18g and 20g, spool up rpm?
 

As per title, the differences between the two seem to be compressor inducer size and 1cm sq difference on the turbine area.
My question is say with peak boost of 1.4 bar at what rpms can I expect full boost on a std wrx ej20? Ie what is the difference between the two?

Hi there

There is lots of variables,but 18G will spool faster on WRX like 20G

I would have look on Billet 18G or 20G they should spool faster than normal one

Jura

Of course, but if the only variable was the turbo, what rpm difference we speaking? My old 20g was full boost 1.4 bar at 3600, what we speaking for the 18g? 3300?

Also when you say "spool faster" do you mean faster or lower in the rpm range?

here's my 20g billet on Blob STI , standard headers, scorpion up pipe,FMIC

Attachment 69705

Smashing, that's bang on 1.4 bar at 3600, obviously goes on to make more boost past that. Just wonder how this compares to an 18g? Are we only speaking a couple hundred rpm?

Would only be a few hundred revs different! Billet 20G is a fun turbo on a 2L

His first hits 1.4bar at 3750rpm - on it's way to a momentary peak of 1.6 - before settling again to an ave. of 1.4 all the way to the redline.

But that's obviously nit-picking.

My old 18g at 1.5 bar spooled at 3200rpm

Thats impressive....

+1 Yeah, great spool.

Tyler, was that with a FMIC

It sure was, i had standard exhaust manifold too. just a decat and a larger up pipe. Will see if i can dig up the graphs for you. It was a proper little animal. Just ran out of puff at the higer revs which was why i went for a MD321

20g non billet...

http://i774.photobucket.com/albums/y...0-25123347.jpg

Do you have the boost graph for that jayallen? Certainly makes the power!

Obviously the cams are helping on the sti, what difference in power would be expected with a 20g at 1.4 bar on a wrx? 360?

What's a non builet 20g like for spool and power wise? :)

Seems like most guys running 1.4 Bar. Any idea what timing? Curious if a little more boost and less timing would make more or less?
Maybe i need less boost and more timing on mine. !.5 Bar and 21 degrees on 98 Octane!

Above 20G running AVCS heads and cars with AVCS heads(New age STI or JDM WRX or cars retrofitted with AVCS heads) will spool larger turbo or any turbo faster/sooner than WRX

Not sure how when will hit full boost,but I would expect around 3500RPM,this really depends on how much boost,headers etc.

Jura

From my experience with more boost you always retard the timing, more boost with less timing will make more power, the flow of the engine and turbo being the restriction.