Hey guys, sorry its not actually for a Torana but I believe someone on here would be able to help... it would be for a EFI Turbo 4cyl
Does anyone know of any good websites/articles/books/dvd's etc etc with good indepth info on designing a custom intake manifold?
interested in
Pleneum Size/Shape
TB Size
Intake runner size/length/taper
Bellmouths
Cheers
Intake Manifold Design?
Started by
_Viper_
, Mar 02 2009 11:06 PM
16 replies to this topic
#2
_jap-xu1_
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Posted 03 March 2009 - 12:13 PM
for all the bits needed to make one call my mate steve at jnt performance. 0242571000
#4
_Viper_
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Posted 03 March 2009 - 10:21 PM
Thanks Jap-XU1... so no one has any info on actual designs? Ive got my basic shape just want to know the required volume of the plenum as well what I should make my runner lengths/diameter
#5
FastEHHolden
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Posted 04 March 2009 - 12:02 AM
1.5 times engine volume
#6
_Terrible One_
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Posted 20 March 2009 - 06:22 PM
I've heard guys going as big as twice the engine volume but that's for massive HP applications, for a road car I think 1.5 times engine capacity would be fine.
#7
_2X044_
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Posted 24 March 2009 - 05:01 PM
I would personnally recommend a book called "Maximum Boost" by a gent called Corky Bell.
As far as I can remember without pulling the book out (as I will tongiht).
The intake plenum serves two main tasks.
1) Slow down the intake charge sufficiently to allow even filling of all cylinders (not preferential filling of those close to the throttle body).
2) Provide a reservoir of air for each cylinder to draw from without significantly reducing the pressure in the plenum.
While I'll be the first to admit there is no such thing as a free lunch, running a turbo removes much of the benefit of a "tuned" intake system. While an ideal NA motor may have a volumetric efficiency of just over 1 a boosted motor will have a volumetric efficiency far greater than 1 or 2 or 3 depending upon boost level.
As far as plenums go. Larger is generally better however and I'm sure this site is full of people that say that lag sucks (NA motor = 100% lag) the larger the plenum the greater the time it will take fill (put your foot down a quarter of a second earlier).
There is a property called the Helmholtz resonance of a system that has some affect however I can not remember the details off the top of my head.
Cheers,
Peter
As far as I can remember without pulling the book out (as I will tongiht).
The intake plenum serves two main tasks.
1) Slow down the intake charge sufficiently to allow even filling of all cylinders (not preferential filling of those close to the throttle body).
2) Provide a reservoir of air for each cylinder to draw from without significantly reducing the pressure in the plenum.
While I'll be the first to admit there is no such thing as a free lunch, running a turbo removes much of the benefit of a "tuned" intake system. While an ideal NA motor may have a volumetric efficiency of just over 1 a boosted motor will have a volumetric efficiency far greater than 1 or 2 or 3 depending upon boost level.
As far as plenums go. Larger is generally better however and I'm sure this site is full of people that say that lag sucks (NA motor = 100% lag) the larger the plenum the greater the time it will take fill (put your foot down a quarter of a second earlier).
There is a property called the Helmholtz resonance of a system that has some affect however I can not remember the details off the top of my head.
Cheers,
Peter
#8
_Viper_
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Posted 26 March 2009 - 10:56 PM
Thanks pete, thats exactly the sort of info im after... would you happen to know where I could get the book from? I checked pitstopbookshop but no good :(
Or if its not easy to get could I possible borrow it? (im in perth too) will buy you a carton or whatever you thinks fair
Or if its not easy to get could I possible borrow it? (im in perth too) will buy you a carton or whatever you thinks fair
#9
_Viper_
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Posted 26 March 2009 - 10:59 PM
Oh wait I did find it on pitstop was just in the wrong section
was just in the wrong section
#10
_Viper_
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Posted 28 March 2009 - 06:59 PM
Thanks for the books pete, Had abit of a read through the intake sections, some good info and answered alot of my questions 
even things I didnt think of... Should be able to fabricate a very efficient intake now
even things I didnt think of... Should be able to fabricate a very efficient intake now
#11
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Posted 28 March 2009 - 07:02 PM
Oh one thing im not sure of... I know how to tune the runners to a specific rpm, but uh how do I know what rpm I want to tune it to? I supposed its based on what I want to do with the car... all out top end or more Torque. But say I want it to be mainly a street car and rev to a max of 6500-7000rpm Should I tune the runners to be at say 4000rpm?
I suppose it will also have alot to do with my cam as well right?
I suppose it will also have alot to do with my cam as well right?
Edited by Viper, 28 March 2009 - 07:03 PM.
#12
Heath
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Posted 28 March 2009 - 09:09 PM
As long as the cam is properly on power at 4,000rpm, I can't see why that would be bad. I would be more inclined to tune it to a ~4,500 so everything peaks at the same time a bit better, but I imagine it wouldn't make a huge difference.
#13
_Terrible One_
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Posted 29 March 2009 - 06:58 AM
Build the parts to make the most torque, hp is a by product of torque!
Seeing its a 4cyl you dont want the power to only be 6-8000rpm etc, if you could shift the meat of the power range down further it'll be more drivable. May not make the same peak hp but it'll be a quicker car all round.
Seeing its a 4cyl you dont want the power to only be 6-8000rpm etc, if you could shift the meat of the power range down further it'll be more drivable. May not make the same peak hp but it'll be a quicker car all round.
#14
_Terrible One_
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Posted 29 March 2009 - 07:02 AM
Build the parts to make the most torque, hp is a by product of torque!
Seeing its a 4cyl you dont want the power to only be 6-8000rpm etc, if you could shift the meat of the power range down further it'll be more drivable. May not make the same peak hp but it'll be a quicker car all round.
Seeing its a 4cyl you dont want the power to only be 6-8000rpm etc, if you could shift the meat of the power range down further it'll be more drivable. May not make the same peak hp but it'll be a quicker car all round.
#15
_2X044_
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Posted 30 March 2009 - 10:07 AM
No probs mate.
What rpm do expect to be your boost threshold to be?
What do you want to use the car for?
Some people like to use the intake manifold to help them to accelerate the motor to above the boost threshold and thus would aim somewhere below that rpm.
It is interesting to note that Ford saw no benefit in retaining the dual length switching inlet manifolds on there XR6T motors and have only used the shorter runners. They do however have a boost threshold of 0rpm (exagerations).
Quote from Julian Edgar interviewing Ford Engineer: http://autospeed.com...04/article.html
What rpm do expect to be your boost threshold to be?
What do you want to use the car for?
Some people like to use the intake manifold to help them to accelerate the motor to above the boost threshold and thus would aim somewhere below that rpm.
It is interesting to note that Ford saw no benefit in retaining the dual length switching inlet manifolds on there XR6T motors and have only used the shorter runners. They do however have a boost threshold of 0rpm (exagerations).
Quote from Julian Edgar interviewing Ford Engineer: http://autospeed.com...04/article.html
Why was the atmo Falcon 4.0's dual stage intake dropped for the turbo engine?
"Well, when you're forcing air into the intake you don't actually need those variable inlet characteristics - it doesn't do anything for you. The harmonics within the runner lengths don't work when you're on boost but, having said that, I think it would have been nice to have a smaller intake manifold volume. With a smaller manifold we would have got better response because you can fill it up quicker - we just didn't want to change from what we already had. We've taken away the dual stage butterflies, though - they were a complication doing nothing for us."
#16
_Viper_
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Posted 31 March 2009 - 11:13 PM
Not sure yet, Im still yet to choose a turbo... still learning all this stuff but after reading the book have learnt how to read compressor maps and ill have to workout the flow of the new motor n choose a turbo and work out the boost threshold.
But its going to be a street car mainly so wanna keep the max revs to about 6500 and have power from 3000rpm...
From what I read in the books i'll benefit from longer runners which will give more low down torque and the turbo will take care of the top end?
But its going to be a street car mainly so wanna keep the max revs to about 6500 and have power from 3000rpm...
From what I read in the books i'll benefit from longer runners which will give more low down torque and the turbo will take care of the top end?
#17
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Posted 14 April 2009 - 10:36 PM
"tuning the A series engine" by David Vizard is an excellent start for non-crossflow inlet design.
"How to Build HP Vol 2" has info on varying inlet runner diameter and lengths. he's had HUGE success with big HP VTEC engines in the states. anyway the key to a good "cold side" (as the yanks like to put it) is runner VOLUME - not length. make a coffee and read this - it'll change your perspective on the old black EFI manifold!!!
this is also a good book .
this is a good calculator.
for an NA application your plenum should be 1.5x the capacity of your engine - for turbocharged/supercharged it should be twice the capacity - as a very basic rule of thumb in OZ.
tapering the plenum from throttle body to the rear cylinder works very well - both honda and toyota can't be wrong here.
hope i haven't made anyone's head explode - this is truly interesting stuff to me and i'm currently testing this out on a turbo'd blue 202 for a friend before i move to my 202.
enjoy
"How to Build HP Vol 2" has info on varying inlet runner diameter and lengths. he's had HUGE success with big HP VTEC engines in the states. anyway the key to a good "cold side" (as the yanks like to put it) is runner VOLUME - not length. make a coffee and read this - it'll change your perspective on the old black EFI manifold!!!
II. CALCULATIONS
How do we calculate and design the IM dimensions so that the stacked columns of air waves arrive at a certain rpm ?
There are 2 ways to calculate the dimensions for an IM. Using:
1. Variable length runners formulas
or
2. A Helmholtz resonator method
II A.) Variable Length Runners Formulas
From the header tech article you have learned that longer tubes create peak torque at an earlier rpm. This is true whether you are looking at air flow in terms of a fluid or in terms of a sound wave.
By choosing the length and diameter of the runners, an intake manifold can be "tuned" for optimum performance at a certain RPM range.
Longer, narrower runners favor lower RPM's because they have a lower resonant frequency, and the smaller diameter helps increase the air velocity.
Shorter, wider runners favor higher RPM's because they have a higher resonant frequency, and the larger diameter is less restrictive to air flow.
...Choosing the right length and diameter of the intake runners is a trade off between high and low RPM performance.
Some more in-depth stuff.
1. / One Formula: David Vizard's Rule for IM Runner Length
The general rule is that you should begin with a runner length of 17.8 cm for a 10,000 rpm peak torque location, from the intake opening to the plenum chamber. You add 4.3 cm to the runner length for every 1000 rpm that you want the peak torque to occur before the 10,000 rpm.
So, for instance, if peak torque should occur at 4,000 rpm the total runner length should be 17.8 cm + (6 x 4.3 cm) = 43.6 cm.
Vizard also suggests that you can calculate the ideal runner diameter by the equation :
SQRT [ (target rpm for peak torque x Displacement x VE)/ 3330 ]
SQRT = square root
VE = Volumetric Efficiency in %
Displacement in Liters
SQRT [ (5800x 1.8 L x 0.95)/3330]
= 1.73 in. or 43.8 mm (1,73 x 25.4 mm/in.) is the ideal runner diameter.
2./ Another Formula to Calculate Runner Length for a Specific Peak Torque RPM: from Steve Magnante at Hot Rod magazine
N x L = 84,000
where N represents the desired engine rpm for peak torque and L is the length in inches from the opening of the runner tube to the valve head.
II B.) Helmholtz Resonator Calculations
Remember at the start of the article I mentioned that the dimensions of 3 parts of an IM can affect where peak torque can occur? Well here is another way we can calculate estimates for our IM dimensions for the peak torque location we want.
A Helmholtz resonator is an acoustic resonance chamber (as described by our plenum above) that modifies the acoustic frequency of a sound wave like a spring oscillating with a mass attached on the end.
where f = the rpm at which you get peak torque ( the natural frequency of pressure oscillations in the acoustic chamber ) , c = the speed of sound (= 340 m/sec.) , S = runner area, L = runner length, V = displacement per cylinder
A simplified version of this is using the Englemann formula for the above which also takes into account static CR of the engine:
RPM for peak torque =
642 x c x [ SQRT (S/[L x V] ) ] x [ SQRT { (CR-1)/ (CR+1) } ]
= 218,280 x [ SQRT (S/[L x V] ) ] x [ SQRT { (CR-1)/ (CR+1) } ]
For a more detailed explanation on the application of Hermann Ludwig Ferdinand von Helmholtz's acoustic resonator theory applied to intake systems, please check out:
http://enaf1.tripod....teche.html#helm
http://www.mecc.unip....suonatore.html
A Helmholtz resonator is used not only in an automotive induction sytem but also in the designing of exhausts to suppress sound and many other non-automotive designing that involves amplifying sound like in the music industry.
III. RAM INTAKE TUBE DIMENSIONS
What are the best intake tube dimensions for the IM that we have just designed for a particular peak torque rpm?
III a./ INSIDE DIAMETER (D) of a RAM INTAKE TUBE
First Method:
D in inches = SQRT [ ( Displacement x VE x Redline) / (V x 18.5) ]
Displacement = Total Displacement in Liters, VE = Volumetric Efficiency in %, V is the velocity of the air flow in the IM plenum for resonance (usually estimated at 180 ft/sec max.)
eg. SQRT [ (1.8 x 85 x 8500) / (180 x 18.5) ]
= SQRT [ (1,300,500)/ (3330) ]
= SQRT (391)
= 1.98 in.
Second Method:
Throttle Body Size is Determined by IM Plenum Size.
from the Dave Thompson of Thompson Engineering and Endyn: http://www.theoldone....old-design.htm
The plenum volume is critical on N/A engines, and a basic rule of thumb is: The smaller the plenum, the lower the rpm range, and bigger means higher rpm. The throttle body size and flow rate also affect the plenum size: Bigger TB, smaller plenum, small TB, larger plenum.
The best way to find out if your TB is too small for your IM plenum is to determine what the intake manifold absolute pressure (MAP) sensor is reading (in the plenum) when you are at full throttle ( or wide open throttle (WOT) ) while the car is accelerating using a datalogger. The MAP should be equal to, or close to, atmospheric pressure. If it isn't or there is a MAP drop at WOT, then your TB is still too small.
Once we have determined the optimal TB size for our IM, we can then determine the best intake inner diameter.
The ideal diameter for an intake is when the intake has 25% more cross-sectional area than the TB's bore cross-sectional area . Your TB diameter (overbored or not) dictates your intake diameter.
Remember that the area of a circle (your TB bore) is pi x radius squared and the diameter = 2 x radius. If you calculate your TB's area and then multiply it by 1.33, you will determine the intake's area. Then, use the area of the circle equation to determine the intake's radius.
Therefore, for example, with a 64mm (plate side bore) TB, the calculated "best" intake diameter is 2.8 in. ID.
III. b/ LENGTH OF RAM INTAKE TUBE
A suggested starting point for the length of a tube with peak torque at 6000 rpm is 13 in.
You add 1.7 in. for every 1000 rpm that you want to move the peak torque below 6000.
Or subtract 1.7 in. for every 1000 rpm you want to move the peak torque above 6000.
this is also a good book .
this is a good calculator.
for an NA application your plenum should be 1.5x the capacity of your engine - for turbocharged/supercharged it should be twice the capacity - as a very basic rule of thumb in OZ.
tapering the plenum from throttle body to the rear cylinder works very well - both honda and toyota can't be wrong here.
hope i haven't made anyone's head explode - this is truly interesting stuff to me and i'm currently testing this out on a turbo'd blue 202 for a friend before i move to my 202.
enjoy
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