Whats the biggest cams for the 4AG?

[NoHachi]

Go and ask Bill whether he would do the same thing to an engine himself. I think that engine is one for the "weird an wonderfull" category, not for the "see whats possible with a stock engine" category.

How do I explain this to you guys.
The stock ecu works on a MAP system, yes? So the ECu figures out how much air is coming in (based on vacuum) and injects accordingly.
Ok, so the stock engine runs in a fixed interval, meaning RPM fluctuates between X and X and so does the manifold pressure.
When you add a wild cam things start going a bit crazy. Sure, the engine still runs within its normal parameters during most times, that means ordinary rpm values with corresponding vacuum (MAP) values, that the engine knows.
These values are present in the computer to be able to handle all sorts off load situations (eg driving up a hill etc). So with the new cam the engine measures a situation thats similar to running downhill ordinarily (only now you are actually driving full throttle on a level road). That doesn't matter, the engine is familiar with this load/RPM combination and will inject the correct amount off fuel.
So when do things start to go wrong? Well those who could understand what I wrote above (don't worry if you don't...lets just say that I make a crappy lectioner) already know that there are two possibilities:
1. The ECU encounters RPM/MAP combinations that it has never seen before.
2. The ecu encounters MAP or RPM values that are outside the programmed bounderies.

Situation 1 is not that big of a problem. The ECU uses a fixed points RPMvsLOAD (vacuum) map. Of course the engine does not run in fixed points, so there's a nifty interpolation algorithm that calculates suitable values for all inbetween points. It keeps on doing that when it sees these unknown combinations, just guess whats appropriate from the known values.Usually thats good enough.

Situation 2 is more problematic. basically there is no programming available for these situations. As far as the ECU knows these values simply do not exist. What it then does is hold the fuel and timing steady at the last familiar point it encounters (and start throwing CEL codes).
In practice this leads to the following: when you remove the revlimmiter it just holds the fuel that it knows from the last familiar point. So you are still getting the fueling from 8000rpm, even though you are at 9000. Not a problem when the engine doesn't increase in power much in those 1000rpm. BAD when it does...
Same thing happens at idle. Vacuum drops of off the map so it just does what it did the last time it saw something it recognised...Not a real problem mind you, unless you start accelerating from that RPM point. You go to full load from the incorrect fueling situation. The ecu needs a little time to recognise the new needs and in the mean time you are running lean. This allows for short bursts of detonnation that almost undetectably starts chewing away at your pistons