Exhaust with Wastegate?

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Mpgingerson
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Exhaust with Wastegate?

Post by Mpgingerson » Tue Feb 16, 2016 1:01 am

Hello. Around summertime I'm getting a custom made exhaust for my turbo Legacy in a shop, and I'm going for a 3" turbo back with no cats, but how about installing a wastegate also, whilst I'm getting the exhaust done why not. I've seen some people having it just after the turbo and into a small pipe that goes straight to the ground and everything heatwrapped. I just love the sound it makes and I was wondering if it's worth it or not.

And please, list any cons and flaws of that kind of setup.

Legacy777
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Re: Exhaust with Wastegate?

Post by Legacy777 » Tue Feb 16, 2016 6:26 pm

I think you're referring to an external wastegate/dump valve. This is more a function of the turbo than the exhaust. The stock and all factory replacement turbos have internal wastegates. You can make a twin-dump downpipe that keeps the wastegate gasses separate for a while and then dumps back in.

An alternative is to have an electronic cut out that will give you louder sound when you want. Here are some examples.

http://www.summitracing.com/search/part ... st-cutouts
http://www.jegs.com/p/JEGS-Performance- ... 9/10002/-1
Josh

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1997 Impreza OBS

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Mpgingerson
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Re: Exhaust with Wastegate?

Post by Mpgingerson » Tue Feb 16, 2016 7:35 pm

Legacy777 wrote:I think you're referring to an external wastegate/dump valve. This is more a function of the turbo than the exhaust. The stock and all factory replacement turbos have internal wastegates. You can make a twin-dump downpipe that keeps the wastegate gasses separate for a while and then dumps back in.

An alternative is to have an electronic cut out that will give you louder sound when you want. Here are some examples.

http://www.summitracing.com/search/part ... st-cutouts
http://www.jegs.com/p/JEGS-Performance- ... 9/10002/-1

Oh yeah, my mistakes sorry! I'm not really sure.. You know when you see tuned cars just casually drive and the engine noise is alright, but when the boost builds the car just roars and goes real loud?

Like in this video

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Re: Exhaust with Wastegate?

Post by mike-tracy » Tue Feb 16, 2016 9:52 pm

I think you are talking about a blow off valve.

People can use them, but they are for noise and not performance on these older cars.
1992 Legacy SS 5mt, build in progress
Josh Colombo wrote:
Mon Jan 14, 2002 10:23 am
Wait....I'm confused now.

Mpgingerson
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Re: Exhaust with Wastegate?

Post by Mpgingerson » Wed Feb 17, 2016 12:06 am

mike-tracy wrote:I think you are talking about a blow off valve.

People can use them, but they are for noise and not performance on these older cars.
No it was the External Wastegate dump from the turbo.. I didn't know what it was before I researched it.

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Re: Exhaust with Wastegate?

Post by mike-tracy » Wed Feb 17, 2016 4:27 am

Ah. What turbo would you be using with it? In theory, installing one is easy - you weld the turbo's wastegate closed, and weld an EWG on the up pipe, and connect it to a vacuum source, right? I've ridden in cars with them, hard to say how much of a difference they made, because they were on bigger turbos.
1992 Legacy SS 5mt, build in progress
Josh Colombo wrote:
Mon Jan 14, 2002 10:23 am
Wait....I'm confused now.

Mpgingerson
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Re: Exhaust with Wastegate?

Post by Mpgingerson » Wed Feb 17, 2016 10:26 am

mike-tracy wrote:Ah. What turbo would you be using with it? In theory, installing one is easy - you weld the turbo's wastegate closed, and weld an EWG on the up pipe, and connect it to a vacuum source, right? I've ridden in cars with them, hard to say how much of a difference they made, because they were on bigger turbos.
Hmm.. Maybe not then. It's going to be on an old STI turbo or something similar that can handle around 300 BHP-350 BHP with more bottom end.

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Re: Exhaust with Wastegate?

Post by dankberries » Wed Feb 17, 2016 4:05 pm

I'm not sure I've seen it on a Subaru, but for the 240sx I've seen divorced down pipes with external wastegate dump. Atmospherically dumps wastegate gas while using an internally gated turbo.

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Re: Exhaust with Wastegate?

Post by Legacy777 » Wed Feb 17, 2016 6:35 pm

I'm going to give you my two cents here. As I mentioned above, the turbo you are using more than likely has an internal wastegate setup. You can do what Mike suggested and weld the internal wastegate closed and have an external one fitted. You could also change the turbo and use one that has an external wastegate. Regarding dankberries's comment above with the divorced down pipe, it's a little more difficult on these turbos because there is a recessed space between where the down pipe mounts to the turbo. Even with a diverter plate if you used the divorced down pipe to atmosphere there's nothing sealing off the exhaust gasses from the turbine section, and that would go to atmosphere as well. This would essentially create an exhaust leak.

What you want can be done, but it serves very little if any benefit for the horsepower and turbo you would likely run other than to make noise. Adding an external wastegate requires modification of the up-pipe so that's additional exhaust work that would need to be done. I don't know what you're looking to spend, but I could see the cost ballooning pretty quickly.
Josh

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Re: Exhaust with Wastegate?

Post by jamal » Sat Feb 20, 2016 6:56 pm

Just to be clear on what a wastegate does, since you mentioned "after the turbo," it is plumbed into the exhaust before the turbo to allow excess exhaust to bypass the turbine once you hit the targeted boost (if there was no wastegate, or it stayed closed, the boost could just keep increasing, uncontrollably, and bad things would happen).

Depending on the turbo, engine, tuning, rest of exhaust etc, a turbo's internal wastegate can actually not flow enough exhaust around the turbine, causing boost creep. So there is one actual legitimate reason to install a EWG on a car with an IWG other than noise, and it can also result in a marginal increase in power because exhaust is entering and exiting the turbo more smoothly.

The best way to do such a thing is to buy an up-pipe that already has the provisions instead of having someone fabricate it. And then instead of welding the wastegate closed in the turbine, you can just install a bracket in place of the actuator that holds the gate closed.

That takes it from a have someone fabricate and weld things situation to bolting on parts. You still need a different boost controller and tuning for it to work, since the stock boost controller works on a solenoid duty cycle map and boost pill specific to each turbo. Since a different OEM turbo is already going to have a wastegate and probably not creep, installing an EWG is still going to be quite a bit more cost and effort.

If you're curious about prices here are some ballparks
up-pipe with ewg provisions - 320-350
wastegate - 280-360
electronic boost control solenoid - 100
IWG bracket - 30

So somewhere in the 750-800 region, and that doesn't return the waste exhaust to the downpipe, fabbing that would be extra. Also doesn't include tuning, which is going to be necessary with a different turbo either way. And I don't even know how you tune the older cars short of an aftermarket ecu.

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Re: Exhaust with Wastegate?

Post by Mpgingerson » Sat Feb 27, 2016 9:28 pm

jamal wrote:Just to be clear on what a wastegate does, since you mentioned "after the turbo," it is plumbed into the exhaust before the turbo to allow excess exhaust to bypass the turbine once you hit the targeted boost (if there was no wastegate, or it stayed closed, the boost could just keep increasing, uncontrollably, and bad things would happen).

Depending on the turbo, engine, tuning, rest of exhaust etc, a turbo's internal wastegate can actually not flow enough exhaust around the turbine, causing boost creep. So there is one actual legitimate reason to install a EWG on a car with an IWG other than noise, and it can also result in a marginal increase in power because exhaust is entering and exiting the turbo more smoothly.

The best way to do such a thing is to buy an up-pipe that already has the provisions instead of having someone fabricate it. And then instead of welding the wastegate closed in the turbine, you can just install a bracket in place of the actuator that holds the gate closed.

That takes it from a have someone fabricate and weld things situation to bolting on parts. You still need a different boost controller and tuning for it to work, since the stock boost controller works on a solenoid duty cycle map and boost pill specific to each turbo. Since a different OEM turbo is already going to have a wastegate and probably not creep, installing an EWG is still going to be quite a bit more cost and effort.

If you're curious about prices here are some ballparks
up-pipe with ewg provisions - 320-350
wastegate - 280-360
electronic boost control solenoid - 100
IWG bracket - 30

So somewhere in the 750-800 region, and that doesn't return the waste exhaust to the downpipe, fabbing that would be extra. Also doesn't include tuning, which is going to be necessary with a different turbo either way. And I don't even know how you tune the older cars short of an aftermarket ecu.
Jesus christ, didn't know all this... But maybe this isn't what I'm looking for then.. I see alot of people using cutouts, and it got suggested to me in this post, but I've read that if you map the car for the cutout it would run really rich when the cutout is closed... Isn't this bad? Because I really want a cutout since it's really badass and suprises everybody.. Has someone done this before and has a picture or can describe it for me as where it's put in the exhaust system for a older type Legacy.

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Re: Exhaust with Wastegate?

Post by SouperPoo » Sat Feb 27, 2016 11:33 pm

Ahh. I see your intention. You want to be able to control the volume of your exhaust. For this you could do an electronic cutout as close to the turbo as you can get it. I wouldn't suggest an electronic one though as they tend to all be junk. Having an on demand roar come from your car would be cool but I have always just ran an open downpipe when I'm in the mood. If your downpipe is 3 inch and catless it's going to be loud and you will hear when the iwg opens. It's a hearty boxer sound with very dominant turbo whoosh. If you are super lazy do the electronic cutout. If you are semi lazy do a manual cutout like example http://www.jegs.com/i/JEGS/555/30750/10 ... AuKz8P8HAQ. If you arn't lazy just take the cat back off when you want.

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Re: Exhaust with Wastegate?

Post by Mpgingerson » Mon Feb 29, 2016 12:03 am

SouperPoo wrote:Ahh. I see your intention. You want to be able to control the volume of your exhaust. For this you could do an electronic cutout as close to the turbo as you can get it. I wouldn't suggest an electronic one though as they tend to all be junk. Having an on demand roar come from your car would be cool but I have always just ran an open downpipe when I'm in the mood. If your downpipe is 3 inch and catless it's going to be loud and you will hear when the iwg opens. It's a hearty boxer sound with very dominant turbo whoosh. If you are super lazy do the electronic cutout. If you are semi lazy do a manual cutout like example http://www.jegs.com/i/JEGS/555/30750/10 ... AuKz8P8HAQ. If you arn't lazy just take the cat back off when you want.

Hmm.. I just drove my friends WRX today and it has a straight 3" catless exhaust and it was loud, but it was as loud as I would like mine to be.. I think I'll stick to the plan of getting just a custom 3" exhaust made up catless, but this gives me another idea.. Whils't I'm getting the exhaust made, why not install a bigger turbo aswell? I know there are countless threads about which turbos to run, but what's your recomondation? I want something that gets me over 300 hp, and something a little bigger and more agressive on the top than my stock turbo... But it doesen't have to be around 300 hp, I always want more, but how much can the stock EJ20G block handle? I think it's closed deck if I'm not mistaken, and money is not an issue, so what's the best for a stock engine? And when you change the turbo, is it dangerous for the engine to run it with stock map or is the map just to get the most out of the setup, it won't harm the engine or wear it down faster?

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Re: Exhaust with Wastegate?

Post by jamal » Tue Mar 01, 2016 8:05 pm

Mpgingerson wrote: And when you change the turbo, is it dangerous for the engine to run it with stock map or is the map just to get the most out of the setup, it won't harm the engine or wear it down faster?
More air without more fuel = blown up engine. The stock ecu, maf and injectors can only compensate for so much.

So you definitely can NOT put on a bigger turbo without tuning and you should probably add bigger injectors, a fuel pump, and an intercooler as well.

I don't even know what the best way to do it would be with these old cars. You can probably still get a link ecu if money is really not an issue and go map/speed density based to get rid of the limitations of the stock maf sensor. You would need to find a dealer and a tuner with a dyno familiar with them and subarus. Otherwise a piggyback air-fuel controller or something?

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Re: Exhaust with Wastegate?

Post by Legacy777 » Wed Mar 02, 2016 4:05 am

The easiest option with these cars is to go with a Robtune ECU. It's not perfect, but it works pretty darn well and makes good power without having to deal with a lot of the issues a stand alone or piggy back adds.
Josh

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Re: Exhaust with Wastegate?

Post by Mpgingerson » Wed Mar 02, 2016 11:54 pm

Yeah, Robtune was planned, mostly because everybody uses it and it's good... And if I'm not mistaken you can get it with launch controll? But yeah.. Okay, I'll slowly upgrade the fuel and air system first, and then the exhaust and turbo when the holiday money comes in (yes, we get holiday money in norway haha).

But my plans for the future setup is probably the normal one for Subarus.

- VF34 Turbo
- 3" exhaust from turbo
- FMIC
- Walbro 255 fuel pump
- 550 cc injectors
- Apexi intake system
- Stage 1 Exedy clutch with Exedy LW flywheel
- Rob's tune to run it all

But roughly how much HP will this make?

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Re: Exhaust with Wastegate?

Post by Legacy777 » Sun Mar 06, 2016 12:49 am

If I had to guess....probably somewhere around 250. However that's a pure guess. I'd suggest searching to see what others with the 550's and Robtune get.
Josh

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Re: Exhaust with Wastegate?

Post by Mpgingerson » Sun Mar 06, 2016 12:46 pm

Legacy777 wrote:If I had to guess....probably somewhere around 250. However that's a pure guess. I'd suggest searching to see what others with the 550's and Robtune get.
250 is a bit low? Haha, I've read people with robtune, injectors, exhaust, etc.. But no turbo, not a fmic and such getting around 280, but how well does the transmission hold up? I'm guessing if I actually reach 250-300 the transmission won't be happy.

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Re: Exhaust with Wastegate?

Post by Pntaste4evr99 » Mon Mar 07, 2016 12:07 am

Mpgingerson wrote:
Legacy777 wrote:If I had to guess....probably somewhere around 250. However that's a pure guess. I'd suggest searching to see what others with the 550's and Robtune get.
250 is a bit low? Haha, I've read people with robtune, injectors, exhaust, etc.. But no turbo, not a fmic and such getting around 280, but how well does the transmission hold up? I'm guessing if I actually reach 250-300 the transmission won't be happy.

My buddy dyno'd his Rob 550 on his 20g with frt mnt and everything through his 6 speed and made around 260.
But, as with chassis dynos, a lot of ppl have there opinions on which ones to trust or not. Just food for thought.....
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Re: Exhaust with Wastegate?

Post by mike-tracy » Mon Mar 07, 2016 7:06 am

Mpgingerson wrote:
Legacy777 wrote:If I had to guess....probably somewhere around 250. However that's a pure guess. I'd suggest searching to see what others with the 550's and Robtune get.
250 is a bit low? Haha, I've read people with robtune, injectors, exhaust, etc.. But no turbo, not a fmic and such getting around 280, but how well does the transmission hold up? I'm guessing if I actually reach 250-300 the transmission won't be happy.
People have dyno'd anywhere from 190 WHP (see Kimo's old setup) to 289 and anywhere in between. It has everything to do with the dyno, time of day, weather, how healthy the engine is, sensor condition, clogged exhaust, correction factor of the dyno software, etc etc etc. Too many variables.

Your transmission can take as much HP as you throw at it, till it breaks. If you can be satisfied not driving your car hard and never launching it, I'm sure it will last a very long time. Only sure thing that can handle the power is a 6-speed from an STI, Spec B legacy, and other JDM stuff.

Personally, I have ran both the Forester XT and STI-RA transmissions. Both are 5-speeds with the wider 1-3rd gears. I felt comfortable launching my car on dirt and wet pavement, but never on dry asphalt. I ran both of them with the Robtune and recommended setup, 550cc injectors and a td05 at up to 18 psi. My old setup was a built ej20g, and currently have an ej22t.

I switched back to the stock SS transmission and was only running wastegate pressure on the td05 when I spun a main bearing. Once the engine is broken in again, I'll be running it at 18 psi again, and I don't feel like with my driving (responsible shifting, but hammering down on the throttle) will cause issues with the trans. But if it does, I have a backup ready to go ;)
1992 Legacy SS 5mt, build in progress
Josh Colombo wrote:
Mon Jan 14, 2002 10:23 am
Wait....I'm confused now.

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