Porting Tools [Merged 3-8] Tool die grinder Dremel

[red91GSX]

i hope this qualifies for this forum but if you have to move it, so be it.

what is the standard tool used for porting say exhaust manifolds, O2 housings, and the such? can a dremel be used for this or should this be done with airtools?

can anyone please advise?

 

[turboholic]

-I used the Dremel, but it's slow and those stone is expensive, I end up using a air die grinder with these cartridges .

 

[candela]

Hey Kevin,

Did that sand paper actually work for porting a manifold/o2 ? That seems like they woudl be far to weak to even take out a little bit... Anyhow that kit looks kind cool for smoothing and polishing things up though. How do you like it, and what did you use them for specifically?

AUstin

 

[eyebrowski]

craftsman die grinder- $89
carbide bit- $25

you can get a cheaper grinder off of ebay for ~$15 but my experience with them is the 1/4" collets are cheap and if you get any chatter off the manifold while you are grinding you will grenade it (i have done it twice). the carbide bit is a must...nothing else will hold up and you will go through TONS of stones or steel bits.

 

[UltraImports]

carbide works best, but make sure to stop occasionally to let it cool off, or the aluminum will make a new best friend with your bit. It works well...the sanding bits work good to smooth it out.

 

[jbillakdsm]

Hey, my dad owns a tool and die shop and I can get you stuff to do the porting real cheap. I used a large tooth carbide bit to take the main stuff of, then a swirled carbide bit to smooth things out a little (3/8 electric drill). On to the Dremel, I used a sandpaper bit like the ones he has a link to for starting the polishing process. I finished off with some CRATEX wheels to give it a mirror finish. I went down as far as I could with this and I'm going to get some of those paddle sander wheels to see if I can completely polish the inside tracks. Hopefully we will have another DSM meet soon so I can show off the work before I have to install it. I'll try and get you a price for all the bits within a couple days and try to get some pics of the final product.

 

[candela]

do that for the bit... is there any carbide bits that will work with my electric drill or dremel that you can get? Thanks

 

[jbillakdsm]

Yeah, what size electric drill do you have? The only wheels that I got for the Dremel that you can't get at the local hardware store are the CRATEX wheels and some tiny grinding wheels for getting further down in. The grinding wheels are considered fine, but I only used one for my entire O2 housing. They are really durable. The CRATEX wheels are what gave me the mirror finish.

 

[candela]

I want something to grind the #### out of my manny and turbo... I have stone bits/sand paper bits I can use for the smoothing

 

[asian312]

I used the standard grinding bits that can be acquired at any hardware store. I was planning on using carbide ones, but none were available locally. They actually worked pretty well and only went through 3 bits on the O2 (granted mine was a tubular o2) and the manifold. Believe it or not a sanding drum will chew up the metal pretty fast. Alos took out the divider of the manifold by rigging a dremel cut wheel to the die grinder, saved mucho time but went through a whole pack of wheels I did this all with a pneumatic die grinder. I'll see about getting pics up.

 

[candela]

Ivew been through 4 regualer dremel grinding bits on my manifold alone!!! I need somethign stronger period! I cannot find anythign that is stronger at any local stores or anythign and these damn bits are like 3$ a piece!!!

 

[UltraImports]

www.grainger.com

I paid $12 for a carbide bit there.

 

[twistedtsi]

i used the carbide bit theres difeerent shapes and size depending on wat your using them for.. it worked great they eat up the cast iron real good and the finish part was also great using the stones and sandpaper bits

 

[jbillakdsm]

Ok, I did some searching tonight and got an approximation on prices:

double and single cut carbide bits (3/8 shank 1/2 dia wheel 1" length) - 32.00

60 grit grinding wheels for dremel - 65 cents a piece (should only need 3 max)

Sandpaper rolls for Dremel - Next to nothing a piece in bulk

Cratex wheels, problem is that it's 65 for a kit (only way to get them). If I get enough interest, I will buy the kit and split it up evenly along with the cost.

I'm going to do some testing with the paddle snading wheels to see what works the best and then I'll ge tthe prices up ASAP.

 

[eyebrowski]

im not sure you want to bring your manifold to a mirror finish...air does not travel well over very smooth surfaces and causes a lot of turbulence. have you ever wondered why golf balls have little divets in them, well its to keep the air flowing uniformly around the ball so it wont shank. the same concept is true here, you do not want turbulent air hitting your exhaust wheel...efficiency will suffer.

 

[InferiorWang]

actually golf balls have dimples to decrease the reynolds number and decrease pressure drag. this is straight from my phys material


<p>Airflow past ordinary size objects is only laminar at low speed.&nbsp; As the airspeed
increases, a boundary layer forms. This boundary layer fills the region behind the object
with a <strong><font COLOR="#008000">turbulent wake</font></strong>.</p>

<p align="center"><img src="http://electron9.phys.utk.edu/phys136d/modules/m1/images/fig15.gif" alt="fig15.gif (40204 bytes)" width="349" height="444"></p>

<p>The figure above shows the airflow past a cylinder as the airspeed and therefore the
Reynolds number increase.&nbsp; In pictures 1-3 the Reynolds number is below 2000, in picture 4
it is approximately 10000, and in picture 5 it is above 100000.&nbsp; The first two pictures
show laminar flow at low speed.&nbsp; The air directly before and behind the cylinder comes to a
stop.&nbsp; The pressure is highest here, but the net force on the cylinder due to pressure
differences is approximately zero.&nbsp; There is no <font COLOR="#008000"><b>pressure drag</b></font>.&nbsp;
In the fourth picture a <font COLOR="#008000"><b>turbulent wake</b></font> has formed.&nbsp;
The
air behind the cylinder no longer slows down and the pressure no longer rises behind the
cylinder.&nbsp; Due to the high pressure in front of the cylinder it now experiences a large
pressure drag. This happens for Reynolds numbers of approximately 2000 to 100000.&nbsp;
The pressure drag is much larger than the viscous drag.&nbsp; It can decrease the forward
component of velocity of an object moving through a fluid or gas very rapidly.&nbsp;
A thrown
object can seem to stop in midair and drop straight to the ground.&nbsp; You can easily observe
this by throwing an air-filled balloon.&nbsp; As the airspeed increases and the Reynolds number becomes larger than 100000, the
turbulent region works itself forward.&nbsp; We have what is called a <font COLOR="#008000"><b>turbulent
boundary layer</b></font>.&nbsp; The flow lines now separate from the cylinder and follow the
turbulent boundary layer, as shown in the fifth picture.&nbsp; We have something similar to
laminar flow around an object of a different shape.&nbsp; The pressure behind the object rises
again and the pressure drag is drastically reduced.</p>

<p>The <span lang="en-us">critical </span>Reynolds number <span lang="en-us">at
which a turbulent boundary layer forms </span>depends on the condition of
<span lang="en-us">the </span>surface.&nbsp; The rougher the surface, the
<span lang="en-us">lower</span> is the <span lang="en-us">critical </span>Reynolds number.&nbsp;
The surface of
many balls used in a variety of sports is intentionally roughed up.&nbsp; Golf balls have
dimples and grooves, tennis balls have hair, etc.&nbsp; This <span lang="en-us">
decreases</span> the <span lang="en-us">critical </span>Reynolds number, so
<span lang="en-us">that a turbulent boundary layer forms</span> even at moderately high speeds.&nbsp; In this way pressure drag
can be largely eliminated and only the viscous drag acts on the ball.
<p ALIGN="CENTER"><img src="http://electron9.phys.utk.edu/phys136d/modules/m1/images/fig16.gif" alt="fig16.gif (26438 bytes)" width="300" height="272"></p>

 

[InferiorWang]

i just copied the source of the web notes

 

[UltraImports]

Originally posted by eyebrowski
im not sure you want to bring your manifold to a mirror finish...air does not travel well over very smooth surfaces and causes a lot of turbulence. have you ever wondered why golf balls have little divets in them, well its to keep the air flowing uniformly around the ball so it wont shank. the same concept is true here, you do not want turbulent air hitting your exhaust wheel...efficiency will suffer.

You are right about the tumbling air not being ideal for the exhaust side, but actually, air flows faster over smooth surfaces. This is great for the exhaust side, but you want the tumbling air on the intake side to promote better combustion.

The dimples in a golf ball have a few purposes, but maily it effects the trajectory of the ball. One golf ball can produce a high trajectory, giving it a soft land (so it doesn't move anywhere). Another ball can give it a lower trajectory, so that it spins and continues to roll. What controls that are the characteristics of the dimples and how you hit it.

 

[candela]

You guys crack me up....
THanks for the links guys!!

 

[InferiorWang]

i think it's mostly how you hit the golf ball. the spin on it coupled with the purpose of the dimples explained above can change the amount of pressure on different sides of the golf ball. I can post a whole lot of sh!t from my physics notes on that too.

I'm the king of too much info ;-)

 

[InferiorWang]

Originally posted by eyebrowski
im not sure you want to bring your manifold to a mirror finish...air does not travel well over very smooth surfaces and causes a lot of turbulence. have you ever wondered why golf balls have little divets in them, well its to keep the air flowing uniformly around the ball so it wont shank. the same concept is true here, you do not want turbulent air hitting your exhaust wheel...efficiency will suffer.

And mebbe we should all dimple our catbacks so that we can get max airflow out. Air flows incredibly well over smooth surfaces. That's why everyone likes shiny mandrel bent stuff.

 

[jbillakdsm]

Glad to see that my efforts aren't in vain. This has got me thinking about my intake now.

 

[turboholic]

Originally posted by candela
Hey Kevin,

Did that sand paper actually work for porting a manifold/o2 ?

-No, those are good for clean up on aluminum only, I use long shank carbide cutters for the rought cut, they are kind of like these but I got mine from them (cheaper), they are of 1/4" shank, can be use on a corded drill.

 

[red91GSX]

ok in reference to dimples on a golf ball and the rate of speed and how you hit it ... then explain how come you can get tragectory changes on a ping pong ball (smoother than baby's balls) that is travlling no fast than say 20 mph off the paddle???

just my .02

 

[jbillakdsm]

I think it has something to do with the amount of spin you can put on the ball at impact vs. the amount of air traveling past the ball on it's flight.