INTAKES: What do you run or are building?
12-07-2014, 10:11 PM
#166
Rennlist Member
Thread Starter
Looks very nice! Similar to Corleone's and Refresh's. Should produce a very good improvement imho.
12-08-2014, 03:36 AM
#167
Three Wheelin'
Just going to throw this out there:
Curved inlet runners work "better" than straight inlet runners on 4V motors.
Straight inlet runners work "better" than curved on 2V motors.
If you want to understand why, get a glass of water and put some sugar in it.
The sugar falls to the bottom because it's heavier.
Now, briefly stir it with a spoon in a clockwise direction (or anticlockwise if you're in the Southern hemisphere)
Remove the spoon and watch.
If the sugar is heavier than the water, shouldn't it get thrown to the outside?
Cheers,
Mike
Curved inlet runners work "better" than straight inlet runners on 4V motors.
Straight inlet runners work "better" than curved on 2V motors.
If you want to understand why, get a glass of water and put some sugar in it.
The sugar falls to the bottom because it's heavier.
Now, briefly stir it with a spoon in a clockwise direction (or anticlockwise if you're in the Southern hemisphere)
Remove the spoon and watch.
If the sugar is heavier than the water, shouldn't it get thrown to the outside?
Cheers,
Mike
12-08-2014, 08:36 AM
#168
Racer
Join Date: Jul 2009
Location: Montreal
Posts: 329
Likes: 0
Received 0 Likes
on
0 Posts
Just going to throw this out there: Curved inlet runners work "better" than straight inlet runners on 4V motors. Straight inlet runners work "better" than curved on 2V motors. If you want to understand why, get a glass of water and put some sugar in it. The sugar falls to the bottom because it's heavier. Now, briefly stir it with a spoon in a clockwise direction (or anticlockwise if you're in the Southern hemisphere) Remove the spoon and watch. If the sugar is heavier than the water, shouldn't it get thrown to the outside? Cheers, Mike
12-08-2014, 01:03 PM
#170
Rennlist Member
Thread Starter
But what happens if I drink that water while flying over the Equator??
12-08-2014, 07:52 PM
#171
Three Wheelin'
And anyone who can explain the sugar behaviour is half-way to explaining the reason that curved runners are "better" for 4V motors.
There was an article in Cars and Car Conversions (a.k.a. CCC) many years ago. They tested an ITB injection setup on a Vauxhall motor using different manifolds and were amazed when the curved runner manifold (actually designed for carburettors) produced the same top-end power as the straight-runner manifold, but with 10% more midrange.
This was opposite to what they expected, and opposite to what they had seen on a BMW motor.
They couldn't explain it.
Of course, the Vauxhall motor was 4V and the BMW motor was 2V, and if they'd thought about that...
Cheers,
Mike
12-08-2014, 08:04 PM
#172
Addict
Rennlist Member
Rennlist Member
Why did porsche decided to use oval intake ports on 2.7 then?
12-09-2014, 12:25 AM
#174
Three Wheelin'
OK I'll stop being a jerk and explain.
The "sugar in a glass" experiment (has anyone tried it?) is also known as Einstein's tea-leaf paradox:
http://en.wikipedia.org/wiki/Tea_leaf_paradox
It is an example of secondary flow: http://en.wikipedia.org/wiki/Secondary_flow
Secondary flow in pipes is hard to visualise but is explained here: http://www.thermopedia.com/content/1...id=104&sn=1420
It can also be seen in flue gas when a wind is blowing:
Note the twin counter-rotating vortices.
Now: how is this relevant to an inlet manifold?
Well, swirl is known to be important to good torque, by providing efficient mixing of the fuel droplets, vapour and air prior to combustion.
And swirl starts BEFORE the intake valve. Any book on porting of cylinder heads discusses the importance of offset ports on 2V motors.
The effect is so valuable that various car manufacturers have come up with complex intake manifolds to achieve this:
http://www.autospeed.com/cms/article.html?&A=111513
http://en.wikipedia.org/wiki/Swirl_flap
But are these relevant to our motors? Well, probably not.
The fact is that a curved runner, by its simple geometry, creates twin counter-rotating vortices that separate off at the bifurcation in the head, and continue past the valve into the combustion chamber.
It's at the heart of the fondly remembered Suzuki TSCC principle: http://katriders.com/wiki/index.php5?title=TSCC
However the magic happens simply due to the bend in the inlet manifold.
That's why CCC picked up 10% more midrange torque over a straight-shot manifold (of the same length) with negligible change in topend power.
Cheers,
Mike
The "sugar in a glass" experiment (has anyone tried it?) is also known as Einstein's tea-leaf paradox:
http://en.wikipedia.org/wiki/Tea_leaf_paradox
It is an example of secondary flow: http://en.wikipedia.org/wiki/Secondary_flow
Secondary flow in pipes is hard to visualise but is explained here: http://www.thermopedia.com/content/1...id=104&sn=1420
It can also be seen in flue gas when a wind is blowing:
Note the twin counter-rotating vortices.
Now: how is this relevant to an inlet manifold?
Well, swirl is known to be important to good torque, by providing efficient mixing of the fuel droplets, vapour and air prior to combustion.
And swirl starts BEFORE the intake valve. Any book on porting of cylinder heads discusses the importance of offset ports on 2V motors.
The effect is so valuable that various car manufacturers have come up with complex intake manifolds to achieve this:
http://www.autospeed.com/cms/article.html?&A=111513
http://en.wikipedia.org/wiki/Swirl_flap
But are these relevant to our motors? Well, probably not.
The fact is that a curved runner, by its simple geometry, creates twin counter-rotating vortices that separate off at the bifurcation in the head, and continue past the valve into the combustion chamber.
It's at the heart of the fondly remembered Suzuki TSCC principle: http://katriders.com/wiki/index.php5?title=TSCC
However the magic happens simply due to the bend in the inlet manifold.
That's why CCC picked up 10% more midrange torque over a straight-shot manifold (of the same length) with negligible change in topend power.
Cheers,
Mike
Last edited by mikey_audiogeek; 12-09-2014 at 04:33 AM. Reason: typo
12-09-2014, 12:26 AM
#175
Three Wheelin'
Executive summary: http://katriders.com/wiki/index.php5?title=TSCC
It's all down to the curved intake runners (the venturi aspect is a red herring)
It's all down to the curved intake runners (the venturi aspect is a red herring)
12-09-2014, 08:45 AM
#176
Addict
Rennlist Member
Rennlist Member
Thanks, good read! 
12-09-2014, 08:52 AM
#177
Three Wheelin'
Finally i did some measurements on my intake!
Intake volume is 6.4 liters
Runner length; not quite sure where it is measured; on the top side it's 13.5cm and on the bottom side 7cm..
Intake volume is 6.4 liters
Runner length; not quite sure where it is measured; on the top side it's 13.5cm and on the bottom side 7cm..
