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Practical Standalone Tuning: Step 9: Full Power Tuning

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Step 9: Full Power Tuning

17.22

00:00 - Now that we've done the steady state tuning, the next step is to do some full power tuning and complete the rest of the tune in the areas that we haven't fully accessed during our steady state tuning.
00:12 Now we've already got a pretty complete map because we've done our steady state tuning all the way out to 5000 RPM for both the fuel and the ignition table.
00:22 So we've already got most of that filled out, so we don't actually have that much work to do.
00:26 Now what I would like to do when I start doing these full power runs, just to safeguard everything, is add a little bit of extra fuel and remove some of the timing just to safen up the tune and means that we're going to be starting from a slightly rich, slightly ignition retarded position.
00:47 Now because we're doing this on throttle position, rather than the example where we're using manifold pressure, we only really need to concentrate on that top row of the map.
00:58 So what I'm gonna do is start by highlighting the entire top row of the fuel table and I'll multiply that by 1.05 to add 5% fuel.
01:08 And then we'll swap through to the ignition table, I'll highlight the entire top row of that ignition table and take two degrees of timing out.
01:19 Now what we'll start with is a run on the dyno out to 5000 RPM and we'll do that run over six seconds which should give us something that's reasonably close to what we'd see on the street.
01:35 So we'll do a run and just see where exactly we lie.
01:53 OK so that's our first run out of the way.
01:55 And everything actually looks pretty good.
01:59 We'll just cycle through to the air fuel ratio screen, I'll just clean that up so we can see exactly what we're looking at.
02:08 OK so what we found there is we've got a slightly lean spot there at 2500 RPM.
02:18 For the most part, the rest of the tune is pretty close.
02:21 We're a little bit rich at about 4250 RPM.
02:26 So what I'll do is we'll start by, we'll forget about the ignition completely.
02:32 As long as we're not hearing any detonation while we're doing this, we can concentrate solely on the fuel at this point.
02:38 So we'll start by correcting the fuelling at 2500 RPM.
02:46 We're gonna add 10% in there because we are quite lean there.
02:51 Then at 3500 RPM we're going to add a little bit of fuel as well, we're not too bad, we're about 2% lean there.
03:01 And at 4000 what we're going to do is add a zone at 4250 RPM and that will allow us to correct that slightly rich area there at 4250.
03:16 So what we'll do is add in, sorry subtract I should say, 3% fuel, 5% fuel there.
03:30 And we'll do another run, so we'll just leave our run length exactly the same at the moment, see if we've corrected those changes.
03:50 OK so that's our second run done.
03:53 You can straight away see that our fuel curve is a lot flatter.
03:57 We're still a little bit rich in there at 4000 and also at about 4500 so we'll just make a small correction there, take 4% out at 4500 and at 4000 we will take out 3%.
04:21 Then at 2500 we still want probably 1.5% in there.
04:30 OK so now we're close enough that I'm happy to go and increase the RPM slightly.
04:36 So we'll go through to 5500 RPM.
04:42 And we will increase the run length out to seven seconds.
04:48 And we'll do another run.
05:08 OK so let's have a look and see how our lambda looks.
05:11 Now you can see we've got a beautiful flat line, everything's looking really really good on that.
05:16 We're just drifting a little bit rich at 5500 RPM.
05:20 At that point we're at 0.86 and we really wanna probably be targeting around about 0.88 at that point.
05:28 You know what though, rich is safe.
05:31 So what we'll do is not worry about that right now and we'll do a run out to 6000 RPM, and just see how that looks.
05:40 So we're gonna increase our run length to eight seconds, and we'll do another run.
06:02 OK so now we've got some data out to 6000 RPM and let's have a look at what we've got.
06:07 OK so you can see the trend from 5500 RPM is followed through to 6000 and we're gone rich down to about 0.85, 0.86 at 6500 RPM.
06:20 So what I would do there is at 6000 RPM we're going to take out 3% so I'll multiply that by 0.97 And if we go back to 5500 RPM we're at about 0.87 We'll take out 1% there so times that by 0.99 Now from 5000 RPM now we've actually got some heat into everything, it's settled down.
06:49 From about 3500 through to 5000 we're actually a little bit rich so I'll multiply that by 0.99 as well and take a little bit of fuel out of there.
07:01 Again we're safely rich so we'll increase our run length out to 6500 RPM and we'll take our run time out to nine seconds.
07:13 And we're ready to do another run.
07:35 OK now everything's looking really good there except at 6500 RPM you can see that it goes really quite rich, we're down to 0.82 Now I wanna just talk a little bit about why that's happened because there's a few clues to it.
07:51 If we look at our torque curve, you can see that the torque is really sharply falling off above 6000 RPM.
08:01 And the torque curve represents the engine's air flow so what that means is we're not getting as much air into the engine, and what that means is conversely we're not going to need as much fuel.
08:12 So what I would do there, we'll go back to our lambda curve, and we're about, at 6500 we probably wanna be about 0.88, 0.87 so we're about 5% rich there.
08:27 What I would do is multiply the 6500 and 7000 RPM columns by 0.95 so we'll remove 5% fuel.
08:37 Now just to keep everything, the curve going, I'll actually take a little bit of additional fuel out of the 7000 RPM row.
08:46 'Cause that torque's going to continue to drop off.
08:49 And you can see if we look at our graphical representation, we've got a nice smooth curve going from 6000 down to 7000.
09:00 OK so being a little bit fussy, we can actually see if we go all the way back to 2000 RPM, we're actually still a little bit rich there, so I'll take 3% out of that point as well.
09:17 And everything else is pretty much on track with where I want it to be, so we can do another run and this time we're gonna go, no we were gonna leave it at 6500 RPM.
09:26 Our red line remember, our rev limiter is set at 6800, which in essence actually comes in 200 RPM earlier which is 6600.
09:36 So 6500 is actually the useable rev range we want to tune the engine for.
09:41 OK so we'll do another run.
10:03 OK so let's have a look at the results there.
10:05 And everything's looking pretty much where I want it to be.
10:09 There's a couple of little places that I would probably just clean up a little bit.
10:14 6000 RPM we're at about 0.88, 0.89 I'd probably put just a touch of fuel in there, maybe another 1% there.
10:23 And yeah we're at about 0.87 at 6500, which is really where I wanted it to be.
10:31 We've got a slightly rich spot in here at 5250 and 5500 so I'd probably also pull a little bit of fuel out of that as well.
10:41 But you can see how quickly we can dial that tune in and how easy it is to start increasing our rev range out and get through to the full extent of the engine power band.
10:56 OK so that's, we're going to assume that's our fuel curve done now under wide open throttle.
11:03 What I'm going to do is just lay down one more base run, remembering that we've still taken two degrees out of our ignition table and we're just going to have a look now at putting some timing back in to optimise that ignition curve.
11:17 So we'll just do another base run that we can use as a comparison when we start changing that timing.
11:40 OK so we've got a good base run laid down there.
11:44 We're gonna change through to the ignition table.
11:46 And the first thing I would do is I would highlight the entire top row and I'd add back in the two degrees that we removed before we started doing our full power runs.
11:57 Now again just to reiterate, we want to be using knock detection gear while we're doing these runs just to ensure that we're not encountering any detonation.
12:07 And you want to be very careful when you do add this timing back in, just to make sure that it is in fact safe and we don't have any detonation occurring.
12:17 Once we've got that timing back in, we can do another run and we can see how that additional two degrees is affecting the torque.
12:44 OK so if we have a look at, it's easiest to see the changes if we look at the actual torque curve as opposed to the power graph.
12:57 Power and torque are closely related, power is calculated from torque, but the torque, the resolution of the torque curve shows the changes much more easily.
13:11 What we can see though is we've actually lost if anything a little bit of torque.
13:17 Particularly through this mid range here from adding that extra two degrees in.
13:21 The only place we've really gained anything is at 5000 RPM.
13:24 And really even what we've gained is almost insignificant.
13:30 We've gained 0.6 of a kilowatt in the top end here.
13:34 So basically when I see something like that, it suggests to me that the engine didn't really need that additional timing and it was probably doing a pretty good job without it.
13:45 What we wanna do when we're setting the timing remember is we're looking for the minimum amount of timing we need to achieve peak torque.
13:56 So if we can get the same result with two degrees less timing, we wanna do it.
14:00 So what I'd do, really the change we saw wasn't good, it didn't help, so I'd take that two degrees back out.
14:07 But just for interest's sake what I'd do is take a further two degrees out and just see if perhaps we were already slightly over advanced, so we'll do another run now with that extra two degrees removed.
14:37 OK so on that run we have actually lost torque everywhere.
14:40 So what that means is we were really pretty much on the money with the initial run we did where we had two degrees removed from what we'd found in our steady state runs.
14:54 And what you can see, the blue run that we've just done, we've literally lost torque the entire way through the rev range.
15:02 It's not a lot, it's not a big difference, and that really shows that this engine is not particularly sensitive to ignition timing.
15:10 It's really not making much difference to the torque or power.
15:15 With that two degrees losing us power, I would go back to our starting point, add that two degrees back in, and at that point we can effectively call the ignition table done.
15:26 So at the point we're at now, we've got the entire engine mapped in steady state up to 5000 RPM.
15:34 We've looked at those areas above 5000 RPM where we know that the engine's only gonna transition through, so they're not as critical, we've checked those and we know that the numbers that we've got in those areas are safe.
15:48 What we've done now is we've done some full power runs and we've confirmed everything under full power to make sure that the engine's tuned all the way through to the engine rev limiter.
16:00 And basically we're ready to take the car off the dyno.
16:04 Now the next step beyond this in most instances would be to confirm the tune on the road.
16:11 Now in this particular case the car is not road legal, it is a purpose built race car.
16:15 So we can't drive the car on the road, and that also takes some of the complexity out of our job because for a race car really our driver's not going to be too worried about fuel economy, they're also not going to be overly worried about what the car's drivability is like at part throttle and maybe 3500 RPM.
16:36 Really that's not how this car's driven.
16:38 So for a purpose built race car, it actually makes our job easier because we really only need to make sure that the car is responsive, that's it's drivable at part throttle to get onto the racetrack.
16:51 Beyond there really most of its time is going to be at higher RPM and wide open throttle, and those are the areas we wanna concentrate on.
16:59 From here what I would do is confirm the tune if needed, using data logging at the race track.
17:07 And we can make some changes to the air fuel ratio if we need to, based on the feedback from that data logging.