Boost...and the misconception
Boost...and the misconception
I was over on the NASIOC board a few minutes ago and I was reading a thread on the boost setting of the new STI. They are saying that the new STI will max out its boost curve at 14.5psi from the factroy. The thing that makes me kind of laugh about that whole thread is to why the new STi is running 14.5 and the WRX is running 13-13.5(I have no clue what it runs stock...just going off what they said) and they can't figure out how they were able to do that.
Well....the reason I have to kinda laugh at this is because there is a common misconception that all boost is created equal. NOT ALL BOOST IS CREATED EQUAL! any 2nd G DSMer knows this. Going from running 15 psi on the stock t-25 to running 15 psi on the 16g. There is a world of difference. The reason......CFM different turbos flow different CFM.
So I am assuming with the combination of a bigger engine and again assuming it has a bigger turbo than the WRX they are able to only increase boost by 1 PSI and make bigger power and torque.
I can relay to people in a way I think.....think of PSI as voltage....and CFM as amperage. Like with the t-25 turbo(on the stock 2g eclipse) it could push 15-17ish (effectivley before just blowing hot air) but it does this at a lower rate of CFM. This would be like running a car amp at 12volts but only being able to obtain 2-3 amps of current.....(good for normal listening but when pushed hard...it will cut out do to power problems.) Where as the 16g runnin 15-17ish PSI which runs a higher rate of CFM due to a bigger housing and a better turbine. This would be like running that same car amp at 12 volts and runnin it with lets say 7 or 8 amps( having great bass response and no cutting out of the amp). I am just using the amperage for illustration purposes...not really sure what a car amp consumes in the way of current...so the next time someone comes up to you and says I am runnin 20lbs of boost....ask them what turbo they are runnin...you'll then know if they are runnin their turbo past its efficiency point.
I think I am pretty on key on this....if I am off someone correct me....but I just though I'd share that tid bit if someone was wondering.
Well....the reason I have to kinda laugh at this is because there is a common misconception that all boost is created equal. NOT ALL BOOST IS CREATED EQUAL! any 2nd G DSMer knows this. Going from running 15 psi on the stock t-25 to running 15 psi on the 16g. There is a world of difference. The reason......CFM different turbos flow different CFM.
So I am assuming with the combination of a bigger engine and again assuming it has a bigger turbo than the WRX they are able to only increase boost by 1 PSI and make bigger power and torque.
I can relay to people in a way I think.....think of PSI as voltage....and CFM as amperage. Like with the t-25 turbo(on the stock 2g eclipse) it could push 15-17ish (effectivley before just blowing hot air) but it does this at a lower rate of CFM. This would be like running a car amp at 12volts but only being able to obtain 2-3 amps of current.....(good for normal listening but when pushed hard...it will cut out do to power problems.) Where as the 16g runnin 15-17ish PSI which runs a higher rate of CFM due to a bigger housing and a better turbine. This would be like running that same car amp at 12 volts and runnin it with lets say 7 or 8 amps( having great bass response and no cutting out of the amp). I am just using the amperage for illustration purposes...not really sure what a car amp consumes in the way of current...so the next time someone comes up to you and says I am runnin 20lbs of boost....ask them what turbo they are runnin...you'll then know if they are runnin their turbo past its efficiency point.
I think I am pretty on key on this....if I am off someone correct me....but I just though I'd share that tid bit if someone was wondering.
!!!! You get a cookie!!!! That is a very good thing to bring up!!!
You sure you're not thinking of the Legacy?
STi is a 2.5L 4-banger..
http://autoshow.msn.com/autoshow2003...oem&xml=Subaru
The STi engine is an advanced 2.5-liter, turbocharged and intercooled, double overhead cam, four-cylinder boxer unit with variable valve timing capable of generating a stunning 300 lb-ft of torque at 4000 rpm. There’s only one transmission offered—a close-ratio, six-speed manual.
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The other thing to keep in mind, is that on a larger displacement engine you need a higher flow Turbo to produce the same boost level. Because the larger displacement motor comsumes more air than a smaller one, the CFM rate of the turbo needs to be higher to match the larger engine's breathing capacity.