How much boost can i run safely in a subaru b4?

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s.joseph

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#54725 19-Dec-2009 18:56

Hey ive got a 1999 subaru b4 twin turbo and was just wandering how much psi i can run on stock parts without damaging anything, im guessing its runnin 8-10 psi stock at the moment as my boost guauge is not really acurate.

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#284063 19-Dec-2009 19:21

i'd say 1 bar or 14.7psi is semi safe.

To be honest, on the stock exhaust, stock fuelling system etc, i would run stock.

Once you open your exhaust up to say a 3" your boost will rise to about 12psi.

Also with B4s they are sequential turbs? so the first turb to kick in is probably where the reading si taken? max boost on either turbo is about 17psi since they are steel wheeled. But small turbos.

Also depends on what fuel, run it on 98 to minimise detonation.

Best to take it to a tuner, where are you located? In Wellington, Shred Performance do good deals. Chch i think still has EFI Tuners?

Also check out clubsub and subzero if they still exist for some good reading

I have moved across the ditch. Now residing in Melbourne as a VOIP/Video Technical Trainer/Engineer.

s.joseph

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#284084 19-Dec-2009 21:51

sweet cheers mate will do, im in chch at the moment but im going back up to wellington for uni so i will get it chekd out up there.

Adamal

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#284118 20-Dec-2009 00:59

Standard Subaru's don't like having the boost turned up. The ECU sees it as a problem and runs really rich.

s.joseph

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#284222 20-Dec-2009 18:55

so it compesates adding more petrol when u add more boost? im guesn id have to get the ecu changed aswell then.

lxsw20

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#284272 21-Dec-2009 00:01

Its a classic case of fast, cheap, reliable. Turbo Subaru's tend to be the first two, especially when you start playing with them. Talk to someone with experience with them, I personally would not just wack a boost tap on a subaru.

stevenz

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#284456 21-Dec-2009 19:55

Get a piggy-back computer and get the thing tuned properly. Get rid of the twin-turbos and put a single big one on it while you're at it, more lag off the line, but more grunt everywhere else.

Or just rip the waste-gate off and see how high it boosts before something blows! It's fun while it lasts. ;)

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Adamal

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#284499 21-Dec-2009 22:37

Alex, you have to change your nick on here now :P

lxsw20

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#284516 22-Dec-2009 01:35

I'll get another SW20 one day :P

chriswiggins

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#284525 22-Dec-2009 07:40

vinnieg: i'd say 1 bar or 14.7psi is semi safe.

To be honest, on the stock exhaust, stock fuelling system etc, i would run stock.

Once you open your exhaust up to say a 3" your boost will rise to about 12psi.

Also with B4s they are sequential turbs? so the first turb to kick in is probably where the reading si taken? max boost on either turbo is about 17psi since they are steel wheeled. But small turbos.

Also depends on what fuel, run it on 98 to minimise detonation.

Best to take it to a tuner, where are you located? In Wellington, Shred Performance do good deals. Chch i think still has EFI Tuners?

Also check out clubsub and subzero if they still exist for some good reading

Basically pretty spot on. Im a very active ClubSUB member and we have so much info in our forums regarding this (no im not advertising!Tongue out)

I have a Subaru 1998 Legacy GTB (stationwagon B4 basically) and running about 18psi. Then again this is on a brand new STi shortblock and on a single turbo conversion. I believe the block in the B4 is a EJ208? If so then really your best option is to get a boost controller and maybe take up to maximum 15psi. Most twin turbo's run 14psi once on the secondary.

s.joseph:

so it compesates adding more petrol when u add more boost? im guesn id have to get the ecu changed aswell then.

No you dont. like I said boost controllers do that fine. To be honest, dont go for higher boost. Its not really a good idea on a standard motor that has done xxxxxx amount of km's. Instead, most people always recommend things like suspension, swaybar, strutbar and tyre upgrades before doing anything about engine power. Subaru's are fairly fast stock anyway so get the car handling better so its safer with the extra power!

I only did mine in the reverse because I blew my BEB (big end bearing - for those who dont know the bearing on the end of the conrod. this blows you are ******) but I have lined up new suspension and tyres etc.

Catch the ClubSub fever! Good luck, Merry Christmas,
Cheers
Chris

rossmnz

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#284542 22-Dec-2009 09:55

2 bar should see you right!

Ignore chris, he is merely the webmaster on clubsub and knows nothing, nothing i say!!!!

2 bar or stock imo!

The force is strong with this one!

Adamal

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#284543 22-Dec-2009 10:01

Why stop at 2?! Go for 3 I say! TTTHHHHREEEEEEEE!!!!!

(Thats 43.5psi for you PSI junkies)

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chriswiggins

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#284553 22-Dec-2009 10:29

Good one Ross haha

lxsw20

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#284637 22-Dec-2009 15:14

3bar!!! What a woman, free boost or fail.

s.joseph

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#284723 22-Dec-2009 22:04

haha ive just decided to go for a single turbo instead.

vinnieg

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#284775 23-Dec-2009 09:20

single turbos on legacys are win :) oh yeah you'll have lots of fun. Be a bit laggier, but much easier to setup than the sequentials they come with stock

I remember my old teenage days with my old GT cruising round. Then I got into skylines and owned too many + the vr4s. Now I've got a nana pulsar, 1999 1.6L, woohooo!!! I do miss the boost a lot though.

I have moved across the ditch. Now residing in Melbourne as a VOIP/Video Technical Trainer/Engineer.

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