Please fill me in on what exactly "ported heads" means. What is common to do with ported heads, as in what kinds of applications do people put them in (don't say "cars...") I mean can they be used with street applications or are they only used with race applications. What does it cost to have a shop machine the stock ones, or is that not a good idea? Would it be better to just buy new heads with better flow? (Please take a limited budget into mind) What kind of power is put out from better heads, assuming a cam swap (22X/22X) is in the works too? I've read quite a bit and don't understand much, but am learning, about the heads...it seems most people that take things to serious levels with their cars tend to just get new heads from somewhere. Is it common to simply get the factory stock ones ported? Is there a difference between "milled" and "ported"? Thanks everyone

 

You're asking A LOT of very involved questions. But I'll attempt a cliffs notes type answer.

A ported head is a cylinder head that has been modified to achieve better airflow and thus more power. This is done by removing material in the head runners (holes in head which transfer air from the intake to the combustion area). Larger valves are also usually added. Ported heads done properly almost always improve airflow, but done improperly can actually hurt it. Improving airflow in an engine makes more power.

Just about every type of engine can benefit from ported head(s). Even extremely mild street cars can pick up power AND efficiency with a better head design.

20-30+ years ago it was typical for most hot-rodders to remove their stock heads and have them ported. That was due to limited head choice/availability, and a small aftermarket. Things are different nowadays. Most opt to buy another set of heads already ported, as it requires much less down time and often the cost difference is very minimal.

Most ported heads will benefit from a more aggressive cam, but cam selection is even more of an art than cylinder head porting. Cam selection varies depending on literally hundreds of variables. What engine are you working with? Car? Weight? Intended use?

Milling a head modifies another part of the head. The runners aren't touched, but the head surface (head deck) that mates with the engine block is. The head deck is shaved down to move the head closer to the engine block and pistons. This increases compression ratio (the amount the incoming air is compressed), and helps to increase power output.

Hope that helps. Again, these are very generalized answers...

Edit: You're average machine shop IS NOT the best place to look to have your heads ported. You'll want to look for someone with a lot of experience with that EXACT head, and if possible talk to those that have that porters heads. Just because someone claims they can port a head does not make it true. Again, an inexperienced hand can actually hurt performance!

I assume from some of your other posts that you have an LS1 correct? DO NOT under any circumstance let any local machine shop touch those heads! Well designed ported heads (new castings, not used) are going to cost you slightly over $1000 just for the heads alone. And that's roughly the same amount it would cost to have your stock heads ported. Typical gains from an LS1 with a good intake and exhaust vary. But with a decent cylinder head, and a very streetable mid 220s duration cam up to 80-100HP can be added.

 

Cool, I was just interested in the topic and wanted to learn more about it...searched over several forums to find anything dealing with porting or milling but couldn't find any stickies. If I were to do anything like this it would be involving a 2000 z28 6speed, though I have no intention right now of doing anything other than exhaust work. Thanks for the answers to what I now understand to be some pretty general questions. Any idea what it costs to port the heads on a stock z28? If I were to ever want more power out of my engine i would most likely be leaning towards N2O, just because of the expense involved with other forms of power-adders.

 

I highly recommend you wander over to the LS1 Technical section here to learn more.

I've never priced getting a used stock head ported locally, but a reputable shop that knows what they are doing with an LS1 head is likely going to be $600-800+ minimum. That's hand ported, as most shops that can CNC port (CNC is a computer port head) won't work with a used head. And depending upon where you are, you're going to have to ship the heads back and forth, and will need to expect weeks of downtime. That's why most people just buy the heads outright. OR you could find some already ported heads that someone has for sale - I do

You work at CarMax? How's the Raleigh store? I work here in Laurel, and may transfer down to Raleigh or Greensboro.

 

I pretty much agree with Marcs post. A couple of other things to add/expand on. As far as a local head porter, local guys are often best to deal with. It all depends who is local to you. We have a number of local guys who are decent porters, for example.

As far as the cost of porting, on most heads there is some gain to a simple "pocket port" for a few hundred bucks. From there, the sky is the limit. Some "porting" jobs involve extensive ADDITION of material by welding. The added material is then reshaped to the desired dimensions. With very high end heads, this can involve literally hundreds of hours of skilled work on a set, making the final price more than your 2000 TA is worth!

Milling refers to taking material off the flat surface (deck) of the head. This is primarily to make it flat and/or to reduce the volume of the combustion chamber to increase the compression. On certain heads for certain applications, angle milling can improve flow by unshrouding the valves. In angle milling, more material is taken off one side than the other. This will in turn require milling of the manifold, etc. and is not something you want to even think about unless you know what you are doing.

And so on. it's an endless subject.

Rich

 

Here's a link to some good information on cylinder head porting.



Cylinder head porting

 

thanks for the replies everyone

marc - what department are you in? i'm in inventory and hate it. haha if you're thinkin of moving down here then i'd recommend sales or detailing...i tried to go to sales but they wouldnt let mebecause my girlfriend works at the C.A.R. desk...so i'm going to try detailing I guess. When do you think you'd be transferring?

 

Service dept., retail tech. I'm a Ford specialist (9 years dealer, 3 years CarMax), but because few here like working on the GM Y and F body cars, I fairly proficient with them too.

 

why were you thinking of coming down to Raleigh? I like the operataions manager and tech managers too, so that would be a good place to work...I heard Greensboro is really nice though, a lot newer than our location