Hi Luke,
I think the real question you might want to answer is What do I want from my car? & How do I want it to perform.
A lot of people swear by the smallport, & it was toyota's improvement on the 1st generation bigport TVIS system. So those toyota engineers probably knew what they were doing...
Those in favour of big ports generally speak about having top end torque & power.
So if you do a lot of street driving small port will be better & your turbo will take care of grunt when your on the highways & freeways.
Having said that, you'll need to consider what size of turbo.
smaller = less lag.
bigger = more lag but better top end highway/freeway response.
The general consensus is the gze block is the best for turbo charging. It's much stronger than a standard 4age block.
If you post some pics up of your gze, people will be able to tell you whether it's big or small port.
Unless you know what year / model of car it came from?
Do you know if it's AFM or MAP sensored?
OR
Remove your intakes on both engines & measure the widest point of each intake port & compare... You already know that your running engine is a small port, so your GZE's gonna be either the same size (small port) or bigger (big port)
Here this might help also:
http://www.billzilla.org/4agmods3.htm
It's up to you how far you wanna go with it. Your capabilities, tools you have OR the depth of your wallet.
Forum member: Terra Operative is well experienced with 4agze engines & sticks to supercharged applications.
He recommends putting bigport cams in a small port head & using adjustable cams to get the most out of these engines.
If indeed you end up having a big & a small port them you may want to try this option.
I think one of the best things he ever said to me was "Make sure all your mod's work together"
So your plenum/intake should be chosen with regard to the size of your turbo.
The same goes for your intercooler.
Then if your not already running extractors, you might like to give some consideration to what type of extractors you're going to run...
Good luck
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