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M52B28 Intake Manifold Change
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<blockquote data-quote="fabianyee" data-source="post: 208926" data-attributes="member: 6"><p>The E36 318is (M42, M43 and M44) has such variable effective lenght intake manifold... </p><p>On these 3 engines, the intake design has 2 parts after the throttlebody: 2 primary intake pipes and 4 secondary intake pipes going into the air intake ports.</p><p>Below 5,000rpm, the butterfly at the junction would be closed and each of the primary pipes would channel air into 2 secondary pipes. Hence the cross section of the air pipe is smaller, hence more momentum at low to mid range RPM and giving better torque.</p><p>After 5,000rpm, the butterfly at the junction would be open and free for all the 4 secondary pipes. The total cross section of the primary pipes is now increased, allowing more air to flow at the high RPM range so that the engine doesn't run out of breath. </p><p>So it doesn't vary the length physically but it increased the cross section of the pipes. However, the 'variable' cross section was equated to 'variable <strong>effective</strong> length'... </p><p>It's the same principle for most other variable <strong>effective</strong> length air intake ie Citroen ZX 16V.. </p><p></p><p>The explanation above is based on my understanding on how it works. U can google for further information.</p></blockquote><p></p>
[QUOTE="fabianyee, post: 208926, member: 6"] The E36 318is (M42, M43 and M44) has such variable effective lenght intake manifold... On these 3 engines, the intake design has 2 parts after the throttlebody: 2 primary intake pipes and 4 secondary intake pipes going into the air intake ports. Below 5,000rpm, the butterfly at the junction would be closed and each of the primary pipes would channel air into 2 secondary pipes. Hence the cross section of the air pipe is smaller, hence more momentum at low to mid range RPM and giving better torque. After 5,000rpm, the butterfly at the junction would be open and free for all the 4 secondary pipes. The total cross section of the primary pipes is now increased, allowing more air to flow at the high RPM range so that the engine doesn't run out of breath. So it doesn't vary the length physically but it increased the cross section of the pipes. However, the 'variable' cross section was equated to 'variable [B]effective[/B] length'... It's the same principle for most other variable [B]effective[/B] length air intake ie Citroen ZX 16V.. The explanation above is based on my understanding on how it works. U can google for further information. [/QUOTE]
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M52B28 Intake Manifold Change
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