DIY HEAD PORTING

[RXBOB]

Touchy subject I know
I have a set of standard heads with 1.900" intake and standard size exhaust Manley valves
heads have been CC'd but know port work.
I have the SE50mm TB and want to match port the heads.
should I polish up the intake and exhaust ports??
Do I just open up the entrance of the intake port??
how far in should I match the port to the TB??
The reason I am thinking the DIY option is that options are very limited down blow here.
I don't what to go over bored but are keen to have a go at doing it myself
any info of the exsperts will be much appreciated

[prodrag1320]

be very careful,we get alot of heads in to be "fixed" after someone trys their hand at DIY porting,we`ve got over 25 of experience porting heads and have 100's of hours into port designs and profiles.have someone who`s experienced with the proper tooling do the work

[mayor]

should I polish up the intake and exhaust ports?? 

I'm not an expert, but I would say no.  Do not polish the ports.  Air moves easier over rougher surfaces (less surface drag).  I agree with kirby, if you can- send them to someone that knows what they are doing....if you feel inclined to do things yourself, just work on blending....not enlarging. 

[RXBOB]

glad I asked I have been talked out of it
now just to find someone to do it

[mayor]

glad I asked I have been talked out of it
now just to find someone to do it

here's a list for you to check out:
http://harleytechtalk.com/htt/index.php/topic,15.0.html

my advice, talk to several shops then make a decision based on who you feel the most comfortable with based on what your golas are.  Don't let proximity be your only criteria.....

[ThumperDeuce]

Check out this site:

http://www.nightrider.com/biketech/

Look in the shoptalk section under cylinder heads.

Also do a web searchh on cylinder head porting supplies.  A lot of info will come up like sources, common mistakes etc.  Some suppliers describe things to do.

[Admiral Akbar]

Porting is easy.. Anyone can do it.. Max

[mscoolone]

Its very easy to screw a head up!

Without the proper tools, equipment, education and the experience it may be a shot in the dark that there will be much of an increase and can actually decrease the performance. I would recommend reading a number of books, internet articles, magazine articles and practice on several old heads to see were performance can be had. Also its difficult to match the quality of work of someone who does this type of work each and every week.

I have done a couple of jap thumper bike engine heads, I don't have a flow bench, and I consider my self less than a novice, but I would match manifold to head, blend the seat to the bowl area only with a minor cleanup of the chamber, polishing the exhaust and rough finish on intake. Removing as minimal amount of material as possible, being very, very careful not to remove any material, especially if I suspected it would decrease performance.

Some of the time I considered what I have done a noticeable improvement, other times I wished I had sent them to someone who did performance heads on a regular basis, and never have I consider that my time, effort and $/hp was worth what I could have had from the expert  $/hp. I do think its a good learning experience, especially the value of what you are actual getting from someone who does this work all of the time.

[prodrag1320]

should I polish up the intake and exhaust ports?? 

I'm not an expert, but I would say no.  Do not polish the ports.  Air moves easier over rougher surfaces (less surface drag).  I agree with kirby, if you can- send them to someone that knows what they are doing....if you feel inclined to do things yourself, just work on blending....not enlarging.

actully,air moves more over a polished surface,but the prob is fuel atomazation,on our flowbench,a polished intake port will flow about 3% more,but in the real world the fuel will not get atomized for a quick and complete burn.(DONT DO THIS!!,but think about having a spray bottle,setting it on stream and spraying at a lit lighter,now put it on mist and do the same thing,the mist will explode,while the stream will be very speratic,or even put the flame out.same princible with ports,LOT of different variables go into a good porting job that most people dont realise.we rough semi polish the intakes,then rough to a 60 grit,while mirror polishing the exaust side

[Jeffd]

so on a carbed bike say you have a manifold with stock (rough) finish and a port with a polished finish won't the fuel be fairly atomized by the time it gets to the valve or would it tend to pool back up when it hits the smooth finish. Seems like velocity would be pretty high by the time it hit the smooth finish?  Seems like a mirrored finish on the exhaust and combustion chamber would make for less carbon build up down the road.

[prodrag1320]

think of the manifold as being a extension of the port,you want a smooth transition from the carb/t.body to the valve,you want it as smooth as possible,but with a swirled finish(like i said,we use a 60-80 grit finish).a stock manifold is too rough and large casting flashes can actully cause droplets of fuel to form

[Jeffd]

makes sense.

[wagon50]

Kirby should I bring my throttle body monday when drop heads and jugs of monday

[L-]

Mayor,
"Air moves easier over rougher surfaces (less surface drag)."   Are you sure of that?  I know that we spend a lot of time making sure that the inside surface of a tube is smooth as a prom queens thigh or like a mirror to get the air to move a lot better. Dealing with a lot more fps though.........

L-

[mayor]

Mayor,
"Air moves easier over rougher surfaces (less surface drag)."   Are you sure of that?  I know that we spend a lot of time making sure that the inside surface of a tube is smooth as a prom queens thigh or like a mirror to get the air to move a lot better. Dealing with a lot more fps though.........

L-

well, I did say I was no expert.    I don't port heads and I don't own a flow bench, so my opinion is based on laminar shear principles. My guess is a boundary layer would be created which should negate an appreciable difference in surface tension.  Again, I'm no expert...but I think that the same principals that help keep little white spheres in the air longer should help move air along radiused ports.     maybe this would be a good subject for Jamie and Adam?   

[prodrag1320]

Kirby should I bring my throttle body monday when drop heads and jugs of monday

yes,

[harley54]

Just 2 cents worth in aviation at least air is disturbed flowing over a rough
surface like icing creating less lift of this I am sure.

[mscoolone]

Not a scientist but my understanding is

Exhaust - Mirror finish
Reduce surface area
Lessens hot spots
Minimize carbon buildup
Increase flow rate
Normally smaller valve size than intake.

Intake - Rough finish
Increases turbulence
Reduces chances of fuel to coagulate at reduced flow and points of restrictions
Increases fuel atomization
If increase flow rates is required the valve and port size can be sized accordingly and still have the benefits of above.

Why do we have are heads ported, to optimize the velocity and flow rates through out the rpm range. Ports and valve sizes can be increased or decreased to achieve the flow rates desired, but the velocity may suffer. Size of the valve and shape of the ports is key to velocity and flow rate.

The intake is normally larger than the exhaust valve. How the air flows, swirls, tumbles into and out of the combustion chamber is the secret to the engines performance. If all ports flow evenly around pinch points and points of restrictions would it be a best possible goal?

[glens]

If all you were doing was pumping air, things would be a bit different than what we have.  There are two aspects of boundary layers to consider.  One involves fluid dynamics and the other involves thermal dynamics.

I think the main reason (beyond weight) that icing on the wings is so detrimental is because it changes the airfoil shape, upon which the boundary layer interacts.

I suspect that if folks don't take both the temperatures of the hard parts and the gases being conveyed by them into consideration when "flowbenching"/porting, along with the makeup of the "fluids", they may be relying on a bit more luck than they'd anticipated.

[HL124]

Turbulence is the last thing you want in a intake port and manifold.80-120 grit finish is smooth but not polished. A rougher finish to atomize fuel is an old wives tale,as their is no ZERO air movement within .040 of the port walls.

[FLTRI]

When asked, Jerry Branch stated that it is a lot easier to sell a mirror polished port job than one that's a bit rough.

Consumers feel there is more attention to detail with a mirror polished port.

Mythbusters proved a rough surface on a car body got better fuel mileage than a smooth one.
A golf ball flies further with dimples than a smooth one.

Polish the exhaust port so spent exhaust doesn't stick to the walls. 
Just my $.02,
Bob

[dunbarton]

So does this theory apply to the intake to a carb or throttle body? I see examples where someone has spent (copious) hours polishing the input throat and slide in carbs to an impressive bright mirror finish. Is this for aesthetic reasons, actually have performance value or perhaps helps justify the cost of other work being done?

[mscoolone]

A quote from Joe Mondello

"As for polishing, Mondello said a smooth finish is great for exhaust ports, but a rougher finish flows better on the intake side. He recommends using 300- or 400-grit paper followed by a Cross Buff for polishing exhaust ports, and 50- or 60-grit paper for the intake ports. A slightly rough surface texture in the intake ports and intake manifold runners creates a boundary layer of air that keeps the rest of the air column flowing smoothly and quickly through the port. "

http://www.enginebuildermag.com/article/2312/porting_for_performance_the_science_of_horsepower.aspx

[Hillside Motorcycle]

....................but what about when the injectors are pointed at the valve head, at the very back of the intake manifold............
Ain't no atoms bein' "atomized" in the manifold then...............
Look at some of Smokey Unick's findings as far as porting, worked then, and guess what, it still does today.
Someone that is mirror polishing a runner/chamber for a photo session is only doing just that. Eye candy.
Scott

[prodrag1320]

So does this theory apply to the intake to a carb or throttle body? I see examples where someone has spent (copious) hours polishing the input throat and slide in carbs to an impressive bright mirror finish. Is this for aesthetic reasons, actually have performance value or perhaps helps justify the cost of other work being done?

polishing in ft of the slide/butterfly(carb throat,venturir,volocity stack) will help with flow,the port from the slide/butterfly to the valve is where you want the rougher texture