Engine Building-What Products?

santa · 10-30-2006

Quote:

Originally Posted by niterydr

The performance gains on a 3 vs 5 angle valve job are noticeable but usually not worth the additional port work required to make it worth while.

So let me get this straight. You're saying that the performance gain of a 5-angle valve job is not worth the extra time (sparing no expense at the machine shop)? The gains seen between a 3-angle and 5-angle valve job are typically 6-7cfm per port (from personal experience on a flow bench), and all you have to do is simply request this from your machine shop. How hard is that? If you are sparing no expense it is definately worth looking into.

niterydr · 10-31-2006

Quote:

Originally Posted by santa

So let me get this straight. You're saying that the performance gain of a 5-angle valve job is not worth the extra time (sparing no expense at the machine shop)? The gains seen between a 3-angle and 5-angle valve job are typically 6-7cfm per port (from personal experience on a flow bench), and all you have to do is simply request this from your machine shop. How hard is that? If you are sparing no expense it is definately worth looking into.

You are seeing 6-7cfm per port on a dsm head by changing out to a 3-angle to a 5-angle valve job? Whom-ever is doing the 3 angle valve job sucks then. Just going by personal experience

. I am assuming you did this in school, or did MAP buy a flow-bench? Maybe you can tell me at what pressures those gains were seen at? Cam height? Valve seat angles? Where were they seen? Peak? Low-lift? Midrange? Overall gains? What size valves were these on? What flow bench? What bore size? Please enlighten me in your experiences.

I have done plenty of research into valve seat angles compared to cfm gains in different ranges, you do realize that the cams we are working with are usually less than .450" lift? I also have done PLENTY of research into wear characteristics and longevity of a 3-angle valve job vs. a 5-angle on a STREET CAR.

Different part selection, changing valve heights, adjusting port configuration are all more things "worth it" on a spare no expense situation.

Finally, if you read the customers post, instead of a my posts, you would realize that he has already paid for a 3 angle valve job on his current head and was inquiring if it should be sufficient. I was simply stating the added costs of going to a 5-angle valve job won't notice him huge gains. Hince the recommendation of going with a 3-angle valve job.

So I will state again. The costs involved compared to the potential performance gains will lead me to state that Mike will be better off keeping his current head and putting the money elsewhere.