Summary

Next question comes from Nick who's asked, is every physically possible ignition cell calibrated by establishing MBT ignition advance? This could get pretty tedious for say a 20 by 20 ignition map. Good question there Nick and the answer is absolutely not. You don't need to tune every single cell. It's a bit of an approach where common sense really pays dividends here.

00:00 - Next question comes from Nick who's asked, is every physically possible ignition cell calibrated by establishing MBT ignition advance? This could get pretty tedious for say a 20 by 20 ignition map.
00:11 Good question there Nick and the answer is absolutely not.
00:14 You don't need to tune every single cell.
00:17 It's a bit of an approach where common sense really pays dividends here.
00:22 For example, I'm going to spend a lot of my time making sure that each cell is properly optimised in the area the car is going to spend the most amount of time running so that would be generally in the cruise areas and the transition up to wide open throttle.
00:37 From there, wide open throttle all the way through to the rev limiter, obviously I want those areas of the map optimised.
00:43 On the other hand if we think about cells at maybe 6000, 7000 RPM and 20 to 40, 50 kPa, part throttle cruise areas, we just don't drive our cars at 7000 RPM and part throttle.
00:54 We'll transition through those areas of the map when we lift off the throttle, get on the brakes or maybe make a gear shift but we don't drive the cars there so we don't need to be absolutely accurate there.
01:06 Of course we do need numbers in the map at this point but in that area it's simply enough to extrapolate the shape of our ignition table out into those areas and know that we're going to be there or there abouts in terms of the timing.
01:19 The other thing we do need to consider here is we do have, as we talked about in the lesson, some pretty consistent trends, both in regard to RPM and in regard to our load.
01:29 So this sort of helps us really establish what the shape of the map's going to be and extrapolate that out as well.
01:35 From there it really comes down to simply how much time you want to dedicate to the ignition tuning.
01:41 It can be enough to skip a particular cell and then simply interpolate between the surrounding cells and it's going to probably get you within about 5-10% of the ultimate timing, provided obviously your surrounding cells have been properly tuned.
01:56 So really there's no black and white answer to this, a lot of it comes down to how much time you want to spend and how accurate you want to be.
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