Author Topic: cylinder head airflow figures  (Read 26772 times)

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Offline johno

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Re: cylinder head airflow figures
« Reply #75 on: June 04, 2012, 03:39:07 AM »
Hi guys, :D
Not many comments on the flow numbers ? hope I'm not boring everyone.  Dont worry,  only a couple more posts and its done,  so put up with me for a bit longer.

So I deliberately only posted the max flow figures until I got my head around things, thought it might raise some discussion. Here are the low lift numbers.

K2 Hi port flow figures:  @ 10 inchs
Lift..............Flow CFM
050 ......... 12
.100 ........ 21
.150 .........36
.200 ........ 46
.250 ........ 56
.300  ....... 68
.350 ........ 73
.400 ........ 74
.450 ......... 78
.500 ........ 83

My thoughts are;
Given it is a 32mm type port and a 35mm valve and a hi angle entry to the back of the valve it flows about what I expected. If you have a good look at the port pic previously you would see it is a fairly parallel type of port with little shape so I feel we could improve the flow rates across the board with more shape.
I didnt get all excited because it raised more dramas than you could poke a stick at. One of the main  reasons to go to the trouble of doing the hi port is to get more flow, port flow in normal modified head is similiar up to around .400 lift but then the high port just gets stronger to over .500 lift.

So I rang 3 cam grinders in OZ, Waggot cams, Crow cams, Ivan Tighe cams discussing increasing the cam lift to take advantage of the extra flow.    However...  :'(  Getting a bit hard to get the extra lift , design is kind of maxed out without major engineering. change rocker ratio or custom cam and cam bearing  mounts to physically get room to do things etc etc.

Given that I have to have the bike ready for scrutineering by Christmas,  pursuing this hi port is not my best option when I can buy a Rieksy's head,  drop it on,  dial up the cam and go racing. Thats my plan so should keep ol Captain Webber happy as I will run them.  I'm a bit confused by the fact that Cycle X have gone to the trouble of running a hi port on their circuit racer when to realise its potential they would need a hi lift cam but on their web site they say they use a megacycle cam 125 / 75 with 3 degrees more duration  which is nowhere near the lift required to take advantage of the effort. Interesting hey ::)

I will keep up with the high port project on the side though just for interest, I have been designing the port on solidworks and having some fun and have started trying to redesign the camshaft and valve train to try and fit a big big big momma lift with normal kind duration as say the megacycle cam.

Attached is the first effort on solidworks for the 32mm port 35mm valve and the flow numbers along side in metres per sec, notice the pretty coloured dots in the port showing velocity.  This was the basic shape as on port but it looks and flows better with some shape, you know entry slight taper , parallel mid section, widen just before the seat kind of stuff..  If I can work out some geometry to fit a bigger cam I'll post the good shape with the all the info .  Hope the attachment works.

Hey the other comment I would like to make is a couple of years ago on a thread Ol Lord moony and Rieksy were playing the fun game of I,ll show you mine if you show me yours,  the two posted pics of their ports and I found it really interesting as they were poles apart but I feel both should have been very effective.
At the risk of stereo typing, I have always felt the poms build circuit racing type bikes and occaisonally go drag racing where as the yanks build drag racing type bikes and take then circuit racing . Given the different type of use I felt the ports reflected that kind of philosophy. I felt ol Lord Moonpie port would have been great for on and off the throttle type action kicking butt through the bends where as Mikes looked great for larger displacement and wide open throttle.  Which is why I'll be contacting Reiksy.

So I have to start focussing on the race build now, i'll keep you posted.
ciao boys..... Johno     
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Offline johno

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Re: cylinder head airflow figures
« Reply #76 on: June 04, 2012, 03:54:38 AM »


I have made life easy for myself by making the intake valve centreline at right angle to the base which is normally 27 degrees from the vertical on the bike, the port is all accurate relative to the valve angle etc.
ciao Johno
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Offline bear

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Re: cylinder head airflow figures
« Reply #77 on: June 04, 2012, 04:17:54 AM »
Good to see you back on deck Johono.
Good luck with the project.
Give me a bell if you think I may be able to help.

Cheers,
Brian
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Offline johno

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Re: cylinder head airflow figures
« Reply #78 on: June 05, 2012, 03:03:54 AM »
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Offline johno

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Re: cylinder head airflow figures
« Reply #79 on: June 05, 2012, 03:05:18 AM »
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: cylinder head airflow figures
« Reply #80 on: June 05, 2012, 09:55:21 AM »
Someone needs to flow one of Mike's big heads and report back  ;)
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Offline Jim F

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Re: cylinder head airflow figures
« Reply #81 on: June 05, 2012, 12:07:03 PM »
Based on these numbers:
can you determent the type of cam you want but also
tell you what is going to be the best carburetors (Flow wise) to use with
these numbers
This is very interesting
thanks
Jim
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Offline johno

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Re: cylinder head airflow figures
« Reply #82 on: June 06, 2012, 05:50:12 AM »
 Cheers Jim,
Bit nervous about responding, this forum is blessed to have some of the worlds best and most experienced sohc people contributing, if i'm not on the money I,m I hope they put their two bobs worth in for all to share. ;)
Re cam and carb selection from flow figures:
I think its about knowing what you want to achieve. If you have a goal you can use a combination of resources to achieve that goal. This forum, component suppliers, experienced technicians or mechanics, technology like engine design software, exhaust design software and flow bench, dyno tests this forum, racing on track or street. Some people have confidence in the local hotshot and buy or choose based on that, others can never be satisfied unless they are continually experimenting for a better combination.  Flow figures are another tool or rescource used to form part of a matrix.  The matrix forms a big picture, your goal hopefully.

So if hyperthetically the matrix consisted of bore , stroke, compression, air in, air out, valve sizes, fuel mixing device, exhaust, cam specs and your goal is x hp or torque , life is easy you just  use the above tools and it wont take long to find out what you need.

Where I'm going with all this is in the old days the person who changed the most cams, carbies, exhausts, pistons, hogged out the most heads etc was generally the wisest and fastest. Whats changed for most older , wiser , experienced , racers is the number one modern tool, COMPUTER, COMPUTERS and COMPUTERS.

Its a cheap way  ( $50  to $1,500) to get a lot of experience quickly, modern computers & engine design software only give back what you put in. SO.... they need information like whats in the matrix to give you the ponies.
You dont need flow rates for these software packages but if you use them,  they make the final figures very very accurate and reliable results encouraging you to buy or make what is in the matrix.

Porting and cam selection was traditionally a black art, arty farty stuff really veiled in secrecy but these days with internet there are a lot of publications and info around and more people have a basic understanding of porting.  Flow cfm information is a reliable way to compare, air speed through the port can contribute to carb selection, cam selection can be fine tuned  using those matrix parts in a software. In my humble opinion the one thing that hasnt changed is you need an artist to make it happen. Physically shaping is a real art, it takes special tools the same skill and mindset as an artist who paints a nice canvas painting.  Over the last few months I have read every thread on this forum and the the most exciting thing for me is looking at the port pics, there is so much good sh#t on this forum if you look.  My artistic days are over but I enjoy the rush of seeing nice port work, its the artistic side of engine building.

Jim Ive been out of the scene for a long time but the call of the sohc and reading threads has rekindled the spirit and I am having a real rush fooling around with a speed project. This solidworks CAD is un Fcukin beliveable,  the port pics above are just snap shots, on the PC screen those mass of dots are a mass of moving colour and everything is just so easy to interpret, I used to spend hours mapping a port and writing the numbers on a bit of paper but it was difficult to get a clear picture in your head on how the port looked as a whole.  This sh#t is not cheap, I paid about $14 grand for the licence and I made sure it had a flow test function , now I,m getting serious and starting to understand how things work I find out its not that accurate, say 5% either way, I queried with the dealer and he says mate you need the specialised flow testing upgrade for your software,  another bloody $14,000.  hmmm I'm thinking something within 5% will be a good indicator, once I get the port close to where I want it I might try the ol one off free trial on the good sh#t programme.

Jim a thread this long is probably not good thread etequette, but sh#t mate I live in the middle of  a desert an feeling lonely, oh by the way, in answer to your question , yes. ;) ;) ;D
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Offline johno

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Re: cylinder head airflow figures
« Reply #83 on: July 08, 2012, 06:57:39 PM »
Hi Guys,
Just when you thought this thread had gone away !  ;D   Harden up and cop this. ;)

Re the subject of a big lift cam to take advantage of the 15 degree raised inlet port:

I have been working with a cam grinder and have sort of got to first base.  First base meaning trying the easiest options first before the tricky stuff like roller rockers and cam relocation. I was thinking in the world of being first this should fall into the secret squirrel catagory but upon reflection at my age who cares as long as its helping the SOHC  cause and gets me a Kwaka beater.
We have selected four profiles of varying lifts and appropriate lift rates. These are mostly Ducati profiles, including two from the Desmo twin rocker cams engines, in particular the leading rocker profile looks interesting.  The lifts are .490 &.480 & .470 & .440  We are welding up the 4 profiles on one stocky cam so I can run a geometry check etc on an engine and determine if by juggling the rocker cam pad radius and valve length to see if we can keep the adjuster in the valve pad.

if thats OK we will tidy things up and do a full grind ant dyno test. If not the next option is for custom rockers with rollers and a roller profile  ( which is not a bad option really , the accell rates on the lobe are heaps better)
So I wait in anticipation for two to 3 weeks for the test cam to arrive.
You know, This is a serious distraction to my build thread salt racer thingo. ::)
Cheers Johno
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Offline scottly

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Re: cylinder head airflow figures
« Reply #84 on: July 08, 2012, 07:45:27 PM »
Whats changed for most older , wiser , experienced , racers is the number one modern tool, COMPUTER, COMPUTERS and COMPUTERS.

Its a cheap way  ( $50  to $1,500) to get a lot of experience quickly, modern computers & engine design software only give back what you put in. SO.... they need information like whats in the matrix to give you the ponies.
You dont need flow rates for these software packages but if you use them,  they make the final figures very very accurate and reliable results encouraging you to buy or make what is in the matrix.


Johno, are you familiar with the first rule of computer programing? GIGO?
Don't fix it if it ain't broke!
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Offline johno

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Re: cylinder head airflow figures
« Reply #85 on: July 08, 2012, 09:07:16 PM »
 :) Does it show Scottly ?
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Offline scottly

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Re: cylinder head airflow figures
« Reply #86 on: July 08, 2012, 09:14:41 PM »
Garbage in, garbage out. Software can only work with good data input; without flow rates, it's just guessing. ;)
Don't fix it if it ain't broke!
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Offline Old Scrambler

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Re: cylinder head airflow figures
« Reply #87 on: July 09, 2012, 12:24:32 PM »
Johno................your already scoring more points on the forum than most..........so keep it coming :) :) :)

Most of the US motor builders were influenced by the older racing tracks that are basically a series of drag-strips linked by corners.........similar to open-road racing for Mustangs and Corvettes.  Our newer tracks are more technical and have fewer long straight-a-ways.  Example: Road America was deemed to be too long for World Cup GP events.

Maximum Flow will certainly change the dinamics of cam/valve duration, timing, spark, chamber design, and piston profile................Hmmm shorter stroke & fatter pistons vs taller lift ??? ??? ???
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Offline johno

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Re: cylinder head airflow figures
« Reply #88 on: October 09, 2012, 04:55:26 AM »


Hi guys, still plodding along, needed a change of pace, I cant get this big cam to suit a hi port out of my head  ;D   head ... get it ! 

 The big cam chat started in the favourite cam thread but Ill continue on in this head flow thingo cos its all about matching a high lift cam to a hi rise port.

So just to show i havent given up I'll take you on a journey, the pic above just shows a stocky head that I'm using to evaluate the rocker geometry, 3 valve sizes , stock 33.5 manley and 34mm Honda. 

The plan is to show the cam profiles evaluated, no cam doctor hear mate , just old fashioned lathe and degree wheel with dial gauge.

Then show the end profile of 4 profiles on the head in position to evaluate the geometry  to see if we can keep the rocker on the valve and see if we can get clearance between the valves.   should be fun hey ;D

Got a couple of options if the rocker adjuster runs of the valve but that can wait.

Two cams in the pic ,  left cam is 125 / 75 the right cam has 3 different profiles 430 lift, 460 lift and 490 lift.   

couple of pics to show the lobes man, looks groovy baby ! ;)   wouldnt it be great if we can make this work ;D ;D

ciao johno       ps sohc camboy  .... thats your cam in the pic Pete
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Offline johno

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Re: cylinder head airflow figures
« Reply #89 on: October 09, 2012, 04:59:04 AM »


th cam where hopefully you can see a change of profiles. :) :) :)
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Offline johno

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Re: cylinder head airflow figures
« Reply #90 on: October 09, 2012, 05:04:02 AM »


Lobe looks horny hey, like something out of a manx norton or something.   ;D

I read on the dyno test thread the Ducati putting out 180 HP or something , gee that makes me envious, I love big numbers man , big lumpy exhaust , big lumpy cam,    crikey this lobe would change the ol exhaust note a tad. ;D ;D ;D ;D
ciao Johno
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Offline Bill/BentON Racing

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Re: cylinder head airflow figures
« Reply #91 on: October 09, 2012, 12:15:43 PM »
Way cool! Keep up the good work.Makes me want to pull my Yoshi CB500/550 head off to show off Pop's work,it's real nice! ;D......guess I'll just go look @ my Stage III Mike Rieck head! 8) Bill
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Offline johno

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Re: cylinder head airflow figures
« Reply #92 on: October 09, 2012, 02:50:40 PM »
At least you got a MR head to look at Bill,  ;D  hes a busy boy.   ciao Johno
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Offline sohc boy

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Re: cylinder head airflow figures
« Reply #93 on: October 11, 2012, 05:53:16 PM »
good to se it put to good use johno, better than it being a shed ornament , have other offerings to the GODS OF SPEED if need be
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Offline johno

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Re: cylinder head airflow figures
« Reply #94 on: October 21, 2012, 03:46:09 AM »


Started with the mega 125 / 75 first , I put in lathe and measured the lift every degree, time consuming but you get a lot of info from having a look at the profile. After this done the next two profiles.
Looking for max rate of change lift per degree, max lift, deg at designated card checking lift.,  style of ramps both open and close,  and general look at the profile and how the two lobes are indexed in relation to each other ( lobe centrelines )
ciao johno
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Offline johno

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Re: cylinder head airflow figures
« Reply #95 on: October 21, 2012, 03:59:23 AM »

Lousy pic , I'll get it right next cam.
This pic shows the eyeball of the geometry in the overlap position, cam doesnt hit anything , the valve adjusters look good on the end of valve stem ( adjuster point contact is spread evanly and centrally across the end valve ) , . If the valve is cut and seated in deeper it can change the geometry so the adluster favours one side of the valve and can be cured by longer or shorter stems or those new ( for me) lash caps the MR uses and put me onto.     Anyway this cam id fine as expected cos a heap of you blokes use them and they dont seem to stress toomany people out.  Next
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Offline johno

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Re: cylinder head airflow figures
« Reply #96 on: October 21, 2012, 04:03:10 AM »

Plenty of gap between the two valves in overlap position . 048 thou

So all good for the mega cam  :D
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Offline johno

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Re: cylinder head airflow figures
« Reply #97 on: October 21, 2012, 04:15:20 AM »


Got a bit excited and wanted to start with the big profile. Went to drop in the cam to have a look at the geometry and walla,   the lobe spanks the cam housing badly,   off the mill tomorrow

This profile is an early Ducati 900, except we stuck with the Honda base circle  and lobe centres hoping to keep the rocker pad on cam and valve on stem,  got a mean arse lift rate of .009 thou per degree compared to others around 005 to 007.  Ill try and master the XL graph on this apple and post all 3 profiles together for comparison. The other profile  i'll look at is a Honda profile but that will be a last resort as the lift is not what I'm after.  I think Mick has one similiar grind in Darwin from Ivan Tighe, ( 585 C   check card at .005 and is 88 / 52  and 56 / 84 it used to be the big drag cam in the ol days for the queensland boys.
ciao Johno ;D
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Offline MRieck

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Re: cylinder head airflow figures
« Reply #98 on: October 21, 2012, 09:08:00 AM »
All the Kenny Harmon CB cam grinds are based on Ducati profiles.  ;)
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Offline johno

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Re: cylinder head airflow figures
« Reply #99 on: October 22, 2012, 03:56:40 AM »
Yeh  Mike, I read your comment in a thread a couple of months ago that you thought KH lobes looked like Ducati profiles, sent me searching his cams with my fingers crossed but they didnt have the lift.

The more I think about this lift required the more I am only interested in around .500 lift and the other cams profiles I have are not in the hunt at mid .400

If you know of any big lift prototypes around Mike please let me know. If this effort to fit in the Duke profiles works and I can have it firmed up by end of this month I will use it for this years motor with the big 15 degree angled ports, if not start of next month I'll advertise in the classified column for one of your stage ? heads , must be a few out there in "one day land " wiling to change their plans for Honda Bretheran and a decent number of greenbacks to ease the state of anxiety. And use one of 3 usual big cams, mega, RC, Tighe.  If you can help Mike  ;)  be appreciated.
cheers Johno
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