Motoring corner With Carlover

“Engine tweaking for better performance” THERE are lots of things one can do to get more power out of an engine.  The various engine and electronic components are made to perform in a given way.

“Engine tweaking for better performance”

THERE are lots of things one can do to get more power out of an engine.  The various engine and electronic components are made to perform in a given way. 

One can change or re-programme one here and another there! Let us look at a few of them.  The Cold air induction kits work pretty well but you need to do your homework first. A lot of cars have throttle body heaters, whereby coolant from the engine is circulated around the throttle body casing.

The idea is to warm up the throttle body to prevent icing in cold weather. For those of you living countries with winter and summer, the problem is that these systems are hard-wired and don’t take account of external air temperature, so even in the heat of summer, hot coolant is routed around the throttle body.

This is a problem for CAI kits because you’ve gone to all the trouble of putting a nice kit in to suck cooler air into the engine, but at the final hurdle it runs through a 75°C throttle body which heats it up again, negating the whole point of the CAI kit in the first place. The solution to this is a throttle body heater bypass, which essentially involves pulling the coolant hoses off either side of the throttle body and patching them together with a length of copper pipe and two hose clamps.

When you do this, the throttle body stays at ambient temperature and the CAI kit gets a chance to do its job. The only downside to this is if you live in a cold, humid climate, you might suffer from icing in the winter. But hey - if you do, reconnect the coolant hoses for the winter.

So you’ve eased the flow of air into the engine, what about the outflow or exhaust? Your typical exhaust setup has kinks and bends in it to make it fit the engine compartment and under the car. In some cases these can be smoothed and straightened out somewhat but more often than not, the exhaust has to take the same route as stock. In this case, the best option is for a larger exhaust. Larger diameter exhaust pipes can accommodate more gas flowing through them and hence provide less constriction to the engine when it is blowing out exhaust gasses.

Typically a factory exhaust will have two constriction points. There will likely be the catalyser at the front (where the exhaust is hottest and makes the catalyser work best) and a muffler can at the back. High-flow cat-back exhaust systems are so-called because the start at the output of the catalyser and replace all the exhaust from there back. They will have larger diameter pipes and a high-flow muffler at the end. Alternatively you can get header-back exhausts which replace everything from the exhaust header to the back, typically removing the catalyser in the process. These are sometimes affectionately referred to as no-kitty exhausts. 

Adding a sports exhaust system can add another 4 to 5hp but you need to make sure you get one which is made by a well respected manufacturer with a good warranty. Because of the change in back-pressure, these exhausts can cause erratic engine problems on some cars that rely on a certain amount of back-pressure to operate properly. Note: back-pressure is the natural resistance to gas-flow in a normal exhaust.

From the exhaust tuning, plugs can also play a very important role.  There’s a little known method of squeezing some more efficiency out of your engine, known as spark plug keying. The idea is simple - expose the spark to the incoming fuel-air charge. If the grounding strap on the bottom of the spark plug faces the incoming fuel-air charge, the spark is effectively ‘shielded’ from the mixture.

Now you know a spark is a spark, and any spark in a fuel-air environment is going to make it burn, but if the spark is facing the intake valves, then there’s nothing obstructing the mixture from getting at it. In thousandths of a second, this does actually make a difference to your burn efficiency. The problem is that when you screw a spark plug into your cylinder head, you have no idea which way the electrode gap is pointing. For best efficiency, it needs to be facing the intake valves or ports as I mentioned above.

The solution is pretty simple. Before you install the spark plug, use a marker pen to put a mark on the insulator that aligns with the electrode gap at the bottom of the plug. It’s important to use a marker pen and not a pencil because pencil lead is graphite, which conducts electricity. You don’t want graphite on the outside of your spark plug insulator!

Once the plug is marked, screw it into the cylinder head remembering that you’ll need a quarter turn to snug it up. If the mark on the insulator is a quarter turn from facing the intake valves when the spark plug is finger-tight, you’ll know once it’s snagged down that the gap will be facing the intake valves inside the combustion chamber.

If the mark isn’t in the right place, don’t go over tightening the spark plug to force it into position! You can get keying kits which are basically replacement crush washers that are slightly thicker or thinner than the standard one. They come in one-third, one-quarter and one-half sizes, meaning that they can affect how far you can screw the spark plug in by the matching amount.

So if you finger-tighten the spark plug and the mark on the insulator is facing totally the wrong way, once it’s snagged down it will still be a quarter turn away from the intake valves. By changing the crush washer to a quarter-turn crush washer, you’ll be able to get an extra quarter turn before the spark plug is tight, which will solve your problem and the electrode gap will now be facing the right way. (To be continued).


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