Tuning a 4AGE 16V

The most common modification for almost any car is the open pod air intake filter. Although they are cheap but by changing this only mild increase in power and it is more to cosmetic modification and the induction noise.

If it’s a 4AGE converted Aussie Sprinter then most likely it will already have one, or if its a JDM stocker fresh off the boat, it’s intake filter has probably never been changed in its life. (Picture below)

Another basic mod is fitting an aftermarket exhaust system. However if your chasing power or better response a decent set of headers or extractors with a 2″-2.5″ exhaust system – mandrel bent and sporting a hi flow cat converter – with a hi flow rear muffler will not only provide you with more responsive engine but real smooth exhaust note as well.

Lastly a lightweight flywheel. Now this is a bit of an unconventional choice for a ‘basic’ mod and while this part is a bit more involved, a decent flywheel of about 3.7-5kg will make a big difference to the response of the engine, giving it the ability rev free and harder.

The standard equipment 4AGE ECU is actually a decent bit of gear for its age, showing that once upon a time Toyota actually knew how make a decent performance car. Obviously the basics mentioned before can be all used without interfering with the limits of a standard ECU. If the engine is still using factory internals and fitted with standard ancillaries all should be well – but its what you can and can’t do with a standard ECU that make things interesting.

Starting at the top, you can run a thinner head gasket such as a 0.8mm TRD metal head gasket along with a bit of port and polish work to the head. The gasket increases compression slightly, and the head work increases air flow – the standard ECU can compensate for this by adding more fuel as it is receiving a signal telling it that is has more air. At this stage there is not much power to be had with the standard ECU but it does provide a low end urge and mid range punch, especially combined with the basics earlier.

Continuing on with the head, you can also run a set of aftermarket camshafts up to about a 264° degree duration. Again, the standard ECU can compensate for this and combined with headwork and ‘the basics’ will provided a nice smooth power delivery right up to the redline.

Moving on to the bottom end, it is possible to run increased capacity on a standard ECU as long as you keep the internals fairly minimal eg: no crazy high compression pistons, but I will come back to this later.

With the standard ECU it is possible to run mild hi-comp pistons but they will not be used to their fullest when lumped with a standard ECU. Modifications like this would benefit greatly from a programmable ECU such as Adaptronic, E & E Freedom or if you’re loaded a Motec. Using a small port bottom end with a big port head will provide a slight increase in compression and again has been use many times with a standard ECU. More on this will be covered in the next part.

With the standard ECU you can stroke a 4A-GE in a number of ways. The easiest way is use the 7AFE block which from AE102-AE112. The 4AGE head, be it 16v or 20v, will fit onto the 7A bottom and still run the factory 4AGE ECU with a minimum of fuss.

By changing the block, it will help to increase the torque of the car but the down side is the rev for the engine will be lower whereby the maximum recommended rev is at 7800rpm. The main reason behind this is the spindly rod the 7AFE comes with, and long stroke nature of the engine. The stroker engines can be given stronger rods and pins to allow it to rev to a higher safe-rpm limit but we will cover this in part two of our feature.

Another option is fitting 83mm oversize pistons, such as AE86 tuner RS YASU does with their engines. Fitting the 83mm pistons gives a capacity increase of about 1660-1690cc or as commonly reffered – 1.7 litres. This mild capacity increase is still usable with the standard ECU for a much torquier and rev happy engine. Having driven forum member Virgilio’s RS YASU ‘86, compared to my high comp engine it is seamless in it power delivery with it making a nice smooth power curve all way to redline.

You do need to be careful when boring the 4A-GE block as fitting anything more than an 83mm piston will cause the block to crack and be rendered unusable. The water jackets and internal water routes will now run close to the cylinder walls, and if bored too far, will split and destroy the internals of your engine.

Any of these mods will provide you a very good street driven engine, that can work in all types traffic, daily driven, and be a weekend warrior on winding road or at the track. If your chasing more power or wish to run bigger cams or quads throttle induction on a 16v 4A-GE then part two of this feature is for you!