Hi there,

obviously sometimes a V8 block develops a crack.

Some say (RPI) that fuel mapping is the cause to that. In some rpms the mixture is too lean and causing overheating, this done by Rover to improve mileage or emissions at certain speeds that are test-relevant (? maybe I don´t recall that correctly).
Heat of course can cause problems because of the different temperature related expansion of aluminium and steel.
Then of course there are theories that the not perfect casting process of the block causes the "flesh" between water passages to liners to become too thin on the 94mm bore blocks.
And some report that the cracks develop quite often near to where a cyclinder head bolt is. And that using a head stud kit does help in this respect.
All the latter can be read in DesHammills book (how to power tune the rover v8).

Now the latest version of the V8 - the 4.9 Thor (Bosch injection) will regulate the air/fuel ration to Lambda=1 under all conditions. Which makes sense because that is where the exhaust gases can best be cleaned by the cat.
But if this is real then there couldn´t be any too lean or rich mixture !?! And, with reference to RPI, this particular engine should not develop any cracks.
Question is, if my assumptions are correct, if it is the case that the Thor-V8 is crack free. This could help to prove the cause.

Any ideas ?

If the lambda is at 1.00, the cats would become unnecessary as all of the hydrocarbons would be reduced to CO2 and H2O. Nitrates, sulfates and the like would be reduced to simple compounds as well.

I'm not as certain that the A/F ratio is necessarily what's causing the problems with liners slipping, just insufficient fuel for load. The A/F ratio may be spot on, but there still isn't enough fuel to provide the amount of power needed, thus stressing the block and causing the liners to move.

Is lambda of 1.00 done with an O2 sensor on each cylinder or for the engine as a whole?

If it's for the whole engine then having individual cylinders running rich or lean is a strong possibility.

Is lambda of 1.00 done with an O2 sensor on each cylinder or for the engine as a whole?

If it's for the whole engine then having individual cylinders running rich or lean is a strong possibility.

One per bank, sometimes one before and one after the cat, but always shared by four cylinders.

Is lambda of 1.00 done with an O2 sensor on each cylinder or for the engine as a whole?

If it's for the whole engine then having individual cylinders running rich or lean is a strong possibility.

Individual cylinder fuel and ignition timing trim is accomplished by monitoring other sensors, for what is referred to as "Roughness". if the Thor EMS is what I think it is.