Robstune options?

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Mpgingerson
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Robstune options?

Post by Mpgingerson »

Hello. I'm driving a Subaru Legacy Turbo 1993, EJ20G engine.

The final plans for mods on my car are: 3" turbo back exhaust (catless), Walbro 255 fuel pump, Apexi intake w/ coffee cup included, FMIC with some sort of blow off valve, vf34 turbo and 550cc injectors, but living in strict Norway, I have to take my car for a checkup every two years and my question is this.

Can I use the robstune on my car, and then swap the exhaust, turbo and intercooler back to stock without blowing everything up? I'm guessing the injectors are the biggest issue?

And based on this setup, will I reach around STI powerrange?
mike-tracy
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Re: Robstune options?

Post by mike-tracy »

Hi, Rob has a tune for either ej20g gray injectors, or the new age impreza STI yellow tops. Either one will get you to around STI power. The tune for the yellow tops allows for a couple extra psi on a td05 or similar (such as the vf34). But your old style ej20g heads might not flow enough to take advantage of it.
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: Robstune options?

Post by Mpgingerson »

mike-tracy wrote:Hi, Rob has a tune for either ej20g gray injectors, or the new age impreza STI yellow tops. Either one will get you to around STI power. The tune for the yellow tops allows for a couple extra psi on a td05 or similar (such as the vf34). But your old style ej20g heads might not flow enough to take advantage of it.
Hm... But how safe is it to run the stock EJ20G injectors on a bigger turbo? Aren't injectors a must when upgrading the turbo? I'm guessing everything will be fine as long as the car does not hit boost right? But then again, I van't trust the people checking the car won't rev it...
Mpgingerson
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Re: Robstune options?

Post by Mpgingerson »

But how will the car respond when I go from full Robs tune with all the supporting mods to stock engine again with just the injectors, maybe the turbo aswell... Depends what they find ;) So the setup would be: Robs tune, walbro 255, bigger turbo and injectors... With stock exhaust, stock intake and stock Intercooler... Is this dangerous to drive around with for a little while?
Legacy777
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Re: Robstune options?

Post by Legacy777 »

I think the first question you should ask yourself is what tests are done on the car and how would the inspectors know you have different injectors or ECU? If they are just looking for physical differences like a pod filter and exhaust then those are easily unbolted and bolted back on.

You can run the robtune with the stock intake and exhaust without any issues, you just may not make as much power. I personally run the stock airbox with a modification to allow a little more air into the engine.
Josh

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Mpgingerson
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Re: Robstune options?

Post by Mpgingerson »

Legacy777 wrote:I think the first question you should ask yourself is what tests are done on the car and how would the inspectors know you have different injectors or ECU? If they are just looking for physical differences like a pod filter and exhaust then those are easily unbolted and bolted back on.

You can run the robtune with the stock intake and exhaust without any issues, you just may not make as much power. I personally run the stock airbox with a modification to allow a little more air into the engine.
I can't imagine the inspectors going really in depth, I think they'll just look at the exhaust and other parts that clearly seem modified and then make a statment about that.. But okay that's god news :) I plan on running it with no restrictions, it's only when they are looking at the car some stock parts have to come back on..

And yes, I'm myself a fan of stock airboxes, but I just love the noises the pod filter makes haha, so I hate and love it...
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Re: Robstune options?

Post by Legacy777 »

If you get rid of the resonator in the fenderwell you can get some of the same noises that you can hear with the pod filter, but they may not be as loud.
Josh

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Mpgingerson
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Re: Robstune options?

Post by Mpgingerson »

Legacy777 wrote:If you get rid of the resonator in the fenderwell you can get some of the same noises that you can hear with the pod filter, but they may not be as loud.
First thing I did for mods om the car, but it wasn't enough haha..

But one question.. What turbo comes stock on these cars? And what are they good for?
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Re: Robstune options?

Post by mike-tracy »

Mpgingerson, the ej20g based legacys had either a vf8, vf10 or vf12. The VF12 was the biggest, followed by vf8. The vf10 was fitted to automatics. The vf8 and 12's made around 220chp from the factory, and the vf10 made 200chp. These are all relatively slow spooling and old technology. They can all make a bit more power, but most people switch to a more modern turbo for better performance.
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: Robstune options?

Post by Mpgingerson »

mike-tracy wrote:Mpgingerson, the ej20g based legacys had either a vf8, vf10 or vf12. The VF12 was the biggest, followed by vf8. The vf10 was fitted to automatics. The vf8 and 12's made around 220chp from the factory, and the vf10 made 200chp. These are all relatively slow spooling and old technology. They can all make a bit more power, but most people switch to a more modern turbo for better performance.

So I have either the VF8 or VF12 then since I don't have an automatic?

But anyways.. Is the VF34 the way to go or are there better turbo's for my build? My goal is around 250 whp, or around the STI power range (but not needed).. I'd rather have 250 whp.
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Re: Robstune options?

Post by mike-tracy »

Most likely you have the VF8, as vf12s weren't fitted to european legacys iirc. Since you already have a vf34, I would run that. It is a very quick spooling turbo. The vf35 is even faster spooling, but is a tiny bit smaller than the vf34. Both will hit 250 whp. Your vf8 should hit close to 250 whp at the ragged edge. But the vf34 is far more responsive and entertaining to drive.
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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Re: Robstune options?

Post by mike-tracy »

Remember that a robtune (or other tuning chip or ecu) will expose any weaknesses in the system. It magnifies any marginal performing electronics, vacuum leaks, exhaust or intake leaks you may have. So after the robtune, your car will probably run way worse till you get everything working properly.

Lastly, im pretty sure the robtune requires a 16bit wrx/sti ecu. I dont believe it will run in the 8 bit legacy ecu. Luckily the wrx or sti ecus are a direct swap into your car. The only thing the Wrx/sti ecu won't do is control your AWIC pump, so you'll need to wire that into a power source that comes on when the car is on.
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: Robstune options?

Post by Mpgingerson »

mike-tracy wrote:Remember that a robtune (or other tuning chip or ecu) will expose any weaknesses in the system. It magnifies any marginal performing electronics, vacuum leaks, exhaust or intake leaks you may have. So after the robtune, your car will probably run way worse till you get everything working properly.

Lastly, im pretty sure the robtune requires a 16bit wrx/sti ecu. I dont believe it will run in the 8 bit legacy ecu. Luckily the wrx or sti ecus are a direct swap into your car. The only thing the Wrx/sti ecu won't do is control your AWIC pump, so you'll need to wire that into a power source that comes on when the car is on.

But if I'm not chaning the turbo, are the injectors really needed? And thanks for the information :O I didn't know that the two ECU's were different.. Will I have to rewire the AWIC even if i'm going to install a FMIC?
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Re: Robstune options?

Post by mike-tracy »

To clarify, you already have the vf34 installed, right? Either way, if you put a wrx or sti ej20g ecu in, you won't change the injectors. If you're adding a fmic, you don't deal with the awic pump wiring at all.

Personally I would install a bigger aftermarket awic panel. It would then have all the advantages of a fmic, with no added lag.
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: Robstune options?

Post by Mpgingerson »

mike-tracy wrote:To clarify, you already have the vf34 installed, right? Either way, if you put a wrx or sti ej20g ecu in, you won't change the injectors. If you're adding a fmic, you don't deal with the awic pump wiring at all.

Personally I would install a bigger aftermarket awic panel. It would then have all the advantages of a fmic, with no added lag.

No, sorry if I was misleading :O I have the stock "VF8" turbo on the car right now..

But I saw now on the website that Rob sells ECU's already programed.. Maybe that's a good option..

And I haven't thought of having a bigger awic panel, where can I get this from? I'm guessing that looks more stock than a FMIC, so why not.. Less lag and more stock apprearing is good for me! :) Then I don't have to mess with the stock diverter valve either do I?

And in what order should I buy these mods? Because of my busy days I want to install new mods bit by bit if that works.. I know first derestrict the car more, but after that.. Can I buy the injectors and install them, or do they have to be tuned to work?
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Re: Robstune options?

Post by Legacy777 »

Check out this post for the AWIC radiator upgrade.

http://bbs.legacycentral.org/viewtopic.php?f=3&t=35394

Injectors would need to match the ECU & tune. The turbo can be added prior to upgrading the ECU, you just wouldn't be able to run more boost. past what the stock ECU/injectors can handle.
Josh

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Mpgingerson
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Re: Robstune options?

Post by Mpgingerson »

Legacy777 wrote:Check out this post for the AWIC radiator upgrade.

http://bbs.legacycentral.org/viewtopic.php?f=3&t=35394

Injectors would need to match the ECU & tune. The turbo can be added prior to upgrading the ECU, you just wouldn't be able to run more boost. past what the stock ECU/injectors can handle.

Ah okay, that's good! But the car won't run lean then? Or maybe it's restricted by the ECU yes?

But as far as cooling goes, I'd rather have a TMIC as it appears more stock looking.. If I don't upgrade the stock water intercooler, will and STI intercooler be a good upgrade?
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Re: Robstune options?

Post by Legacy777 »

Mpgingerson wrote:Ah okay, that's good! But the car won't run lean then? Or maybe it's restricted by the ECU yes?

But as far as cooling goes, I'd rather have a TMIC as it appears more stock looking.. If I don't upgrade the stock water intercooler, will and STI intercooler be a good upgrade?

Regarding the larger turbo, you're not drastically changing the turbo size. So let's say the stock turbo puts out 100 cfm at 8 psi and the new turbo puts out 150 cfm at 8 psi. That difference isn't that large and as long as you run stock boost pressure it's likely that the stock ECU, MAF, & injectors has the headroom to put more fuel in to keep the AFR's happy. It's when you start increasing boost and the volume of air going into the engine by a lot where the stock components are at the upper range they can operate and you can no longer control the appropriate amount of fuel being injected, which can cause the AFR's to go lean.

If you feel you're at that limit with the stock turbo and stock boost levels then it would be a good idea to just run wastegate boost pressure with the new turbo.

As for the intercooler, since you already have an intercooler it may be easier to use a TMIC if you can find something that bolts in. But honestly, I'd just keep your AWIC. It truly is the best of both worlds TMIC vs. FMIC. The main reason the OEM's have moved away from it is because it costs more money and is more complex.
Josh

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1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

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Mpgingerson
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Re: Robstune options?

Post by Mpgingerson »

Legacy777 wrote:
Mpgingerson wrote:Ah okay, that's good! But the car won't run lean then? Or maybe it's restricted by the ECU yes?

But as far as cooling goes, I'd rather have a TMIC as it appears more stock looking.. If I don't upgrade the stock water intercooler, will and STI intercooler be a good upgrade?

Regarding the larger turbo, you're not drastically changing the turbo size. So let's say the stock turbo puts out 100 cfm at 8 psi and the new turbo puts out 150 cfm at 8 psi. That difference isn't that large and as long as you run stock boost pressure it's likely that the stock ECU, MAF, & injectors has the headroom to put more fuel in to keep the AFR's happy. It's when you start increasing boost and the volume of air going into the engine by a lot where the stock components are at the upper range they can operate and you can no longer control the appropriate amount of fuel being injected, which can cause the AFR's to go lean.

If you feel you're at that limit with the stock turbo and stock boost levels then it would be a good idea to just run wastegate boost pressure with the new turbo.

As for the intercooler, since you already have an intercooler it may be easier to use a TMIC if you can find something that bolts in. But honestly, I'd just keep your AWIC. It truly is the best of both worlds TMIC vs. FMIC. The main reason the OEM's have moved away from it is because it costs more money and is more complex.
But now I'm changing to bigger injectors just to be safe, but Robstune is also for the 440cc's, but injectors aren't that expensive, so why not.. And yes, I think I'll keep the stock AWIC and maybe modify it like your guide shows :-) But I ran into a problem now.. H&S are the only ones that sell a exhaust that bolts straight up to the Legacy turbo, and this is good because I don't have a welder or the expirience to weld up a new exhaust.. But I found out the exhaust they sell is 2,5", not 3".. For a 280-300 hp setup, does it really matter that it's 2,5"?

And thank you so much Josh for helping me with every stupid post I have and answering every stupid question I have, I appreciate it so much :-)
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Re: Robstune options?

Post by Mpgingerson »

How good is a VF30 turbo? Someone offered one to me, should I buy it? Haha
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Re: Robstune options?

Post by mike-tracy »

Mpgingerson wrote:How good is a VF30 turbo? Someone offered one to me, should I buy it? Haha

Same thing as the vf34, but it spools slower due to conventional bearings.
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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Re: Robstune options?

Post by Mpgingerson »

mike-tracy wrote:
Mpgingerson wrote:How good is a VF30 turbo? Someone offered one to me, should I buy it? Haha

Same thing as the vf34, but it spools slower due to conventional bearings.

Ahh... So VF30 vs TD05 16G.. What's better?
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Re: Robstune options?

Post by mike-tracy »

[quote="Mpgingerslagged wrote="mike-tracy"]
Mpgingerson wrote:How good is a VF30 turbo? Someone offered one to me, should I buy it? Haha

Same thing as the vf34, but it spools slower due to conventional bearings.[/quote]


Ahh... So VF30 vs TD05 16G.. What's better?[/quote]

The td05 is even laggier than the vf30. Has better top end though. When i had it on my old ej20g setup, I wasn't a fan. I value throttle response, and felt that while it was a fun turbo in boost, I spent too much time waiting for something to happen lol. I still have that same turbo on my ej22t. Completely different animal, as the extra 10% displacement bump makes it a quickish turbo. But my heads can't flow well enough to really take advantage of / justify this turbo's top end push. So im still stuck wanting a more responsive turbo ;)

Honestly, with a robtune you'll be happy with any turbo you get, as pretty much anything is an improvement over the stock vf8/10/12. If you want my opinion on which turbo you should buy, make it the most responsive factory STI one you can get. Vf35/vf23/vf34 are top of that pile.
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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Re: Robstune options?

Post by Mpgingerson »

mike-tracy wrote:[quote="Mpgingerslagged wrote="mike-tracy"]
Mpgingerson wrote:How good is a VF30 turbo? Someone offered one to me, should I buy it? Haha

Same thing as the vf34, but it spools slower due to conventional bearings.

Ahh... So VF30 vs TD05 16G.. What's better?

The td05 is even laggier than the vf30. Has better top end though. When i had it on my old ej20g setup, I wasn't a fan. I value throttle response, and felt that while it was a fun turbo in boost, I spent too much time waiting for something to happen lol. I still have that same turbo on my ej22t. Completely different animal, as the extra 10% displacement bump makes it a quickish turbo. But my heads can't flow well enough to really take advantage of / justify this turbo's top end push. So im still stuck wanting a more responsive turbo ;)


Honestly, with a robtune you'll be happy with any turbo you get, as pretty much anything is an improvement over the stock vf8/10/12. If you want my opinion on which turbo you should buy, make it the most responsive factory STI one you can get. Vf35/vf23/vf34 are top of that pile.[/quote]

Allright, thanks Mike! But I'm not sure if I really want a VF turbo when it's time for a rebuild, maybe a upgrade. I don't mind the extra lag that much. And as you said it doesen't matter what turbo I get, then I think I'm going to safe it on a "modern age" turbo that has a lot of options on it.

But how well will a 2,5 turbo back exhaust flow for a 300 hp setup? Any disadvantages og positive sides of it?
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Re: Robstune options?

Post by Legacy777 »

I'd recommend trying to stay with 3" turbo back exhaust.

A turbo essentially works on heat and pressure differential. The lower the pressure on the downstream side of the turbine the larger the pressure differential and quicker the spool. I don't have any empirical data to say that a 2.5" exhaust will cause a certain percentage decrease in spool, throttle response, power, etc. However, from an overarching principle the 3" is going to be better.
Josh

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1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

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