Porting and Polishing

Is there any advantages to P & P ing a 1z head?

As this is a direct injection engine i take it i can mirror finish both intake and exhaust manifolds?

Has anyone gas flowed a 1z head before and after?

Just curious before i take the dremel to it....

before you do that lookup a term called "boundry layer" and fully understand that and it's relation to smooth and rough surfices. also a turbo purtty much overcomes any thing put in the way of the ports just think how well these cars still perform with a pluged up intake.

Porting and polishing is used to increase the "volumetric efficiency" of a normally aspirated engine. When the piston goes down, and the valve opens, a vacuum thus created pulls the cylinder full of air. The cylinder would produce 100% of its potential power if the cylinder was full of air. Since the volumetric efficiency is never 100%, designers design intakes to achieve the maximum possible through equal length runners, and ports that do not change the velocity of the air as it moves through the intake to the valves. Porting and polishing improves what normal manufacturing cannot do.
Turbo charging pushes the air into the cylinders and fills them greater than 100% full. There is where the power comes from.
It is no advantage to port and polish a diesel head on a turbo diesel auto.

dzl_nator said:

It is no advantage to port and polish a diesel head on a turbo diesel auto.

Click to expand...

This should really say "It is no POWER ADDING advantage to port and polish a diesel head on a turbo diesel auto"

There *may* be some advantage in the way of keeping the intake-plenum and cylinderhead clean. I used to polish the top of the piston and the head on 2-stroke engines to keep them from accumulating carbon-deposits. A mirror-like finish is practically immune to having carbon stick to it. (I am talking about the kind of carbon-deposits that get over 1/8 inch thick.)

If you are really asanine about it... polishing the inside of the exhaust manifold will also reduce carbon-deposits. (a bead-blaster does this nicely)

Guys have extrude honed intakes and they carboned just as fast.

If there are any casting marks, it might be worthwhile... but I didn't see any on the two heads I have seen

it is common practice to port cylinder heads in turbo motors. Many people say that increasing valve size has no impact on performance either. It is still a common practice to improve performance. Lots of turbo motors make more horsepower from porting and polishing alone.

While it may not make horsepower it has the potential to fill the cylinders faster and more efficiently. This leads to faster spool times and lower EGT. Thats a big focus for a turbo engine that uses a very small turbo.