Practical Standalone Tuning: Driving Techniques
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Driving Techniques
07.43
| 00:00 | - Tuning without the benefit of a Dyno, does require some specialist driving techniques and this is really one of the key parts of the section of the course. |
| 00:09 | I'm going to show you the techniques that I've personally developed over 15 years of tuning, to help me get the most out of tuning a stand alone engine management system out on the road. |
| 00:21 | Now from the Dyno tuning section you'll know that Steady State Tuning is a really key part of being able to accurately access each of the cells and the fuel and ignition tables. |
| 00:34 | And on the Dyno it's really easy, because the Dyno will hold the engine rpm constant. |
| 00:38 | On the road we don't have that advantage and in fact it's a little bit more difficult. |
| 00:44 | If you consider what would happen if we were driving in fourth gear at 3,000 rpm, just barely touching the throttle and maintaining speed. |
| 00:52 | If we want to move up in the load areas and access our fuel cells at higher throttle openings, we obviously need to open the throttle. |
| 01:01 | The problem with this is when we open the throttle, the engine naturally will end up making more power and more torque. |
| 01:08 | With this increase in torque, the engine will start to accelerate. |
| 01:13 | So we find that our car will accelerate on the road and the result is that our engine rpm increases and this makes it impossible to stay steady in one rpm column if we're just solely relying on using the throttle. |
| 01:28 | So the technique for controlling the engine rpm, is the technique of left foot braking. |
| 01:35 | And using this technique, as its name implies, we're applying the brake pedal at the same time as we're applying the throttle and we're using our left foot on the brake. |
| 01:46 | So what we're doing here is applying some load or resistance to the engine to stop its accelerating, using the car's braking system. |
| 01:55 | Now this technique does require some finesse, it's going to take a little bit of practice to get used to, particularly for those who haven't used left foot braking before. |
| 02:07 | Initially when you start using that technique, it feels quite unnatural. |
| 02:11 | Most people would be more used to using their left foot on the clutch pedal of a manual transmission car and that requires a much more aggressive pressure from your left foot. |
| 02:22 | If you've been driving an automatic transmission, chances are your left foot spends its entire time sitting on the foot rest, so it's not even doing anything. |
| 02:31 | When we're using our left foot on the brake, it requires a very subtle amount of pressure to accurately control the engine rpm and initially when you first start trying to use the technique of left foot braking you're going to find that it will feel unnatural and it can result in the car being jerky and you can struggle to accurately maintain engine rpm. |
| 02:56 | Like any skill, it just comes with practice. |
| 02:58 | We're going to look at how we can use that technique in the next section, to help us with our Steady State Tuning. |
| 03:06 | The other aspect of left foot braking, obviously is that it is going to put a lot of heat into the braking system and you need to be aware of this and understand how to manage it. |
| 03:17 | The amount of heat that's going to end up in your brakes will depend on how powerful the car is, so how much power we're trying to brake against, and also to a degree the size of the vehicle's braking system. |
| 03:32 | But you do need to be aware of this and if you ever end up with vibrations coming back through the brake pedal, if the brakes become spongy or don't feel as effective or if you can smell that the brakes are getting hot, that's a good sign that it's time to stop, get your foot off the brake pedal and allow the brakes to come back down to a normal operating temperature. |
| 03:57 | Now when you do this, we don't actually want to simply come to a stop on the side of the road or in the pits. |
| 04:02 | What that's going to do if your brakes are very hot, is result in localized heating for the brake rotors, where the calipers or brake pads are contacting the rotor and it's a very easy way of warping your brake rotors. |
| 04:15 | So the best technique if you've got a lot of heat into your brake system is simply to get off the brakes, but continue to drive on the road or circulate on the race track at a normal speed, that's not going to require large brake inputs. |
| 04:29 | The speed, the car actually moving out on the road, or the race track and the air flow that that results in, is going to be the best way to bring your brakes back down to normal operating temperature. |
| 04:40 | So when we're using the left foot braking technique, we're alternating between periods of using the left foot braking technique to control the engine rpm and then we are also alternating with periods of allowing the brakes to come back down to a normal operating temperature. |
| 04:58 | What you're going to do there, as I said, will depend on the brake system on your car, as well as how much power your engine's making. |
| 05:06 | The other aspect that's important to consider when we are road tuning is the way we apply the throttle and it's important to make sure that we're always making smooth changes to our throttle position. |
| 05:21 | If we're making aggressive changes to the throttle position, this is going to result in transient or acceleration enrichment being commanded by the ECU and this can affect the measured air fuel ratio and can be a little bit misleading. |
| 05:36 | So it's always important to make very smooth changes and particularly when we are tuning the fuel table, we want to make sure that we're central in the particular cell that we want to adjust and allow the engine to operate in that cell momentarily, so we can see the air fuel ratio is stable. |
| 05:53 | If we flash through a particular cell very quickly, we're unlikely to get an accurate idea of what the air fuel ratio is in that particular cell. |
| 06:03 | The last bit we need to be aware of with road tuning, is managing the engine coolant temperature and intake air temperature. |
| 06:11 | Unlike Dyno tuning, where we're generally sitting with a fan constantly blowing air through the engine bay, with road tuning on a road race track or on the road, we're often going to be sitting on the side of the road or in the pits where we're making changes. |
| 06:27 | This gives a lot more opportunity for the engine bay to heat soak and this isn't going to give us representative temperatures in the engine, so I'm talking here about a intake air temperature, engine coolant temperature and even the fuel temperature in the fuel rails. |
| 06:45 | So what this means is that for the first minute or so, after we pull out of the pits or pull away from the side of the road, there's a period where the engine needs to reach normal operating conditions. |
| 06:56 | So it's always important to make sure that before we start our tuning process on the road or on the race track, that we allow the engine a period of time to come back to normal operating conditions. |
| 07:07 | If we begin making our tuning changes immediately after pulling out of the pits or away from the side of the road, when the engine is heat soaked, this is going to mean that our tuning changes are likely to be inaccurate, and this can be very frustrating, because you can spend a lot of time chasing your tail, making changes that don't seem to be having the effect that you'd expect, once the engine has reached normal operating conditions. |
| 07:33 | Alright, now we know about the driving techniques we need to use, let's see how we can apply these on the road or racetrack. |
