>intake
>port to a fine finish is a bad idea because the turbulence caused by
>the
>rough walls helps mix the fuel with the air. The exhaust, on the
>other
>hand, can be polished within an inch of its life although the cost vs
>benefit of this is questionable for a street engine.
I used to race bikes, along with go-karts, and though the engines are
smaller, a lot of the same principles apply. I found that porting helped
A LOT. Though this is probably due to the fact that stock heads weren't
really meant for high HP. I also thought that polishing helped becuase
smoother walls helped the mixture flow through the heads better, and gave
it less pockets and crannies to get stuck in. Also, with less
turbulence, it was more likely to get all the mixture to the chamber, and
not have some of it backup due to the turbulence. I ported and polished
everything I owned, even down to my model airplane engines, so
unfortunetly, I really can't compare much. It may be better to leave a
street driven car unpolished to get better mileage, and a cleaner burning
car. I was always looking for more HP, I really didn't care if the
engine sucked up gallons of gas, if it was loud, etc. I can't really say
one way or the other. I do know that porting helped, but I polished
without really thinking about it.
>I let the A idle at 600-700 rpm. This is too slow really but I think
>it
>sound neat. I guess this is a carryover from my thumper / Harley days
>where I like to hear each cylinder hit. It does idle a lot smoother
>at
>900-1000 rpm though and it also hold more oil pressure at that speed.
You too, huh? :) I got one go-kart to really sound good one year, big
open pipe, slow idle, it sounded great :) I now wonder how good this was
for the eingines though, as it made them run real rough.
>I am
>also running a little rich but this helps keep the engine cool. Life
>is a
>compromise.
I also wonder if this really helps much. Unlike a 2-stroke, where the
oil is contained in the fuel mixture, and richening the engine introduces
more oil, in a 4-stroke, you are just adding more fuel, which may result
in unburned fuel going through the engine, which besides wasting fuel,
and smelling bad, you could have other problems relating to it. I
personally would vote for more oil pressure, or look for ways to raise
the pressure if you want to keep the low idle.
Eric Klos <aurora-guy@juno.com> Harrison Twp. MI
WANTED:Datsun Z car and MG slot cars, static models, diecasts,
literature, etc.
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