Small Intake Ports

[whtrthanu]

Thats exactly why a road race engine is totally different from a drag race engine.........I spoke with Darin Morgan a few years ago about the heads they were doing for schumacher, you would be suprised on what they were using, and also the fact that he would almost tell you the truth about what they were doing......Like for example he was very quick to tell me the port volume of the pro stocker, but get him to tell you the length of the port
Valve size was also another topic which he would tell you last years size...
Gotta keep everyone 1 step behind

[gazza414]

A quote from the man as mentioned above

Items to remember when choosing a cylinder head:
 
 Airflow is not the No. 1 criterion.  Bigger is not always better!

Port volume, runner shape, mixture velocity and cross-sectional area are extremely important.   

Combustion chamber shape significantly affects performance.

If you are debating between port sizes, smaller is usually better.
 

[enginetuna]

A quote from the man as mentioned above

Items to remember when choosing a cylinder head:
 
 Airflow is not the No. 1 criterion.  Bigger is not always better!

Port volume, runner shape, mixture velocity and cross-sectional area are extremely important.   

Combustion chamber shape significantly affects performance.

If you are debating between port sizes, smaller is usually better.
 

Yep, sure is right.  I've got flowbench, dyno and also test a lot on track.  You can increase airflow on the flowbench and end up going much slower both on dyno and on track.  You can also improve on the dyno and still be slower on track.  All depends how you test with the dyno of course   Don't rely on peak numbers in a 4th gear roll-on, you are pissing into the wind there Yes, smaller ports are usually better, the key is knowing just how small you can go.  And its not just the choke size, the ramp of the csa is hugely important.
Those pictures of the R6 ports are from motomans site.  Its got some good info on there but the port shapes are a bit outdated for use on the newer heads.  Might not be too bad on busa though.

Darkfalcon, thanks for the link, thats pretty cool.

[Steve S]

And its not just the choke size, the ramp of the csa is hugely important.

ET, are you referring to the rate of taper when you speak of ramps.?

[enginetuna]

Yes

[gazza414]

And its not just the choke size, the ramp of the csa is hugely important.

ET, are you referring to the rate of taper when you speak of ramps.?

Steve, there is more than a Phd or a post doc involved in this....perhaps a padded cell too!!!!

[Steve S]

Gazza, we've probably read some of the same stuff.........it's almost unmanageable.

[enginetuna]

Hey its alright for you guys that do it for a hobby, i wake up at 3am and have to start drawing up port ideas and equations that have woken me up in a sweat!!!  Very sad i know, but at least its not train spotting

[gazza414]

Sometimes, hobbies become obsessions

Try plane spotting ET...very sad people IMO

Terminal 1 @ Heathrow

[dakinebusa]

When all you guys are thinking about this bit of fluid mechanics please reemember this is highly turbulent, PULSATING, two phase flow with evaporation and maybe condensation.

Although all these phenomena are undoubatably ruled by the Navier Stokes equations, only a few supercomputers can really do a credible job of modeling some of the phenomena that occur.

Data, data and more data is required to understand complex flows and challenge one's own bullshit.

Good ole boy, Smokey Yunick had a motoring flow bench made from part of an engine that gave a true pulsating flow in the '70's.

If I was motivated to work on this problem, I would build a busa based motoring flow bench out of parts the board would provide (old block, jugs, crank, etc..) and a big ass electric motor.

You could probably use a Briggs and Stratton.....

Then, I would make some silicone rubber ports and maybe some acrylic ones so I could probe the flow with whatever tools I could get.

Pushing around the silicone ports and generally changing the shape through applied pressure would let a person check out a bunch of theories quite quickly.

Any budding PhD canidate mechanical engineers out there that need a thesis topic?

Anybody got a spare Laser Doppler Velocimiter of the scanning kind?

[gazza414]

DakineB, the big companies can design a new engine from scratch these days with in house and proprietary software and be within 5%

thats HP , TQ and emissions

we are rank amateurs here

[DarkFalcon]

 

[DarkFalcon]

Hey its alright for you guys that do it for a hobby, i wake up at 3am and have to start drawing up port ideas and equations that have woken me up in a sweat!!!  Very sad i know, but at least its not train spotting

How much does train spotting pay and do they offer good benefits. I wont tell you why I am asking but I play the markets heavily.

[dakinebusa]

The reason that the big buck models work so well is that they have been developed in conjunction with a vast experimental program.
The models have been calibrated using lots and lots of carefully constructed experimental data.
I'm a card carrying fluid mechanics guy of the experimental flavor.
Getting a bulletproof data set that blows away some computer jock's favorite solution makes my day.

I think you guys have been doing some good thinking in this thread.
I have never worked on this kind of problem so I'm listening.
I get concerned when port flow is discussed as a steady flow problem.
The pulsating nature of port flow and the effects of resonant tuning are key to getting real world results.
Small ports are more affected by pulsating flow than big ports...that is important.
I expect that measuring mass flow as the intake is closing would give substantial insight into the advantage of small ports.
It is really about building momentum in the intake that gives exceptional volumetric efficiency.

The advantage shown by Ducati this MotoGP season has to do with very aggressive valve ramp rates.
Slamming the door shut after the horses are in the barn works.

[enginetuna]

Looking at steady state is mostly a waste of time.  A flowbench is good for examining things like different seat configurations and testing bolt on parts like throttles/carbs.  Also for probing a port to find dead areas with a pitot tube.
However, many people are obsessed with steady state flow numbers, this is why heads often sell based on a cfm rating.  Now it is very easy to increase the cfm substantially and loose large amounts of power, its also possible to decrease it and gain power.  But that is not a rule.  You could drop cfm and drop power and gain cfm and gain power. The clever bit is knowing which way it needs to go for both a given head and the required application.  Racing on a tight circuit and top speed testing do not want the same motor.
There are other features to look at in the ports such as velocity profiles, shape, entry into the combustion chamber, chamber flow.  Much of these last few can only be tested or observed accurately using a wet flow bench or derived from years of experience and testing.
Now of course, it does not stop there.  These are just factors to bear be aware of.  The cam profiles, exhaust shape/size/length, inlet shape/size/length, airbox volume, spark advance, fuel type and distribution, etc etc.  It goes on and on.
The basic thing to remember is the engine is an air pump.  Your torque comes from the ability to trap air with the required ideal amount of fuel for that air.  The measure of this trapping is known as the compression.  So of course if you fit long duration cams, you drop the dynamic compression in the midrange because the valves are held open longer and hence trap less air.  But then short cams will not pump the air at high rpm as well.
The hard bit is understand the wave motions going on.  Things like timing the reflected waves back from bellmouth to inlet valve and exhaust juntions and end to exhaust valve.  Time these right and, in simple terms, you can gain a lot of power by supercharging the inlet or using the exhaust wave motion as a vacuum.

So in answer to the original question on the filled port.  The reasons why the intake filling work so well on many bike engine in my opinion are these:-
1)  You are reshaping the port and removing the flaws in the original design, or rather optimising them.
2)  You increase the intake velocity which supercharges the intake charge more.
3)  You increase the transient response of the motor. - a bit like fitting a smaller turbo, it spools quicker and has sharper response.
4)  It requires less fuel after to make the same power.
5)  You change the intake runner volume and hence its tuned length.  Power curve peaks will generally shift around some.

Its a shame there aren't more people who will talk about this stuff.  Its a very guarded trade though!!  Black art my ass, protected art more like

[enginetuna]

Oh and i think Ducati were much faster because unlike the other idiots, they ditched the big bang format as well as having the most efficient valve train out there.
Why big bang with the torque of an 800cc and traction control systems that were developed for the delivery of a 990?

[DarkFalcon]

I get concerned when port flow is discussed as a steady flow problem.
The pulsating nature of port flow and the effects of resonant tuning are key to getting real world results.
Small ports are more affected by pulsating flow than big ports...that is important.

Dakinebusa, you know as I do the complex nature of this pulse activity. If we brake this down into to tract recovery and cylinder filling, I would have to say the latter is the more complictaed as during the milliseconds of filling there is constantly fluctuating pressure differentilas, wave activity, reversion and inertial filling........just to mention the things that immediately come to mind. Where is MANDY when we need her.

[gazza414]

Its good that DakineBusa has reminded us that this is a highly complex Dynamic situation and that most are still hell bent on ultimate flow numbers given by a porter in some terms that most struggle to understand.....it sells

I think some have eluded also to the fact that head tracts , cam profile and rpm etc etc realy only work well or are optimised for a "sweet spot"...ie 1 combination doesnt suit all. ET, it appears from published papers that there is still some black art to all of this , although the science is overtaking and the modelling is being fine tuned every day.

When you add fuel into the equation or more correctly the bigger picture the situation becomes more complex .....unless its steady state conditions...all engineers love steady state , transient conditions are difficult to control because its difficult to measure.

There's no getting away from the fact though that cfm makes power...and so do rpm's

Maybe some one can start a thread up discussing what would be the differences  ( subtle or otherwise ) if they were to choose a head for  a 200hp , 225hp or a 250hp Busa motor and what would the variations be if it were for street use , drag racing or land speed racing??

[Yngve]

yup , thems intake ports allright....

who did the work ?

Bill the work was done in NORWAY on a R6 some 4 or 5 years ago

prob ET is aware of this and in particular for a bike that needed throttle response


Norway's Kai Børre Andersen dominated the European supersport championship this year with 4 wins out of 8 races. The points total tells the story: KBA finished with 153 points, and the second place rider had 93 points... !

Despite winning the championship with 1 race to go, Kai Børre went on to finish the last round with a resounding 6.5 second win in Cartegena, Spain !!

Kai Børre's 'secret weapon' ?? His Yamaha R6's unique engine set-up features smaller than stock, High-Velocity intake & exhaust porting by Jørgen Johnsen of Fast Bikes http://www.fastbikes.no in Oslo !!

Congratulations from all of us at Mototune USA !!

Read all about it in MC Avisa:
http://www.mc-avisa.no/default.asp?aid=4096
(in Norwegian)

DON`T belive anything you read on the net. 

I know Kai Børre Andersen and I also know the guy who did the engine who he used to win the last race and it was NOT Fast Bikes or anybody who has anything to do with Mototune USA.

It was in fact Erik Marklund of Mc-Xpress Sweden who made that engine.

[LE05BUSA]

This thread is funny.

There are a few people who know a fair bit. 

There are a lot of people who know very little. 

And of course, as always, there are a few people that know absolutely nothing but are convinced they can convince you they are experts and worthy of your attention.



With two ports with identical port length from the 45° to the intake or exhaust interface and one has a larger runner volume than the other (and the smaller volume runner flows more air from .050"-max" lift, steady state, at the same depression), the smaller runner will make more HP and LB-FT 99% of the time ACROSS THE BOARD on a gasoline fueled ICE. Why? Increased port velocity.

Small cross sectional area ports are highly sensitive to surface finish...I.E. - you may see as much as a 15% increase in flow by producing an intake port with a Ra of 15 (microinches) v.s. one with an Ra of 75 as a result of the low Reynolds number and the corresponding laminar flow. I have found this to be even more likely in ports that have a cross sectional area at the short turn window of less than 1.375 sq. in. and have high swirl.

Since this is now in print again, I'd suggest you guys pick up a copy. Everything has been done before, except he did a lot of it for the first time...75 years ago.  

[enginetuna]

This thread is funny.

There are a few people who know a fair bit. 

There are a lot of people who know very little. 

And of course, as always, there are a few people that know absolutely nothing but are convinced they can convince you they are experts and worthy of your attention.



With two ports with identical port length from the 45° to the intake or exhaust interface and one has a larger runner volume than the other (and the smaller volume runner flows more air from .050"-max" lift, steady state, at the same depression), the smaller runner will make more HP and LB-FT 99% of the time ACROSS THE BOARD on a gasoline fueled ICE. Why? Increased port velocity.

Small cross sectional area ports are highly sensitive to surface finish...I.E. - you may see as much as a 15% increase in flow by producing an intake port with a Ra of 15 (microinches) v.s. one with an Ra of 75 as a result of the low Reynolds number and the corresponding laminar flow. I have found this to be even more likely in ports that have a cross sectional area at the short turn window of less than 1.375 sq. in. and have high swirl.

Since this is now in print again, I'd suggest you guys pick up a copy. Everything has been done before, except he did a lot of it for the first time...75 years ago.  

Sure was, its amazing how fast development moves in time of war.  I remember when 4V per cylinder became the great thing in the car world like it had just been invented.  Gee, they had that in WW2 as well in the fighter plane engines.  The big thing we now have is materials and processes have caught up with theory

But don't wait for too many subscribers to your knowledge and experience on forums, "port and polish" (spit spit) rules.  And thanks to places like wikipedia and the cut and paste facility in windows, you can be assured that further poor information continues to spread.

[Competition CNC]

Guys, If you are serious about designing or re-designing cylinder head ports you need this book.  Its cheeper thru SAE if you guys are members. You can save $20 or so.

Design and Simulation of Four Stroke Engines    By Gordon Blair

If you have the resourses to invest, buy the software.  But I warn you its not cheep ($36,000 anually) and its very complex to use.

[enginetuna]

Blairs book is very good, but you need to be nigh on degree level in mathematics to use it usefuly.  A large portion of it is devoted wave motion on the intake and exhaust system.  Very little towards port designs though other than understanding the entire 4-stroke process.  Well worth a read.

Here are some other i can recommend that are a little less taxing on the brain:-
"scientific design of exhaust and intake systems" by Smith and Morrison
"tuning for speed 6th edition" by phil irving

Pretty old and more based around single 500cc but none the less very useful.  And all of these cover the basic concepts of air pumping which are not understood by most.

And of course there is the smokey Yunick power secrets.  Again, well worth a read if not just for the fact he thinks his way through everything.

Happy reading.

There is also a lot of software out there for simulation.  Obviously there is blairs one.  Ricardo wave is awesome but huge cost.  Lotus do one too, i believe there is a demo which is single cylinder only.  optimum power are linked to blair but huge huge money.  Then at the cheap end there is engine analyzer pro from performance trends which is very useful and also dynomation and pipemax.  The last three are very affordable for the enthusiast with pipemax being very effective for exhaust design.  You test cam profiles quite accurately before buying.

[Steve S]

This thread is funny.

There are a few people who know a fair bit. 

There are a lot of people who know very little. 

And of course, as always, there are a few people that know absolutely nothing but are convinced they can convince you they are experts and worthy of your attention.

Which group do you fall within in this sampling?

[whtrthanu]

With two ports with identical port length from the 45° to the intake or exhaust interface and one has a larger runner volume than the other (and the smaller volume runner flows more air from .050"-max" lift, steady state, at the same depression), the smaller runner will make more HP and LB-FT 99% of the time ACROSS THE BOARD on a gasoline fueled ICE. Why? Increased port velocity.

Small cross sectional area ports are highly sensitive to surface finish...I.E. - you may see as much as a 15% increase in flow by producing an intake port with a Ra of 15 (microinches) v.s. one with an Ra of 75 as a result of the low Reynolds number and the corresponding laminar flow. I have found this to be even more likely in ports that have a cross sectional area at the short turn window of less than 1.375 sq. in. and have high swirl.

This is hard to prove with a large inch motor............if its a small inch, i agree...I have proved that increased port volume over velocity will make more power and run faster...........Now, we need to know the balance of volume and velocity for the displacement...........