McGlynn's 306 HDi Dyno Video

[mcglynn]

Stops the injectors and high pressure pump taking a beating.

Also, after extensive testing / dyno sect, I've found you make very little extra power for lots more fuel pressure... Simply due to losses in the system.

JP

Exactly.

People always want more rail pressure like it's an isolated variable that you just turn up and et voila, more power comes out.

Unfortunately the system is a massive feedback loop of pros/cons and balancing them all off against each other nicely is more important than just having 'big' values in isolation like headline figures.


I think the fact that our HP pumps have a 3rd piston de-activator at low-load shows that there is parasitic losses significant enough to warrant that feature being added. Imagine the extra power needed to provide big injections AND more rail pressure just to run the pump. Chances are when we are running up against the limits of the standard turbo's turbine flow limits already, that extra potential gained from slightly earlier EOI and torque boost is probably lost right away in mostly more turbine intake pressure and power used to turn the HP pump!

Never mind the rail control valve duty cycle mapping is nicely calibrated for OEM range injections and pressures. Get too far out again and it's just not really doing what you expected it to do, so staying near standard as much as possible where you don't NEED to make changes, makes everything work better generally.



As per the dyno results, looks ok but it's always so hard to tell without all the dyno details and an @ wheels plot. Was it dyno dynamics?

Dave

Fair post Dave.

Me and JP have came up against problems with rail ressure in this car, even on a small extent to try and clean up the burn a little it doesnt seem to like it (i guess at a sensor issue).

I guess he was looking to point out it isnt as necessary as people seem to think. The car still has the standard sensor on there and it didnt see a raise over 1350bar for this dyno run, showing that its totally possible to pull a good figure with a bit of smoke on a standard turbo without a peak rail pressure rise.

The figure ATW was displayed on the 'figure calculation' program, i think it was named TAT Flywheel Calculations or something along those lines. I dont think the dyno is dynodynamics either, although i couldn't tell you a brand.

I should have the graphs by tonight and i will post them up for everyone to look at/comment on. Hopefully they make the results a bit more believeable and will give me and JP a good idea where the map can be fine tuned & tweaked, although much of this was done in preparation for the rolling road.

There was cars on the day like new shape Civic Type R that sounded like it had a bit of work, which rolled ~ 209 bhp i think which isnt a bad figure in terms of accuracy, as well as a few other cars but ive a bad memory and cant remember results lol.