I pretty much use that as my standard SR20 turbo IGN map these days. That one has been whittled down over years of tuning. Mostly around 15psi boost. And mostly on smaller turbos (T25, T28, GT2871R, etc). This is only for DET's. Getting power from DE's is completely different and I consider it a black art, practiced by mysterious beings who tend to be into self abuse and can find great satisfaction in 5kw power gains.
OK, I had some spare time this arvo, and people seem to be needing some direction in this area, so this has become a bit of a "War and Peace" of SR20 IGN timing. Grab a coffee and read on if you're up for a bit of waffle PL style...
SR20DET IGN timing.
1) Load Scales. You've got to get your load scales right for the combination of hardware you're using. This means injector size and AFM size - which both affect your K constant. Once you've got K approx right you need to adjust your load scales so that at max boost the last load column is just being used. If the figures in your load scales are too high then you'll find that you'll be using values towards the centre of the map instead of those out towards the right side. Meaning IGN timing figures higher than you want = detonation.
If your load scale values are too low then it'll bang straight over to the last load column even before full boost is reached. Usually resulting in timing which is too retarded at lower boost levels. It'll work (and I've seen many tunes like this) but it's a long way from optimal. It's typically what happens if somebody cranks boost up and doesn't adjust the load scales.
2) SR turbos typically have a somewhat unusual timing curve in that you need to remove a lot of timing in the midrange to avoid detonation (I find I'm usually using 11 to 13 degrees here at 15psi). I can only assume that this is because they tend to generate a lot of midrange torque and reach max VE quite early. Once revs start to rise the VE drops off and you can start to feed timing in again. They love timing at high revs. It can really wake them up if you can avoid detonation. Typical values are 18 to 22 degrees at 15psi.
3) Boost transition area. This can make a big difference to driveability and it's something that can only be done on the actual car cos it varies greatly, depending mainly on turbo size. Little 'uns boost up early, so you gotta be quick to pull timing out as they boost up. It's the big 'uns that really benefit from more timing here. Crank in the timing as boost is ramping up and it can really help liven them up. The standard technique is to have the "trail" function on in NIStune. Then do some runs and let it paint which cells are being accessed. Then go to town in these cells in the timing map.
4) Fuel economy. Adding timing in the low load areas and tweaking your AFR's will help here. And often improve part throttle response. But don't go too crazy or your SR will get all nasty and jerky. And I don't mean beef.
5) Unhappy engines. Sometimes you'll get an engine that just won't take timing. This will mean that power is down. And it's usually due to something like a restrictive exhaust/intercooler messing things up. And/or small turbo.
6) Happy engines. Other times you can add a bit more timing. This usually happens when somebody has paid attention to detail and fitted a quality intercooler with good plumbing and a decent dump pipe with free flowing exhaust. And/or big turbo. As soon as you can add more timing the power will come. As an example I did Matt's R34 (sure - it's not an SR but the same rules apply) and it made 220rwkw on 11 to 12psi. That was just a baseline run without even touching the ECU tune. Then I did my brother's R34. Even after 2 hours hard tuning on the dyno it struggled to make 200rwkw. The difference was that Matt's car was fitted with quality name-brand components - ARC front-mount and a full NISMO exhaust and dump. My brother's car had a cheapy eBay front-mount, factory cast dump pipe and an unknown 3" exhaust that was on the car when he bought it.
7) AFR's. If you add more fuel then you can usually add more timing. But it's a real trade-off as to where to aim. You'll get more power with more timing (to a point of course) but running richer mixtures will usually make less power. So you gain with one and lose with the other. There are various schools of thought here but I personally aim for around 12:1 on lower boost cars and richen things a bit to 11.6 - 11.8 once we turn things up a bit. Ideally you'd monitor EGT's to work out best mixtures and then tune IGN timing to suit I guess. One of my friends had his CA18 tuned by asking the tuner to "crank in IGN until it detonates and then put it out with fuel". I'll never know if this was a good technique (or what figures they ran) but the car went exceptionally well.
Fuels. We pretty much tune for 98 RON fuel here. So all timing figures I've referred to are for this fuel. If you can get better fuel then go for it. You'll be able to add timing and get more power. If your fuel quality is poor then I'm afraid you'll need to back things off...
9) Ethanol based fuels. My favourite thing. Once you go here then all bets are off. E10 will let you add quite a bit more timing and the power curve will simply march upwards. And E85 is the madman. I've found that anything with ethanol in it will help you to fill in that classic SR20 midrange hole in the timing map. And up top you can run the extra timing that the SR craves - keeping power coming way past their typical 6500 roll-off point. Actual values vary hugely though, so I'm not even gonna mention any figures. E85 is quite spooky - you can keep adding timing without hearing any detonation. So you need to watch the torque curve and simply stop adding timing when torque stops increasing.
10) Safety factor. Remember that just cos it was a nice cool day when you tuned your engine, it may not always be like that. Here in Australia we get down to less than 10 degrees C daytime temps in winter and above 40 degrees in summer. If you tune to the edge in the middle of winter then you'll become good mates with the engine builder come summer. Forget the big number at the top of the dyno sheet and remove a couple degrees - no matter how many times your SR asks you to leave it in there.
These are just things I've learned. I'm not a professional tuner and I wouldn't wanna be - although I probably tune one car every week or two. I feel for the guys who do this every day. But as a hobby/obsession it suits me just fine. And I've been lucky enough to hang with some very smart people who live to tune - and have given me direction when needed. Simon at Morpowa, Trent at Status Tuning and Skyline Stu - thanks guys.
Enjoy your SR tuning - I do!
Pete L
PS: If anybody dissagrees with any of my waffle above then I'd like to hear from you. Nothing like some healthy discussion to get the brain thinking.
and it's always good to have this forum to discuss these things.