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Discussion Starter · #1 ·
as i read deeper into the topic of pnp i understood that i don't want to touch the head, maybe only polish it a bit when taking off and so on. there is no one who can handle that in my country with quality, that's what i understood, cause the flowbench is unknown word there.

so there are my questions:
-porting exhaust: is it hard to do? how much can i over bore the stock ports safely? does anyone have pics of before and after pnp?
-porting im is as i understood not hard to do too,it's just as it is, port everything you can reach for bigger flow, no water jackets there..?
 

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ive gone pretty big in the stock i4 IM and had no problems
I basically port matched the openings and went back around 4inches which was as ar as the tools i currently have wil reach. I plan on getting some longer reaching stuff. And the outsideis getting polished too. *bling* too bad it wont work on my car.


ill see if i can find the pics.
 

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apkraven said:
as i read deeper into the topic of pnp i understood that i don't want to touch the head, maybe only polish it a bit when taking off and so on. there is no one who can handle that in my country with quality, that's what i understood, cause the flowbench is unknown word there.

so there are my questions:
-porting exhaust: is it hard to do? how much can i over bore the stock ports safely? does anyone have pics of before and after pnp?
-porting im is as i understood not hard to do too,it's just as it is, port everything you can reach for bigger flow, no water jackets there..?
First I just want to mention that the term "port and polish" is a dated expression from the 60's when the general consesus was that polishing the ports was a good thing. Not true. Simply porting or shaping is more accurate.

Porting a head is a touchy thing. It's very easy to remove too much material and do more harm than good. Aluminum is a comparatively soft metal and a carbide burr bit can easily take a huge chomp out of a port if you're not paying complete attention to what you're doing.

Porting is not just making the port bigger. Small ports have high gas velocity, improving cylinder filling at low rpms but the gas FLOW at high rpms falls off quite fast. 90% of stock heads have small ports to improve part throttle response at low revs, since most cars spend their lives puttering around town in stop and go traffic or cruising on the highway.

WE, however are interested in going fast, keeping the gas flow high and packing in as much air as possible at high revs. Knowing where to remove material, and sometimes where to add material isn't something you can read in a textbook. It takes experience, and know-how. These are things I don't recommend you try getting taking a grinder to a DOHC 4 banger head. This may suck, but honestly 16 ports mean you have 16 chances to mess up. Get a junk head and start practicing. Focus on the short side radius and blending the bowl, those are the most common problem areas on stock heads.

Serious porting should only be attempted if you have a flowbench. I think you are fully capable of doing some things yourself though. Like removing all the casting flash inside the ports, polishing down any high spots or bumps in the combustion chamber to reduce potential hot spots, and port matching the intake and exhaust manifolds. Good luck
 

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All of the warnings you see about ruining the flow of your head have to be taken with a grain of salt. You see, professional porter's make a living by convincing you to pay big bucks for their CnC ported, flow bench tested, Ultra high polish, 16 angle valve seat, combustion chamber CC'd, Oversized valves, specialty port job's. If everyone is afraid to touch their own head's, they're gonna make more money. If your looking for an ultra race port and polish, go ahead and pay for it. I say anyone with a die grinder is qualified to do a mild port job. it doesnt take a CnC machine to knife edge the flow divider, clean up casting marks, match the head to the valve seats and put a uniform but rough texture on the intake runners. Go ahead and purchase yourself an extra head. they can be bought in the for sale thread here for about 150 bux + shipping. i got mine for about 120 bux canadian including shipping from a wreckers. port it and swap it.
 

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Discussion Starter · #6 ·
hey, guys, i don't have a flow bench and i think no one in ukraine has, i just found out lol that exhaust ports are located in the cyl.head too. lol. we are doing with guys at the workshop the hardest part to make it all work now, pnp and tuning later,now fitting an i/c pipes and so on. i guess i'll leave it alone for now. buying for 100 is good. shipping for about 100 more is not so good . thanks for info guys, i'll polish maybe some inprerfections and leave it be, i do not plan to go over 270whp with alky, anyways.
 
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