Originally Posted by
John
dude, if you can guarantee 32 hp on a 4 cylinder head, you can charge double, maybe triple that, and you can quit your day job. But that's not gonna happen. Maybe on older pre 1990 model cylinder heads, but modern 4 cylinder heads are really tough to get hp out of.
To bad I like my day job. I can ALMOST garuntee 10% more power from a stock head. This is matching the combination to the port. I do full port velocity profiling, rework the combustion chamber, do a VJ based on port design, not that it has to last 200,000 miles. As for port and polish, gasket matching, thats a little overused.
Long description here.
First I figure the combination-decide on what I think, based on manifolding and rpm is a max VE%.
Then I will take a theoretical max to the port to give me something to work for(just a baseline) This is called the discharge coeficcient.
Then I will creat the MAX cross sectional area's I need to maintain a thoeretical velocity/flow.
Next, I will work the bowl/seat to improve low-lift #'s.
Now is where the real magic happens. I will balance the CSA's in relation with velocity, fuel seperation/centrifuge problems/port "energy"(my term for effects on wane motion) and about 262,000 other variables. I never polish anything besides the exhaust port. Chambers-I like them to absorb and transfer heat, and int runner I finish with a 60gt to help boundry layer conditions.
And guess what? If power doesnt improve like I say you dont pay a dime. So I guess I do GARUNTEE the results.