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The Wife and the Car
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Discussion Starter #1 (Edited)
I read some interesting posts on head porting. Tried adding to them but failed.
This subject has always been at the back of my mind to share.

So here goes.
When I started porting about a decade ago I did like most people with a Dremel.
Then moved onto what they call a hanging motor. Now-days everybody is making them. You get a foot controlled hanging motor with a flexi shaft and a hand piece with a mini chick on the end for peanuts from china these days. The RPM will be lower but they have more torque.

Then there where the larger 400 volt Mitaka die grinders which take 6mm burrs. A lot like the one Joe Mondelo uses.

We all go thru the same progression of starting with too high an RPM with not enough torque to turn the bit on a dremel and we wonder why out finish never looks right.

We then figure out slower speed and more torque allows us to cut without super heating the metal creating a hardness which lends it self to uneven surfaces.

A quick trick most of us wish we had hit upon early on is the using of wax polish on the metal. Any wax will do Ive used shoe polish in a pinch. Floor wax works well to. If your in the USA get the real porting wax.

It helps you bit stay cool, it also gives you way more control over the cut.

We all start out doing our own heads then a few mates and if your any good your soon doing it for 8 hours a day. Everyday.

Now using all of the above tools would have given you serious carpel damage and you hands will hurt like hell.

The you will wish somebody had told you about Pneumatic grinders.

There is a reason why the Pros use Pneumatic grinders.
It offers you a level of control and easy of use that makes you feel like a brain surgeon. It also does far less damage to your carpels.

Flow benches are over rated. I learned what ever I felt there was to learn playing with one for a few weeks. After that you realize that its just a tool to help you show improvements in flow and to help you balance the various ports.

You don't need a flow bench to achieve this. There was a guy on HMT who rigged up a simple apparatus with a home vacuum cleaner using the blower tube hooked up to a tube with some water in it he was able to measure flow improvements.
Im in the process of collecting some old vacuum cleaner motors to build my own.
Most people think there are huge gains to be made with a port and polish I feel its mostly psychological.
Was it Bissi who posted somewhere that you dont need to do much to these honda heads. In fact I think the more you port it the more your hurting power somewhere. The gains are minuscule at best on your average street build.
It may require serious porting for 500 BHP plus motor but for those of us with lower targets I think the stock will do a fine job.

If you want to invest in your head. Go for bigger valves or cams vs trying a port and polish.
Most gains if any seen after a port and polish are more from the head shaving that gets done at the same time.
You would see more gains with performance valves with the right back cut vs a costly port and polish.

In summary.
Dont hurt your self. If you find your doing more than 2-3 heads a month.
Switch to pneumatic power tools. While your hands are still good.
Avoid cutting too much from anywhere on a honda head. For your average street build the ports are fine. At best do a mild surface clean up. Blend out the steps.
Think of smarter ways to spend your money and time. there are better places to look for power.
If you do port. Invest in some good cutting burrs. A good quality burr from somebody like SGS Burrs will not be cheap. But one good burr is worth the same as 10 china made or low quality burrs
Try and get innovative with your flow studies chk DIY Smoke Machines and get a good sized vacuum cleaner / blower.
If you do port make sure you have no sharp edges anywhere flow loves a nice radius. So burr or contour the edges of your over hang. On the intake and exhaust sides.
Also remember its more about velocity off flow than amount of flow. Any increase in port sizes is going to shift your power band higher up in the RPM band.
This is from my exp. of porting barrels and heads for the past 10 years.
Most of it self taught. With the help of some good books on the subject. If you like doing this like somebody said its therapeutics then get the books and read them.
Try not to copy what others are doing instead try what you think will work. Try and avoid falling into the quater mile trap or dyno numbers trap instead build what you think would be a fun motor to drive everyday. For me 1000 hours of fun on the road is more critical than 10 seconds of glory.
But its ok we all start out on the quarter mile trip.
We have guys here who will strip a haybusa head and be porting it with a carpenters drill gun and a dremel.
Saying they are boosting power. I feel like crying when i see stuff like this.
 

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Inteesting stuff here.
I agrewith you 100% about porting honda heads. There is a time and a place where portr work will start netting you gains in power (high rpm/big power), but the stock ports are more than enough for most of the NA and turbo builds you see.
There is a huge amo unt of misconception when it comes to porting, especially porting on Turbo applications.
If you take a 2.0L 200hp turbo engine and a 2.0L 200hp NA engine, the turbo engine will have MUCH smaller ports. Port size and hp do not go hand in had between NA and FI applications.

The only time I could ever see myself bothering to port a honda engine would be on the exhaust side with a big power nitrous setup.
 

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2007 Dodge ram
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rdc I have to agree... The stock Honda head flows quite well just exactly as it is for a typical 400hp car or less. Porting makes no great leaps in capability but does take driveability away for street use due to the rpm powerband shift caused by larger runners.

Polishing/deburring on the other hand will help quite a bit in the power dept... But it shouldn't be limited to just the head. The first place to start polishing is in the intake runners on the d-series engines. Most of the intakes I have seen (stock) have a very rough and bumpy finish. While it does aid in the velocity of the flow, it causes turbulence that is counterproductive the volume of flow.

Following theories of compressable fluid dynamics, the eddy currents caused by the rough surface actually cut into the overal size of the available runners for volume of flow (basically making the runners seem smaller than they actually are). In order to counteract this problem you should polish the surface of your intake runners and head in a spiral type pattern to help spread the air along the surface and thus opening up the corridor of flow for more volume. The spiraling flow will also create a more laminar flow and increase the velocity as well. This holds tru for N/A as well as F/I engines.

Moving on to the exhaust side things get a little different based on the application. For an N/A car you would want to match the ports as closely as possible to the exhuast headers to help with exhaust gas scavenging and evacuation. The faster the gas can be evacuated thru the exhaust the more vacuum it will provide for the intake charge on a N/A engine.

For a F/I (turbo charged) engine it is opposite (to a degree) you actuall want the exhaust to have some turbulence between the head and the exhaust runners creating a narrow flow corridor and speeding up the flow and creating a more dense exhaust gas charge to aid in exhaust turbine spool up time. The faster and more dense the exhaust charge is the more focused the force is exerted on the turbine wheel and the faster the spool is on the turbo which will net more torque and better performance on a street engine.

An all out drag F/I engine is also slightly different in the fact that it is designed to be used in the upper RPM range with a limited powerband and thus more overall flow is desired because of the much larger turbine wheel it is trying to spool... That is just about the only time I would modify the exhaust ports to match the runners on a turbo application...

Turbo porting is a whole other subject that has yet another set of quidelines based upon desired application...

Just my .02 on the subject...
 

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Honda City
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We have tuners here whose sole job is to make ports bigger. I have seen them porting a head like a labourer digging up a road with a jackhammer. Real, no exaggeration. I then ported my head myself, concentrated on smoothness and velocity rather than size, polished up the combustion chamber and took it to the porter to get it shaved by 0.001 inch just for a uniform surface to mate with the HG. He asked me who the tuner was or if I had imported my head from outside India :D. Funny thing is, he works on motorsport heads and is outsourced to by every tuner in my city. LOL.
 

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The Wife and the Car
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Discussion Starter #5
Porting in our country should be banned. 99.9% of all port jobs are just ruining their heads.

I had a similar story when I did my first head. Took it to a suposed to be expert. He was quite amused to see what I had done.

Every tom dick and harry with a Drill gun thinks he is a porting Guru.

I often used to wonder how are these guys doing such lousy porting jobs. And yet. Customers say they feel the car is moving better then I figured it out.

They where shaving the hell out of the heads. Increasing compression.
Now days I tell people. Make sure you know whats happening to your head.

If your going to port. Make sure its just porting and not butchering + shaving.
 

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Honda City
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LOL, banning porting. Out here, porting/polishing is considered some holy ritual anyways. None of the guys who get their head done-up even look at it before it's bolted back on. When the head is "ported and polished", they are good to go, and their cars are now making 20% more power. No info given about port sizes, volumes, various diameters, etc. Who is going to argue with the holy man who ports the head anyways? He's 50 years old and looks like one of those mad scientists that you see in the old movies.

I do have a friend who regrets getting his head ported. He finally realised his mistake after he got it back and realised that the ports had been hogged out so much that his 4 banger Toyota was producing less torque within 8k than it did before. The guy with the most powerful Honda in the country got his head done up by the same guy, but was around there the whole time it was being worked on. This is after his block was fucked up and he had to buy a stroker kit to keep it usable.
 

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rep for all guys. Thank you for the insight. After reading this thread i have decided that during my build this winter i will match the head ports to the exhaust and intake manifold. Clean up the roughness in the both manifold ports the best i can and then let her buck!!! No need for more than that. Thanks a bunch guys.

p.s. I have never heard of an electric die grinder lol. All my tools are pneumatic but they spin at high rpms. Good torque though with the high-price grinders though and they are variable speed.
 

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92 cx
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I have a pneumatic matco 120 angle head die grinder. With a 80 gallon/175psi compressor that will shake your parts off the shelves when turned on, but last for a LONG time without having to turn it back on again.

The only real problem I have is limited space and finding a non-ferrous burr quality enough to run long enough to do the whole head. Anyone know where i can find one?
 

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I have a pneumatic matco 120 angle head die grinder. With a 80 gallon/175psi compressor that will shake your parts off the shelves when turned on, but last for a LONG time without having to turn it back on again.

The only real problem I have is limited space and finding a non-ferrous burr quality enough to run long enough to do the whole head. Anyone know where i can find one?
snap-on selld a set of non- ferrous burrs that have extra long 1/4 shank i cant remember how much though i bought like 3 of the bits not the whole set cause some wouldnt be usefull i thing the were like 30 a piece and are quarenteed
 

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I always used a pneumatic die grinder. I had one once with an extra long narrow stem so the carbide utter could be used deep into the port.

I long ago learned to use a wax or lubricant when porting, especially with aluminium so it does not clog up the teeth on the carbide cutter. I mostly use bees wax or something like WD40. It certainly helps.

I agree many heads are ruined by to much porting or removing metal from the wrong place.

Before 4 valve heads became common, great gains could be had by porting as the factory heads where very rough, but modern heads tend to be much better from the factory, so there is less to do and what needs doing is often less obvious.

How much to port depends on how good the factory port is and what power band you want.

Using bigger valves also depends on how good the factory valves are. If they are already optimum, leave them alone except for detail and precision with your vale job.

I find a flow bench, especially with a velocity probe is a very useful tool, but it is not god like. It is only a tool and you need to intelligently interpret the results and match them to your needs.

You need to be sure air speed will be a little below supersonic at the maximum rpm you intend to use, but not to slow at your minimum rpm.

It is also important that airspeed gradually increases as you approach the valve seat.

It is also important to consider the chamber, the valve seat, the back of the valve head, the port including the guide and guide boss and the manifold in unison as one system. The plenum, throttle body air duct and filter also need slightly separate consideration.

Airflow also needs to be considered along with piston speed and valve lift at every point in the cycle. You only need maximum airflow and full lift at higher piston speeds.
 

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The Wife and the Car
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Discussion Starter #15
The only real problem I have is limited space and finding a non-ferrous burr quality enough to run long enough to do the whole head. Anyone know where i can find one?
Im not sure what you mean by non-ferous burr ?
Burrs come in two types. Hardened steel (Not designed to work on metal of any kind) and carbide cutters.
Carbide cutters come with various coatings.
A good carbide cutter will see me thru at least a dozen heads.
 

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Im not sure what you mean by non-ferous burr ?
Burrs come in two types. Hardened steel (Not designed to work on metal of any kind) and carbide cutters.
Carbide cutters come with various coatings.
A good carbide cutter will see me thru at least a dozen heads.
Non-ferrous are for aluminum heads. They have wide open flutes and will not cut iron.
Non Ferrous Cutting Tools

Ferrous are for iron heads. They have close flutes and clog up if used on aluminum.
Carbide Burs and Cutting Tools
 

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The Wife and the Car
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Discussion Starter #18
Oh thanks. Didnt know that.
We just buy carbide burrs.
For cast iron you get one type and for Ali you get another.
Like you say its all in the flute shape. And the shape of the cutter.
But why would his bits wear out if they where made form carbide ?
Only time that ever happened to me was when trying to us the metal cutting burrs sold by Dremel. Latter was told they are not carbide so they loose their cutting edge really fast.
 

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92 cx
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I just want a high quality carbide die that will last through a few heads when i have a pneumatic grinder that spins at a very high speed.
 

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The aluminium ones still work on iron OK so long as they are tungsten carbide, but the iron ones clog up more on aluminium.
 
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