Port Polish

[BonesDT]

I've just learned about port polish recently. From what I understand, you can port polish any engine and it brings significant improvements. It also seems that it is relatively possible to perform this yourself.

Has anyone port polished their explorer engine, in particular the SOHC? Is this a recommended mod?

 

[Alec]

I'm getting some ported and polished heads to help my supercharger out. Dunno if they'll help much on a N/A SOHC.

 

[mrboyle]

You can't just go and port and polish any engine. It takes knowledge of the air flow characteristics of the entire engine, from the intake through the ehxaust mainfolds. True, polishing and prot matching the exhaust ports can be done without any major training, but the results are minimal. Even a fully ported head will not make a significant gain in performance. You will get some, but not a lot.

 

[james t]

dont even bother to attempt to do this yourself, no matter how bad you want to. dont even have someone else do it unless their shop either has or has access to a flowbench. alot of "porters" just take the head and hog it out. this my produce more hp on a dyno, but will kill low-mid torque. it is possible to gain 20-30hp with this method, yet turn your truck into a gutless wonder at the same time. ask me how i know.

you can get anywere from decent to flat out awesome hp. gains by having this done. it all depends on the head in question, and the guy doing the work. i personally know a local shop that can get 50hp (not a typo) out of a set of GT-40P heads. this is very much more than porting, as it also includes a 5 angle valve job, cutting for install of chevy valves, keeping runner volume small to maintain velocity, etc. etc. the guy does the work to your cam specs and engine requirements.

i really dont know the potential of the V6 heads, but i assume when done right you could expect some decent gains. doing them at home in the garage with a die grinder and a flashlight could very possibly make the truck a turd. take it from someone who has already been down this road years ago...

if you are refering to just polishing up the combustion chamber etc, dont waste your time. polishing in itself does very little for hp. if you have a die grinder and really are set on using it, port match all of the intake and exhaust gaskets. this will produce a bigger gain than just polishing.

sorry about the long post.

 

[poconosms1]

How much did that cost?

 

[james t]

it really depends on who's doing it, and what needs to be done. plan on spending anywere from $250-800. you would really have to check around and see who would do them, what they would actually do, and about what they would charge.

 

[STANN]

it sounds to me as though this mod isnt particularly worth it and could basically do more harm then good...
is that assumption right?

 

[james t]

it all depends on who does the work. if its a well known shop, that does lots and lots of custom head porting, it is definatly worth it. if it is some guy who has a die grinder and aint afraid to use it, i wouldnt bother. it wont do any harm unless you hit a water jacket. on the other hand, i wouldnt want a OHV 4.0 with 20 ft. lbs. less torque in the rpm range i drive in every day.

basically, either have a shop do it that is very highly recommended, or dont do it at all.

 

[rocklaurence]

IMO, there are a few safe mods that can/should be done on performance heads. First, a performance valve job (3 angles on the seats-2 on the valves). Second, reshape the area around the valve guides (in the pockets). Third, gasket match all the assemblys. Forth, polish everything, most importantly, polishing the chambers will help prevent detonation. The 1st item is the most important while the others only provide minor gains. The minor work will improve flow but dosent open the heads up too much killing velocity.:redexp:

 

[BonesDT]

i thought you dont really want to 'polish' everything. there should be a certain degree of roughness to tumble the air, right?

 

[SteveVB]

Bones - that was true with carbed vehicles where the fuel was suspended in the air - with fuel injection you for the most part are moving air and the smoother the better.

I think that any mild head work is worth the effort- Im not talking about contour changes or resizing the ports and/or chambers. James is correct that radical port and/ or bowl work should be left to someone with access to a flow bench and preferably some experience.

On the knock prone 4.0 anyone who has the heads off MUST polish the CC if not polish then at least remove the many sharp edges that it seems to have around the spark plug boss and the CC. At a minimum on just about any engine a gasket match, CC polish, and valve guide work is worth the effort, and most can be done at home with little effort and some care(and TIME). Rocklawrence has a good receipe in his answer.

Would I remove heads just to port them and polish- no. If they are off for a rebuild and or cam swap would I - YES