| 00:00 |
- Hey it's Andre from the High Performance Academy, and welcome back to the next in our series of free tuning lessons.
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| 00:06 |
So far we've already discussed the fuel delivery side of EFI tuning and we've also looked at the ignition timing and how ignition timing affects power and torque and how we correctly go about tuning the ignition advance on a dyno.
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| 00:22 |
In this particular lesson we're going to look at tuning a turbo charged rotary engine.
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| 00:28 |
Now the reason we're going to be looking at this turbo charged rotary engine is to show you that it doesn't really matter what type of engine we are tuning, whether it's a naturally aspirated four cylinder, a V8, turbo charged or super charged, or in this case even a rotary engine, the same principals that we've already looked at can be applied.
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| 00:50 |
Now I want to also touch on the software that we use to tune the engine or how we actually go about applying the lessons we've learned so far.
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| 00:59 |
Now in the lesson's we've looked at we have been using standalone engine management systems so aftermarket programmable engine management systems and we've looked at the AEM Infinity, the Haltech platinum series, the Motec M1.
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| 01:12 |
In this lesson we're going to be using the Link G4 Plus ECU.
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| 01:17 |
And it's really important to understand that it doesn't matter what platform you're using for doing your tuning.
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| 01:24 |
The interface may look different to you, the fuel and ignition tables may be laid out slightly differently.
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| 01:30 |
And maybe the way the ECU goes about applying our changes will be slightly different.
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| 01:35 |
But it's the principals that count and tuning fuel and ignition timing is no different regardless of what platform you are tuning on.
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| 01:45 |
Now we get a lot of questions about particularly turbo charged engine tuning and that's why we've taken the opportunity in this lesson to incorporate both a turbo charged engine and a rotary engine.
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| 01:58 |
So we're throwing something really different out there in the mix and I'm just going to demonstrate how regardless of that engine combination, the same principals still apply, we've just got a few more parameters thrown in the mix that we need to be aware of and watch out for.
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| 02:14 |
Now one of those things before we get started I will mention the rotary engine is quite particular in terms of its tuning strategy or the way we go about tuning the engine.
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| 02:26 |
Two things about the rotary engine, first of all compared to a comparable piston engine, a rotary engine does need to run significantly richer.
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| 02:37 |
So remember that means that we're adding more fuel.
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| 02:41 |
The other thing about a rotary engine is that they're very intolerant of any level of detonation.
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| 02:48 |
Now remember I talked about detonation when we were looking at ignition timing, and detonation is a point where we get pockets of unburnt fuel and air in the combustion chamber that spontaneously combust.
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| 03:00 |
Now if that happens in a rotary engine, it's very easy to damage the apex seals.
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| 03:05 |
And it doesn't take a lot of detonation to do damage in a rotary.
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| 03:09 |
So we want to be a little bit more cautious about how we go about tuning the ignition timing.
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| 03:15 |
That being said the rotary engine does respond in exactly the same way to a piston engine.
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| 03:21 |
So let's get started, we'll start our rotary engine up, and we'll do a run on the dyno first and foremost.
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| 03:27 |
And then we can discuss what we've got ahead of us on the dyno screen.
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| 03:33 |
So let's get the car running in fourth gear now.
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| 03:36 |
And we'll do our first run.
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| 04:10 |
So that's our first run done there on our FD-RX7 with a 13B turbo engine.
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| 04:16 |
And let's have a look at the results on the dyno screen.
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| 04:19 |
So first of all we'll get a slightly more realistic scale to our power graph.
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| 04:24 |
And again for those of you who work in horsepower rather than kilowatts, I apologise, but it doesn't really matter the numbers we're looking at, it's all relative and that's what counts.
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| 04:34 |
So on the graph here on our dyno screen, we've got, in the top we've got our manifold air pressure.
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| 04:40 |
So our boost pressure.
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| 04:42 |
Obviously on a turbo charged engine this is a really critical aspect that we want to watch while we're tuning.
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| 04:48 |
If the boost gets out of control or gets too high it can be very dangerous for the engine, so we want to pay a lot of attention to the boost pressure.
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| 04:56 |
The next graph we've got is our air fuel ratio, our air fuel ratio being measured in the exhaust, and you can see that I've set up some bounds here, some lines to just give me some guidance on the sort of air fuel ratio I want to see with this engine.
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| 05:11 |
And lastly at the bottom we have our power, as I say being measured in kilowatts.
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| 05:16 |
So that's pretty typical of how we would set up our dyno when we're tuning a rotary engine.
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| 05:22 |
Now let's have a look now inside the laptop tuning software.
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| 05:26 |
And this time as I said we're using the Link G4 Plus platform.
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| 05:31 |
Looks a little bit different to the other ECUs we've seen, but essentially it's doing exactly the same thing.
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| 05:37 |
In the top left corner here we have our fuel table.
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| 05:41 |
And this just simply dictates how much fuel's being delivered to the engine at any time.
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| 05:47 |
That is again being displayed graphically over on the right hand side.
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| 05:52 |
And we can swap to our ignition table which is going to show us the other side of the tuning element.
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| 05:59 |
Now the important part to remember when we're tuning a turbo charged engine, I do want to start with the minimum amount of boost possible.
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| 06:08 |
We want to start with our minimum wastegate spring pressure and start tuning from there.
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| 06:14 |
And that's going to give us the minimum amount of stress being placed on the engine.
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| 06:20 |
We always want to start with as little stress on the engine as possible and then start building up.
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| 06:25 |
Now and the way we do this is really no different than how we approach tuning a naturally aspirated engine.
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| 06:33 |
And let's have a look at that procedure now.
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| 06:36 |
So if we use our dyno this time in steady state mode, what we're going to do is we're going to get the engine running on the dyno and we're going to just simply start with a very low amount of RPM.
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| 06:54 |
And we're going to start with a very low throttle opening which is going to apply a minimum amount of stress on our engine.
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| 07:03 |
So at the moment you can see the yellow cursor is showing where abouts in the fuel map the engine is accessing.
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| 07:11 |
And by using the feedback from the wide band air fuel ratio meter connected to the dyno in this case, we can see that our air fuel ratio data is being plotted up here in our tune data.
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| 07:25 |
At the same time we can see our RPM and our manifold air pressure.
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| 07:29 |
So what we wanna do is just use that data to optimise the air fuel ratio so that it matches our target so no different than how we tune a naturally aspirated engine.
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| 07:42 |
Now obviously this engine's already got something of a tune in it so there's not a lot of work to do.
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| 07:46 |
Once we've tuned an individual site we can increase the throttle opening and you can see that just drops us down to the next site in the table.
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| 07:56 |
Now if there's any discrepancy between our target air fuel ratio and our measured air fuel ratio, we can just make adjustments to the numbers in that fuel table until our measured air fuel ratio matches our target.
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| 08:10 |
Now you can see at the moment I'm sitting in the zero kPa row.
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| 08:15 |
So this is atmospheric pressure.
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| 08:17 |
And this is where things start to change a little bit for the turbo charged engine.
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| 08:21 |
This is as far as we can obviously go with a naturally aspirated engine so beyond this we would move up in the RPM and continue our tuning exercise.
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| 08:32 |
With a turbo charged engine though now if I open the throttle further you can see that we move up into positive boost pressure.
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| 08:39 |
At this point we've got 20 kPa of positive pressure.
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| 08:43 |
And if we look at our dyno you can see this is being displayed in psi instead of kPa, that's 3.5 psi.
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| 08:51 |
So you can see that as we move up into our positive boost pressure the procedure remains the same.
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| 09:00 |
At the same time though our target air fuel ratios will be slightly different to what we were running in a naturally aspirated engine.
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| 09:09 |
Now remember back to when we were talking about tuning the fuel delivery or talking about air fuel ratio.
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| 09:16 |
We said that under maximum load, when we're demanding full power from our engine.
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| 09:21 |
We need to add some additional fuel and there were two reasons for that.
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| 09:25 |
One was to make sure that we got the maximum amount of power out of the air entering the engine.
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| 09:31 |
The second part was to help control that combustion temperature.
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| 09:37 |
Now if we look at what's happening in a turbo charged engine as we move into positive boost pressure, we're simply cramming a lot more air and fuel inside that engine.
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| 09:48 |
When we've got more air and fuel inside the engine we have a larger combustion event, and that's how we get more power from a turbo charged engine.
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| 09:56 |
That larger combustion event however does have the side effect of higher combustion temperatures.
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| 10:02 |
And hence as we move into positive boost pressure with a turbo charged engine, we're going to start targeting a richer air fuel ratio than what we would use for a naturally aspirated engine.
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| 10:15 |
Again remembering back to our test of how the air fuel ratio affects power on our naturally aspirated 350z.
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| 10:25 |
I said that typically for a four valve, modern four valve, naturally aspirated engine, we may be using a target air fuel ratio of perhaps 13.0:1 Now if we tried to apply that same air fuel ratio to a turbo charged engine, and particularly a turbo charged rotary engine, we're going to end up damaging the engine very quickly.
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| 10:48 |
The effect of that lean air fuel ratio is that we get a lot of heat in the combustion chamber, that can quickly damage the engine components, and it also makes the engine much more prone to suffering from knock or detonation.
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| 11:02 |
That's all bad stuff and we want to stay away from that.
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| 11:05 |
So we can see that in our rotary engine, if we drop back to our dyno plot here, you can see that under positive boost pressure, and we've got our boost pressure here sitting at 15 psi, and under positive boost pressure, we're targeting closer to 11:1 so much much richer.
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| 11:24 |
And the two reasons for that is of course we've got 15 psi of positive boost pressure there.
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| 11:30 |
The other thing is because we are tuning a rotary engine, we're going to be targeting a little bit richer than if we were tuning a turbo charged piston engine.
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| 11:40 |
Essentially the whole procedure is exactly the same though.
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| 11:44 |
Nothing really changes, just that our target air fuel ratios will be different.
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| 11:49 |
We're also going to need to be more conservative with our ignition timing because as we increase the combustion pressure, so as we add boost pressure into our engine we'll need to retard the ignition timing to prevent detonation.
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| 12:04 |
So by this point I've covered most of the fundamentals behind EFI tuning and you've seen me put some of these techniques into practice on the dyno.
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| 12:14 |
Of course there's lot more to know than what I've been able to give you in these short videos.
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| 12:19 |
However this is a great taste of what EFI tuning is all about.
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| 12:24 |
Now if this has wet your appetite and you're interested in learning more, perhaps you want to learn how to tune your own car, or you want to take that step and begin a career in the performance EFI tuning industry, our next lesson is going to be critical.
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| 12:40 |
In our next lesson I'm going to cover what you specifically need to know.
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| 12:45 |
And also I'm going to cover how you need to apply that in a practical sense.
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| 12:51 |
So how you'd actually go about tuning a car or an engine on a dyno or alternatively out on the road.
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| 12:59 |
We're also going to talk about the various techniques that that tuning information can be applied through aftermarket standalone ECUs, or reflashing.
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| 13:08 |
This next lesson that'll be coming to you in your email inbox shortly is going to answer a lot of your questions and it's also going to reinforce that tuning isn't a black art, it's a science that we can teach, and it's a science that you can learn.
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| 13:26 |
Thanks for watching and we'll see you shortly.
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