port and polish

[doom26464]

I have been trying to do some resarch on port and polish. To be honest I never fully understood the term till some google searching till now:aigo: . So I tried searching the forum but didn't get to much in terms of info.

so my questions consete of
1.) How much does a machine shop typicaly charge for a port and polish on a 7m head??
2.) is it really worth it(performance wise)
3.) If so then does it help with throttle response, turbo spool up and such??/

Feel free to toss any other info in about it:icon_bigg

 

[EdgeSupra]

I haven't had a head ported before (supra got wrecked before I did anything big), so I don't know price.
But it's definitely worth it. Your goal is to get the head to flow more substantially more air while keeping its velocity in the ports.
Allowing the air to enter and escape the combustion chamber faster will improve response.

-Justin

 

[starscream5000]

I'll atempt to add my personal opinions on this thread:

1. Any place will charge an arm and a fucking leg to P&P any head on a car, no matter if it's a 4 banger or a V8. It seems like they charge 200.00 and up for each "stage" you go up to when they do it for you. Save yourself shit loads of money (but not time ) and buy a Dremel and a head porting kit and do it yourself. There are instructional videos out there on how to do it, what types of tools to start out with, and which ones to fine polish with. I searched this a long time ago on Yahoo.com and found a long, detailed article on how to do it. I will be doing it myself when I have my other head.

Practice on a junk head before you dive into the head you plan on using. I suggest gasket matching the intake side and intake manifold (upper and lower runners). DO NOT gasket match the exhaust side. You can gasket match the exhaust manifold, but not the head on that side... Or better yet, gasket match the exhaust manifold, then check how much of a reversion dam there is between the head and the mani (this is what you need on the exhaust side to promote the scavenging effect. It's essentially a smaller port in the head compared to the port on the exhaust manifold). Once the exhaust mani is ported, you may be able to port out the exhaust side of the head some, just make sure you leave a reversion dam between the two . As far as doing everything else. The biggest gain will be to remove the casting flash inside the head and smooth out the air flow path from the combustion chamber into and from the respective exhaust and intake manifolds. Now the combustion chamber itself. You want to polish it pretty good, but not to a mirror finish. You need a little turbulence inside the head to promote atomization of the fuel and air mixture (or something along those lines, I'm just typing down the stuff I can remember off the top of my head). This turns out to be a very time comsuming process, but you can do it little-by-little in your free time. It's almost free horsepower (besides money spent on Dremel and tools, and your own personal time, but then again, the supra is where you should spend all of your time ). There are detailed, pictured articles on how to do this on the web, use the pictures as reference to what I'm talking about.

2. I kinda answered it in the first one, YES, it's def worth it .

3. It "should" improve all of the above when done correctly. Remember, practice first before you dive in head first .

Hope this helps!

 

[themadhatter]

If your really seriouse about getting a port and polish you need to pick a shop that has a flowbench any one can guess how porting the head will effect air flow but with out a flowbench its just guessing. Allso see if you can find a shop that will c&c the head its more accurate than doing it buy hand.Allso you may want to have the head exhaust manifold and turbo extrude honed I have seen gains of up to 30hp in cars pushing a lot of boost by nothing more than an extrude hone.

 

[88-7MGTE]

I have read somewhere that you should port and polish the intake but, nothe exhaust is that true ? I read in some topic in SM.

 

[supraguy@aol]

You don't want the exhaust ports much larger than they already are. The reason is that the ports are supposed to be smaller than the manifold they dump into (as stated above), so that the exhaust gases will have less ability to reverse back into the cylinder. That's whats called the reversionary dam (again, as stated above). You can smooth the inner walls of the exhaust, just don't widen it to the point of matching the manifold.

 

[supraman7mgte]

ever price extrude polishing? WAY too much.

 

[a_sesshoumaru]

I ported mine myself.
http://s174.photobucket.com/albums/w113/a_sesshoumaru/?action=view&current=supra205.jpg

It is really worthy

 

[bmoss85]

the machine shop that i use that works for toyota building the engines for the rolex series cars, charges $1200. but that is for everything p&p surfacing and valve job

 

[Halsupramk3]

http://www.sa-motorsports.com/diyport.shtm

http://cylinder-heads.4mg.com/

http://www4.tpg.com.au/users/loats/technical/7mge/headporting.html

here are some sites to research on porting. i also think there is some info on to4r.com .

you can do this yourself but you have to be sure to pay attention to detail to make all the same changes in each port. be sure not to touch the valve seats or head deck. getting rid of the raised lip under the seat will help alot. when you decide on what to cut do the same thing to each port before continuing to another step. that way every thing will be the same. go slow. read these articles several times. be sure to try to make the port slightly smaller at the exit than the entrance. the intake ports get slightly smaller approaching the bowl area (at the valve seats) to keep velocity up. air will flow faster if the pipe it is flowing thru is just so smaller at the exit than the entrance. the exhaust ports are smaller as the get closer to the exit at the manifold.

finish up the intake ports with a 60 or 80 grit to make side slightly rough to keep fuel off the walls. The exhaust runners need to be glass smooth.

i attached a pic of the bottom of the seats. one seat is untouched. also a pic of my finished chamber. i had my head chambers and exhaust ports coated by swain tech. along with my piston tops and skirts. i had a thread on supraforums somewhere. here it is

http://www.supraforums.com/forum/showthread.php?t=270783