Engine Info

[Ice88]

In regards to your question Daniel, was easier to answer here then type the below out on my phone :S

VE is volumetric efficiency. Which essentially the efficiency at which the engine can move the intake charge into and out of the cylinders. This is expressed as a ratio of air inside the engine vs the outside. I.e. an efficiency rating of 70% means that there's 70% of the air outside of the engine inside the engine. From a maths point of view this would mean that at peak VE youd have difference of 4.4ish psi difference between inside and outside the engine.

This figure can be increased by high compression and/or aggressive cams as well as a well designed intake and exhaust.

In regards to the figures I provided you, I made a mistake when entering the port size and used your throttle body width so the figures will be out. I also had to assume your VE given your cams I assumed 85% whether this is correct I have no idea. Not sure how efficient a BP is stock. Further the figures I gave you were for a complete manifold i.e. runners etc.

If you wish to proceed with the manifold there are a few things that I feel compelled to impart you with. If you use a plenum your engine response will drop. This is what ITBs are good at, they also allow you to run a wilder cam without imposing the same negative impacts that would normally occur.

What you wish to achieve is more torque down low, there are two ways of accomplishing this. Either tune for lower rpm, i.e. custom exhaust manifold with longer runners. This would reduce your power up high but would give you a nice mid range. This would be best done in conjunction with a stock manifold or a custom one thats been well designed.

The only real way around the poor bottom end power is higher compression, which would produce more power throughout the entire rev range. (Also improve your idle )

EDIT: Oh and the simplest way that would keep your engine response etc would be to ajust your cam gears to dial back some overlap. Also has the benefit of being able to be adjusted in a car park. I.e. pre and post mountain run

EDIT2: If you still wish to go down the manifold route let me know, will let me know the port size and Ill rerun the numbers.