Port and Air Flow in practice and in theory II

In my last article, I talked in some paragraphs about how porting will get you more flow. I also discussed how for a street ride, removing a lot from the ports is probably not the best idea as it can reduce torque at lower RPM.

That said, most of how the Eastwood video presented porting, shouldn't be taking anything away from a street ride or "streetable ride". This was also in my first article:Port and Air Flow in practice and in theory.

Streetable ride approved technique:
Reducing the machinist ridge in the combustion chamber in his example wasn't aggressive enough for me, because those create turbulent air. This is something that won't take away for a streetable ride.

Streetable ride approved technique:
The smoothing of the casting down to 80 grit sand paper? That's perfect from what I learned from David Vizard's book on this subject. The tiny imperfections and roughness may pick up carbon, but that'll happen anyway, you might as well have a desirable roughness to create small vortices, which make small roller bearings to make for faster.

Another item I disagree with on Eastwood's video on my last article, is that you should have spare valves that go in to protect the valve seat while you remove machinist ridges. That way, you can get right in there, next to the valve, and make a trench and then smooth that out.

Here's an example picture of the areas in question for a machinist's ridge: (be sure to click on the another article of mine. It has a lot more pictures, and when you click on them there, they get bigger; head gasket)

Port and Air Flow Theory III

A couple of points of re-study for me since video I made and embedded above, as this subject can make me feel left wanting again and again...
...David Vizard says that focusing on the points of the most restriction will make a port much more efficient. While hogging out a port where the air is already the slowest is likely to make a port simply lazy.

Back cut valves, rolled valve seats? Huge. It's been a while since I was in his book instead of on YouTube where I couldn't see the charts, but he made an example of how much air had to get past valves. In the picture, most of it is air, and beside it, is a little man to scale for how much air goes through a particular race engine. Yet, of course, still, there is that little valve, which is smaller still than the man when you see the math for how much "surface area" an imaginary cylinder from the valve seat to the cuts on the valves. That little sideways space, where all the action has to take place. Can you imagine it?

What is next to that moment of greatest restriction is often a machinist ridge in the combustion chamber. Most people won't touch it. The trick is to have a set of valves you don't care for as a guide to your single cut burrs, and round out a small trench around the valve, exactly the size of my smallest burr. Then blend it. Surely, everyone's fear is you've made the combustion chamber bigger! The tiny drop in size, vs. having air and fuel tumble and bounce through this section, which forms larger droplets, is more my worry. Plus, with the increased flow, while static compression is slightly lower, dynamic compression will be higher.

Make effort on the port side of the valve, working in the bowl ... I'll continue my thoughts on this at a later time. :)

Source: DON'T POLISH when Porting and Airflow Theory III by DENichols
By AutoBravado

"Cold Air Intake vs Short Ram Intake - Explained" blog reaction to Engineering Explained

Before I get into my reaction to Engineering Explained's good video and the comments below it, I've also done my own article about intake modifications
Weapon R Dragon Intake Review 
 :

Randy Knight, on Engineering Explained's video was talking about laminar or straight flowing air, vs. turbulent flow and entrance length. He has a good grasp on some of the issues facing intakes for sure!

I reply:
+Randy Knight Something to add to your considerations is the intake manifold after the throttle body. It does more to handle what you're worrying about than the intake ever does. Intake valves don't just take air in, they also lose air back into the intake manifold and that's a tough consideration for engineers that have handled these issues wrong in so many ways (It's very complex and many better and worse things have been tried). Try David Vizzard's book on porting an engine.

As I think on your comment again, I really believe that the intake manifold design is the most important for what you're thinking on and a short ram or cold air intake's only role in this is the temperature and volume of air.

The short ram's concept is to minimize the resistance to getting more air, but as it may be drawing hotter air than the cold air intake, hotter air is supposed to be less dense.

I think a short ram works for me so well, because I've done some mods going for colder air only to find ways to heat things up instead for the colder months as engine's are designed to waste fuel just to stay hotter during those times - that's a power killer. I've recorded my views on these points.

The other thing to consider is that the cold air intake has more metal to take on heat and help pre-heat the air as it comes into the engine. I combated this by adding piping from the front of the car to blow on this metal and cool it down. Depending on the cold air intake, it could take care of this on it's own.

Link to the video with the above conversation:

Cold Air Intake vs Short Ram Intake - Explained   by Engineering Explained

More after that reply:

In engineering explained's tests, he found that the short ram intake or SRI as he shortens it had more benefit between 2-3k RPM on his Integra and 4-5k RPM in 2nd gear for 3 runs averaged. He found a loss between 3-4k RPM. This may explain that my PCM is very smart on my Chevy Prizm as it usually switches gears just after 3k RPM even if I'm at WOT (Wide Open Throttle). The exception is when my family is in the car or I have a lot of tools in the car. Then it'll shift around 5,500 RPM and it'll have about the same wHP at shifting there as it would at 3k. If I do have a 3-4k power drop like Engineering explained did, it's explain why the PCM sticks with it through the losing period to get the 2nd gain rather than changing gears and having to climb back up to the power range available in higher RPM. This does assume that my PCM is infinitely wise in how it manages power as PCM or power control module implies. :) I found this written article much easier to extra data from than the videos themselves. Engineering Explained's Cold Air Intake vs Short Ram Intake - Explained.

I have zero data between 1 and 3 k RPM about patterns of power as my torque app announces peak power at an RPM rather than giving me a useable graph (it has graphing, I just don't find it helpful in my tests). It's easy to get a feel at different speeds and RPM where my power is at by simply letting off the gas at a given speed.

By AutoBravado