If all you are doing is massaging the intake manifold, you're not going to gain much - not worth the time/effort/expense, IMNSHO.
As part of changing all intake/exhaust plumbing, all that is really needed is some port matching and polishing. Even then, it's not going do do much for a NA engine. Any changes in plenum/runner volume or shape should be left to the experts.
40 years ago, you could get a noticeable boost with a good port/polish job. Not so much nowadays as the engineers have already done most of that in order to meet emissions and MPG regulations.
PS: Don't know if it still applies but when we were doing a port/polish job on 60-70s engines, we'd go ahead and match the exhaust ports and trim the valve guide bosses, too. Trimming didn't do a lot of good, just an as-long-as-we-have-the-engine-apart thing.
|