legacycentral bbs

I was just thinking, seeing as the Liberty RS has the same turbo as the US
Spec. Legacy Turbo and makes 200 hp I was wondering what is the stock boost
level is on those cars? I realize this car as the EJ20T VS our EJ22T plus a
water-air intercooler. But I'm thinking my car running the same boost with an
air-air intercooler must make about the same amount of HP maybe more. Right??

Fred

You would think so. I have mine on 15psi at the moment and it goes hard.

I might have this all wrong, and someone please correct me if that's
the case, beacause I've been wanting to know this for awile... BUT

Is 15psi actually 15psi in any engine, or is the effect of 15 psi in
a smaller, say 2.2 liter engine, significantly better than if you put
15psi through a 5.0 liter V8.

OR,

Does if have to do with the size and efficiency of the turbo, meaning
where our dinky little stocker can give up 15psi on our 2.2 block, it
would only be capable of giving the 5.0 about 7psi?

Considering that example #2 is correct, you should be able to get
more boost into the EJ20 than the EJ22t using the same turbo, all
else being equal. (which they aren't)

Let me see if I can get this right...

Pressure and air flow rate are two seperate issues.
15 psi has roughly the same effect in any engine - it
will cause roughly the same percentage horspower
increase. That's a gross oversimplification, there
are a lot of other factors, but that's the gist of
things.

Airflow rate is seperate but related. A 2.2L at 15psi
will need more air flow than a 2.0L at the same boost.
BUT, unless you have an inadequate turbo for the job,
it should have no trouble pumping either engine up to
15psi. Once the turbo is spooled up and blowing
enough air to make 15psi, the wastegate opens to blow
off any excess air and regulate things down to 15psi.
In other words, in the 2.0L engine, the wastegate will
have to blow off MORE air because this engine won't
require as much air. Only if you pick the wrong turbo
for the job, then it's possible that it wouldn't
source enough air to maintain boost. Then your
thinking might be true... that it would make higher
boost in a smaller engine.

The bottom line is: You have to pick a turbo that
matches your engine's characteristics, including how
much airflow it will try to suck in at a given
pressure-boost and rpm.

Sam

Doesn't compression ration have something to do with boost?

Yes it would. Run a higher compresion ratio and it will boost earlier.

What's the deal! Doesn't anyone on this list know the stock boost
pressure of the single turbo Liberty???????? This is not a complicated
question!

Fred

I think it depends on if you have an aussie built one (12psi) or
a jap one (8psi) but I am only speculating. Also it depends on what
year you have and if it is a GT or an RS as they have different turbos
(but run the same boost)

stock boost on Uk modle is 10psi

10.8PSI BUT SOME i HAVE FOUND RUN AT 12PSI LIKE MINE.

10.8psi.