Why would polishing use more fuel, you would think that if the mixture
flowed better and you did not loose some in the "pockets" you would have
better fuel metering and actually get better mileage.
Thanks
Randy Rees
Windows NT Test Team
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> -----Original Message-----
> From: aurora-guy@juno.com [SMTP:aurora-guy@juno.com]
> Sent: Wednesday, November 05, 1997 4:35 PM
> To: william.eastman@medtronic.com
> Cc: mgs@autox.team.net
> Subject: Re: Short porting, Idle vs timing.
>
> >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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