MotoMan

Presents:

Think Fast !
(Introduction To Intake Porting )

It's easy to understand why so many people automatically think Flowbench - Porting, or "more is better" is a way to improve power.
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Without closer examination, 
it seems quite logical. 

 Okay, Let's examine it a little closer !!

We were all taught to think of a 4 stroke engine by the traditional textbook explanation of Intake, Compression, Power & Exhaust. 

Textbooks and magazines achieve a sort of instant credibility that comes from the association with $$. 

Example:  
"This source must be right ... after all, there's obviously
some big money behind it ..." 

Because of this association, the vast majority of people never question the things they learn in school, or read in mainstream publications.

In the last issue of Power News you learned to think of a four stroke engine in a whole new way... 8 Phases !!

In the 8 phase engine article, 
you'll remember that the intake "stroke" 
actually consists of 3 phases. 
( Overlap, Suction and Charging. )

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Stock Yamaha R6 Intake Port

Uh - Oh ...
It turns out that a flowbench measures the least  
important aspect of intake cycle efficiency !!

Stock Yamaha R1 Intake Port

So in the final result, the first 2 phases don't matter if the 3rd phase is unsuccessful !! The total intake volume that will be burned is determined by the amount that remains in the cylinders after the intake valves close. That means that an early gain during the suction phase can be easily lost during the charging phase. And, if the intake charge returns back into the port during the piston's upstroke, the result is going to be a net loss !! 

It gets worse !
On a carbureted bike the reversing charge will create an effect called double carburetion, which means the mixture will become even richer with fuel as it passes back over the main jet nozzle for a second time. 

Have we lost enough power yet ??

Wait... it gets even worse !!
Here's a real "out of the box" idea: high flow ports also flow really well backwards !!! All that work on the flowbench comes back to haunt you when the piston now has even less resistance to pushing the intake charge back into the " high flowing port " !!!!!!!  When you begin to consider the consequences of all this, the whole idea of "more flow is better" comes crashing down like a lead balloon.

What's The Secret ??
Using the race analogy, if you increase the Port Velocity, by making the port smaller, the intake cycle "race" starts out slower, gains momentum and makes a tremendous charge on the "last lap" to overtake the high flow port and win the "race". The interesting thing is, this type of port will always lose in a flowbench contest !!!

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Remember 
The Scientific Method:

Evaluate 
one set of conditions. Make only one change, test the result and compare it to the first set of conditions.


 

Hey MotoMan,
If "they" could put a man on the moon, 
why hasn't anyone else 
thought of this before ?!?!

One reason is that people only think of "Scientists" as scientists. Everyone can and should be a scientist !! That means you !!

In real world situations, many people forget to apply the simple principle that all productive science is based on: The Scientific Method.

When someone builds a superbike engine, they usually port their cylinder heads and make other modifications like higher compression, valve job, different cams and big bore kits.  

The combination of all these modifications usually results in a net gain in power. The problem with attributing a gain to the porting in this scenario, is that it goes against the scientific method, because there are 4 other variables coming into play.

Know the difference between association and causation ! 

In this case, flowbench porting of the cylinder head has been associated with horsepower gains for so long that no one bothers to question it. That doesn’t mean the porting actually caused any of the gain. 

Could More Flow = Less Power ??
Flowbench Porting has always been associated with more power... Superflow even says more flow equals more power in their official owner's handbook !!
Yet, in most cases, Flowbench Porting motorcycle heads actually results in less power! 

(Actually, a few creative thinking tuners in Europe do already know about this. They're not anxious to reveal this info, because their success on the racetrack is somewhat dependent on it remaining a secret.)

What happens when we apply the scientific method to intake porting ??  
To find out, let's test 2 progressively smaller porting specs against a stock head, 
without changing any other variables ... 
 
I chose the Yamaha R6 for this test,
because it has the least flow and the smallest valves of all the current 600's !!

Then I asked the question: 
Are the stock ports still way too big ???

The Verdict ??
Smaller Volume = Higher Velocity
=  
Better Power

By reducing the intake port size by 30 percent: 

The Yamaha R6 increases 5 hp. from 103.1 to 108.3 That's a 5 percent gain in top end power !

Notice that the power gain at 8,000 is from 60 to 65, also 5 hp...

That's the same hp increase, but it's actually an 8.4 percent gain where it makes the biggest difference, at the turn exit.


30% Smaller Ports make the most midrange & top end power !!

600 Lap Record Smashed on a Borrowed R6 !!
In May of 2000, Derek Shoeberle borrowed an R6 from one of my customers. On that super windy Sunday in May, the races were dominated by the man on the mysterious red bike. Not only did Derek smash the 600 record, he came within 0.88 of a second of the overall motorcycle lap record ... 

... which was set in 1993 by
an FZR 1000 with Mototune High Velocity Ports !!

High Velocity Intake Porting  
A power improvement that enhances your suspension, and dramatically improves rear tire traction !!

In addition to the overall peak power gain, the biggest advantage of Mototune High Velocity Intake Porting is its perfectly linear power delivery. When you open the throttle two percent, you get exactly two percent more horsepower, then when you want ten more, you get exactly ten percent. 

When you look at the photo, notice how Derek's confidently turning the throttle on while he's still at his outrageously steep lean angle ... through one of the bumpiest turns in roadracing. That's smooth power !! 

Super - predictable mid range power delivery makes it easy for anyone from novice to expert to get incredible drives off of turns, since the power doesn't break your rear tire loose like it does on most superbikes. It doesn't take much practice to turn the throttle harder, it just intuitively feels right when the power is so smooth.

That Confidence Makes a Huge Difference in Your Lap Times !! 

The increased driveability and top end speed from the High Velocity Intake Ports allowed Derek to ride at an entirely new level. During this race he absolutely smoked 2nd place, and turned an incredible 1:13.88, lowering the Blackhawk 600 lap record by over 1 second 
on a very windy day !!

Derek Shoeberle Powers Through Blackhawk Farms Raceway's Notoriously 
Bumpy Turn 4. 

" High Velocity Intake Ports
Are Incredible !! "

CBR 600F3
Before & After

The Blue Line represents a cylinder head that was "flow bench ported" by a well known U.S. motorcycle performance tuning company. 

 The Blue Line shows that enlarging the stock intake ports a small amount, caused this engine to lose power throughout the entire power curve.

The good news is, The Red Line shows that after fixing the "flowbench ported" head by  making the ports 35% smaller... this CBR 600F3 gained more than 10 HP !!

Since The Blue Line's head ports were already "flowed out" even bigger than stock, there was about an extra 3 horsepower recovered.

In this case, a stock head would have worked better than the flowbench ported head. 

Flow Bench Porting usually costs 
around $500 - $1,000 ...  

,It's a total waste of money !!
 This dyno graph dramatically shows the power loss caused by lowered intake port velocity:


Note: 
The difference at the beginning of this dyno graph is because the dyno operator opened the throttle for the red run at a later rpm point than the blue run. 

The comparison isn't accurate until both runs are at full throttle and full power, which is at about 35 mph on the graph.

" It's Time Somebody Did Something About Bread !! "

  Warning: Bread is Evil.

1) More than 98 percent of convicted criminals are bread eaters !

3) In the 19th century, when virtually all bread was baked in the home, the average life expectancy was less than 55 years; infant mortality rates were unacceptably high; many women died in childbirth; and diseases such as typhoid, scarlet fever, smallpox and influenza ravaged entire nations !

4) Statistics show that more than 75 % of violent crimes are committed within 24 hours of eating bread !

5) Bread is made from a substance called "dough." Researchers have proven that as little as one pound of dough can choke a large animal like a horse. The average person eats more bread than that in one month !

6) Bread is known to be extremely addictive. Subjects deprived of bread and given only water, actually begged for bread after just two days !

7) Bread is a "gateway" food item, which usually leads to such items as butter, jam, peanut butter and even ... bacon !

8) Bread has been proven to kill. Scientists have now uncovered alarming evidence that 100% of the people who eat bread will eventually die !

9) Unattended newborn babies can choke on bread !

10) Bread is baked at temperatures as high as 425 degrees Fahrenheit ! Don't laugh...that kind of heat can kill a full grown adult in less than five minutes.

11) 96 % of cancer victims eventually admit that they've eaten bread !


12) Sadly, 9 out of 10 bread eaters are unable to distinguish between significant scientific fact and meaningless statistical babbling.

                               (Not Critical Thinkers Like You !!)

Misinformation
One could argue that every one of these individual "factoids" about bread is "true."  The way the "factoids" compare bread with danger, and the use of official - statistical -  scientifical sounding words cause the unthinking reader to make connections of logic that aren't true. 
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The only one that's mostly true is #12. 
The others falsely imply new information that really isn't there !!

(The very real problem is that much of the information in our modern society is presented this way.)
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