VR 304 Part Throttle Spark Advance

[calais5l]

Hi Guys,

Just wanting to know if anyone has played around with the part throttle advance on a stock auto 5L and seen any improvements in response/efficiency. Mainly in the 800-2400 RPM 30-70 MAP region. The manual 5L tune seems to have much more advance at 30-40 MAP for some reason.

Running PULP I would expect that some extra advance in light load timing would be necessary, as the factory tune would be based on 91 RON. I have increased certain areas in the spark MAP and have noticed some difference, but sometimes reducing advance in areas seems to give better response which I find unusual.

Thanks.

[VK_3800]

Not that unusual; remember that ignition timing is not about getting the maximum advance possible, its about matching the timing of the spark to the characteristics of the engine to get the best possible burn and the most efficiency (and therefore torque). Do a quck read up on spark 'hook tests' for a clearer explanation of the topic.

[calais5l]

Thanks VK, had a quick search for spark hook tests and actually found some interesting stuff.

[brindo]

Does increasing spark advance at a particular load point just until peak manifold vacuum is achieved a reasonable approach if you don’t have access to the dyno?

[Holden202T]

yeah thats an ok way of doing it provided you can get a second person with a stead enough foot in the car

[delcowizzid]

or lowest tps reading works. i get my mate to drive and he keeps telling me if hes lifting off to maintain speed untill he starts putting his foot back down to keep speed

[Holden202T]

yeah thats right least tps and most vacuum usually go hand in hand!