BL/BP Legacy - Boost Controller Questions.

[imantisnz]

Hiya guys, new to the forums and was hoping to find some information in regards to helping a mate with his turbo Legacy.

We've looked into manual boost controllers, and he's really keen on getting one. I'm helping him install it, but just want to get some clarification from some Subie gurus first! Basically, I'm on a hunt to find out how much we're able to safely add boost without damaging the engine. I read online that factory boost cut is 13psi, and that people have run their Legacy's standard up to 12psi with intercoolers. Now, first question is, would this be true for top-mount intercoolers? I'm all in the know on how to safely adjust boost, slowly adding more and more while watching the gauge and ensure the car is running healthy. Apparently the ECU is able to ensure there's enough fuel and everything for the car to run at 12psi easily, can anyone confirm this? And does anyone have any tips or vital information that would be needed for such an install.

Cheers in advance!

[Guest]

Get a proper reflash. Far bigger gains in power and economy without the risk. If its running a vf38 you want to be nice to it.

[imantisnz]

 evowrx said:

Get a proper reflash. Far bigger gains in power and economy without the risk. If its running a vf38 you want to be nice to it.

We have cost in mind as well, haven't investigated reflashing but we're interested in just a boost controller at this time.

[Andy_Mac]

Don't know where the 13psi came from but mine before a tune would boost up to 18.5psi and taper down to about 15 further up the rev range. When logged the stock tune was pretty messy. Have it setup now to 17psi tapering down to 15 and its a lot smoother. This is a vf45 though, essentially the ballbearing vf38. The vf38's journal bearings don't like over boosting and pack it in real quick.

18-19psi seems to be the max people go to with vf38's, but that's with a proper tune.

Is his one nz new or import? And what year? There are two completely different engines within the bl/bp era.

I had mine e-tuned Which needed a cable that was $200 plus tune was $250 if I remember correctly, and any future tunes/logging use the same cable. Even if you do just do a boost controller its'd be worth getting the cable just to see how safe it really is. What you see/feel may seem fine but you'd probably find it'll pull timing all over the place, especially if it's an import, and end up being no better off than without it.

All I can really say is these are nice cars, not the cheap kinda ones you drive into the ground so why not just do it right and not have to worry that one day it'll croak it all for saving a couple of hundred bucks.

[imantisnz]

He's bringing it over to mine tomorrow so I can get all the information from the car that I need, I'll talk with him and let him know what you've suggested. I didn't really consider tuning as much as I've had previous cars, for example a SR20DET Primera with a factory, non-tuned ECU that had a bleed valve (I personally am more of a Nissan man) and it ran smooth. This, needless to say, leaves me inexperienced with Subarus and due to the Primera having no tune, I thought the Legacy would be similar.

Any more thoughts on it would be great!

[DacerX]

if you really want to do a boost controller. get a ebc and a boost gauge. at least then you can see what your changing. But honestly reflash is way way better with the later legacys.

[imantisnz]

Yeah, we're installing a boost gauge today to get an idea of the factory boost psi and working on the boost controller later on, will let him know about the reflash suggestion. Anyone know who would do a good one for a cheap price?

[philr8]

https://www.facebook.com/pages/Dynotech-Industries/509938849041709

 imantisnz said:

Yeah, we're installing a boost gauge today to get an idea of the factory boost psi and working on the boost controller later on, will let him know about the reflash suggestion. Anyone know who would do a good one for a cheap price?

[Andy_Mac]

Raijin would be a good one to get hold of for a tune. Road tunes so works out way cheaper since you don't have to book any dyno time. I did mine through a guy called cryotune in the states

[Guest]

Perhaps sharing your location would help with tuning advice...just a thought unless Ive missed it.

The road tune idea/cyrojobbie is better than a boost tap well anythings better than a boost tap and buttometer really. Adding 2psi or whatever without tuning doesnt do much for a car but tuning it at the same or more boost will net you a nicer curve all over.

[GorGasmSpecB]

No point in the boost controller. Save the pennies and get it tuned.

[boon]

As everyone has basically said, there's a bit more to a modern ECU than the one running the old 20DET... you put a boost tap on it and the ECU is more likely to go "wtf, something is wrong with the wastegate solenoid, CEL and limp mode please" rather than "chuck moar fuel in!"

[Kiwi_Fozze]

+1 to what's been said.

boost tap = f**ked engine.

these newer engines are a LOT more picky about how and where you get power. if it comes on too early, limp mode

not enough boost at set range, CEL and limp mode

too much boost, limp mode, if you dont break something.

i'd STRONGLY suggest saving the money you'd spend on a GOOD controller, (think gfb electronic or hks number) and investing it into a tune. have heard some fantastic results from cryotune, and raijin tunes are f**king fantastic.

another side effect of a good tine, is it won't soot up the exhaust tips and bumper, it'll run smoother and cleaner and you should also have an increase in fuel economy. basic road tunes in my v7 netted me an extra 150kms around the city, at 6psi more boost (24psi) and 220kw ish at all 4 wheels. theres huge improvements to be made over the stock tunes, as they are set up to be very safe.