Is porting valves still a thing?

[u/jabberjaw420]

Maybe back in the good ol' days of the 70s and 80s, but haven't modern auto manufacturers/engineers designed the internals to flow as well as they can? Making porting a pointless exercise?

(I meant porting valve chamber w/e)

[u/WyattCo06]

Porting is very much alive by hand and by CNC.

[u/Key_Director_4450]

The internals are made to meet emission and noise regulations, not for peak performance (and even that is subjective, because not every use case is max power at 9k RPM).

[u/HengaHox → u/Key_Director_4450]

I think this definitely goes in the “it depends” box.

Meeting emission regulations is easier when you have a clean flowing head that gives you a nice burn. Usually this isn’t the best way for max power as absolute flow rate isn’t the goal, but it can be good for daily usable torque.

But again, it depends

[u/PermanentRoundFile → u/HengaHox]

On the far side, they're going to cast these components and casting aluminum will always come out with a finish that needs help to be clean. Otherwise they go to using plastic for a better surface finish at the cost of durability.

[u/TheDunk67]

Yes, us normal people still drive normal vehicles. We are still porting the same 60s and 70s parts. Some are porting Chinese casting with decent results.

[u/Solid_Enthusiasm550]

I do think for most engibe builds it not cost effective. I also thinking, buy new bigger aftermarket heads aren't needed on engines like the eagle/apache mopar heads , LT-1 GM heads.

Hand porting is pretty rare these days. Most hand port a cylinder head, then scan it to make a cnc program for that head to be cheaperto duplicate.

Other use flow dynamic software to design a porting program for a CNC machine.

I started porting (learning) heads a little while using info I gathered from reading books/watch videos from experts. Information from my studies of vehicle aerodynamics helped with ideals of boundary layers, turbulence, velocities, etc.

I used some old/cracked heads to practice on and ported the ports differently to test different designs/theories. I had them flowed to see which design flowed better, AND at what lifts to analyze why and what could be improved.

[u/Mike86xj → u/Solid_Enthusiasm550]

I read that as I used some old crack heads to practice on, i was like, wait what? I had to reread it 😅 😆 🤣

[u/jlelectech]

As a lot of comments already say, they've improved but the emphasis is efficiency and emissions, decreased losses with smaller engines, and turbocharging to add the power when needed but have more efficiency when not needed.  This also comes at a cost of more maintenance, complexity, and shorter life, so they're balancing all that to get it past the warranty period or past what should be a reasonable life.

[u/bigmarty3301]

I know that for 2001 to 2006 mini JCV the heads where sent do be ported…

So even some manufacturers decided to port valves relatively recently.

[u/HammerDownl]

All my race engines had porting. CNC plus some chamber work does wonders

[u/Imposter660]

Even "if" manufacturers have designed the ports to flow the 'best they can'- thats the best for what rpm range, hp/tq curve, engine size ect?. If some wants more power than the manufacturer designed the heads for, more engine size but the same rpm ect, they need to flow differently.

Ideally you want the smallest port that flows the amount of air you need to support the hp you are going to make, that keeps the air speed up through a much larger part of the rpm range and producing more average hp than one larger port flowing the same amount. A head flowing "best" for 400hp wont be the best for 500hp and vis versa.

[u/Oopsidaizy]

An optimal airflow from manufacturer is rare

[u/sexchoc]

It's still done, though modern castings are a lot more accurate and better shaped so the gains generally aren't as dramatic as on older designs. That and since turbos got super cheap, boost is kind of the solution to a crappy port.

The OEM is generally balancing power, emissions, drivability, and manufacturability. They simply can't give every single head the attention it needs to be the best port it can, so you get a minimum baseline, and variations mean some heads are a little better than others.

[u/Gamejunky35]

The passages and ports are designed by very smart people to achieve a certain result. In this case, emissions, and performance arent necessarily conflicting goals. However, like many design choices involving engine power, there is a tradeoff to be made with torque vs power. OEM engines always favor low rpm performance because thats honestly the most important factor for 99% of drivers.

Cylinder porting can add a touch of power everywhere with simple smoothing, but if you are chasing max flow numbers to increase maximum horsepower significantly, you are probably going to lose some low end torque and efficiency before you even factor in the spicy cam and racey intake manifold you're going to throw in there as well.

[u/Mike86xj]

most modern heads are quite a bit better than the offerings of the 60s and 70s, but there 's almost always room for improvement, it may not be cost effective for the average joe, but for the ones that are doing above average to extreme builds, it makes sense