Tech:Engine/A Series/A-Series Engine FAQ

As there are so many different variants of the A-Series motor, some people have trouble deciding which is the best for their application. I'll cover the more common variant (The 4AGE) in this FAQ.

16 Valve vs 20 Valve

There are a few different variants to the 4AGE, The cylinder heads were initially a 16 valve head, but later down the track Toyota moved to a 20 valve head. There is nothing wrong with either a 16 valve or 20 valve 4AGE head, just most people buy a 16 valve 4AGE as they are cheaper and more common than the 20 valve 4AGE. Even though people argue that the 20 valve 4AGE is not worth the effort they are still a very popular engine.

Smallport 4AGE vs Largeport 4AGE

With the 16 Valve 4AGE engines there were 2 different head designs, more commonly referred to as the Smallport and Largeport heads. Depending on your application the decision of a small/large port head may be a crucial decision to make. "Small" and "Large" port refers to the size of the intake ports on the head, this decides the air intake velocity of the engine. Smaller ports increase the intake velocity and are better suited for a naturally aspirated setup. Small port heads are still able to flow enough air if you turbocharge them though. Largeport heads have what is refered to as a "TVIS Plate" to keep their intake velocity up, though you can remove it if you run an aftermarket ecu and machine a plate to replace it. By removing the TVIS and machining out the intake ports you will be able to flow more air than the smallport which is more ideal for turbocharging.

Air Flow Meter Vs Manifold Air Pressure

16V Vs 20V

N/A Vs S/C vs T/C

Engine Power Figures

86Kw / 88Kw / 100Kw

5 Rib Vs 7 Rib

Front Cut Vs Engine Package

Basic Modifications