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Introduction to Engine Tuning: What is a Dyno?

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What is a Dyno?


00:00 - A dyno, which is short for dynamometer, is one of the key pieces of equipment we as tuners use to help optimise the tuning on an engine.
00:10 When most people think of a dyno, probably the image that comes to mind is of a rolling road.
00:16 When a car sits on a roller, or a set of rollers, it is driven just like you drive on the street.
00:23 This isn't the only type of dyno, and I'm going to talk about the other types shortly, but for now, let's just stick with the rolling road.
00:32 The dyno has two main jobs to do: first of all, it's there to apply a load to the engine via the car's wheels.
00:41 The aim of doing this is to replicate the load applied to the engine by driving on the road.
00:48 I often get asked why we can't just tune the engine by jacking the wheels in the air, and this is because with the wheels in the air, there's no load on the engine.
00:58 If we apply even a small amount of throttle, the engine will just sit on the rev limiter because there is nothing to resist the engine accelerating.
01:08 The dyno, therefore, allows us to simulate real world driving conditions in the safety and comfort of the workshop, and this allows us to make accurate tuning changes in the same areas of the engine's operating envelope that it will be using on the road or the track.
01:27 The other job of the dyno performs is to measure the amount of torque being produced by the engine.
01:34 By measuring torque and RPM, the dyno can also calculate power, and these are the key metrics we want to monitor when we are making tuning changes.
01:46 Since the dyno can show us engine torque and power, we can instantly decide if the tuning changes we've just made have been positive, or we've perhaps gone backwards.
01:57 When it comes to types of dyno, we can broadly separate these into engine dynos and chassis dynos.
02:05 Chassis dynos, like the rolling road we just discussed, allow the engine to be tested and tuned while still installed in the vehicle.
02:14 Engine dynos, on the other hand, require the engine to be removed from the car and fitted to the dyno for testing.
02:22 Chassis dynos are popular because they allow testing and tuning to be performed with relative ease.
02:29 We can normally get a car onto a dyno in 15 minutes or less, and we're ready to begin running the engine and making changes.
02:37 The other advantage is that the engine is being tuned in the exact state it will operate in with the entire exhaust system and intake system attached.
02:48 The downside is that if we want to change components on the engine such as, exhaust manifolds, cylinder heads, or camshafts, this can be very time consuming as the engine is still in the car, which makes it more difficult to work on.
03:05 Since the engine dyno requires the engine to be removed for testing, it's a much more time consuming exercise and it's a much more expensive way of tuning the engine.
03:16 There are some big advantages to an engine dyno that can be useful depending on what you're wanting to do though.
03:24 For example, since the engine dyno connects directly to the engine's flywheel, and we don't need to worry about the power loss associated with the gearbox and differential, the dyno gives us a direct measurement of engine power rather than the power at the wheels, like a chassis dyno.
03:43 The engine dyno is also typically more accurate and offers better repeatability than a chassis dyno since the dyno is directly connected to the flywheel, and this can be important when you're doing engine development work.
03:58 This leads me to another advantage of the engine dyno, which is that because we have easy access to the entire engine, it's much quicker and easier to perform product testing and evaluation on an engine dyno than it is with the engine still installed in the car.
04:15 While we're talking about types of dyno, I'll also mention that chassis dynos aren't always rolling roads, and the other popular option is a hub dyno.
04:25 When the car is jacked up, the wheels removed, and then splined adapters are bolted on in place that then connect to the dyno.
04:35 A hub dyno still offers the convenience of a chassis dyno, but eliminates the possibility of wheel spin, which can be an issue with high powered cars on a rolling road.
04:46 Since the tyre contact patch is eliminated, a hub dyno can usually show better consistency as well as repeatability run to run.

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