6G Celicas Forums

Here is a 5S-FE head, note the shape of the combustion chanber and the angle of the valves, they are almost vertical.



Here is a 3sgte cylinder head, notice how the valves are almost sideways. Rather than go around two 90° bends, the air can almost flow straight through.


side by side-


The FE head on the right is narrower than the GE/GTE head on the left. The reason is notice how much farther apart the camshafts are spaced on the GTE. The camshafts are located almost directly over the valves on the 5SFE, hence the camshafts are close together. The camshafts are farther apart on the GE/GTE because the valves are pitched at a more sideways angle.
So the point is that with a 5sfe head, the airflow will have to make 4 sharp bends- 1) from horizontal flow through the intake port to nearly vertical downwards through the valve; 2) once it passes through the valve into the combustion chamber it must turn nearly 90° to flow towards the exhaust valve; 3) another sharp nearly 90° bend into the exhaust valve; finally another nearly 90° out the exhaust port.
The 3SGTE/3SGE has these same bends, but the angle are all significantly less. I would go so far as to conjecture that the airflow through the head has to make HALF the degrees of turns.

Yes there are many things you can do to improve the airflow of the 5sfe head, but the single most cost effective performance mod you can perform is to simply swap from a FE to a GE/GTE head.



Edit** ok so I finally found the specs buried in the forums, the 5SFE has a 22.3° valve angle, whereas the 3SGTE and 3SGE have 44.5° valve angles.

3S-GE is all top end power, lacks torque. Where the 5S-FE is low end and falls on its face around 60 - 65mph. Cruzing around the city with a 5s is nice. Sucks ass on the highway though. Good MPH for trips as long as you're not screaming at 80 the whole way.