eightinavee
Well-Known Member
The simple answer to the better fuel consumption is that the 3.5 engines ALL run a basic closed loop bank fired system - with NO input on the ignition system.Gems and Thor both run from a far more accurate ignition system without a crap distributor,making good use of knock sensors to run as much advance as possible,backing off individual pots if needed.They also inject sequentially.And are adaptive,learning the individual engine,the 14CUX has limited adjustment to please the oxy sensors.
All these little improvements add up to the goal of controlling the conditions in each combustion chamber for every firing event.So more efficient...In the ideal world for this you would have a set of sensors for each cylinder - in practice this is not very practical,nor cheap.
If your Gems unit ran lean at cruise there was something wrong with it.There is very little you can do either side of the rich/lean signal from a narrow band sensor when running closed loop.The major changes in the fuel map are where the software chooses to come out of closed loop - ie, under WOT conditions/heavy load.
Engine temps are controlled by the thermostat - and its position,coolant flow,rad and hose layout/design,etc,etc.That the 94mm bore R V8's cant cope with a higher running temp just shows its a crap engine with little margin of strength.The 3.5 would have just put up with it,often with a poorly maintained cooling system too.
I've had a 3.5 2 door RRC in with oil boiling in its sump it was so hot.There was no coolant in it - at all.We thought it was toast,not so,the following day it was refilled with coolant and had an oil change.Has done a lot of work since with no apparent ill effects.
Show me a 94mm engine that would cope with that....
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Notwithstanding other issues, the cooling system is the prime cause of so much trouble on the V8's.
We run our Thor 4.0 with 3/4" extra water in the header tank, it is far easier to notice any fluid loss and gives you a bit more leeway should you have a slow leak.
OAT coolant is expensive, which is why so many don't bother, and then wonder why they get cooling system faults...
I don't know what the thermal conductivity is of the 50% OAT solution, but our radiator is the original and we have had no troubles with cooling problems, even in France in 36 deg C temperatures and towing our big trailer.
As I said before, if the external water pipes are corroded inside, expect trouble. Philip's V8 has them all corroded from the inside out, and the engine was a mess.
Peter
We run our Thor 4.0 with 3/4" extra water in the header tank, it is far easier to notice any fluid loss and gives you a bit more leeway should you have a slow leak.
OAT coolant is expensive, which is why so many don't bother, and then wonder why they get cooling system faults...
I don't know what the thermal conductivity is of the 50% OAT solution, but our radiator is the original and we have had no troubles with cooling problems, even in France in 36 deg C temperatures and towing our big trailer.
As I said before, if the external water pipes are corroded inside, expect trouble. Philip's V8 has them all corroded from the inside out, and the engine was a mess.
Peter
