Quote from tristancliffe :

W4H - so many times you've popped into a 'technical' thread, make a pointless comment, and then run away.

I didn't run away, I just forgot this thread existed! This whole thread is pointless anyway.

i've just tested it in LFS with the UF1, and in LFS the powerful engine braking in first gear is absolutely missing...

the engine breaking is due to the fact that the engine keeps running (which means friction), but the combustion has already stopped (when you're foot is off the throttle, the throttle valve is closed, and there is also no injection / no ignition (not sure about that last one))... this means that there is more counter-power then when revving the engine... and in first this effect is huge...

when i'm driving my moms citroen c3 1.1i, i always tend to shift as quick as possible to 2d gear, because the engine braking is so huge (when idle in first, revvs fall down very hard) now i recorded the revv-backfall with an uf1, and is goes al smoothy... something for patch Z?

http://rapidshare.com/files/10 ... ngine_falls_down.spr.html

It's not huge in real life, and it's about the same intensity in LFS.

Would you mind using Citroen gearing in LFS, and comparing your g-meters for accelerations. Sadly, you can't do this based on feel because there isn't any in LFS.

Also, your reasons for why engine braking exists have been covered in this thread, and you're not quite right.

As for how the rev drops on your Citroen, consider that one car does not a standard make. I don't know what 'features' the Citroen has to control the idle so aggresively, but it's a fair bet then the UF1 won't have this. It might even be on carbs for all we know. As the UF1 isn't a Citroen C3 (or a Saxo) it seems unfair to say the UF1 is wrong.

Quote from dendc :

the engine breaking is due to the fact that the engine keeps running (which means friction), but the combustion has already stopped (when you're foot is off the throttle, the throttle valve is closed, and there is also no injection / no ignition (not sure about that last one))... this means that there is more counter-power then when revving the engine... and in first this effect is huge...

Combustion never stops in an engine unless you cut spark, which even on a computer controlled engine, never happens. Unless of course, you hit the rev limiter. This also means that friction is always overcome by a constant firing of the pistons. Fuel is always being injected, especialy in a carburated engine.

Engine braking is mainly manifold vacuum creating vacuum in the pistons, I can repeat that a thousand times and it'll be right every time.

Lets set up a concept. You have 2 engines, both at 1000cc. One is a wide bore short stroke engine, the other is a long stroke narrow bore. Both have 4 pistons, 250cc each piston. Both engines are connected to cars traveling side by side down the road in 1st gear at 7000rpm.

The wide bore engine has alot more surface area on the pistons even though the capacity is the same, this means that the vacuum from the closed throttle has more area to act on. This is what creates alot of engine braking.

Because both engines are operating at the same speeds provided the gearing is the same, both drivers release the throttle. What happens now is that the engines where operating at 7000rpm and now the throttle is set to go to idle, vacuum rises almost instantly and the engines decelerate quickly. Even though the gearing is the same, the wide bore engine will hit idle faster, because the vacuum has alot more surface area to act on. And provided the intake systems of both cars are the same, vacuum pressure will also be the same.

Engine braking on my Honda XR is high enough in first gear that it nearly threw me off a couple times. But I have 3 ratios between engine and wheel, so its alot different. I have a main step down ratio, internal transmission ratio, and then a final drive ratio.

I can tell a 1 cyl 2-stroke engine has serious engine braking, 23cc in my rc car, it had air in the fuel lines due to a roll, ran up to 40kph, almost died out while at full throttle, slipper clutch failed so it blocked tires completely untill clutch let go.
Thats some serious braking power because even brakes cant do that to mine.

learnt me to let the car idle half a minute after jumps or a roll :P

Haven't you noticed that the last post was written almost an year ago?