Benfits of polishing
11-20-2002, 08:37 AM
#2
Re: Benfits of polishing
Originally posted by 96BLUMAX
What would be the benefits of sanding down and polishing the inside of the intake manifold and throttle body?
What would be the benefits of sanding down and polishing the inside of the intake manifold and throttle body?
...other than that, it looks pretty too.
-A
11-20-2002, 10:40 AM
#4
Donating Maxima.org Member
Join Date: Dec 2001
Posts: 325
you'll get a different answer from every tuner you ask.
some feel the rough surface of the casting was good to stir up the air and fuel....which has carried over from the carburetion days. fuel injection puts out such a fine mist that mixes very well that I don't think its an issue.
a smooth pipe will flow better than a rough one in general, but the level of impact from this depends what kind of velocity the air is at (whether the flow is laminar or turbulent).
a smooth pipe will also transfer less heat to the air, which could possibly be of benefit.
my opinion is that a good port shape has more impact than a smooth surface. improving port shape is loosly defined as "porting" but can mean many things. the best thing the home tuner can do is make sure the port shapes match up where one parts connects to another...like the collector tot he manifold in the Maxima's case. I am also a big fan of cleaning up flaws...like big cast lumps and parting lines that you see inside ports or machining marks where the valve seats are machined into the head....which is something extrude honing can do for you.
like some one else said, this work is best left to a pro...but even some "pro's" don't know what they are doing. any guy that tells you bigger is better should be avoided...its shape that counts. Bottom line i wouldn't spend much money in this area unless you are looking for every last HP you can get from a a naturally aspirated engine. I tried extrude honing on a few bikes head and had good results....can't speak for the maxima intake....and even then on th emaxima there's the collector, manifold and heads...will doing one of the three have a gain...?
some feel the rough surface of the casting was good to stir up the air and fuel....which has carried over from the carburetion days. fuel injection puts out such a fine mist that mixes very well that I don't think its an issue.
a smooth pipe will flow better than a rough one in general, but the level of impact from this depends what kind of velocity the air is at (whether the flow is laminar or turbulent).
a smooth pipe will also transfer less heat to the air, which could possibly be of benefit.
my opinion is that a good port shape has more impact than a smooth surface. improving port shape is loosly defined as "porting" but can mean many things. the best thing the home tuner can do is make sure the port shapes match up where one parts connects to another...like the collector tot he manifold in the Maxima's case. I am also a big fan of cleaning up flaws...like big cast lumps and parting lines that you see inside ports or machining marks where the valve seats are machined into the head....which is something extrude honing can do for you.
like some one else said, this work is best left to a pro...but even some "pro's" don't know what they are doing. any guy that tells you bigger is better should be avoided...its shape that counts. Bottom line i wouldn't spend much money in this area unless you are looking for every last HP you can get from a a naturally aspirated engine. I tried extrude honing on a few bikes head and had good results....can't speak for the maxima intake....and even then on th emaxima there's the collector, manifold and heads...will doing one of the three have a gain...?
11-20-2002, 10:41 AM
#5
Senior Member
Join Date: Oct 2002
Posts: 553
Polishing does increase flow. Many manifolds are sand cast and have rough surfaces. Polishing these surfaces smooths them out and increased laminar flow and reduced drag. Porting is usually done in conjunction with this procedure to increase flow capacity.
11-20-2002, 10:46 AM
#6
11-20-2002, 10:37 PM
#8
Originally posted by 96BLUMAX
Been there many times thinking about whether i should put down the money for it. Kind of expensive. How much of a gain is expected for NA?
Been there many times thinking about whether i should put down the money for it. Kind of expensive. How much of a gain is expected for NA?
...but then again, it varies because this is custom work and no two custom ported/polished pieces are the same.
-A
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