If I change engine suuplier but don't refit engine, which engine am I running?

Hi,
The title says it all really there are really two parts to my question.
Here is the scenario... I have been running engine A, change supplier to engine B, engine A has done a couple of races and it's condition is at, let's say 90% but I don't refit a new engine for this race. So despite running with a new supplier, if I don't refit before the race, am I running Engine A or Engine B?
If I'm running Engine B is this at 90% or 100%? 
Logic seems to suggest that if engine condition shows 90% and I do not refit, I should still be running old engine (Engine A) but I don't want to take this for granted.

Any help on this is very much appreciated.

Warren.

I am also confused about this, I am thinking you may change engine after restock...

Nobody really has an answer to this except for the developers (most likely Jack).

But I'll answer this anyways.

If you sign a new engine supplier, your unused motors and motors in the cars are automatically rebranded to those of your new engine supplier.
Chances are you have unused motors and an old motor installed to your team's car(s) from your previous engine supplier.
If you switched from Rednote to Murk, all your motors will represent the performance capabilities of the Murk motors.

Why is this? The fuel consumption predictions from the Technical Director will likely change (may depend on who your fuel supplier is), which would prove that there is no programming that brands the motors.

This is further backed up by how in the new version of iGP Manager, the cars aerodynamic and mechanical component developments and choice of suppliers will influence how well suited a car will be to each race track. This level of sophistication does not exist here in the current version of iGP Manager.

I asked Jack about this privtely before now to clarify, therefore I know my response is correct :)

When you sign a new engine supplier, they become immediately active without refitting engines.