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Get your own Free Home PageThis was the first performance modification that I had ever tried, and indeed was the first real work I had ever performed on a car. The extractors themselves set me back $75 from a newspaper classified add.
Installing the extractors appears to be a simple bolt on operation, but when it came time to bolt everything back together it became apparent that it wasn't going to be that simple.
Firstly, there were strips of metal running between the exhaust ports of the extractors. These stopped the intake manifold from going back on. So apart everything came again, and a hacksaw soon dealt with those strips. I've never had any trouble with the exhaust leaking from the join with the head, so I guess the strips were superfluous.
Secondly, the extractors were longer than the standard exhaust manifold, so a piece of the exhaust pipe had to come off. And it is not easy to cut a pipe that is well under a low slung car by lying on the ground next to it and holding a hacksaw at arms length. Of course now the freshly cut end had to be rejoined to the extractors. And no I did not have a welding kit lying around. So... a cut open coke can was wrapped around the join, with two large hose clamps holding it in place: No worries.
After a while it became apparent that the aluminium coke can was not capable of surviving long term contact with hot exhaust, so a change was made to a steel bakedbean can. After all, if a baked bean can can't survive contact with noxious gas then what can?
One thing that would help is colder intake air. Boyle's Law tells us that as a gas (such as air) is cooled down, it becomes denser. Denser air has more oxygen in a given volume (such as the volume that will fit into a 3.3 litre six). More oxygen means more fuel can be burnt, giving more power.
Hence anything that will cool down the intake air can give the engine more power.
This is why turbo engines use intercoolers to cool the hot air after it has been heated by the turbo.
With the standard HQ, the air was drawn from the top of the engine bay. This is not the coolest air available. It was a simple matter to include a duct leading down to a forwards facing opening just below the radiator.
The duct was made out of the finest, free, cardboard I could find, painted black so as to provide some sort of water resistance and to make it stand out slightly less. (It was still quite visable with people often asking about the mysterious duct that protruded from the bottom of my car.)
Sometimes, on a cool morning, the duct did work, and removing it and replacing it would reveal a noticable power increase. It also revealled a Radar trap on the hill on the way to university :(
But in general, the duct did not provide air that was much cooler than normal, and so it was useless. I did intend to make another duct to tap air from the ventalation intake plenum, which I reckon would be ideal, but as it required cutting into the sheetmetal of the plenum I never got around to it.
As described above, the temperature of intake air is of great importance. This is especially so in a forced induction or high compression ratio car where 10° could be the difference between loads of power and fatal pinging. So it is very useful to be able to tell the temperature of your intake air while driving. This can save you from the problem also described above of building a cold air system that is not actually drawing from a source of cold air.
This project starts with the purchase of an ACME indoor-outdoor thermometer.
This one cost about $10 at a Coles supermarket. Originally this thermometer had an "inside" sensor mounted on the body and an "outside" one mounted at the end of a long wire. However it is simple to unsolder the "inside" sensor from it's mounting and reattach it at the end of long wires too. That way you have two long distance probes which is very useful in comparing the temperatures at the same time.
I used two separate wires but this causes difficulties when it comes to laying them out through the engine bay. Using twin wires such as some cheap speaker cable would give much better results. One could try using just one wire and then using the earth of the car body as a return circuit but given the very low signal strength I suspect that interference could cause troubles.
Eventually I got a new engine and while installing it I broke the temperature probe. And the new engine had a normal fan. I still have the fan and will install it with a new thermostat for some purpose eventually.
The above projects were mostly sensible, but some of my ideas are just silly. These can be seen here.
You can read about my search for my next car here.
Autospeed is one of the very few, if any, magazines that has any really budget performance information in it. If you have a $50 000 Nissan GTR but now want to hot it up for less than $100, then this is what you need.
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