what does "port & polish head" mean?

Im enw to this stuff and I was wondering what Port & Polishing the Head means, and what it does, and if its good or not??? please let me know

Porting is when you enlarge a chamber for more airflow usually. It is done using anything from a die grinder to a dremel depending on what you need to port. The idea is that stock head castings are very restrictive and do not allow for the actual amount of potential air to move through your cylinder head.

Polishing is basically the process that happens after you Port the head. The idea here is to make the surfaces of the intake and exhaust ports as smooth as possible. This cuts down on restriction when the air "rubs" against the wall of the head as it passes through.

I have been told that there isnt a large gain to be had when port and polishing certain Honda cylinder heads because they are pretty well done straight from the factory. Basically what i think it boils down to is the bang for the buck isnt worth it in the long run. I would still do it if I had the money around.

I hope this helps. Im not very good at explaining this process. if anyone has a better explanation please continue.

i've read that polishing doesn't do anything. air is proven to flow the same over rough and smooth surfaces.

Originally posted by Tominos
i've read that polishing doesn't do anything. air is proven to flow the same over rough and smooth surfaces.

I would have to disagree. although the increase in horsepower is minimal is does make an improvement.

Yea, given the circumstances of a car engine, I wouldn't think you can notice a difference between a rough tube and a smooth tube, but I bet at hi rev your pistons might be pulling a little harder through the valve to get air into the cylinder.
What makes sense to me is it would just extend the life of the entire cam/chamber assembly

i just got my head polished not long ago, i havent put it back on yet but it looks brand new and all that carbon and crap in the tubes are gone so.....

yea, thats the other thing, you get a higher cool looking factor with part polish

there actualy is about 20-35 hp increase depending on the application and the quality of the job and if you cant tell the difference then someone riped you off. I would recomend a good old port and polish to anyone who is serious about their car.

And about how much would it cost to Port & Polish the Head????

probaly depends on the engine size.

How about a B18C-R (B18C5) or maybe a B16A2????

Originally posted by 98AccordF23A1
probaly depends on the engine size.

It more depends on the construction and shape of the head and how much you want to port and polish it. More porting and polishing obviously takes greater time and care. I also agree with twisted 4 runners post, you should be able to tell a noticable difference with a good port and polish job. I drove a 91 std hatch today with a SOHC Si swap and it was impressive.

A standard port and polish on a single head motor should run around $1000-$1200

well I found a site that sells a head and cams and everything that is Port & Polished and it seems fine... Hers the link, tell me waht u think?

http://mmrusa.com/gudehead.htm

It is definitly worth it if you are going to do it yourself i.e. after you have gained some confidence working on and modding your car. The best reason for this is if you plan on doing some kind of forced induction like T/C or S/C. I personally like all motor better but thats just my opinion. Look at a set of Weber style individual throttle bodies. The ones for the b16's add like 125 hp for 3k. But it is all motor and no lag, or reliability probs.

LoL! Show me the Dyno's where a standard port and polish alone to a B18c5 or a b16a2 adds 25-35hp. I call Bullshit. Go to Endynes site for an eye opener on a lot of BS aftermarket partsellers feed you.

As for any types of throttle body system alone adding 125 hp, dream on. They may claim that, but not a chance. You would have to do a lot of other mods to slap that much more HP into a 1.6L or 1.8L engine.

Now correct me if I'm wrong, but I see the main reason to increase your port size is to gain a little horse power if you are rasing your power range or increasing your displacement considerably. As for polishing, make sure they texture the surface afterwards, or it just invites carbon build-up.

A port and polish isn't worth the money in my opinion unless you are doing it in combination with other engine work. If you do, make sure the shop knows EXACTLY what they are doing.

just so you know these are legitamate hp gain done to a 100% factory motor And I know what im talking about I didnt just get into this game bro

last I heard you could get a good job done for 500-1000 depending on the application check-out dpr's website.increases of 25% in hp are not unheard of if you can't tell the difference afterwards you got burned.

So you say a port and polish as the sole mod to a stock honda B-series motor can net you 25-35hp?

I think you're full of shit. Show us the money. Post a link to a site with dyno's, or any link to a real dyno that indicates such a gain.

If you could bump a 170 HP motor to 195-205 HP with a simple port and polish, don't you think they would just make the ports that size from the factory and spend an extra couple hundred dollars to polish the head? Please! You may not be new to the game, but you sure are naive.

You see, Honda's engineers were pretty smart and their heads already flow very well. This is why Honda can economically squeeze 160hp out of a naturally aspirated 1.6L four cylinder engine and still get nearly 30mpg on the freeway. :)

The increase in hp you claim is about the difference in hp between a GS-R(170hp) and Type-R(USDM 195hp) (JDM 205hp). Note the differences in the: more direct intake manifold, better flowing head design, more aggressive cams, valve size, stiffer valve springs, higher compression pistons, stronger rods, higher flow header, higher rev limit and probably more I didn't mention.

Hmm, sounds like a bit more than port and polish?

Link to show hp of Integra's mentioned: http://raceseek.com/honda_specs.htm

Now if in addition to your port and polish you replaced the cams, springs, valves, retainers, and maybe lifters and keepers; then you might see your 25-35hp. But that's a lot more $$$.

It seems that there are a lot of misconceptions here about head porting.
I will try to address some of them here.
First off you will get more airflow with a rougher surface finish,this has to do with how the boundary layer acts in the port, in a very smooth port the boundary layer will sort of stack up on itself and reduce the effective port size while a rough surface will generate some small scale turbulence and keep the boundary layer smaller. Most good porters will
leave the intake ports a little rough while the exhaust ports get a higher degree of polish, this lessens carbon buildup in the port
Yes, Honda's heads flow very well in the stock state, but decent gains can be acheived. A knowledgable do it yourselfer should be able to get
about 7-10% improvements on a honda head, someone with a lot of experience and a flow bench can acheive upwards of 15-25 percent improvement in airflow,but even 25% improvement can be wasted if the whole intake and exhaust system is not taken into account. This means a great cylinder head can be held back by a restrictive throttle body, intake manifold, exhaust manifold or exhaust piping. I've had my flowbench for 17 years now and it has taught me a great deal about airflow and I've seen a lot of mistakes by amateurs when they bring me a head to flow. I hope this long winded post helps, feel free to post other questions.

What RPM said sounds far more reasonable to me than most of the claims made by some of the previous posters.

I have a question for you RPM. If I understood, you stated that an amatuer could get 7-10% by doing a headjob himself. What would you recommend for a stock b18c1(94+ GSR) head? Is there a certain texturing method or maybe some atomization dimples one could add to the head that a wanna-mech could do?


Maybe it would be too complicated to explain here. I'm just curious as I wouldn't mind an extra 15-20 from my engine. :)

there are so many veriables to port and polish, most good port and polish as a stand alone mod wont make a ton of ponies especially in a import. its all about balance( i sound like a karate instructor) no one componet of your top end(or bottom for that matter) should be weaker then the rest, all your horse power come from the top end so good head work is allways a must: Some basics to remember port match both intake mani and headers any larger then their openings is a waste, allways have the exhuast polished smooth and gen the intake likes swirls, oversized stainless valves are a good up grade, with stiffer titanium springs, guides etc. but too large a valve can cuase shrouding and actually rob you of power. a good multi angle valve job is recomended. cheap trick is to index your plugs (real easy to do when the head is out), cam is the conductor of this orchestra and also your starting point. you can go on and on, basically what om trying to get at is do it do it right, pick peoples brain do your homework, and make everthing match. if your not going to change your injection find out how much flow it can put out and then start amtching everything to those numbers

What does it mean to index your plugs?

Sulsa, in reference to port finish, I use a mounted stone to finish the intake ports. Forget about gasket matching, that's not where the restrictions are. get a good 3 angle valve job on the seat and put a 30-35 degree backcut on the valves, your machine shop will know what that means. Don't get to ambitous and remove too much metal.

Indexing the plugs is lining up the plug so the spark can propagate the easiest to the center of the mixture, this is usually done in wedge type combustion chambers due to the proximity of the plug to the chamber wall, you want the open part of the gap to face the center of the chamber so the spark is not shrouded. In a pent roof style chamber (Honda) where the plug is centrally located the gains would be much smaller.

Dayamn! This guy is a wealth of info. Thanks for answering my questions.

I have 2 preludes, a 92 base model(really nice), and a 93 SRV (uglier but faster, I was told that if i did my top end and chipped my car i would be up to 280 hp, do you think it is smart for me to port and polish my lude or will it cause too many problems and is not worth it. Carbon build up is a big worry so how should i do it with the least amount of trouble. Also how much do you think this would cost me in canadian $?

TELL ME EVERYTHING YOU CAN! ... i was told to research and you look like have had a good start so fil me in ...THANK YOU!

I have 2 preludes, a 92 base model(really nice), and a 93 SRV (uglier but faster, I was told that if i did my top end and chipped my car i would be up to 280 hp, do you think it is smart for me to port and polish my lude or will it cause too many problems and is not worth it. Carbon build up is a big worry so how should i do it with the least amount of trouble. Also how much do you think this would cost me in canadian $?

TELL ME EVERYTHING YOU CAN! ... i was told to research and you look like have had a good start so fil me in ...THANK YOU!

A good port job should not cause any problems.The last B16 head I did picked up 15 whp, that would be about 20 at the crank.I don't know what the exchange rate is but it would run 800-1000 U.S.

20 at the crank on a B16 would be what? 25-30 for an H22?...I'm leaning towards doing this myself..... I've researched it a lot and will probably practice on an old piece of shit head..... think its a smart idea for a 16 year old?

20 at the crank on a B16 would be what? 25-30 for an H22?...I'm leaning towards doing this myself..... I've researched it a lot and will probably practice on an old piece of shit head..... think its a smart idea for a 16 year old?

Read my earlier post again,about a pro w/flowbench vs. a typical amateur.