285 whp!

[RallyBob]

Originally Posted by RallyBob

Jack had previously chopped up a spare stock EG33 intake manifold, and I got to looking at it the other day. In terms of basic design, it looks very good, there are very generous transitions from the plenum to the runners...factory 'trumpets' if you will. The crossover valve is a moot point for our application. The engine's running vacuum is already lower than standard, and the engine rarely sees low rpms on the track. So the crossover is always open as it is. As well, the intended original application was for a relatively heavy Grand Touring vehicle with an automatic transmission, so down-low torque was a priority to the engineers.

None of those factors apply now, so my thoughts are to eliminate the crossover, and utilize one common plenum at all times. A trial bit of math also shows that the plenum volume is very small relative to the engine's displacement. I'd like to investigate the effects of changing the plenum volumes to work with the improved breathing and extended powerband of the modified engine. If possible, I'd like to make it modular (bolt-on plenum addition) for testing, so I can determine which is best for our needs. Then , once the proper plenum volume is determined, I'll make a permanent version with reworked (slight porting and polishing) internal runners.

I'm thinking of trying 80%, 90% and 100% plenum volumes...2.64 litre, 2.97 litre, and 3.3 litre. Plus or minus a few CC's....

The first step will be to CC the stock plenum, and go from there.

It won't be tomorrow, but over the next 4-6 weeks I'll see if I can free up some time to tackle this project, and will post the progress here.

While I have had no time to work on this project personally, I spoke with Jack about it, and he had XXTuning's current fabricator (Sean) modify the stock intake per our discussions. What this means is the entire center plenum area is basically open, the IRIS is gone altogether, and the manifold lost 7 lbs of weight too! The forward-facing 'wall' area is curved to direct air to each runner side, but other than that the entire plenum is a huge box now. Plenum area has been basically tripled compared to stock.

I sort of like the 'consultant' aspect of this for me...I didn't need to get my hands dirty at all!

He didn't make the plenum area 'adjustable' like I had originally hoped (I sometimes tend to complicate things by making them overly adjustable), but I think we're likely to see a significant change, good or bad.