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> Why is the 3s better than the 5s?
post Feb 22, 2013 - 10:22 PM
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homebuilder

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I am considering an engine swap. I see the 3sge and the 3sgte are both more powerful than the 5s. I can understand the turbo one being faster, but why is the 3sge?

I was reading where the 5s was basically a newer improved version of the 3s, but it looks like it is not as fast, is anything about it better?


I have the 5sfe now with a manual. I value reliability, low maintenance and fuel efficiency. Power is great but not the main deciding factor.

Thoughts?

 
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post Feb 22, 2013 - 10:37 PM
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Special_Edy



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The 5S-FE is an updated version of the 3S-FE, not the 3S-GE
S is the engine family, as noted on your model# ST-204 (the models with the A series engine are AT-200's)
5 or 3 are the revision of the block, so the 5s block is a newer revision as you correctly guessed
F or G stand for fuel-economy(F) or performance(G) based.
The E on the end stands for Electronic Fuel Injection.

The 3S-FE is comparable to the 5S-FE. The 3S-GE(and its turboed(T) variant the 3S-GTE) have a totally different cylinder head design. I believe the 3SGE/3SGTE block is actually reinforced and fitted with higher quality internal components(rods, pistons and such) than the 3SFE and 5SFE because its intended to generate more power. But of course the largest difference is in the cylinder head. All toyota FE engines have a 23 Degree valve angle while the GE engines have a 44 degree valve angle

QUOTE (Special_Edy @ Jan 25, 2013 - 1:08 PM) *
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.


This post has been edited by Special_Edy: Feb 22, 2013 - 10:40 PM

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