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. The 16 valve head also offers a "lumpy idle" when performance camshafts are fitted, where a 20 valve has a smoother idle as it has VVT (variable valve timing), only one or 2 camshafts can be changed to a performance item.
Smallport 4AGE (100KW) vs Bigport 4AGE (86KW)
With the 16 Valve 4AGE engines there were 2 different head designs, more commonly referred to as the Smallport (100KW) and Bigport (86KW) heads. Depending on your application the decision of a small/big port head may be a crucial decision to make. "Small" and "Big" 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 turbo charge them though. Bigport heads have what is referred 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 turbo charging.
Air Flow Meter Vs Manifold Absolute Pressure
The computers that drive the 4AGE use a few different fuel metering methods, There are 2 different methods. An Air Flow Meter, Which meters how much air is going into the engine. Or a Manifold Absolute Pressure sensor which calculates the air pressure inside the manifold. They both do the same job though most people opt for a MAP sensored version of the 4AGE. Apparently you can put larger cams in an AFM 4AGE engine without having to change the stock computer.
Naturally Aspirated Vs Supercharged Vs Turbocharged
A 4AGE is most commonly found as a Naturally Aspirated engine, Though they did come out as a supercharged engine (4AGZE) and can also be found fitted with an aftermarket turbo setup (4AGTE). If you want your car to be a daily Driver, I would strongly suggest the N/A version. Though if you want a fast Street/Track car the 4AGZE / 4AGTE option would be the better way to go. The advantage of the Supercharged engine is you are boosting from idle to redline. The Turbocharged engine will have to spool up first before it will hit full boost, this is also dependent on the turbo you use.
3 Rib Vs 7 Rib
The 4AGE came out with 2 different block revisions, they are more commonly referred to as 3 or 7 Rib blocks. They can be identified as 3 or 7 rib by counting the number of ribs across the block. The earlier revisions are 3 Rib and are not as strong as the later 7 Rib blocks. There are also 2 revisions of the 7 Rib blocks, those that have don't have oil squirters in the bottom end and those that do. To get a 7 Rib block with oil squirter's in the bottom end you can buy a 100KW / GZE / 20 Valve engine. 7 Rib blocks with oil squirters are the best block to use when you are wanting maximum power out of the 4AGE.
86Kw vs 88Kw ECU
The different 4AGE engines are run by different ECU's, The 86KW 4AGE was designed to run on Unleaded petrol, though there was another revision of the ECU that took advantage of Premium Unleaded Petrol to boost the power to 88KW. The 88KW ECU's are mainly from Japanese Domestic Market AE86's.
There are lots of aftermarket parts available for the 4AGE which makes it a great engine for a conversion. A good place to start upgrading would be to remove the stock ECU and install/tune an aftermarket one. Once you have done this you can start upgrading things like your Cams, installing Cam Gears and installing larger injectors. You can also upgrade your ignition system by removing your distributer and installing a CAS (Camshaft Angle Sensor) with coil packs. (These can be found on 4AGZE/20 Valve engines).
Front Cut Vs Engine Package
You can purchase your engine a few different ways, In a front cut or as an engine package from someone. It's cheaper to buy an engine package off someone who is maybe upgrading to a bigger engine most times. By buying a front cut though you are able to sell the remaining parts in the front cut to help fund your project. Some people buy front cuts though so that they can use the brakes and other running gear from it.
Article by Medicine_Man
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