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Location:
Sunshine Coast
Registered:
July 2004
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4AGE Modifcations
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Sun, 25 July 2004 23:55
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I was interested in purchasing an old KE30 Corolla and doing some mods to it, and anyway my first mod would be the engine conversion, i am leaning towards the 4AGE from the AE86 or the Levin or even the Celica it came in RWD or so im told anyway. My question is i came across this site billzilla or something, and it has all the different HP increments and what you need to do to get them there can you tell me if this guy knows his shit or is he talking through his arse, and the costs involoved in doing these things
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!
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