260DET Posted December 13, 2009 Share Posted December 13, 2009 Designed this with some help to overcome uneven air distribution with the previous side entry plenum. A rear entry design was chosen because it gave the most height at the entry point, important because the incoming air has to turn down to fill the cylinder intakes, the nearer the intake to the entry/the lower the plenum roof, the sharper the turn. The extra complication of using bellmouth intakes was decided on to improve flow significantly and assist even distribution, they are 30mm high off the plenum floor and have a specific shape to maximumise their efficiency. The entry into the plenum is 76 x 100mm wide and it incorporates a central turning vane for the purpose of spreading the air as it enters. Otherwise it would tend to concentrate at the outside of the intake turn and so tend to enter the plenum favouring the left side. The plenum has been fitted and the engine run up on the dyno. A plug reading indicates that each cylinder is breathing equally, the plugs read identically. Pics should be self explanatory. EDIT this was supposed to go in the V6 engine forum, somehow........... Quote Link to comment Share on other sites More sharing options...
Jared Posted December 13, 2009 Share Posted December 13, 2009 What's the volume of the plenum? Quote Link to comment Share on other sites More sharing options...
260DET Posted December 13, 2009 Author Share Posted December 13, 2009 The plenum itself would be ~4.5 liters I guess, the entry ~2.5. Might add that the design took no notice of volume, it was all about optimumising flow, the physical limitations of the location and serviceability. Quote Link to comment Share on other sites More sharing options...
Jared Posted December 13, 2009 Share Posted December 13, 2009 What is the power goal? That has a lot to do with volume. Quote Link to comment Share on other sites More sharing options...
260DET Posted December 14, 2009 Author Share Posted December 14, 2009 We had it up to 15PSI boost on the dyno when the plugs were checked, final power will be ~450 non optimistic DynoDynamics WHP, depending on driveability. May have to drop the GT35R rear housing down one to get that. Quote Link to comment Share on other sites More sharing options...
Gcontrol Posted December 20, 2009 Share Posted December 20, 2009 how was the flow compared to stock manifold? Quote Link to comment Share on other sites More sharing options...
260DET Posted December 20, 2009 Author Share Posted December 20, 2009 It can flow more than enough for a three liter engine, that is certain. The crucial point is that apparently it is flowing evenly to all cylinders @ 15 PSI boost. Quote Link to comment Share on other sites More sharing options...
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