Reddit reviews Design and Simulation of Four Stroke Engines [R-186]

I do engine design for FSAE so I'll throw in a bit more info that may be relevant. Okay, first step I can advise a pair of books that will be very helpful. A Graham Bell's Four Stroke Performance Tuning does a good job of introducing science to engines and engine theory. The book that puts Science with a capital S into engines is Design and Simulation of Four Stroke Engines by Gordon P Blair.

But I'll give you a little primer on this to save you from reading. You can do a lot of nice calculations with intake tuning because speed of sound through air is relatively constant. Selecting exhaust resonances is a bit trickier because of the whole really really hot exhaust gases thing. Blair writes about 15 pages on this, in which he says, "yeah just simulate it". I wound up doing just that with Ricardo Wave and attempting to validate the results back to EGTs but you also have a temperature gradient that changes drastically through the engine cycle.

As far as resonancies, I tuned the intake hoping to see a secondary resonance. I tuned primarily for the third resonance but you can see a secondary resonance in the fourth. So I was looking at a primary resonance around 10500 RPM with a potential secondary resonance in the 8500 range, if memory serves. Deciding which resonances to go after was largely about packaging for us, 1st and 2nd resonances require such short headers we couldn't fit them in a reasonable way.

If you PM me your email address I'll send you a few good papers on organ pipe length resonance.

CFD is a drop in the bucket when it comes to Intake and Plenum Design.

Look at the top 5 teams design try to understand why they run that. By looking at current designs you can learn why they do something, the way they do then improve on it for your design.

Search the FSAE Forums, lots of info there. Maybe not always directly but its helpful.

Google FSAE Intake Paper, use other key terms there are a few papers that you can find that talk about plenum design. Also before buying or complicating your self google the SAE Papers name you can find many of them for free.


Tip: Just because something flows better does not mean it will perform better. You might get higher power but throttle response suffers.

Reccomended book
http://www.amazon.com/Design-Simulation-Stroke-Engines-R-186/dp/0768004403