You must have heard Spark Production Timing (SPT) earlier and you may also know what it is. But do you know how it affects your car? Well, this post will tell you about both — What Spark Production Timing is? and How does it affects car’s performance?
What is Spark Production Timing (SPT)?
Spark Production Timing is the not the time period in which the spark exists. Don’t confuse with it. Spark Production Time is time when the spark from the spark plug is created. SPT is like when the spark is produced, in which stroke? at point of the stroke? was piston up or down when spark was produced? All this matters a lot in engines performance and it seems a bit difficult to understand all this. But actually, when you will end reading all this, you will find that understanding all this is much easier than you think. So, SPT is time when the spark is produced. That’s it. Keep things simple!
How change in Spark Production Timing (SPT) affect car’s performance?
There are two types of changes in SPT which are advanced spark and retarded spark. Both have their own significance in producing race cars and mileage cars.
When the engine speeds up, the movement of pistons also speed up. So, there becomes an increasing need of advanced spark to let the pistons move. But if the spark is produced too early, then the peak pressure (highest pressure) in cylinder may decrease.
The best time to produce a spark is when the piston is down and intake stroke has just completed, this will give the maximum peak pressure to cylinder and hence maximum power to engine. Letting the spark production time early when piston is down just after intake stroke will let the spark stayed in the combustion chamber (cylinder) and as soon as the compression stroke is started that is, as soon as piston starts moving up, and as soon as the minimum pressure required for combustion is reached, the combustion of fuel starts and combustion stays for much longer time increasing the temperature and pressure. This is called advanced spark which is used in race cars. Please feel free to ask if you didn’t got this.
But in many cars, power is not required but mileage is must. In that case, increasing peak pressure of cylinder will not work but decreasing the exhaust (decreasing temperature and pressure) can increase mileage without increasing power. This can be done by using retarded spark. It will decrease the peak pressure of cylinder and temperature. Lower temperature doesn’t let the formation of many emission gases like Nitrogen Oxides, thus decreasing the amount of exhaust. Best time for a retarded stroke is when the piston is at the top during the compression stroke. This will reduce the complete time of combustion and hence less power for engine will be generated but more mileage will be there.