1.9L VW/Audi/Skoda/SEAT Diesel Mod alert! :)

[Julian Edgar]

Numerous papers and test stand experiments show that a diesel with a leaner mixture ( more air and using the same amount of fuel ) produces more power.

Certainly not what I understand to be the case. Can you produce some references?

[ConnClark]

Originally Posted by Julian Edgar

Certainly not what I understand to be the case. Can you produce some references?

One very informative paper I keep referencing is

http://aerade.cranfield.ac.uk/ara/1937/naca-tn-619.pdf

in figure 8 they show power output with boost pressure for fixed fuel increments per cycle.

In figure 10 they show what a restriction of air intake does to performance.

in both cases the more in the cylinder results in more power out and higher efficiency for a given quantity of fuel.

[Arragonis]

@Julian

I've been waiting for this since part 1

Briskoda had a 'definitive thread' on the PD160 a while ago. Lots of "yeah much faster" but no solid ABA testing and then repeating this with a remap I could see. So I saved the cash. I did plan on a remap without it but didn't go through with it although I do have an uprated clutch fitted.

As for yours, dissapointing results so far especially given the effort involved and the improved flow. I await the exhaust and remap installments though.

Are you planning to test the remap without the intake and exhaust, as in full on A-B-A to see the effect of flashing alone ?

[Julian Edgar]

Are you planning to test the remap without the intake and exhaust, as in full on A-B-A to see the effect of flashing alone ?

no

[Julian Edgar]

One very informative paper I keep referencing is

http://aerade.cranfield.ac.uk/ara/1937/naca-tn-619.pdf

in figure 8 they show power output with boost pressure for fixed fuel increments per cycle.

In figure 10 they show what a restriction of air intake does to performance.

I like old engineering but I think that referencing a 1937 paper as indicative of how a current diesel behaves is stretching things a bit. What engine speed was used? What compression ratio? How well was the fuel atomised?

[Julian Edgar]

As for yours, dissapointing results so far especially given the effort involved and the improved flow. I await the exhaust and remap installments though

I actually wasn't disappointed at all. I thought the pressure drop improvement was very impressive.

[Arragonis]

Originally Posted by Julian Edgar

I like old engineering but I think that referencing a 1937 paper as indicative of how a current diesel behaves is stretching things a bit. What engine speed was used? What compression ratio? How well was the fuel atomised?

It seems to be a paper about testing compression engines at different altitudes. 2000 rpm was the speed quoted. It used roots type superchargers too.

[Piwoslaw]

Julian, at the end of the second part of the article, there is a graph of acceleration vs rpm for the standard and the new intake.

Do you have any idea why acceleration wasn't better through the whole rpm scale, but was actually worse below 1500 and above 4000rpm, even though the pressure drop was greatly reduced? Would this imply that just swapping the intake for something larger would harm performance and/or fuel economy when the driver's style keeps rpms between 1000 and 2000?

[Arragonis]

The pressure drop is good. I meant the accell tests.

Just a thought, is the standard intake plenty for a 1.9 litre engine only revving to 4500 rpm? If it was a petrol screamer then maybe that would release more power with this mod.

Also do you have any idea of increased boost pressure actually reaching the engine ? I'm wondering if the turbo / relief valve combination more or less sets the boost level at WOT no matter how much extra air the intake is allowing. If you restricted the intake then that would have a negative effect obviously.

[euromodder]

One of my first ecodriving techniques with my current car, was to ever so gently reduce the throttle. It kept up the speed (sometimes it'd lose 1 or at worst 2 mph), but fuel consumption dropped significantly, and well beyond what you'd expect from a 1 or 2 mph drop in speed.

So it made the same power on less fuel, i.e. by leaning it.

It was rather tricky to reduce the throttle, as overdoing it meant the speed dropped like a stone, and any bump could change the position of my right foot, often ruining the whole thing.

As far as I can see, the cruise control seems to do something similar, but far more consistently, and with a lot less effort on my part