Hi,
it looks a bit starnge to me, that if I set air intake restricion for an ammount, the engine brake is reduced with that ammount. If I remember the engine brake depends on the length of the connecting-rod, because if I use the engine brake there are no fuel in the cylinders, so the intake restriction is not affecting the engine brake. It looks like, now the engine brake is calculated from the horsepower and the torque. So, if I set a 40% restriction for a car, the connecting-rod's length is not changed, so it shouldn't change the power of the engine brake by 40%. Actually it should stay at full power.

Regards,

Less combustion = more inertia?

Why does intake restriction matter if the throttle is fully closed, anyway?

Slightly off topic but how does engine brake reduction work on the BF1?

Quote from sil3ntwar :

Slightly off topic but how does engine brake reduction work on the BF1?

It leaves the throttle open a little once you let off the gas. So, at 100%, it leaves the throttle open enough that the engine is not slowing down the car at all.

Quote from wheel4hummer :

Why does intake restriction matter if the throttle is fully closed, anyway?

The engine would be completely silent if there was no burn off throttle. So intake restrictions woudl deminish burn even more.

It looks like you don't understand what I was trying to say. So, if you don't press the throttle there is no petrol to burn. For the burning sequence the engine needs air. If air intake restriction is set, on off power the cylinders are still empty, so the air intake restriciton should not effect the engine brake, because the engine don't need any air. Now if resticiton is set, the engine brake is reduced by the ammount of the air intake restriction.

Qoute Wikipedia.org - Engine braking

When a driver downshifts to spin the engine at high angular velocity (or RPM) without pressing on the accelerator pedal, the engine converts energy from the vehicle's speed, which is kinetic energy, into a temperature increase in the fuel-air mixture. These hot gases are exhausted from the vehicle and heat is transferred from engine components to the air.

It's not really clear to me, but it looks like, the engine do not need any air whilst engine braking. But, in LFS it needs. ???

Depending on engine configuration, a significant part of engine braking is due to movement of air underneath the cylinders, the rest is friction. There is little loss of energy above the piston, because the air acts as an energy retaining spring. With the fuel cut off on a V8 type engine, the engine braking effect is about the same regardless of the throttle position.

In the case of an opposed multi cylinder engine, if the opposed pair of pistons move side to side at the same time instead of inwards and outwards, the engine braking effect is greatly reduced.

In the case of almost all racing motorcycles, some street motorcycles, and some racing cars, "slipper" clutches are used to reduce engine braking. I'm not sure it was intentional, but GPL behaves as if it has a slipper clutch, because lifting on the throttle instanly lowers rpms without changing car speed.

Quote from hariel-HUN- :

It looks like you don't understand what I was trying to say. So, if you don't press the throttle there is no petrol to burn. For the burning sequence the engine needs air. If air intake restriction is set, on off power the cylinders are still empty, so the air intake restriciton should not effect the engine brake, because the engine don't need any air. Now if resticiton is set, the engine brake is reduced by the ammount of the air intake restriction.

Qoute Wikipedia.org - Engine braking

When a driver downshifts to spin the engine at high angular velocity (or RPM) without pressing on the accelerator pedal, the engine converts energy from the vehicle's speed, which is kinetic energy, into a temperature increase in the fuel-air mixture. These hot gases are exhausted from the vehicle and heat is transferred from engine components to the air.

It's not really clear to me, but it looks like, the engine do not need any air whilst engine braking. But, in LFS it needs. ???

I'm just pointing out that the engine does keep running when you're off the throttle. Otherwise where does all that sound come from?
If there's fuel still being burnt, then having air restrictions would deminish fuel burn even more and thus counter engine friction even less.. Hence greater engine breaking with air restriction.