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    • Archive for April, 2009

    Intake Manifold Experiments

    Posted by Ken Lanham on 16th April 2009

    I have beem working on a little project to improve the airflow into my Volvo’s 16v engine. I could have built a complete intake from scratch, but this is alot easier. And the factory volvo parts will still bolt to the intake, things like the throttle body, throttle cable, cruise control, fuel injectors, and vaccuum ports are all still able to bolt on in their factory designed location. I hope this mod will extend the rpm range of my engine upward by several hundred rpm. Some flow testing by a friend showed that the stock intake runners flow 190cfm each. To put this into perspective, the stock unported head can flow 230 cfm at 10mm lift on an intake port. My head with some port work flows more like 260cfm. So you can see the bottleneck is quickly becoming the intake manifold. I have suspected this for a long time because my torque curve falls so quickly after 5000 rpm. This engine shouldn’t be losing torque so quickly. Something is choking the flow at higher rpms.
    The plan is to cut open the stock manifold, port the runners as much as possible, and then weld the parts back together more or less. The runner length will also be shortened for better flow and a higher rpm tuned length.
    Intake saw work

    Intake saw work

    The intake was cut apart using a small table saw with a carbide tipped blade. Its just your normal high quality woodworking blade. It goes through Aluminum quite easily and the fence allows for a nice straight cut. There are no pictures of the ported insides, but roughly 1mm in all directions was gained. The parts were then welded back together. Notice that I added 1″ aluminum bar to the plenum area to increase plenum volume. This should help improve flow balance between the intake runners, and give a nice reservoir of high pressure air from the turbocharger.

    Welding the intake back together again.

    Welding the intake back together again.

    Everything was carefully TIG welded back together, using 4043 filler rod. The cast aluminum welds relatively easy despite living a life in an oily engine. There is a little black residue around some of the welds, but mostly it welded cleanly. The parts were sandblasted clean during the prep. Clean parts always weld better.

    I hope to have some results soon, the drag strip is open for business this week. I have a couple things to do before im ready, but I’m working hard to make it out to a Wednesday test night soon.

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