s4 TII motor vs s5 TII vs jdm s4 TII vs jdm s5 TII?
 

are there some "key differences" that are easy to spot between the different "versions" of s4 TII and s5 TII motors out there?

i have some wacky cooling system things and a vacuum rack that seems to be different than other USDM s4 motors out there. so are there any tattle tales that are easy to spot to say this is an s4 or s5 or even a jdm motor thats been swapped?

i found this
http://fc3spro.com/TECH/FAQ/ZVK/zvk.html

which is good but doesnt address the jdm motor bit

The UIM's are different between the two motors.

all S4 engines had a cast aluminum thermostat neck.
all S5 engines had a formed plastic thermostat neck.


the S4 has more linear intake runners on the UIM, the S5 UIM runners step up from front to rear.
the S4 turbo bolts to the exhaust manifold at a 45* angle and has one ear offset, the S5 turbo bolts on at the same angle as the manifold to block and has a rectangular bolt pattern.

the S4 engine has a mechanical oil metering pump with a rod going to the throttle body, the S5 has an electric oil metering pump with 2 white connectors mounted to the alternator ear nearest the thermostat.

the S4 throttle body has a single pot 3 wire throttle position sensor, the S5 has a 2 pot throttle sensor with 6 wires.

is there anything on the keg that would tell you its a jdm vs usdm motor?

all those things can be swapped rather easily to keep it running off of an s4 chassis

measure the bridge in the casting between the spark plug holes

S4 USDM= 23mm
S4 JDM+all S5/6= 28mm

if it's 23mm then it is a USDM block. if it's 28mm then check for a threaded hole above the plugs for a knock sensor, if the hole isn't threaded or isn't there at all then it is a S4 JDM block, if it is then it is a S5. there is no discernable difference between a JDM S5 turbo engine and a USDM one aside from the lettering on the intercooler and the smaller smog pump found on the imported engines.

is that center to center measurement on the plugs?

just the bridge, the flat surface between.

this is a dumb question....between leading and trailing plugs on the same rotor housing right? this isnt the measurement between leading and leading plugs on two different housings right?

same housing. you're measuring the timing split between the plugs.

Great looking build, I really like the willingness to do things right!

Hey man, nice build. Im up in NOVA (manassas area) and just started a turbo ii build myself.