Port n polish tools

Grinding away the irregularities as was stated is a good start but, I am also concerned about making the port larger as you have stated as it really can change a lot of things in your acceleration and power curves. Be very careful making the port larger by much. Interesting, but as someone who spent years with a Superflow Flow bench modifying cylinder heads for the GTU and Camel Light Prototype Classes of the old IMSA racing organization and doing cylinder head quality control on heads coming into the race shop good cleanup is all that should be attempted without the use and hours upon hours of practice in front of a flow bench and test heads.

A good clean up of all casting flash and irregularities with a fairly textured finish grit seems optimal. Larry Meaux has been rough texturing port surfaces with a rough carbide burr and seeing HP gains! All in all, a nice instructable The only thing i can suggest is to add pictures for step 4. I understand how to do this step but some May not. Other then that great diy. Flow characteristics are yet another and both port or polish can change the dynamics of the head.

Velocity is something to take into consideration when working on a head. A sbc motor and many other lose performance when someone ports the bottom of the exhaust port on the slow side which is the bottom. By enlarging it, it actually decreases the velocity of the exhaust leaving the head and hurts performance. If you want to port and or polish look into the head you are working on.

Don't jump into doing this without looking into the perimeters first. I ported a few heads back in the day. And ruined one or two. The principles are the same. For those unaware be very careful when modifying the ports on your head s. Minute changes can drastically change the air flow in the port. Bigger is not always better. Professional porters use a flow-bench to verify that changes are actually doing more harm than good. Once you have achieved a port mod that actually works you need to have templates for the intake and exhaust so you can repeat the ports in the rest of the head.

Read a bit. Most successes are to start small with a little work under the valves in the pockets paying close attention to the last 20mm or so to the approach area underside of the valve. A five angle valve job will bring marginal increases in flow, but will also shorten the life of the valve because of the narrower margin on the valve seat.

There is a bit of a compromise in a street engine because you are trying to increase airflow and fuel into the engine for more power without dramatically altering the torque curve.

You want a curve that's flatter not peaky unless you are building an F1 engine for high rpm. Matching your ports to the gasket and your manifolds would do more than you would believe in respect to the power. On a fuel injected engine a throttle body 2mm larger would compliment your 'street' porting in conjunction with a cold air intake that gets the air from outside the engine compartment. Not some powder coated aluminum tube that looks cool Aluminum attracts heat.

Composites like plastics and phenolic s do not. A high flow catalytic converter with a good muffler not a fart can Will help. The engine works as a system so, changes to the airflow affect fuel requirements, ignition timing and spark demands. You might even want to purchase a book or two on modifying engines and porting before you plug in the dremel and start grinding.

There is some solid science behind this beyond just grinding ports bigger. Not to mention the potential for cutting a little too much and discovering where the water jackets are on your DOHC Honda head. There is a reason why people keep some stuff secret and make people pay for a quality port job that increases power.

Learning curve is steep. Nice instructable! I think I'm going to do this to my new cb four. I just have a few questions. It seems like you could get even more power by opening the passages to be able to move a larger volume in the same amount of time, but then you would be fighting the valve size.

Honestly though, I have no idea what I'm talking about, because I haven't worked on four strokes much. With a little gas stuck in the grooves, there will be a layer of gas that forms which will be much smoother than you can polish.

You don't want any ripples in the surface, but wouldn't it be better to have a slightly rough think sandblasted surface? I know polishing will stop carbon buildup, but there shouldn't be much carbon buildup in a 4 stroke unless you're burning oil. I'm hoping to make a instructable on porting, polishing, and port matching 2 stroke engines soon. I mostly work on small displacement 2 strokes which are way different from a 4 stroke. Keep up the good work! Whether or not you get a lot of gain depends on how bad your intake and exhaust are to begin with, and how rev happy your engine is.

The lower the revs, the less it matters. I've seen heads where there isnt much to be done, and I've seen others that are really awful.

Glass smooth finish does create problems on the intake, but not just for the reason you mention. On the intake, if you have a carburetor, or an engine with single point injection IE an older engine , the problem is worse.

The droplets are bigger to start with, and they're traveling a longer distance. Reply 12 years ago on Introduction. Port and polishing is worth the effort if you plan on doing significant modification to the engine.

A stock engine with stock exhaust and intake won't see much of a gain but an engine with full bolt ons or a turbocharger will. The gasoline won't form a film on the sides of the cylinder, if it did it would significantly reduce your gas mileage that's fuel that isn't getting to the pistons.

The only reason you would want the intake port to be rough would be for atomization of the fuel. In the case of the LN2, the small bump on every intake port is for that purpose. The exhaust should be glass-smooth all the way through. For the CB, I'd suggest looking around a bit more as the instructable was written on a fuel injected engine. I can't say myself whether or not there are any differences on carburetted engines as I don't have much experience with them other than driving.

Here is a link to some information that can help all most anybody regarding head porting and matching it applies to most of all engines except rotary engines it's shown being done on a Mustang cylinder head but it still the same principle. Reply 10 years ago on Step 6. Introduction: Beginner's Port and Polishing.

By hellinabox Follow. More by the author:. Did you make this project? Share it with us! I Made It! Simple in concept, and at one level at least, amazingly enough it is entirely correct. So the reality is there, at least on paper, and it would seem to be not such a hard thing to do. However, from there the situation takes a sharp turn toward reality. First of all, there is only one reliable way an individual doing porting can know that he or she is accomplishing anything other than making aluminum dust.

That way is by using a flowbench. The flowbench is an instrument which simulates having an engine attached to the cylinder head. This machine circulates air through the ports and measures how much air the head can pass in a minute. The builder takes a few swipes with the porting tool, attaches the head to the flowbench, and sees whether the result is good or bad.

The experience is sobering. Most people approach their first porting project with more zeal than knowledge. Before the project is done, however, the avid engine builder comes of age, so to speak. He or she discovers how agonizingly difficult it is to increase flowbench readings. Because even if flow gains are realized, the bike may end up being slower on the road. Two pitfalls await the unwary. First, just because a head is made to flow more air doesn't mean the engine will achieve that quantity of air movement.

After all, the head doesn't move the air through itself, the rest of the engine does. If the engine can't support the head's potential, it is just that -- potential, and not practical reality. Take for example the Evo Harley-Davidson engine. This engine's heads flow more air on a flowbench than many cars' heads, yet stock s make the least power per cylinder displacement of practically any current engine. This engine just doesn't create the forcefulness of combustion required to move great amounts of air.

The second problem is that the flowbench indicates only the amount of airflow a head is capable of. It tells nothing about where in the rpm range this flow is going to happen. Using the example again, not only does this engine not push its piston down hard enough to move a lot of air, it doesn't do it frequently enough either. That is, this engine is not a high rpm engine.

In other words, what good is a flowbench-registered 20 CFM improvement in airflow if subsequent calculations show that it occurs at 3, rpm above the engine's redline? That 20 CFM will never show up as improved road performance.

The way to avoid useless and even hamrful porting is to focus on port velocity. The surest way to do this is by avoiding increases in port cross-section. It is merely intuitive that the port with more cross-section, that is, diameter, will flow more air. However, that air's speed will decrease. The reduced velocity will affect mixture distribution in the cylinder, making the air and fuel less thoroughly mixed at lower rpm.

Reduced midrange power will result. For the porting job to be a success therefore, every gain in CFM must be obtained without losing port velocity. A special tool called the velocity probe helps here. It is attached to the flowbench, and inserted into the port before and after each touch of the porting tool. But even using this tool isn't as reliable as simply not enlarging the ports to begin with. But how then can airflow be increased, you might ask.

The quest for fast flow begins before the port is ever modified. Typically, the engine builder pours RTV silicone into the port to obtain a flexible cast of its contour. After removal, this mold permits visualization of the port's shape in three planes. Only then can you see every part of the port, including where it can be improved, and where it must be left alone. Much of it depends on experience, but there are some hard and fast rules.

In most cases, for example, it is impossible to make curved intake tracts straight. The tract must somehow empty into a cylinder, and to do so it will have to turn a corner or two.

Usually, the tuner hopes only to make the port "think" it is straighter, by performing whatever shaping tricks are necessary, guided by the flow meter and the velocity probe. A port whose ceiling squeezes downward under a valve spring, for another example, is improved by widening the tract at that particular point. This makes this point in the port's flow area consistent with the rest of the port. Or, as is true in many older engines, the port may need a hump filled in and the radius leading into the valve throat increased.

In fact, nearly all engine's ports respond to increasing their radii. That is, reshaping its bends so that both inner and outer parts of the curve have as large a radius as possible. And grinding isn't the only way to do this. In fact, in professional porting, filling with welding or epoxy is much more common than metal removal.