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Brought over from a thread in Intake/Exhaust section of forum:
Originally posted by xmetallicaxguitaristx
I just read something interesting
"Why Not Polish The Ports ??
Doesn't Air Flow Better on a Smooth Surface ???
Remember that the ultimate goal isn't "flow" ... it's POWER !!
The intake port is going to flow both fuel and air. The problem with fuel is that, since it weighs more, it's difficult to keep it evenly mixed with the air as it follows the contours of the port.
Boundary Layer
The next time you drive a car in the rain, notice that when the car is going 60 MPH, the rain drops go up the hood of the car at walking speed. That's because the smooth surface of the car creates what's known as a boundary layer, and the portion of that layer of air that's nearest to the surface is almost still.
The same thing happens inside an intake port. Except instead of raindrops, it's fuel droplets that will run down the port wall slower than the air. That causes a serious change in the fuel air mixture by the time it reaches the cylinder, ruining much of the engine's potential power.
Polishing the port walls will ensure that this happens.
The phrase "Port & Polish" always makes me laugh ... I think the idea came from 70's Hot Rod magazines or something. Anyways, the last thing you want to do is polish your ports !!!
Instead, by making a series of rough 60 grit lines that purposely go against the flow, the "boundary layer area" will be turbulent, and the fuel will stay suspended in the air.
Here is a bit blury pic, but you can make out the difference i have in surface texture between intake/exhaust ports. Seem sufficient?
Also I really am hoping to get somekind of reply, how does the exhaust port look, along with the chamber? Intake is just being roughed in, but I really do want some opinions on the exhaust/chamber work... as far as I'm concerned they are 100% done, I will move onto the other cylinders next and will basicly just copy what I did here. Want to be sure there are no big flaws I'm missing.
The valve seats are still nasty.. will get them when heads are done. And the way it's looking now I think I will do all the exhaust work first, then chamber, then go back and hit the intake ports.
Those valve guides do not stick up much. When I did my heads on the 357 for my 79 camaro, I really cut those down alot. I personally would cut them down some more, but that's me. Also, I've read on a few sites that you leave the intake ports a little rough, maybe 60-80 grit the finest. This helps atomise the fuel some. The exhaust ports/chambers should be smooth as silk. Looking good so far. I gasket matched the intake sides, then opened up the exhaust slightly, but left them slightly smaller than the exhaust manifold gaskets to help with scavaging.
Dremel is electric and die grinder runs off a air compressor.
08' L76 6.0L 4X4 Chevy EXT.Cab LTZ Vortec MAX with Snug top cover, Dynomax exhaust,Hptuners& K&N intake
96' Camaro M5 to A4 conversion, alot of mods . GT35R Turbo full suspension. Built engine
what is the difference between a dremel and a die grinder?
A Dremel uses a 1/8" shank and looks like a toy compared to a 1/4" die grinder. Die grinders come as pneumatic or electric but have tons more power then a Dremel.
If you put it on it's max setting and you are working with metal, if you put too much pressure on it the wheel will slow down (stop if you press hard enough.. don't do it, but it's to prove a point).
So is it safe to use a die grinder if your just doing a light port and polish on intake runners?
Yes, die grinders are made for that. If it's pneumatic, just use a regulator. Most electric die grinders are variable speed, just use as much RPM as your comfortable with. If you leave it turned all the way up, it can get away from you FAST! All of your porting kits and supply's are for 1/4 shank mandrels that fit die grinders. I used to have some links to porting supply's on my desk top, when I get on it I'll see if I can find them to post.
Yes, die grinders are made for that. If it's pneumatic, just use a regulator. Most electric die grinders are variable speed, just use as much RPM as your comfortable with. If you leave it turned all the way up, it can get away from you FAST! All of your porting kits and supply's are for 1/4 shank mandrels that fit die grinders. I used to have some links to porting supply's on my desk top, when I get on it I'll see if I can find them to post.
Do you have a link to a good but cheap die grinder? Maybe something off ebay or some store?
Also a porting kit like you are talking about.. I have seen them before but I can't remember where I have seen them.
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