35 replies to this topic

[thatTTguy]

Hey guys
I know its an old thread but i thought rather than create a knew one, id post here.
Anyways! I just installed my boost gauge today, one of the drift digital ones which are meant to be pretty accurate, then went for a drive and noticed boost on the first turbo was about 15psi then second was getting up to 19psi.
I do have a CAI, turbo back exhaust and have had a tune, but should i be worried about that level of boost?

Thanks
Adam

[Daniel-B4]

Mine was tapped to 15. i was told its 8

[Richo]

I do have a CAI, turbo back exhaust and have had a tune, but should i be worried about that level of boost?

What was it tuned to ?

[B4TT]

If it aint pinging or doing anything weird, no.

[Delete This Account]

19 psi should be fine, mate.

Mine's been at 18 psi for the last 4 years and haven't had a problem.

[thatTTguy]

What was it tuned to ?

Im honestly not to sure, as i only just learned yesterday that the boost can and does get changed via your ecu when you get your car tuned....I thought thats what boost controllers were for... oh wells

If it aint pinging or doing anything weird, no.

19 psi should be fine, mate.

Mine's been at 18 psi for the last 4 years and haven't had a problem.

Awesome! thanks for the help guys

[XXB4XX]

Just responding to Dylan's post about my old b4,

On winter nights it was actually boosting 16 on the primary, with a final boost of 22 psi

[Shadoxity]

i dont get how the B4 runs less on sequential .. weird tuning .. my GTB on stock ECU with 2.5" dumps with vf25/27 runs ~15psi on primary then ~20psi on sequential .. that would suck to get less boost on sequential in a b4 ??

That would be because when its on both turbo's it is moving a lot more air, so 10psi during twin mode is pushing more air and therefore more power than the single pushing 14psi.
So it does make sense

20psi? Geeze, i dont think i would be game enough to put mine up to that high, especially with it being a higher compression engine.

Im still yet to check to boost on mine, just a quick one, with the tunes (ecutek) do they 'up' the boost? Or just change all the other settings? im not sure how it work, but i know it works

Yea, some of the places will give you the option of having a switchable boost map between like 12 and 16psi or some just tune it with more boost.

Dont bother getting an ecutek for these, ecutek is shit!

They dont do anything to do with the changeover or the primary turbo. Well they do minimal.

There is much more you can do, I have retuned my B4 and it is so much nicer to drive on the primary turbo now, picks up so much quicker and is a lot better on the first turbo

Im honestly not to sure, as i only just learned yesterday that the boost can and does get changed via your ecu when you get your car tuned....I thought thats what boost controllers were for... oh wells

Awesome! thanks for the help guys

Your car comes with a boost controller and those settings are in the ECU

Just responding to Dylan's post about my old b4,

On winter nights it was actually boosting 16 on the primary, with a final boost of 22 psi

22psi, holy crap... How long has it been running that?


The std map from subaru (for an MY02 AUD b4) targets for 13-14psi on the primary and 12psi on the secondary.

Im half way through tuning my one and have the primary going to 16psi, also the method they use in the std map to build boost on the primary is crappy so it spools slower, this is an easy change and much better

[TSG]

I get ~12 peak on Primary, when Secondary is active, I've only ever seen it peak at ~15. But I rarely drive it that hard haha.

I had a guy on another forum confused as hell why the car boosts differently on primary and secondary, I thought it was pretty obvious with it being sequential instead of parallel... but anyway.

[Shadoxity]

I get ~12 peak on Primary, when Secondary is active, I've only ever seen it peak at ~15. But I rarely drive it that hard haha.

I had a guy on another forum confused as hell why the car boosts differently on primary and secondary, I thought it was pretty obvious with it being sequential instead of parallel... but anyway.

Just for everyones reference, here are the boost maps from the std 2002 AU B4.



It is shown in bar (and remember to remove 1 bar for atmospheric pressure or there abouts).

The IAS open map is when the 2nd turbo is involved and IAS closed is when its on single primary.

So essentially 14psi primary 12psi secondary.

[BigWillieStyles]

So essentially 14psi primary 12psi secondary.

What gear did you test in? The secondary being slightly larger would be expected to require a bit more boost wouldnt it?

[TSG]

So essentially 14psi primary 12psi secondary.

Yep, sounds about right it had been a while since I checked. Was cooler today after a storm and I had a mate in the car decided to check.

[Shadoxity]

What gear did you test in? The secondary being slightly larger would be expected to require a bit more boost wouldnt it?

3rd gear, plus numerous other runs while logging

The 2nd being larger means that it requires less boost to make the same/more power than the primary

[Jimbo]

Interesting. I know that the TT obviously increased total flow with both turbos going but i still find it bizarre the B4 drops less boost on sequential.

Sometimes in the right conditions, my old GTB would get up to 18psi on primary and anything from 25 to 30psi if i kept the wellington down. Most i ever saw out of it was 35psi and off the scale ... thing was... it loved it!

[Daniel-B4]

on mine the first turbo is 5 and the second turbo is 17... i think its 10 stock.

[bd-850]

according to the Datascan i get 17psi 4th gear 100kph+ foot down