1969-1984 [Subscribe to Daily Digest] |
When modifying the air intake there are some factors you must consider.
1) The temperature of the air being sucked into the engine. The colder the air the better. Sadly it is impossible to do better than ambient temperature but this should be your aim.
2) Flow restrictions in the intake. These include the airbox, airfilter, CIS airflowmeter, every bend and intersection in the intake. Even straight pipes create some restrictions. You should aim to minimize these.
3) Risk of sucking "bad" things into the engine, i.e., water, insects, the neighbors cat. You do NOT want to place the intake too close to the ground. I got very lucky the other day as I drove into about 1,5 feet deep water (a flooded roundabout by the seaside. I had to clean seaweed from the top of the intake manifold!, and there was salt everywhere wreacking havoc on the electrical system). But I still had my original airbox and I think this is what saved my engine as no water was sucked into it. Just something to keep in mind.
Now before you start cutting and changing everything, you should check how well your oem intake system is performing. This will give you a good benchmark to measure you're mods against.
First thing to check is the temperature of the air. Place temperature probe as close to the filter element as possible, preferably on the inside of the element (just make sure it doesn't get sucked into the engine!) and go for a drive. Note the out side temperature as well as the intake temperature. You should make all measurements whith the engine fully warmed.
Next using a manometer (for info on manometers, search google.) check the restrictions in the intake system. Measure the pressure loss in several locations, one just behind the filter, one in front of the CIS airflow plate, one behind the plate and one in front of the throttle plate. Do NOT make a measurement on the engine side of the throttle plate with the manometer. The high engine vacum would suck all the water from the manometer damaging the engine.
Now all you have left to do is find a good place for the intake. The chief thing to aim for is high pressure. Tape the hose from the manometer on several good looking places for air intake, and then drive the car at a constant speed (always in the same direction if it's windy) and read the pressure from the manometer (have an assistant drive the car or read from the manometer). When you've found the best place (with high pressure, away from the ground, and not sucking in hot air).
Now that you've found a good location, you can start making the neccessary changes to the intake system. Always taking measurements to check the difference from the oem setup.
It has also been noted that different filter elements of the same shape and size (oem paper filter, kn filter, pipercross etc.) make little or no difference in airflow. A larger or differntly shaped one may however have some effect.
The CIS airflow plate is a big restriction in the intake system. By going after an aftermarket fuel injection such as MegaSquirt or more expensive preassembled units you can greatly reduce the restrictions in the intake system, and probably reduce fuel consumption with a computerized fuel controller. This is however a very involved project and something I'll leave for a later discussion.
Best regards,
TJ
posted by 81.15.4...
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
