Something Everyone Should Know About Head Porting

[Spaz Racing]

With everyone claiming there ported heads R the best please read this:

Their R a lot of cnc ported head shops that R stealing other shop designs not all but a lot.
Beware of the head porter that sells u a small port head then two months late tells U that U need his new Big port head. And then a year later goes back to a small port. WTF
Shops R advertising that they push the guides down for big cams this can B bad for two reasons 1) after pushing the guide down U most do a valve job no matter what. 2) Who wants to have a nice head ported and then push the cast iron guides down. Now u have even less of a weak guide to begin with. I say the best way for shorter guide is to install shorten bronze guides. Or U can turn don the retainers .040 with no problems. But on the other hand we already know U don't need big cams in a 1397cc-1440cc
Also beware of the head ported that just ports ur head. I think ever head needs to be ported to the size the the engine size they R running.
A stock piston engine gets a different port design then a 1397 does and so forth.

Also remember that a cnc ported head is only as good the the original hand porter did from the begining.

This is what U get from Spaz Racing when I port a head

Completely clean the head and valves, Inspect and grind the intake valves and check the for trueness check exhaust valves for trueness
weld exhaust pair valve hole shut. Port intake and exhaust ports. Rework the combustion chambers check head for flatness and mill.  Inspect the valve seals replace if needed Assemble head with new race valve springs.

[busa416]

How much are you getting to do a head ?

[Spaz Racing]

$900 complete back to ur door.

[Adrnlnjunky]

Completely clean the head and valves, Inspect and grind the intake valves and check the for trueness check exhaust valves for trueness
weld exhaust pair valve hole shut. Port intake and exhaust ports. Rework the combustion chambers check head for flatness and mill.  Inspect the vale seals re place if needed Assemble head with new race valve springs.

So you are able to grind the valves. I thought they had a heat treatment or coating on them.

[db_130+]

whats the matter spazz?  cant take the heat about your headwork at psychobike so you have to come over here and grind your ax ?  the shops out there that are doing good work dont need to come online and bust on others.  seems like your 1 trick pony shop cant cut it 

[gnd111]

whats the matter spazz?  cant take the heat about your headwork at psychobike so you have to come over here and grind your ax ?  the shops out there that are doing good work dont need to come online and bust on others.  seems like your 1 trick pony shop cant cut it 

Just an FYI - there are at least 1 performance shop that is HUGE using Spaz heads off the shelf for sales so MANY people are using his product.  No i am not defending anything...

[BRYAN]

Something Everyone Should Know About Head Porting.........

This is an interesting thread.

http://psychobike.com/cgi-bin/ikonboard.cgi?s=3c0c90aec794613688f909fa56297341;act=ST;f=1;t=53224

[Competition CNC]

That’s an interesting thread Bryan.  Thanks for posting the link.

I'm not going to post over there on that thread because I don’t sponsor that board, but I would like to make a few points, so I'll make them here. Maybe someone will link this thread to that thread....

Some good points were made.  A good head porter that understands the relationship between camshafts, seat timings, average port velocity, average cfm (28"h2o), max port velocity, max CFM, seat design, throat choke, min cross sectional area, port taper, port length, overall port volume, engine displacement, desired rpm of peak VE, desired rpm of peak hp, etc......  can port any head if he has the information needed.
The notion that someone has to only port motorcycle engines or 4 valve engines to be any good at 4 valve engines is ridiculous.  Sure some of the formulas are different for 4 valve heads vs. 2 valve heads but that shouldn’t stop a good head porter.
CNC porting has advantages and disadvantages.  The advantages are consistency, product reliability, as well as the ability to precisely control very small details in the port geometry.  The disadvantages IN THE PAST have been the lack of ability (or willingness) to account for core shifting during the casting process.
By this I mean that when a head is cast the many pieces of the moulds are assembled and they are almost always not assembled 100% correctly.  So the ports come out moved to the left, moved to the right, moved up, moved down, moved in, moved out, etc. from where their proper place is.  In a production engine this is acceptable.  This is the reason that race teams in the past that race in classes that don’t allow head porting would buy many, many heads and test them all and pick out the best ones to use and sell the rest.
The CNC machines of just a few years back were cumbersome to change small areas of an NC file to account for small changes to each port on each head each time.  So it simply wasn’t done.  Some places in the port would be untouched if the core shift was dramatic so to make the whole port cut every where every time they would make the port larger than it needed to be just to make sure the whole port cut and it LOOKED good to the customer but the oversized ports would loose velocity and the engine would loose power in the midrange and shift recovery rpms.  Or they would just let large sections of the port just not get cut because of the core shift.
But with the latest in 5 axis technology where you digitize right in the same machine that actually cuts the head, you can probe each port at its flange opening and each valve throat and bring that data into the software and make adjustments as small as .00000001”.
Ok,  .00000001” is possible but ridiculous, but we do adjust the port models of the Hayabusa heads to get the tool paths of the models of the ports to within a few thousandths of the actual shifted ports.  So, what does this do for you?   Well it allows us to cut an exact amount of material out in places where we don’t want to cut much material.   It yields port cross sectional area consistency and control down to .0005 sq. in.    This allows us to predict and control the exact velocity (stored energy) that the column of air and fuel will have as the intake valve is closing.  Each port cross sectional area is exactly the same every time.  So your cylinder head comes out the same as the one done last week, month, year etc.

Did you know that the average Hayabusa cylinder head varies on its longitudinal axis rotation (deck) by .26 degrees? And its ports can shift as much as .018” on any 3 axis.  It may not sound like much but when your CNC porting it can make a difference of 10-15 FPS of port velocity.  That’s a lot when you consider your velocity target variance is +/- 3 FPS.
But shuuuuush!! Don’t tell anyone we do racing V8 heads too!!!

[BRYAN]

Jim,

 Without giving up any trade secrets can you elaborate on your valve job?

Thanks Bryan

[osti33]

Jim,

 Without giving up any trade secrets can you elaborate on your valve job?

Thanks Bryan

I'm just guessing here but I don't think someone that ports heads is going to give up much info on that. However, I have been wrong many times before.

[whtrthanu]

Damn, you guys are killin each other in here.............There are many ways to port cylinder heads......How ever you you get from point a to b is up to you.......
im not picking on anybody here, but I think you guys are starting to split atoms over this.....
Can you measure the difference between castings, yep, can you take out a .00000000001.....yep...
In the real world, what the hell is it going to do for a guy with an average motor, even a race motor.....
It is nice to have the equipment to do it, and it will come out to have balanced ports,symmetrical, and even port volume....we know it takes alot of patience to port a head, and thats is where the good guys are separated from the bad ones....
There is no way you can port a head in one day I dont care who you are, if you do than it really isnt ported well...unless it is a fluff and buff......
What alot of shops wont tell you is the truth about porting because every shop has to look better than the next one..
How can i make my shit look better than his, its all marketing.....remember the pet rock!!!
There are good motors and there are duds, what makes one better than the next? We all look at the head because it is the most important part of the combination. You can have 2 identical engines, run the same tune up, same rider, and have 2 totally different results, why? becasue there is alot more to a package than the head, you can have your rear tire misaligned and scrub off 1 mph, and that would make one motor better than the other one...All im saying is that results will vary from jsut a head, 1 job someone did for a customer he ran great, the same set up ran like shit another customer, and he says bad shit about him, and its the owners fault because his stupid,cheap, lazy ass cant put a chain on his bike..you guys know what im getting at because you have had these guys in your shop......
Like I said, i am not pointing fingers at any of the guys here, just putting my change into the conversation, we all need to make a living, but the greed tends to get to us and make us do less than a perfect job.....
When it comes down to it, its the damn governments fault!!!!!!
if it wasnt so expensive to live guys wouldnt have to rush out jobs to pay their rent!!!!!!!

[Competition CNC]

Jim,

 Without giving up any trade secrets can you elaborate on your valve job?

Thanks Bryan

Well, I can’t go into cutter design details of course but...

We do not use a live pilot (Serdi) valve seat machine for several reasons. But that’s a debate for another thread.
We use a new Sunnen VGS20 machine.
We use carbide cutters that we design in Master Cam for each cylinder head application. They have Sunnen part numbers that are assigned by Sunnen to these specific cutters. They are proprietary and you couldn’t order them, even your Sunnen rep. couldn’t order them even if he had the Sunnen part number.

It seems the valve job is under rated these days.  I've seen some really bad valve jobs over the years and I still see really bad valve jobs.  You would be shocked to see some of them.  One or two angles, even just the 45 cut into the head with no throat angle or shape.  Sometimes the seat runout is .004" even .006" The shape of the valve and seat is important for power but minimizing seat runout is important as well. We check runout on every head and this machine minimizes seat runout and chatter is non existent. Again, I'm not going into the Serdi live pilot vs. tapered pilot machines debate, but we found the Sunnen VGS20 (tapered pilot) to produce the least amount of seat runout. The single point cutting machines (Newen) are excellent as well but are more than twice the cost, so you don’t see many shops using them other than Cup shops etc. and besides once you get below .001" on seat runout its mute, because the valve wobbles in the guide at high speed more than the runout thus negating any benefit of a seat concentricity less than .001"
The guide clearance can make up for about .002" of seat runout, but that’s about it on these tiny valves.  After that the valve has to "bend" to seat. And with a 65# seat tension spring on a valve that was designed for a 35# seat tension spring it does bend the valve shut.  Imagine the harmonics of that poor valve bending and wobbling at 10,000 rpm!!!  Have you ever seen a slowed down video of a properly set up valve train in action at high rpm? Ferrea has one, it would scare you!  The valve is flexing and the spring is wobbling. The bottom line it will cost power AND durability.

Our mission is simple. We are bringing well engineered cylinder head design and execution to the masses at custom pricing.  It’s just a tiny part of our overall business but motorcycles are a passion of mine and that’s actually the main reason we even got into the bike market.  Believe it or not, it’s not about the money.
I think this spring when our heads start appearing at the tracks around the country some folks are going to take notice.

Take care guys.

[Competition CNC]

Jim,

 Without giving up any trade secrets can you elaborate on your valve job?

Thanks Bryan

I'm just guessing here but I don't think someone that ports heads is going to give up much info on that. However, I have been wrong many times before.

Ryan, its so hard to try and debunk myths and educate without giving up the candy.  I try thou. 

[IllusionalTA]

so what does a typical cnc head go for? i see spaz's are 900.. what do your's go for? i'll have to talk to my head guy up in PA.. he's doing my all pro's for my SBC>. maybe i can drug deal somthing..  Good Reads' none the less....

[Competition CNC]

so what does a typical CNC head go for? i see spaz's are 900.. what do your's go for? i'll have to talk to my head guy up in PA.. he's doing my all pro's for my SBC>. maybe i can drug deal somthing..  Good Reads' none the less....

We offer CNC porting 3 ways so if you are a shop you can do some of the work yourself to save some money.  Option 2 is the most popular for guys doing the R&R work themselves.
Option 1 is for bike shops that can do the disassembly and reassembly.
Option 3 is fully assembled ready to bolt on.

Our new website is under construction but until then you can go to our old site... http://www.competitioncnc.com/

Thanks

[Spaz Racing]

I would like to know how U push the guides down and think the valves will B in line without doing a valve job?

OPTION 1 JOB SHOP SPECIAL: CompetitionCNC Stage 1 CNC Porting, Custom contoured valve seats, resurface deck, (to customer spec) check, inspect, lower valve guides for high lift cams and tap and plug emissions ports. $920 (head received disassembled and clean without valves and springs)

[spdingtkts]

I would like to know how U push the guides down and think the valves will B in line without doing a valve job?

OPTION 1 JOB SHOP SPECIAL: CompetitionCNC Stage 1 CNC Porting, Custom contoured valve seats, resurface deck, (to customer spec) check, inspect, lower valve guides for high lift cams and tap and plug emissions ports. $920 (head received disassembled and clean without valves and springs)

I don't know, but I think you answered your own question.

[gnd111]

I would like to know how U push the guides down and think the valves will B in line without doing a valve job?

OPTION 1 JOB SHOP SPECIAL: CompetitionCNC Stage 1 CNC Porting, Custom contoured valve seats, resurface deck, (to customer spec) check, inspect, lower valve guides for high lift cams and tap and plug emissions ports. $920 (head received disassembled and clean without valves and springs)

I don't know, but I think you answered your own question.

But without the valves present you can't 100% verify they are correct...

[Competition CNC]

We do valve jobs on all our CNC ported heads.  The valve job is just as important as the porting. They work together and were designed together.

You just need to have a valve of the proper size to do a valve job. You don’t need the actual valves. As long as you have one valve you can check where the seat contact is.
We check the seat run out with a dial indicator setup that mounts on the carbide pilot and rides on the 45 seat as you turn it.  We also check the valves for runout as well.

We aren’t new at this, this isn’t my first rodeo.   

The average engine we build is 10-15k but many are as high as $50,000.  We fabricate one of manifolds, cylinder heads, blocks, pistons, you name it.  We are a full engine machine shop with a DTS engine dyno, 2 flow benches, and specialize in custom 100% race engines, drag, circle track, road race, marine, turbos, blowers, alcohol, and fuel engines. Our engines are on race tracks in many countries in Europe and here in the USA.  We know how to make power. 

Its gonna be interesting this spring.   Stay tuned

[Shamrock]

Why do you guys tap and plug pair valve holes  why not weld up ? Just wondering ?

[whtrthanu]

I drill and tap mine also......The main reason I dont weld them which
i used to do was because of the heat....Any time you put heat like that in a head you have seats and guides as well as the cam journals start to move around........Aluminum is funny stuff when you put heat to it...........

[girl on busa]

Spaz does great work hands down   

[genarr3]

I drill and tap mine also......The main reason I dont weld them which
i used to do was because of the heat....Any time you put heat like that in a head you have seats and guides as well as the cam journals start to move around........Aluminum is funny stuff when you put heat to it...........

You screw a plug in through the exhaust port, or on the outside of the head? There isn't an epoxy or puddy that will work?

[LE05BUSA]

Jim,

 Without giving up any trade secrets can you elaborate on your valve job?

Thanks Bryan

Well, I can’t go into cutter design details of course but...

We do not use a live pilot (Serdi) valve seat machine for several reasons. But that’s a debate for another thread.
We use a new Sunnen VGS20 machine.
We use carbide cutters that we design in Master Cam for each cylinder head application. They have Sunnen part numbers that are assigned by Sunnen to these specific cutters. They are proprietary and you couldn’t order them, even your Sunnen rep. couldn’t order them even if he had the Sunnen part number.

It seems the valve job is under rated these days.  I've seen some really bad valve jobs over the years and I still see really bad valve jobs.  You would be shocked to see some of them.  One or two angles, even just the 45 cut into the head with no throat angle or shape.  Sometimes the seat runout is .004" even .006" The shape of the valve and seat is important for power but minimizing seat runout is important as well. We check runout on every head and this machine minimizes seat runout and chatter is non existent. Again, I'm not going into the Serdi live pilot vs. tapered pilot machines debate, but we found the Sunnen VGS20 (tapered pilot) to produce the least amount of seat runout. The single point cutting machines (Newen) are excellent as well but are more than twice the cost, so you don’t see many shops using them other than Cup shops etc. and besides once you get below .001" on seat runout its mute, because the valve wobbles in the guide at high speed more than the runout thus negating any benefit of a seat concentricity less than .001"
The guide clearance can make up for about .002" of seat runout, but that’s about it on these tiny valves.  After that the valve has to "bend" to seat. And with a 65# seat tension spring on a valve that was designed for a 35# seat tension spring it does bend the valve shut.  Imagine the harmonics of that poor valve bending and wobbling at 10,000 rpm!!!  Have you ever seen a slowed down video of a properly set up valve train in action at high rpm? Ferrea has one, it would scare you!  The valve is flexing and the spring is wobbling. The bottom line it will cost power AND durability.

Our mission is simple. We are bringing well engineered cylinder head design and execution to the masses at custom pricing.  It’s just a tiny part of our overall business but motorcycles are a passion of mine and that’s actually the main reason we even got into the bike market.  Believe it or not, it’s not about the money.
I think this spring when our heads start appearing at the tracks around the country some folks are going to take notice.

Take care guys.

What HMC are you using? Did you build the fixturing yourself?

[Competition CNC]

What HMC are you using? Did you build the fixturing yourself?

We have a new Centroid 5 axis machine dedicated for head porting. The head fixtures are made by Centroid.
All other head work is done on other machines.  The 5 axis could do surface milling, valvejobs, guide work, just about anything actually but its designed for head porting and thats all we use it for.

We have a SuperFlow 110 flow bench for sale if you know anyone interested.  Also a rod resizing machine and a head/block resurfaceing machine.

[crazybill]

I drill and tap mine also......The main reason I dont weld them which
i used to do was because of the heat....Any time you put heat like that in a head you have seats and guides as well as the cam journals start to move around........Aluminum is funny stuff when you put heat to it...........

 you dont have to put that much heat into the head . I can pick a head up and carry it around the shop immediatly after welding . literally hundreds of welded busa heads and not a single one had a problem .
They dont get nearly as hot as one thats gets a bridge rebuilt . not to mention the heat you have to put into one to install new guides . The head on my personal bike had come from a crashed bike and had the upper right motor mount boss badly cracked but we welded it right up then milled off the outter spigots and moved the outter ports inward 5mm each ,welded on new outter spigots and its got almost 10k street miles , over 130 documented dyno pulls(R&D BABY !) plus was on my big stroker all last summer .
Simple little thing like welding the emissions ports doesnt move a thing... I have a good welder though too....

[LE05BUSA]

What do you want for the 110? I know somebody that might be interested.

[enginetuna]

We have a new Centroid 5 axis machine dedicated for head porting. The head fixtures are made by Centroid.
All other head work is done on other machines.  The 5 axis could do surface milling, valvejobs, guide work, just about anything actually but its designed for head porting and thats all we use it for.

Roughly what sort of money does one of those machines run at?

[crazybill]

 was quoted 125k for the cheaper one . 20k of that was for the mastercam software though . I prefer solidworks or surfcam....

[enginetuna]

That's not so bad then.
Does anyone with one use ot for other jobs like machining crankcases/bellmouths/general one-off parts?

[Competition CNC]

Yea $135-150,000 will get you set up. 
You will need some plates tools other misc stuff.  Not too bad.

When we get our second machine it will be for digitizing, piston domes, and oddball stuff.
Anytime you digitize you arnt making chips. And making chips makes the money.
Thats the drawback of this machine, you digitize right on the machine in 5 axis with the probe in the spindle so it ties up thae machine.
I have a 25 degree rotary tilt table for sale also if you wanted to set up your own.

I'll ask my partner what he wants for the flow bench. Its actually his.

[enginetuna]

What is the kind of time to digitise a head and then again to machine it?
Like you said things have to make money.  Profit is key, not turnover

[Competition CNC]

Well, digitizing depends on port complexity and size. That applies to cutting as well.
Four valve heads are treated as two separate intake ports for each cylinder so a Busa head would have 6 ports to digitize and 16 to cut.
The actual probing time is several hours. But you need to set up an initial digitizing tool path and then start the 5 axis digitizing.  When I’m digitizing I’m not making chips. So you can see why I need a second machine!!!

For example I can digitize a SBC intake port and exhaust port in a day or so. Four valve heads take twice as long or even 4 times longer if you need to digitize two intake ports because they are different.   Then it takes a day or so to bring the data into MasterCam and work with the splines and create a surface and have the ports ready to cut.  Then you have to transform or copy, mirror etc. all the ports to the right places.  It’s usually 2-3 days but can be 3-4 days.    All in all it can be 4-5 days before you are happy with the port and actually are ready to cut.  So you can do the MasterCam work while you are making chips.  Time management is key.


When I cut a Busa head I use a .020" tool path step over to give the port the desired surface texture. That takes three times longer to cut than a typical .060" stepover used on many automotive heads. So you tie up the machine 3 times longer.  I make a lot less money on Busa heads than a typical pair of race V8 heads.  But I personally love the bike stuff and want to bring engineered cylinder heads to the bike world.
The stage 1 head was designed for street 1397's with mild aftermarket cams. That combo isn’t that far from the factory performance envelope of a stock Busa.  Watch what an engineered stage 2 head on a 1500+cc busa and then the stage 3 on a 1650+ cc engine will do.  Hang on boys, I cant wait till spring!!!

[Competition CNC]

You don’t have to put that much heat into the head. I can pick a head up and carry it around the shop immediately after welding.

I agree its very localized spot welding and there isn’t enough heat or time to heat soak the head.

But over heating the head and loosing the heat treatment is a very real danger.   But it’s not going to happen from welding the air injection holes.

We sent out a set of VERY expensive heads to get a ceramic coating on the combustion chambers several years back and they came back SOFT as SOFT can be.  I forget the Rockwell number now, but they were ruined, the heat treatment was gone!!!  We never used that company again.

When any of you guys are heating heads you should either do it in an oil bath or use an oven. Never use any kind of direct flame.
A head should be heated between 250 deg. F and 300 deg F. for guide work.  If you get to 400deg F the head starts to relax and its gets worse the hotter it gets until you have a soft head.  At that point you throw it out, its scrap. It will usually cost more to fix it than to buy another one.

[spdingtkts]

I remember the guy that does my aluminum welding telling me about the first time he welded an aluminum head.

He did it for a dealer and it needed a lot of work all over the head. When the guy from shop came to get it all the seats fell right out of it.

Lesson learned that day.

[whtrthanu]

im not saying you guys are wrong by welding the emission ports, i was just stating that I dont  prefer to do it that way........
As far as you welding the spigots on the other head, you bet there was alot heat put in that one...
I do alot of welding.......alot of aluminum....I actually do welding for UL .........under writers labs.....So I think im pretty ok at what i do, and so do they..........
i did an oil cooled head years ago Like that with spigots and skull caps.........There wasnt a straight piece left on it.............You can leave it alone, and run it......or you can go over it and see how bad it moved.....i actually re machine the cam journals because they definetly move.....but everyone does things different....im not saying your wrong or im wrong just givin you my opinion...........

[enginetuna]

Well, digitizing depends on port complexity and size. That applies to cutting as well.
Four valve heads are treated as two separate intake ports for each cylinder so a Busa head would have 6 ports to digitize and 16 to cut.
The actual probing time is several hours. But you need to set up an initial digitizing tool path and then start the 5 axis digitizing.  When I’m digitizing I’m not making chips. So you can see why I need a second machine!!!

For example I can digitize a SBC intake port and exhaust port in a day or so. Four valve heads take twice as long or even 4 times longer if you need to digitize two intake ports because they are different.   Then it takes a day or so to bring the data into MasterCam and work with the splines and create a surface and have the ports ready to cut.  Then you have to transform or copy, mirror etc. all the ports to the right places.  It’s usually 2-3 days but can be 3-4 days.    All in all it can be 4-5 days before you are happy with the port and actually are ready to cut.  So you can do the MasterCam work while you are making chips.  Time management is key.


When I cut a Busa head I use a .020" tool path step over to give the port the desired surface texture. That takes three times longer to cut than a typical .060" stepover used on many automotive heads. So you tie up the machine 3 times longer.  I make a lot less money on Busa heads than a typical pair of race V8 heads.  But I personally love the bike stuff and want to bring engineered cylinder heads to the bike world.
The stage 1 head was designed for street 1397's with mild aftermarket cams. That combo isn’t that far from the factory performance envelope of a stock Busa.  Watch what an engineered stage 2 head on a 1500+cc busa and then the stage 3 on a 1650+ cc engine will do.  Hang on boys, I cant wait till spring!!!

Ok thanks for the answer on that.
Seems like a lot of time.  May have to rethink that idea because there wouldn't be the volume to pay for it over here.  Even copying their best heads for people, the labour cost with up to 5 days would render the price out of all but a handful of peoples budgets.

[Competition CNC]

Ok thanks for the answer on that.
Seems like a lot of time.  May have to rethink that idea because there wouldn't be the volume to pay for it over here.  Even copying their best heads for people, the labour cost with up to 5 days would render the price out of all but a handful of peoples budgets.
[/quote]

Yea you have to do your digitizing, in between production cutting, and manage your time well to keep the cost to the customer down.  Most of the custom digitizing I do Is for the high end of the market. But I'm getting the speed down now, each one I do now its a little quicker.
These guys http://www.vhmotorsports.com/home.html just bought the same machine. I think they might be using it by now.

[enginetuna]

These guys http://www.vhmotorsports.com/home.html just bought the same machine. I think they might be using it by now.

Rumour has it they already have a good share of the AMA superbike paddock as far as head porting goes.  So i guess they are up to speed now.  Nice to know that is the machine they have though, thanks again.

[chavcat]

Any truth to the rumour that the ZX14 head is inferior to both the Busa an ZX12 heads even after modifications?

[gnd111]

Any truth to the rumour that the ZX14 head is inferior to both the Busa an ZX12 heads even after modifications?

www.dragbike.com lists the results for the total amount of flow but it mentions nothing of velocity which is a big deciding factor in power/mph/etc...

[crazybill]

Any truth to the rumour that the ZX14 head is inferior to both the Busa an ZX12 heads even after modifications?

www.dragbike.com lists the results for the total amount of flow but it mentions nothing of velocity which is a big deciding factor in power/mph/etc...

velocity was measured but not conventionally.... so it wasnt posted . I have all the flowcharts for that head and a couple other port designs for the 14 .