valve angle job

[90talontsigsx]

what is the difference between a 3 angle valve job and a 5 angle valve job? What am I expected to see in gains if any?

 

[blcknspo0ln]

from my research, a 3 or 5 angle valve job is needed only at 450+ whp applications..

what it does? no idea. try howstuffworks.com or something

 

[95blackGsTurbo]

Anything over 3 is a waste of time. It just provides more angles for the valve to seat up against. But you can get too many and then it won't seat at all. All the "big Honda" guys live by the 5 angle valve job but I never do more than 3. On our race motors, 650+ hp V8's we stick by the tride and true one angle valve job. Seals perfectly fine. If you are getting one done I wouldn't do more than a 3 angle job. Just to be safe.

 

[psychlow]

A flat surface (no angles) will seal better than an angled surface.

The idea is that with more angles on the valves, there's less sharp edges to create turbulence so that air can flow more smoothly.

IMO, anything over a 3-angle valve job isn't worth the extra effort and price. But again, that's my opinion only.

Beyond the labor-intensive, intake and exhaust port finessing, there are also numerous considerations that involve each particular cylinder head’s valve arrangement. The unique size, angles, and spacing of the cylinder head’s valves are all factors that must be taken into consideration during the porting process as airflow must also be finessed in the violent realm of the combustion chamber as well. The spacing of the intake and exhaust valves relative to the ports is unique to most cylinder heads and the grinding techniques that best unshroud each valve for optimal airflow are also different for each cylinder head.

The shape and angle of the valve seat is also very critical in the effort to improve airflow. In the interest of speed-of-manufacture, most factory valve-jobs feature a single 45-degree angle cut, or a two-angle cut on the seat. Multi-angle valve jobs are expensive for mass production engines that are normally not expected to engage in ultimate performance contests. The three-angle valve job, the universal, performance-engine standard, utilizes an initial throat cut that is about 60-70 degree, which leads to a 45-degree seat cut on the valve. The third and final cut is the top cut that is generally about 10-20 degrees and is made immediately after the valve seat.

The angle of the top cut helps reduce valve shrouding and improves airflow past the valve as the valve begins to lift off the valve seat. In more extreme cases a 5-angle valve job can be employed that uses additional, shallower cuts for the entrance and exit to further enhance airflow. In addition, the surface of the valve head can be swirl polished to help further enhance airflow. The machined swirl pattern is effective in a similar way that dimples help a golf ball travel further, the slight swirl grooves help reduce the boundary layer of air atop the valve and reduce drag.

The valve job is a critical element toward improving airflow at lower valve lift, and performance lower in the rev-range. The basic performance valve job is a highly- effective means of improving airflow when the valve is near the seat, such as at lower valve lift situations. An effective valve job will improve power throughout the rpm range without any drawback or potentially negative effects on durability. Larger valves can often be installed into a head, but the potential gains might be mitigated by a reduction in flow velocity, a thicker, more obstructive valve stem or the fact that the edge of the valve is now closer to the combustion chamber wall.

 

[92GSXBaltimore]

i was under the impression that out stock heads have 3 angles, i would stick witht that

 

[90talontsigsx]

thanx alot fellas