Polishing Intake ports - Good / Bad

[TunedPort 335]

I've never heard this in person, but after reading on some message boards...some guys are saying that its bad to polish the intake ports. Most importantly on carbed cars where the fuel has to travel the whole distance of the intake port (where as some EFI systems the injector sprays directly into the intake port, and is already atomized, doesn't have to travel as far).

They say it makes the fuel puddle up, because there is no "roughness" to cause the fuel to stay atomized. But what I don't understand is how fuel will puddle up on something that is smooth:wtf1:

Is this true or not.

[Mr Joshua]

it's been debated as long as fuel injection and carburation has existed... there have been multipage threads on www.corral.net about the subject.. and after reading them. i can't find any clear evidence for or against either conclusion..
:eh:
if you find out something let me know..
~J

[540Malibu]

Originally posted by TunedPort 335
I've never heard this in person, but after reading on some message boards...some guys are saying that its bad to polish the intake ports. Most importantly on carbed cars where the fuel has to travel the whole distance of the intake port (where as some EFI systems the injector sprays directly into the intake port, and is already atomized, doesn't have to travel as far).

They say it makes the fuel puddle up, because there is no "roughness" to cause the fuel to stay atomized. But what I don't understand is how fuel will puddle up on something that is smooth:wtf1:

Is this true or not.

picture you and a hot chick inside your car getting busy and fogging up the windows, you stop to notice that there is moisture collecting on the inside of the glass, the air inside the car is humid, but the rough surfaces cloth on doors are not dripping wet, only the hot ass and the glass.

the fuel (if not already a vapor) droplets will slam into the runner wall, and since water doesnt bounce very well it will puddle.

Also, the smooth runner walls tend to be a higher temperature than the mixture (less surface area with air flowing across it means hotter) and due to the venturi effect the cool mixture coming in combined with the hot runner walls makes the fuel condense onto the walls.
with a rough finish in the runners the runners stay quite a bit cooler and the fuel doesnt condense on the walls.

you can polish it, just dont go anything over 80 grit.

[TunedPort 335]

Thanks Spence, that gave me a better idea of how it works. But on exhaust ports, its the exact opposite right...you'd want the smoothest as possible to reduce carbon buildup and improve flow?

[540Malibu]

yes the exhaust port can be polished as smooth ad posible, as well as the compbustion chambers. The intake runners and ports can be "smooth" but not polished, when builders say polished, unless they are moron's what the really mean is smoothed.

[383BackInBlack]

a quick look down the intake port of an AFR cnc head will show you what they oughta look like :)

[bren]

Originally posted by 540Malibu
picture you and a hot chick inside your car getting busy and fogging up the windows, you stop to notice that there is moisture collecting on the inside of the glass, the air inside the car is humid, but the rough surfaces cloth on doors are not dripping wet, only the hot ass and the glass.

A wet dream is about as close as your going to get to that Spence.

Unless you like midget love, the pickup line "EVER SEEN THE BACKSEAT OF A......79 MALIBU!!?!?!?!" wont work.

[igotasweetride]

Originally posted by 540Malibu
picture you and a hot chick inside your car getting busy and fogging up the windows, you stop to notice that there is moisture collecting on the inside of the glass, the air inside the car is humid, but the rough surfaces cloth on doors are not dripping wet, only the hot ass and the glass.



do you know anything about physics? the reason the water beads form on windows is due to the difference in temperature on either side of the glass, it has nothing to do with the smoothness. and before you say "if it wasnt smooth, it wouldnt form" get a piece of stained glass thats rough and put it in a sealed car with a high moisture content and higher temp on the inside and cold temp on the outside.


tunedport: if you polished the first 1/2 of the intake runner depending on size (leave the last 2-3" semi rough) then this will be the best of both arguments, its been done by professionals and been advised to do so in many publications by professionals.

[96Z28SS]

This really only applies to wet intakes with carbs.
An EFI system the injector is placed so that it sprayes toward the intake port on the heads. You want the smoothest flow of air going into the heads.

We have a set of heads and intake at the shop for a Mustang Renegade Car that is blown the intake and cubustion chamber is so polished that it looks chrome.

Rob
www.nedyno.com
www.dynotune.org

[igotasweetride]

Originally posted by 96Z28SS
This really only applies to wet intakes with carbs.
An EFI system the injector is placed so that it sprayes toward the intake port on the heads. You want the smoothest flow of air going into the heads.

We have a set of heads and intake at the shop for a Mustang Renegade Car that is blown the intake and cubustion chamber is so polished that it looks chrome.

Rob
www.nedyno.com
www.dynotune.org


the reason i read to leave the last couple inches rough was to create some turbulance otherwise the air is moving in such a straight stream that it would mix with the fuel evenly.

[merlin]

Originally posted by igotasweetride
the reason i read to leave the last couple inches rough was to create some turbulance otherwise the air is moving in such a straight stream that it would mix with the fuel evenly.

eh, isn't that what the quenching pads and good fuel injectors are for?

[540Malibu]

Originally posted by bren y0
A wet dream is about as close as your going to get to that Spence.

Unless you like midget love, the pickup line "EVER SEEN THE BACKSEAT OF A......79 MALIBU!!?!?!?!" wont work.

my car doesn't have a back seat, but your mom didn't mind hanging from the cage.

[540Malibu]

Originally posted by igotasweetride
do you know anything about physics? the reason the water beads form on windows is due to the difference in temperature on either side of the glass, it has nothing to do with the smoothness. and before you say "if it wasnt smooth, it wouldnt form" get a piece of stained glass thats rough and put it in a sealed car with a high moisture content and higher temp on the inside and cold temp on the outside.


tunedport: if you polished the first 1/2 of the intake runner depending on size (leave the last 2-3" semi rough) then this will be the best of both arguments, its been done by professionals and been advised to do so in many publications by professionals.

i guess the leading cylinder designers in the world don't know anything about physics either. go sit yourself yourself on a reduced base circle cam and when you finally get a clue of how to build a motor come bring something to the table.

[FATBLOCKMARO]

Originally posted by 540Malibu
my car doesn't have a back seat, but your mom didn't mind hanging from the cage.


SFM!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!: :lol: :lol: :lol:

[igotasweetride]

Originally posted by 540Malibu
i guess the leading cylinder designers in the world don't know anything about physics either. go sit yourself yourself on a reduced base circle cam and when you finally get a clue of how to build a motor come bring something to the table.


your reference had nothing to do with a motor, it had to do with a high moisture content and unequal temperatures in two atmospheres on the sides of glass. learn how to read something other then cam specs carb boy :thumbsup:

[540Malibu]

Originally posted by igotasweetride
your reference had nothing to do with a motor, it had to do with a high moisture content and unequal temperatures in two atmospheres on the sides of glass. learn how to read something other then cam specs carb boy :thumbsup:

you failed to completley read the reply, go back and do so and it will make more sense, i was using unequal temps in order to bring the presensce of moisture (fuel) glass would be a polished runner, and anything not slick would be the unfinished runner.

[igotasweetride]

Originally posted by 540Malibu
you failed to completley read the reply, go back and do so and it will make more sense, i was using unequal temps in order to bring the presensce of moisture (fuel) glass would be a polished runner, and anything not slick would be the unfinished runner.


but you used a piss poor example. the reason water beads on glass is because of unequal surface temperatures.

[383BackInBlack]

as a matter of fact, if you've ever studied fluid dynamics,

when you have a very very smooth surface, the flow right next to the surface becomes more turbulent and irregular (im not sure if anyone knows exactly why) you get small eddy currents and shit all over the place......a rough surface, not irregular but rough/porous acutally gets a very, very thin layer of fluid (air, fuel, whatever) right next to it, and the other fluid rushes past it smoothly without much turbulence in the way

[bren]

Originally posted by 540Malibu
my car doesn't have a back seat, but your mom didn't mind hanging from the cage.

dude, tisk tisk, that is weaksauce, actually is probably something i would say at 4 in the morning resting my head on the keyboard.

Well you have alot of work to do now, go into the Lounge and look at the other threads you were bashed on today.

[Jack ffr1846]

I don't actually know if polishing or not polishing is better, so I'll stay out of that. But on water vapor condensing....that's pretty much related to due point. If the moisture in the air hits a surface that's at a temperature below the due point, then water will condense on it. I notice that every time we get a quick warm spell and look in my garage. Everything that has any significant thermal mass has water condensed on it. Engine/tranny/metal body/glass/vinyl seats.....

[Devin Mac]

yeah, spence. i hate to be a prick. but you're wrong again. condensation will only happen if the surface is COOLER than the ambient air's dewpoint. it has ZERO to do with "bouncing"...

however, if it did, your explanation still blows... a rough surface would have even more surface area than a smooth one, which (along with the higher turbulence it would create) would actually cause more "bouncing".

really the only reason for not polishing intake runners to a mirror finish is to make up for the shitty atomization properties of a carburator... in this situation, 383 is correct in his explanation that the rough walls trap a "pad" of air and sort of buffer everything else from collecting. however, you are sacrificing cfm to get this effect.

an engine is an air pump, sacrficing cfm = sacrificing potential ponies. period.

[H3llphyre]

Originally posted by 383BackInBlack
as a matter of fact, if you've ever studied fluid dynamics,

when you have a very very smooth surface, the flow right next to the surface becomes more turbulent and irregular (im not sure if anyone knows exactly why) you get small eddy currents and shit all over the place......a rough surface, not irregular but rough/porous acutally gets a very, very thin layer of fluid (air, fuel, whatever) right next to it, and the other fluid rushes past it smoothly without much turbulence in the way

Interesting. I now have something to research today.

[540Malibu]

Originally posted by Devin Mac
yeah, spence. i hate to be a prick. but you're wrong again. condensation will only happen if the surface is COOLER than the ambient air's dewpoint. it has ZERO to do with "bouncing"...

however, if it did, your explanation still blows... a rough surface would have even more surface area than a smooth one, which (along with the higher turbulence it would create) would actually cause more "bouncing".

really the only reason for not polishing intake runners to a mirror finish is to make up for the shitty atomization properties of a carburator... in this situation, 383 is correct in his explanation that the rough walls trap a "pad" of air and sort of buffer everything else from collecting. however, you are sacrificing cfm to get this effect.

an engine is an air pump, sacrficing cfm = sacrificing potential ponies. period.

wrong, take a 325cc cylinder head that flows 240cfm at lift point x....take a 295cc cylinder head that flows 240cfm at lift point x, the 295cc will make alot more power because of the velocity.

[96Z28SS]

The ports can have a very smooth surface it depends more on if they were ported and polished correctly. If the heads have very good velocity then there will be no puddling.

Rob
www.nedyno.com
www.dynotune.org

[Devin Mac]

Originally posted by 540Malibu
wrong, take a 325cc cylinder head that flows 240cfm at lift point x....take a 295cc cylinder head that flows 240cfm at lift point x, the 295cc will make alot more power because of the velocity.

that is almost not even an argument in this arena, spence... first of all, what the fuck does it have to do with polishing anything? specifically, what does it have to do with polishing intake runners?

your example doesn't make any sense in this thread, spence. (i said it twice to make sure you got it)

i'll say this again, as well, since you apparently don't get it. rough surfaces sacrifice cfm. period. smooth surface, air flows easier, cfm #'s go up. cfm goes up, potential for power goes up. (it might shift that power higher up in the rpm range, but that's another discussion). if your 240 cfm 295cc head was polished and could now flow 245, it could make more power. you going to debate that?

[540Malibu]

Originally posted by Devin Mac
that is almost not even an argument in this arena, spence... first of all, what the fuck does it have to do with polishing anything? specifically, what does it have to do with polishing intake runners?

your example doesn't make any sense in this thread, spence. (i said it twice to make sure you got it)

i'll say this again, as well, since you apparently don't get it. rough surfaces sacrifice cfm. period. smooth surface, air flows easier, cfm #'s go up. cfm goes up, potential for power goes up. (it might shift that power higher up in the rpm range, but that's another discussion). if your 240 cfm 295cc head was polished and could now flow 245, it could make more power. you going to debate that?

you know nothing about carureted motors or how they like to make power, and you obviously base everything you comment on on book physics, but explain to me how a bumble bee flies when your precious physics say its 100% impossible.

[540Malibu]

Originally posted by 96Z28SS
The ports can have a very smooth surface it depends more on if they were ported and polished correctly. If the heads have very good velocity then there will be no puddling.

Rob
www.nedyno.com
www.dynotune.org

yes the ports can be very smooth, but they cause puddling when polished.

[383BackInBlack]

Originally posted by 540Malibu
you know nothing about carureted motors or how they like to make power, and you obviously base everything you comment on on book physics, but explain to me how a bumble bee flies when your precious physics say its 100% impossible.

spence,

your point is correct, the principles at work in a carb engines intake are pretty different to those in an injected motor

But nothing defies the laws of physics........"book physics" is 100% completely right.......the problem is not with physics.....but with people incorrectly or half assed applying the theory and calculation.

bumble bees dont break the laws of physics at all, its just a much more complex process of flight than meets the eye

[540Malibu]

Originally posted by 383BackInBlack
spence,

your point is correct, the principles at work in a carb engines intake are pretty different to those in an injected motor

But nothing defies the laws of physics........"book physics" is 100% completely right.......the problem is not with physics.....but with people incorrectly or half assed applying the theory and calculation.

bumble bees dont break the laws of physics at all, its just a much more complex process of flight than meets the eye

nope, my high school physics book specifically said "bumble bee's are a miracle of nature, according to all logic and principle and theory, they cannot fly". and maybe neon boy should apply the proper theories, because if you mist a water bottle onto a polished surface it will puddle, if you mist a water bottle onto a rough/porous surface it will take longer to accumulate and will not puddle as much.

[H3llphyre]

Originally posted by 540Malibu
and maybe neon boy should apply the proper theories, because if you mist a water bottle onto a polished surface it will puddle, if you mist a water bottle onto a rough/porous surface it will take longer to accumulate and will not puddle as much.

Well, there is one main reason for this. A rough surface makes it harder for water to build surface tension (the hills and valleys account for this), hence water "puddling" up.

[H3llphyre]

Originally posted by 540Malibu
nope, my high school physics book specifically said "bumble bee's are a miracle of nature, according to all logic and principle and theory, they cannot fly".

Yeah, this all has to do with some mofo named Bernoulli.... LOL. Actually, they have a pretty good idea how they fly, they just never knew how efficient the bumblebee was at doing it. Something about the pressure wave of the downward stroke of the wing making it possible to gain energy on the upward stroke... Weird shit, but yes... there is a principle for how they fly, it just took them a LONG fucking time to figure out how they did it.

It amuses me how we can build nuclear bombs, but it takes forever to figure out how a bumblebee flies. Even more amusing. How money is wasted on that research when cancer still exists.

[Devin Mac]

Originally posted by 540Malibu
nope, my high school physics book specifically said "bumble bee's are a miracle of nature, according to all logic and principle and theory, they cannot fly". and maybe neon boy should apply the proper theories, because if you mist a water bottle onto a polished surface it will puddle, if you mist a water bottle onto a rough/porous surface it will take longer to accumulate and will not puddle as much.

i hate to say it like this, but dude, yer getting fucking ridiculous now. so you're saying that if i spray water on a sponge (about as porous as yer gonna fine, honestly...) that it's not sticking to the sponge?

porous surfaces hide the amount of liquid they condense because it has nooks and crannnies to fill up. not because less shit condenses on it... the only thing that determines how much stuff has a chance to condense on a surface is the number of molecular collisions, which is directly related to temperature.

and yes, the principles at work in a carb'd motor are different. however, they're also inefficient as hell, which is why you can make more power more efficiently in a fuel injected setup. how many new high performance cars are built with carburated engines nowadays?

i also like how you seem to have skirted the airflow issue entirely in favor of your assinine puddling theory.

but you know, spence, now i'm curious about something else. if smooth can be better than rough, polished is somehow worse than smooth? wouldn't smooth puddle more fuel than rough would, by your argument? and what is the breaking point of smooth -> polished that suddenly makes you lose all kinds of power? when does smooth get too smooth and fall into your horrifying "polished" stage? i'd LOVE to see a graph of this one...

(by the way, the bumblebee example was based on the assumption that a bee's wings work as if a bird's would, flapping up and down at a fixed y-z axis slope. what wasn't taken into account when this retarded claim was made was that bees, along with many other insects, actualy rotate the wings to a different angle on the upstroke and downstroke, allowing for lift on both strokes, as jay mentioned. i was a biology major before i was an engineering student. nice try though)

[540Malibu]

Originally posted by Devin Mac
i hate to say it like this, but dude, yer getting fucking ridiculous now. so you're saying that if i spray water on a sponge (about as porous as yer gonna fine, honestly...) that it's not sticking to the sponge?

porous surfaces hide the amount of liquid they condense because it has nooks and crannnies to fill up. not because less shit condenses on it... the only thing that determines how much stuff has a chance to condense on a surface is the number of molecular collisions, which is directly related to temperature.

and yes, the principles at work in a carb'd motor are different. however, they're also inefficient as hell, which is why you can make more power more efficiently in a fuel injected setup. how many new high performance cars are built with carburated engines nowadays?

i also like how you seem to have skirted the airflow issue entirely in favor of your assinine puddling theory.

but you know, spence, now i'm curious about something else. if smooth can be better than rough, polished is somehow worse than smooth? wouldn't smooth puddle more fuel than rough would, by your argument? and what is the breaking point of smooth -> polished that suddenly makes you lose all kinds of power? when does smooth get too smooth and fall into your horrifying "polished" stage? i'd LOVE to see a graph of this one...

(by the way, the bumblebee example was based on the assumption that a bee's wings work as if a bird's would, flapping up and down at a fixed y-z axis slope. what wasn't taken into account when this retarded claim was made was that bees, along with many other insects, actualy rotate the wings to a different angle on the upstroke and downstroke, allowing for lift on both strokes, as jay mentioned. i was a biology major before i was an engineering student. nice try though)

well maybe you should go back to school and learn how to read, because obviosuly you can't and havent read the entire thread.

and next to mention, you still know nothing about about carbureted motors, so to say one is better than the other when YOU don't know the difference is pure speculation. everything i ahve posted about the question asked is 100% accurate and dyno proven, you still have yet to prove anything ecept the fact you raped mr wizard.