Overboost.

Olivier · Post by **Olivier** » Tue Oct 17, 2006 8:35 pm

Hey.

I am new here in the subaru-world.

I have just bought a Legacy gt sedan from 92.

In that Legacy theres a FCD and i have a wideband lambdasensor to check that the afr is allright.

If the engine is in good shape, how much boost should the stock engine could handle?

And what is the first thing to blow up and at what psi?

Im from denmark so my english i'snt very good, sorry

From Olivier

rwcoop · Post by **rwcoop** » Wed Oct 18, 2006 12:11 am

hey, ive always used 12 psi as a rule for maximum boost.
This is on an intercooled engine. you could prob go a wee bit more but ull have no probs at 12 pound.
Hope this helps

Olivier · Post by **Olivier** » Wed Oct 18, 2006 9:34 am

Okay.
Which parts should be swapped if i wanted to go 16 psi?
And still i have the LM-1 Wideband Lambda to check that the afr is allright.

Splinter · Post by **Splinter** » Wed Oct 18, 2006 9:40 am

You need to swap the turbo to do anything above 12 psi

Olivier · Post by **Olivier** » Wed Oct 18, 2006 9:48 am

The stock turbo can make just about 18 psi. I have tried once to take of the vaccum hose from the wastegate, then it made about 18 psi.
The turbo properly not made for these high pressure, but it can do it...

rwcoop · Post by **rwcoop** » Wed Oct 18, 2006 9:51 am

yeah thats right. Depending what engine it is if you boost any more tah about 14 the injectors wont be able to keep up and you may melt pistons.
First thing i guess would be to get bigger injectors and then i guess upgrade ur fuel supply. ie fuel pressure regualtor, bigger lines etc..

Olivier · Post by **Olivier** » Wed Oct 18, 2006 9:57 am

okay, thanks very much for the help!

Olivier · Post by **Olivier** » Wed Oct 18, 2006 9:59 am

The engine is from the Legacy turbo 4wd 92'.

Olivier · Post by **Olivier** » Wed Oct 18, 2006 10:23 am

How big is the original injectors?

free5ty1e · Post by **free5ty1e** » Wed Oct 18, 2006 5:29 pm

Stock VF11 will overboost to ~22-23 psig at sea level. Speaking from experience.

Not the best level to run, but the turbo will pump it out. I'd bet the compressed air stream would be pretty damn hot running that far off the efficiency island...

(edit: seriously though, please don't purposely run any more than 15psig intercooled on the stock turbo, EVER...)

Post by **Legacy777** » Wed Oct 18, 2006 5:58 pm

Guys.....remember.....he's got an overseas model with the 2.0 liter engine and intercooled.

Olivier, do you have an air-to-air intercooler or air-to-water intercooler?

Olivier · Post by **Olivier** » Wed Oct 18, 2006 6:10 pm

My intercooler is an air to water.
When i tried to max the boost out it made around 18-19 psi and the AFR was all the time just about 11-12.

Yes, it is a 2,0 originally from germany, just picked it up from Frankfurt am main for three weeks ago

edit: It is the same as this one. exept it is a sedan.
http://www.bilgalleri.dk/html/gal_visbil.asp?ID=66421

rwcoop · Post by **rwcoop** » Wed Oct 18, 2006 7:30 pm

Id say it could be the same as mine considering its a legacy. do u guys have legacys in the states or "libertys"
The stock turbo our GTs (auto) is a vf10 and a manual a vf8.
Hope this helps

AWD_addict · Post by **AWD_addict** » Wed Oct 18, 2006 8:43 pm

In the states we have Legacies with VF11s.
I think the Libertys were just in Austrailia.

legacycentral bbs

A forum for 89-94 BC-BF(BJ) Legacy Owners and Fans

Overboost.

Overboost.

12 psi