This Lyco manual says, on page 6 of the PDF (page 3-4 of the document)
That sounds outrageous in engineering terms, because to make the engine “falter” you almost need to be seizing it up.
Think of how much grinding of metal on metal must be going on when you are just short of making it “falter” 
I believe the faltering has more to do with mixture and the temperature of the combustible mixture than friction.
Cobalt wrote:
I believe the faltering has more to do with mixture and the temperature of the combustible mixture than friction.
Agreed!
Engine is warm enough for take-off when the throttle can be opened without the engine faltering.
Or in other words: when the cylinder head temperature is high enough that fuel does not condense on the intake port walls, causing lean misfires when the throttle is opened, then the engine temperature is high enough for differential thermal expansion to have established clearances between components that are acceptable for full power operation.
You can let the engine warm up, or find your oil pump gears as metal in your oil filter. I’m happy to wait
Two points mixed up?
1) oil needs to be warm enough, to operate as designed. Yes indeed, especially on a turbo. But even my little 912 (N/A = normally/naturally aspirated) requires 50 degrees C oil temp before take-off. Disrespect this and you’ll ruin your engine, as described.
2) as equally exquisitely described, inlet manifold ( s ) must be warm enough to avoid fuel condensation.
Where’s the problem? Start engine as soon as possible, leaving as many checklist actions as possible for execution during engine warm-up. And never take off in a hurry. But then really NEVER
I can sort of believe the explanation re fuel condensation. That’s interesting.
But why would condensation prevent the engine running at higher rpm but not prevent it running at idle? If condensation was an issue, I would expect the idle speed to be very unstable, because the idle fuel flow (or any other fuel flow) is controlled from the fuel servo alone which has no idea what the engine is doing (apart from seeing how much air is getting sucked in). There is no feedback from the engine RPM (as there is on most fuel injected cars) so any wastage of fuel would result in an unstable RPM.
Peter wrote:
But why would condensation prevent the engine running at higher rpm but not prevent it running at idle?
I don’t think it’s that was is meant. It’s during accelerating the engine to full RPM. When throttle is applied, more fuel is needed to accelerate the engine. It’s this “excess” fuel that will condensate (or not evaporate in the first place) when the engine is cold. If you increase slowly, this won’t happen
Operation at steady RPM is not the issue. As a starting point for explanation, engines often have accelerator pumps that add fuel as a solution to the natural tendency for the intake flow to lean out as the throttle is opened. I believe that’s something to do with inertia of the fuel droplets (?) Anyway, the accelerator pump only functions while the throttle is actually moving, but when the engine is warm the standard accelerator pump setting adds enough extra fuel to prevent misfires as the engine accelerates. When the engine and intake ports are dead cold, the mixture tends to pool in the port and is poorly distributed, so the accelerator pump setting does not supply enough extra fuel to prevent misfires as the engine is accelerating.
A slight tangent may be useful: my little A65 Continental has no accelerator pump on its Stromberg carb. When its started in cold ambient temps and thereby has relatively low CHT for takeoff, unless you are very slow in opening the throttle it will often misfire and pick up again. When warm it picks up cleanly. However, even when warm if you lean the mixture (using the very rudimentary mixture control) and then smoothly push the throttle open from idle, it will quit. Some people shut them off like that, because there is no mixture cutoff and the engine is otherwise shut off with the mags, leaving the intake tract charged.
Re idle smoothness when cold, engines in a higher state of tune than aircraft engines need a choke or mapped equivalent (i.e. continuously richer mixture) to idle smoothly when cold. Aircraft engines are pleasantly tractable devices and instead can get by with a slightly rich idle mixture setting. That’s why we lean them on the ground at idle, using the mixture control.
Re mixture feedback on injected car engines, there is no feedback during rapid acceleration. They use mapped fuel control for rapid transients.
PS I remembered to note that carbureted engines with non-CV carbs see a drop in manifold vacuum when the throttle is opened quickly, stopping fuel flow, and that creates a particularly noticeable lean condition. However, I believe based on limited experience that injected engines (speaking generically, not just for aircraft) sometimes have acceleration enrichment too.
