v9 heads with a spoolinator kit with a 3067 and contemplating with the g30 660 to get 450ish


I dont think anyeone is like california just to be honest

Last edited by subaru_gc8; 09-08-2020 at 01:23 PM.
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Old 09-08-2020, 07:50 PM   #4
snow_bound26
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Default Decisions decisions (IWG vs EWG)

Quote:
Originally Posted by subaru_gc8 View Post
if you ware worried about emmissions testing, I wouldnt go ewg. on that turbo its not going to make a big difference anwways. Personally I had a 16g with a iwg and a ewg, and it didnt make a bit of difference at 22psi. BUt here is my 2 cents about he way the 207 makes power. It makes power way up to. so you want to match a turbo that will get you up there not some small turbo thats going to choke and screw your power band up. the 207 really start to make power ast the 4000 mark so trying to make power below that is really not going to happen. So with that said I would go with somehting bigger than the 1.5 at least a 2.5 if not bigger or a gtx gen2 3076. but that is my opinion right now I have a 2.1 with v9 heads with a spoolinator kit with a 3067 and contemplating with the g30 660 to get 450ish


I dont think anyeone is like california just to be honest


I get that the engine really comes alive once you reach a certain amount of air flow. But my goals aren't 400+ hp. I'm not trying to have a turbo that spools as fast as possible during a pull either. If that were the case then I'd stick with my VF34. For the way I drive and use the car, mid to upper 300s are plenty. Transient response is most important to me. Letting the turbo breathe while I'm doing laps is important to me. I'm trying to find a good compromise between size and useable power. Getting a power band from 4000-7000 or a little more is plenty. The g30-660 has some appeal to me but there aren't many people posting about these turbos in this community. The g25-660 seems to lack. Just appears to be an awkward combination and I have a feeling the g25-550 is more efficient and balanced in the g25 options. I've also thought about the GTX2867 or the 3071 gen 2 turbos. Just not sure the extra money spent on these options is really worth it over the Dom 1.5. I'm not saying the Spoolinator isn't worth it, if money wasn't an issue it's the option I'd go with. But, money only goes so far right now. Unfortunately it's rather hard to find anyone with a 207 let alone a 207 similar to what I'm looking to do and get a ride. And most information out here is 257 based. This is why I'm trying to find the balance. Dom 1.5 3" inlet, 10cm housing and EWG might be the best balance.

No UT isn't as bad as CA because they don't do the BAR side of it. However, they do a sniff test and if you fail that then they do a visual inspection as well. I've been spending my winters there for 7 years and know what I need to do to get around it. IWG is definitely easiest. No question. But if I can route a dump pipe into the OE down pipe and weld a 3"-2.5" v-band adapter where the OE flange is then I don't think it would too difficult to swap out for emissions. I'm still registered in NY for Oe and have time to figure it out.

Last edited by snow_bound26; 09-08-2020 at 08:00 PM.
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Old 09-08-2020, 07:54 PM   #5
snow_bound26
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Join Date: Jul 2014
Chapter/Region: Tri-State
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2005 92x Aero
Blue(retired�ȸ

Default Decisions decisions (IWG vs EWG)

Quote:
Originally Posted by KillerBMotorsport View Post
There's no doubt that an EWG is going to enhance performance, but that does scale up with power level as well. If track time is in your future, stick with the larger turbine housing. It will reduce EGTs and turbulent pre-turbine exhaust flow as you will be bypassing less exhaust gasses through the WG with the larger turbine.

At your power level, doing a recirc setup will still yield good benefits to the EWG. Heck, I run them on bigger turbos just because I don't like attracting every cop in a 5 mile radius. Maybe I'm just getting old, lol.

If you're worried about future emissions, you can follow the same path I do. High quality high flow cat in the DP, with the EWG recirc going around the cat. Running the cat as far down the DP as you can will also improve performance vs up close to the turbine. I don't know specifics about NY and UT, but unless the car is on a loaded dyno (again, with a high quality cat), you should be fine. Pic for reference...



That's pretty close to how I was thinking about setting up the dump pipe. Was actually planning on having the cat further back still but I'm not sure how far is to too far since it doesn't reach full efficiency until it's up to a certain temp.

NY is quite simple for emissions. They just check for codes and readiness. So I'm not worried about that. UT is the concern.

I think I'll actually give you guys a call tomorrow about another idea I've been tossing around.

Last edited by snow_bound26; 09-08-2020 at 08:01 PM.
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Old 09-08-2020, 08:23 PM   #6
subaru_gc8
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Quote:
Originally Posted by snow_bound26 View Post
I get that the engine really comes alive once you reach a certain amount of air flow. But my goals aren't 400+ hp. I'm not trying to have a turbo that spools as fast as possible during a pull either. If that were the case then I'd stick with my VF34. For the way I drive and use the car, mid to upper 300s are plenty. Transient response is most important to me. Letting the turbo breathe while I'm doing laps is important to me. I'm trying to find a good compromise between size and useable power. Getting a power band from 4000-7000 or a little more is plenty. The g30-660 has some appeal to me but there aren't many people posting about these turbos in this community. The g25-660 seems to lack. Just appears to be an awkward combination and I have a feeling the g25-550 is more efficient and balanced in the g25 options. I've also thought about the GTX2867 or the 3071 gen 2 turbos. Just not sure the extra money spent on these options is really worth it over the Dom 1.5. I'm not saying the Spoolinator isn't worth it, if money wasn't an issue it's the option I'd go with. But, money only goes so far right now. Unfortunately it's rather hard to find anyone with a 207 let alone a 207 similar to what I'm looking to do and get a ride. And most information out here is 257 based. This is why I'm trying to find the balance. Dom 1.5 3" inlet, 10cm housing and EWG might be the best balance.

No UT isn't as bad as CA because they don't do the BAR side of it. However, they do a sniff test and if you fail that then they do a visual inspection as well. I've been spending my winters there for 7 years and know what I need to do to get around it. IWG is definitely easiest. No question. But if I can route a dump pipe into the OE down pipe and weld a 3"-2.5" v-band adapter where the OE flange is then I don't think it would too difficult to swap out for emissions. I'm still registered in NY for Oe and have time to figure it out.
Yeah i think the g25 really need a bigger hotside as it seems to really need alot of flow. In other words theres my too much backpressure to make power up to. I know when I had my 16gxt on my 205 it really would make power to 6500 even though the redline was at 7500 the turbo fell of so much that it wasnt event worth going up that high. that is why my thinking is the g30 660 is a much better match and the guys from speed academy on youtube pretty much proved it. they got an extra 80ish whp with just the upgrade.
As far as the ewg thing goes, I remeber reading somewhere that you need to go up in pipe size if you were going to reroute the ewg back to the exhaust. but my thought were you can put a muffler on it to quite it down like the old school porsches.

Last edited by subaru_gc8; 09-08-2020 at 08:33 PM.
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Old 09-08-2020, 09:22 PM   #7
snow_bound26
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Quote:
Originally Posted by subaru_gc8 View Post
Yeah i think the g25 really need a bigger hotside as it seems to really need alot of flow. In other words theres my too much backpressure to make power up to. I know when I had my 16gxt on my 205 it really would make power to 6500 even though the redline was at 7500 the turbo fell of so much that it wasnt event worth going up that high. that is why my thinking is the g30 660 is a much better match and the guys from speed academy on youtube pretty much proved it. they got an extra 80ish whp with just the upgrade.
As far as the ewg thing goes, I remeber reading somewhere that you need to go up in pipe size if you were going to reroute the ewg back to the exhaust. but my thought were you can put a muffler on it to quite it down like the old school porsches.


I saw that episode which is why that turbo interests me in the long run. It makes me wonder if a g30-550 would be a possible hybrid option eventually. But that might be too unbalanced in the other direction. What little I have been able to find for our engines I agree, 30r and g30 seems to be the way to go for efficiency up top. For my driving purposes I've been aiming for 7000-7200 and having the extra rev range for downshifting.

I've found it odd how there seems to be a lot of turbos that die off below 7k and several that hold to 8k it not many in between. I wish these engines could be as efficient as my SR20 was. Didn't take a lot to get what I wanted out of it.

Let's look at a different avenue for a minute. What if I did spend the money for a Spoolinator kit with a 3071 gen 2. Would I be too far below it's efficiency range if I keep the boost down and aim for 350-375hp and try to flatten the torque curve so it holds solid up to 7500? Would it be possible to produce a smooth linear power curve rather than aiming for peak power?
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