115hp - 134hp
This is the sort of horsepower that standard 4AGE's have around the world. The Air Flow Meter (AFM) TVIS versions make 115hp and are commonly found in the US & other countries. The Manifold Absolute Pressure (MAP) sensor TVIS versions, which are slightly more common, make 127hp. They are commonly found in Japan, Australia, and New Zealand. Both these types are found in the AE-82, AE-86, etc Corolla's, and have the large size inlet ports. The AE-92 Corolla's 4AGE has no TVIS, small inlet ports, and makes 134hp with a MAP sensor. For more information on all these engines, take a look at my Standard 4AGE page.
Some points to note -
- The 'small port' and 'big port' computers are occasionally interchangeable, but will rarely increase or decrease the power output of the engine.
- The AFM and MAP type computers are not interchangeable, unless you also change the rest of the wiring loom to suit.
- Since all the MAP sensed engines have much the same amount of power and torque, it is not worth changing the engine (to, say, a small port version) to try to get more power. There are more effective ways of spending your money.
140hp - 150hp
Bolt-on external mods are all that is needed for this much extra power. Simple mods, such as a free flowing exhaust and cold air inlet pod will give you a few more HP. Synthetic engine oil will also give you a few more HP over conventional mineral oils.
By doing all of these things you'll gain a good 10hp or so over a standard engine, but anything more than that and you'll need to start digging around under the cam covers ...
Towards the 150hp mark, you'll need to go for cams of around the 256° duration. If timed properly, they'll idle and run just like a pair of standard cams.
Aftermarket 'chips' for the factory computer will also help the power output, but they vary greatly in quality and results - Do your homework before buying!
150hp - 160hp
The standard cam timing is 240° duration, from seat-to-seat, and this is typical for a modern road going twin cam engine. A pair of 256° cams and the mods mentioned in the 140hp - 150hp paragraph will get you around 150hp if everything else is right, but to get much more you'll certainly need bigger cams, around the 264° mark. This size cam is the upper limit of the cam duration that you can use with the factory computer, as they need a decent inlet manifold vacuum to sense to work properly. The AFM versions may be a little better off, but I've had no information on this.
You won't get 160hp with the factory computer, however, and so you'll need to spend a few dollars on an aftermarket system. I highly recommend getting a programmable system rather than a new 'chip' or a simple 'add-on' for the factory computer, as if you want more power later on then you won't be limited to whatever the chip/add-on has already programmed.
Once you have an aftermarket computer, you can run pretty much any size camshafts that you like, with little penalty, so to ensure that you end up with the power more like 160hp, you should run 272° cams.
Note that with cams larger than about the 260° mark you will actually benefit from removing the TVIS, if fitted. The TVIS, when used with cams smaller than about that duration, will give you more low end ( < 4,400rpm) power, but this effect disappears with the bigger cams.
150hp - 160hp is also the point at which you'll need to get some work on the head. Fortunately, there's not a lot to be done and if you've got the head off then it's worthwhile spending a little more time and effort to make the mods to allow the head to flow up to ~180hp - 190hp.
There are four areas that need attention on the 4AGE heads - The area just above the valve seats, the combustion chamber, and the ports themselves, and the valves & seats.
- The area above the valve seats are a little too parallel, and should be narrowed up a little to create a bit of a venturi effect.
- The combustion chamber has numerous sharp edges that need to be smoothed off, to eliminate pre-ignition, etc.
- The inlet and exhaust ports are quite good standard, but they are a little too big on the big port heads and a little too small on the small port heads. The small port head is easy to make a bit larger, but making the big port smaller is quite difficult, so don't try it - Just clean up all the nasty little bumps & casting marks in the head instead.
- The valves & seats benefit greatly from a good three or even five angle cutting job.
Please read my Engine pages for more information on porting, etc. Note that a lot of engine shops leave the ports with a near-mirror finish and the port dividers almost razor sharp - This is the wrong thing to do!
160hp - 170hp
Starting to make serious power now! You can pretty much forget about passing any emissions laws.
You'll be needing cams of at least 288° duration, and will also have to start looking at modifying the bottom end. It's also getting near the end of what the standard inlet manifold can do, so this is around the point where things start getting expensive.
All the head work that you've done in the previous paragraph will cover you for this amount of power, so, to improve on 150hp - 160hp you'll need to raise the compression of the engine. There's two ways of doing this - by shaving the head or getting new pistons. The stock pistons are good for 160hp no worries, but much past that I'd recommend using good aftermarket units, such as Wisco's. You'll be needing a compression ratio of at least 10.5:1, and with 96 octane fuel you can run up to about 11:1 compression without worrying too much about pinging.
The stock con-rod bolts are good for up to about 170hp, but past that you should replace them with the best you can get, such as ARP or small block Chevy. (I mean, if you're going to replace them you may as well do a good job!)
You'll also need to be able to rev the engine to 8,000rpm, and maybe even 8,500rpm.
The inlet manifold is a bit of a problem, but if you're sneaky then you can make a twin Weber style manifold with throttle bodies quite cheaply. (ie, for around Aus$150, whereas buying all the gear to do the same job 'off the shelf' could easily cost over Aus$1200!) What I did was to buy a section of alloy plate ~8mm thick and another bit of thick-wall alloy tube 52mm dia. I cut the alloy to make the flanges of the Weber base and the cylinder head base. I then cut the 52mm tube to the right length (four times) and partly crushed one end so it matched the shape of the inlet ports. I then spent a few days cleaning it all up so the parts fitted each other neatly, then got them MIG welded up. And then spend another few hours filing away at the welds to smooth & blend it all again. I then ran a milling machine over both flanges to make sure that they'd seal up against the straight edge of the head and throttle bodies.
For the throttle bodies (typically Aus$400+ each) I simply have used a pair of 'dead' Dellorto 45mm carbies. I have removed all of the internals so that only the throttle butterflys remain, thus making them cheap TB's.
All that being said, it may be easier to simply use something like a pair of 45mm Webers, but I highly recommend the use of electronic fuel injection over any carburettors anytime, because of the ability to control the fuel scheduling far more accurately & consistently than you possibly can with any carby.
A quick note - the 4AGE that I have in my AE-86 Sprinter has 288° cams, an aftermarket computer, 10.5:1 compression, and a small amount of head work done. It makes about 160hp with a completely stock bottom end. It runs to 8,500rpm without any worries.
170hp - 180hp
Still not any huge differences between the big and small port engines here. Not a lot more work required to get the extra 10hp from the engine now; just slightly bigger cams really. I'd recommend 288 to 304° duration.
4AGE 20 valve engines
I have never worked on a 20v, but to a large degree an engine is an engine is an engine. The only hassle is that they have three inlet valves, and so some of the usual rules don't work. Toyota advertise them as being 162hp (165ps) for the first version, and 167hp (170ps) for the second and last version. FWIW, the first version has a silver cam cover and an AFM sensor, while the later one has a black top and a MAP sensor.
One thing to note is that Toyota are telling fibs when they state the power output of the 20 valve engines - on all of the dyno reports I've ever heard of them, they only make around the 145hp - 150hp mark. So, I guess, possibly the easiest way to get a 4AGE from the stock 115hp - 134hp up to about 150hp is to simply fit a 20 valve engine. The only hassle with doing this is that with a RWD car, such as the AE-86, the distributor on the back of the head of the 20v will either require a hole cut in the firewall or a crank trigger system fitted.
From what I've seen of them, there's not a huge amount to be done except for a good clean up of the ports (remove casting flashes, etc), and a multi-angle valve seat job. The alignment between the inlet manifold and inlet port is rather bad and some good improvements can be made there, as can the area just above the inlet valve seats as they have a very nasty machining mark from the factory.
Everything past that is purely bigger and bigger camshafts to get more power, and I believe that again when you come up to the 200hp mark you have to start changing the internals for stronger and lighter units. This again comes from a combination of increased power, but mainly the increased revs needed to pump enough air to make big power figures. FWIW, the bottom end of the 20v is much the same as the small port 16v 4AGE, but the pistons are different on both types and so cannot be swapped over.
(So when I get people asking if they can simply pop a 20v head onto a 16v block, the answer is a qualified 'maybe'!
Yes, you can as it'll bolt straight up ok, but No, because the pistons don't have the cut-outs for the valves in the right places. They're a non-interference type head and so the valves won't hit the pistons anyway, but it's still a good idea to get the correct pistons for it.)
The most power I've ever heard of in any 20v 4AGE is about 215hp, or nearly 30hp less than a good 16v 4AGE.
145hp - 165hp
The earliest 4AGZE has 145hp, and there's basically three ways to get more power from them - by either simply fitting a later version that already makes 165hp, or by fitting the engine with the bigger crank pulley (that spins the supercharger faster, thus making more boost at less revs) from someone such as HKS or Cusco. The third way is to 'hot up' the engine, in much the same way as you would with a naturally aspirated engine, ie, bigger cams, ports, etc. The thing to remember is that you are limited in revs by the maximum speed of the supercharger, which really doesn't like being spun at more than about 10,000rpm. The reason for this is the tips speed of the rotors gets too high, and they will start to melt the teflon seals.
So, you're limited to about 8,000rpm engine speed (the supercharger is run at 1.25 times the engine speed standard, and even faster with the NEVO, HKS, etc, pulleys) which means that whatever you do it must make the engine flow more air at stock sort of revs.
This means that to get another 20hp or so from a 145hp 4AGE then a good clean-up of the inlet manifold & head, and perhaps some larger cams (256°) should easily give you that 20hp that you want. A larger intercooler and far more efficient air ducting (it could hardly be worse in the factory installation!) in & out will also help a lot.
165hp - 185hp
Again, the easiest way to get 185hp from a 165hp 4AGZE engine is to simply fit it with the bigger pulley, and maybe some minor mods to clean up any inlet and exhaust restrictions. Towards the high end of this power scale, I believe that the inlet manifold is a big restriction, as the supercharger dumps its air into a single point in the inlet manifold, which then divides the air up into four runner, one into each cylinder. The problem is that three out of the four runners enter the head at angles far from straight, and so the sharp angle at the junction will cause unwanted turbulence. (FWIW, the #1 cylinder's runner comes in at a ridiculous angle!) So, I'd say that if the time and effort was spent on making a decent inlet manifold (or perhaps just fitting a RWD AE-86 type manifold, perhaps) then the vast majority of that extra 20hp would come quite freely.
Larger cams, as in the 264°'s mentioned before will help a lot, but also as with the 4AGE anything much more than that and the factory computer will have trouble sensing inlet vacuum. You can of course run an aftermarket computer that uses throttle position rather than using the MAP sensor, but the success rate of aftermarket computers with 4AGZE's is not great - Persistence will win the day, but I would strongly suggest that whatever computer you look at getting has at least these features - throttle/MAP blending, an external on/off output which is controlled by MAP and/or throttle position, and oxygen sensor closed loop feedback.
185hp +
The best 4AGZE I've ever heard of is supposed to make up around 200hp, and I believe that the chap in question has done all of the above mods to get that much. I think that a good way to help the power output would be to fit the engine with a 1GGZE supercharger, which is about 17% larger in volume and so can be spun slower to pump the same amount of air at the same revs - This means that the engine will suffer a little less power loss that what it otherwise would with the smaller supercharger. This power loss that I'm talking about is the power that the engine needs to spin the supercharger over at high revs. It increases rapidly as the revs build up, and so anything you can do to decrease that loss will help a lot.
This is the problem with supercharged engines - They suffer from rapidly decreasing increments in improvement due to the cost of spinning that blower over ...
So, the trick it to set a target revs in your mind, say 7,000rpm, and make the engine pass as much air as possible around that revs. Again, all the same tricks as mentioned in the above paragraphs is the way to go.
That old skool feeling
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