Driving the new car today, I decided to checkout the performance. Quick glance down at the rev counter and I am at 5,000rpm and not on a limiter, in the red zone. I thought there was a limiter at 4,500rpm.

Dont know for 2.0, but tdis never had classic rev limiter like on a petrol but there was something like mechanical limit on arround 5100 rpm.

the rev limit is set by the ecu.

If you use Vag-Com to log RPM, you'll find it increases in fixed-size steps (21 rpm in the case of my Fabia vRS). Assuming 256 steps in the fly-by-wire system and you get 256 * 21 = 5376 RPM as the maximum the system will let you ask for. A rev limiter of sorts.

Interesting indeed.

There is also an indicator in the logs when you exceed max revs allowed..

Havent seen one of them on a diesel, only petrol.

Diesels kinda dont have or need a limiter... itll just stop revving as the combustion efficency cant create the power to spin the engine faster

Diesels kinda dont have or need a limiter... itll just stop revving as the combustion efficency cant create the power to spin the engine faster

a diesel engine will keep revving faster and faster until eventually it ends up burning all the oil in the sump then it kills itself quite sepectacularly, usually pushes a rod through the side of the block!!

the way the engine speed is limited is by restircting the amount of fuel being fed to the injectors

This is also why there is a flap in the EGR valve that can be shut so this avoids total disaster when it 'runs away' on a turbo failure (something like that anyway).

Why would you drive a diesel at max revs anyway ? Power and torque drop off by then, be better to select the next cog ?

Why would you drive a diesel at max revs anyway ? Power and torque drop off by then, be better to select the next cog ?

Because when you put your foot down in a 2.0 tdi in 2nd gear, you wip up through the rev range very quickly

No doubt about that, but changing at 4k would probably get you there faster ?

http://www.superchips.co.uk/curves/octavia20tdi.pdf