Does anybody know about the above subject?

Ok, so here is my understanding and the gurus, Please correct me if I’m wrong.

In 99% of cases diesels do not have throttle butterflies, Thus meaning the engine consumes to same amount of air regardless of throttle position (obviously imagining the RPM doesn't change)

So the way we increases the RPM is to increase the amount of fuel the injectors are firing in. Thus richerning the mixture or lowering the AFR.

With this in mind is it actually possible to have a rich or lean diesel? Surly the rich it gets the faster it will spin???

The only way I can see possible of it to be rich or lean is when the engine is under heavy load and there isn't enough fuel to accelerate the engine??

Also I have been reading about diesel AFRs and that Diesel will ignite between 4:1-50:1

That being case does anyone know what AFRs you should see in different cases. i.e. Idle, Cruse, Hard acc, High RMP ect ect.

Thanks.

 

i would also like to no this

 

anyone shed some light on this???

 

i put my wideband lambda up the arse of my 205 dturbo as i was curious just like you! At ticover it was soo lean it never registered, and only when you accelerated hard did it show an AFR of 17:1, and my car was quite black at this! not sure about the science. Basicaly i think the leaner the more efficeint (obviously!) and if you are too rich you just make smoke! i too would like to know the science!

 

bit of a 'black' art judging by the lack of reponses

 

Black as fook in my case

 

I would think that there is no constant AFR in a Diesel as you say the air is more of less constant with the fuel being metered, and that is probably the reason why when tested at idle it was very lean as you have a high AFR.

I to think the same as you if you didn't have enough fuel it wouldn't run.

Martin

 

air is not constant on turbo diesels though? and timing will also affect power/lambda emmissions! its too complicated!
On my 1.9 xutd, i screwed the wastegate as tight as it would go (a diesel unlike a petrol will only make as much boost as the ammount of fuel you put into it) and i screwed up the max fuel screw a substantial ammount, i then fiddled with the diaphram in the boost compensator to try and reduce smoke emmisions off boost. it was really quite nippy after that! 22 psi of boost lol. Common rail stuff, if you had the software would be quite in depth to tune i would think.

 

Here this link may be of use http://www.motorsport-developments.c...AF280_tech.pdf

Martin