MickeZX7R
Posör
Erfaren "portare" kommenterar en guide för nybörjare angåend portning:
"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.
Considerations to the lift and duration of your camshaft as well as the RPM range and intended use (Street/ Race) Lots of cylinder heads have been ruined and most will (shockingly) flow less than before you attacked it with the grinder.
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.
"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.
Considerations to the lift and duration of your camshaft as well as the RPM range and intended use (Street/ Race) Lots of cylinder heads have been ruined and most will (shockingly) flow less than before you attacked it with the grinder.
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.
