Oversized Valves Question

[2muchboost]

Was curious about what the advantage to having oversized valves was? Was also curious about what would be have to be done to the engine in order to accomodate the oversized valves (machining process etc.) What are the pros and cons to the oversized valves and any other information. Thanx in advance.

[spegt]

s13 or s14? It does make a bit of difference. Oversized valves are always good, except for adding a slight amout of weight to the valvetrain, which is never good. When I did a 99 s14 head(hi port, vs the s13 low port) there wasnt even enough valve seat to work a 5-angle job, so 3-angle had to do. There isnt a lot of room andwhere in this motor and fitting in oversized valves is no exception. I am just going to put stock valves in my head( when I get to do my own)

[S14DB]

You don't really see any major increases in HP(less than 3hp). Pent-roof cyl. heads flow extremely well and the 1mm you can stuff in there barely helps at all. Most of the gain is from the 3/5 angle cuts made in the valve seat to make the valve fit.

If you are replacing the valves and seats anyway it can't hurt. But, if you are looking for just performance gains. Cams are going to be the same price as the valve job.

OHV Heads are totally different and should not be compared.

[spdfreek0o]

Originally Posted by S14DB

Most of the gain is from the 3/5 angle cuts made in the valve seat to make the valve fit.

Is there really any need for a 5-angle grind?

[S14DB]

Originally Posted by spdfreek0o

Is there really any need for a 5-angle grind?

Depends on the valves you get.

[spdfreek0o]

As in brand, size, material?

[S14DB]

Originally Posted by spdfreek0o

As in brand, size, material?

Brand, Most valves come pre-cut for 3 angle. you just have to cut the seat to match.