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Engine Specific Info and Questions => IDI Engine => Topic started by: regcheeseman on November 05, 2010, 04:48:51 am
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Just trying to clarify a few things about twin plenum design, with reference to my high quality CAD drawing...
(http://i492.photobucket.com/albums/rr281/regcheeseman/twinplenuminlet.jpg)
The plate in blue that divides the two chambers is slotted, should the slot be tapered as shown or should it be parallel? Should the area of the slot be equal to the area of the single pipe coming from the intercooler i.e about 5 sq inches?
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I would contact the AKI76 guy. He made mine and it is definately parrallel, but no idea on the area of it.
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I've sent him questions in the past and received nothing... :(
Reading through 'TurboJ's' Jetta thread, you are suggested as the man to talk to.
I'm building a motor up based on a 1.6 bottom end, VNT turbo and a 10mm headed pump.
Currently I'm thinking of using the original 1.6GTD head (with a little flow work) unless a 1.9 head turns up or do you believe the 1.6head is adequate for 150bhp?
I have either a NA 1.9 or NA1.6 inlet manifold and was thinking of using the 1.6 one and building a twin plenum chamber inlet manifold.
Do I keep the long runners or shorten them to limit low down torque?
Are each plenum volume = 1600cc or greater
And the tapered slit between chambers? How big? how tapered and does the taper get narrower nearer the intake pipe connection?
I'd really appreciate any help you could offer me with this project or pointing out someone or something (book/internet) that will help.
Thanks
Regcheeseman
Sent sept 7 2009 - shows how long this has been on the 'back burner'
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(http://c3.ac-images.myspacecdn.com/images02/71/l_3137b0d632e44f39bae01944282d5ea2.jpg)
There is the one I am not using until I get a VNT. IIRC AKI said something about it is a ratio of the inlet pipe, but i don't know how much. I woud guess that it is right around the piping area or maybe just a bit more.
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Thanks for that, I've seen that pic before I think, and I still had to look twice before I could tell that the slot was actually parallel - the shadow makes it appear tapered.
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I think Andrew hit it on the head. A large volume single plenum like the passenger performance intakes is the best DIY without some proper maths. If anyone has access to a SolidWorks workstation with the flow works add on you can do some pretty great modeling like this very easily.
(http://www.google.ca/url?source=imgres&ct=img&q=http://bmcrace.com/Manifolds/Intake-Manifolds/cfd/Stage2asis/Primary3.jpg&sa=X&ei=dTjUTL_THYj2tgOU6KWQCw&ved=0CAQQ8wc46AE&usg=AFQjCNFF51kHCBKOaEQAP2JyKrFBqpj0-g)
On a side note, check out the intake restrictors on those turbo's!!
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Pretty picture...sadly I've forgotten everything I used to know about flow or FEA.
Well, almost everything. Next time you're at a fancy-smancy resturant... one where their idea of ambiance is to remove the ceiling tiles and spray paint everything flat black... have a look at the HVAC while you're waiting for your lobster bisque. If the air distribution pipes are long enough you'll probably find that they are stepped down in diameter gradually as the air is distributed... on purpose to help keep the velocity consistent as the pressure decreases.
Makes you wonder a little about how much you actually gain by slapping on a gasser manifold or anything else with "straight pipes"?
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I know very little about this myself, but I do know that Aki asked many questions to get an idea of how to build it for me.
He asked what I was going to go for upper boost wise. Intercooler piping size. If I was going to put a different cam in it. Daily or drag race, or road race type of driving. Then all the obvious questions like what engine, pump, car, etc. He asked all of that for some "math" equation that he had to plug them into to get to come up with pipe size, size of the slit, and something about the 2nd plenum.
You could probably achieve the conical effect on the inside and still make the outside look like a regular pipe.
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Pretty picture...sadly I've forgotten everything I used to know about flow or FEA.
Well, almost everything. Next time you're at a fancy-smancy resturant... one where their idea of ambiance is to remove the ceiling tiles and spray paint everything flat black... have a look at the HVAC while you're waiting for your lobster bisque. If the air distribution pipes are long enough you'll probably find that they are stepped down in diameter gradually as the air is distributed... on purpose to help keep the velocity consistent as the pressure decreases.
Makes you wonder a little about how much you actually gain by slapping on a gasser manifold or anything else with "straight pipes"?
Gasser intake runners are far from straight. they are VERY tapered.. they are FAIRLY HUGE at the plenum..
or were you talking about some other sort of "straight pipes"?
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Yeah, poorly worded, what I was trying to describe is the 4 identically-sized runners (tapered or not) that come straight off the main plenum.
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The purpose to the dual plenums is to reduce the turbulence going into the second plenum and evenly distribute the air to the individual runners. My imagination tells me that without the diminishing cone compensating for the loss of pressure from the initial air flowing into the second plenum, the result would be added turbulence in the second plenum and unequal pressure to the runners. I also imagine that the plenum being straight and the slit being larger toward the inlet would be highly detrimental as it would allow excess air in at the highest pressure area and very little air in where the pressure would be least and the slit smallest. It would seem to be better, if the initial plenum is a "cylinder" rather than cone, that the slit should be smallest toward the inlet and largest toward the later runners in order to compensate for the pressure loss across the initial plenum. Designing the initial plenum to be an appropriately sized cone would be easier and more effective. I've also been of the opinion that without knowing what the goals were and the design parameters and calculations to achieve those goals one could easily cause very little benefit and possibly cause more harm as good. I suspect that many DIY dual plenum intakes are of the "wing it" design and their effect is questionable. Not to criticize AKI in any way (his efforts are very remarkable) but before I emulated his intake design in any way I'd want to know what calculations he used for the design and how he arrived at using those calculations and so far, despite seeing several people on this board ask, zero info on calculating the size/shape of the plenums/runners has been provided.
A couple of things -
> the area of the slot should be LESS than the inlet pipe area. This is because we want the first plenum to be "pressurised" compared to the second one.
> the diminishing cross sectional area of the first plenum that we see on the audi race engines is ideal, but tricky to make
> the way you have described the "slot width relationship" is not correct. The thing you need to remember is that the air mass has plenty of velocity, and hence, inertia. Lets imagine there was no slot, just a single plenum (like a gasser manifold). This design will almost certainly preferentially feed the cylinder furthest away from the inlet pipe so some extent. In reality, to try to balance the flow by changing the slot geometry, you need to minimise the area of the slot at the end furthest from the inlet, and maximise the area at the end nearest the inlet.
In the other thread with my manifold, I have make the slot area 85% of the inlet pipe area, so as to ensure that the first plenum is pressurised compared with the second. This is effeectively the same as reducing the velocity of the air, and hence the iniertia. This means any feed preference due to the inertia of the inlet gasses is minimised.
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I have not calculated my runner lengths. They are just as long as they are.... I don't think its vital for my application to "tune" them to a certain length because all I'm really trying to do is improve over the standard aaz manifold, which has no runners at all to speak of.
As far as the total slot area parameter - I managed to get a guy on another forum who was building a 2.5 5 cyl TDI drag engine (for a transporter no less :-) to tell me how he calculated the size of the slot area.
As far as the information I gave about inertia and feed preference - this is based on a bunch of thinking that I did a while back when I was thinking about making a manifold, and I spoke to a colleague of mine who did a lot of work in fluid dynamics with our CSIRO (Commonwealth Scientific & Industrial Reseach Orgasnisation). Basically it became obvious that the fluid inertia is the biggest problem, and that keeping that in mind, what you need to try and do is make flow through the slot the same velocity from one end to the other, if it is parallel.
I imagine that the better the primary plenum design is, the closer in area the slot can be to the inlet piping - so you achieve better flow. I have made my slot that much smaller than the inlet pipe because my primary plenum design is poor.
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You could split the IC piping 4 ways equally and then put a dual plane on each cylinder???
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You could split the IC piping 4 ways equally and then put a dual plane on each cylinder???
EDIT... I haven't actually drawn it yet!But my description is clear as ever ;D
Haha,
I've just downloaded a 'free' CAD to draw my 'same' idea.
'Tiger CAD'
http://www.freewarehome.com/index.html?http%3A//www.freewarehome.com/Graphics/Drawing_and_CAD_t.html
On the straight part create an adaptor that goes one into four then with gentle curves, tubular runners into simple flanges.
IMO, the problem with the balanced slit, which would give equal pressures along the chamber, is the actual pressure drop across.
The crude [no disrespect intended, I wish I could weld like that ;D] blunt cylinder must suffer from lots of turbulance and 'dead' or even very much alive and interfereing air.
The nice AUDI cone feature reduces that, but still has to be a resistance, to perform.
Compare with the equivalent sharp 90 degree bends, like in cheap modern central heating which are terribly inefficient and create hammering when taps are opened. [Contrast with the earlier "good ole days's" central heating's swept bends]
Likewise, the laminar flow you and I envisage must be better, and easier to construct.
Perhaps a little home casting to make the one into four.
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Andrew,
Your right, I know my "references" are poor ones. I don't want to "toot my own horn" so to speak.... I don't know what training you have, or what you do for a living, but I know my own training and my own expertise, and I know other people with expertise that may or may not be pertinent to this subject. I can't give you any hard references about what I have said about the fluid dynamics, all I can say is that my education and training allowed me, upon investigation myself over the past 12-18months on this subject, to speak with people who's job it is to know fluid dynamics, and understand the how's and why's about turbulent flow through these types on pipe/chamber arrangements.
I am a university trained mechanical engineer, and I work as a mechanical engineer, but I do not work in fluid dynamics, so I can certainly say I'm NOT an expert on it. But, like I say, I know people who do work in this field and asked them about it. My own training merely gives me the capacity to more easily understand the explanations I seek. At the end of the day, this is my weekend tinkering hobby, not my job, so I'm never too careful about writing anything down because... I'm lazy. It all just sits in my head.
Now, I should have been a bit more tactful when I stated that something you wrote was "not correct" - especially given all of the above. However, if you would like me to try and explain why I said what you wrote was incorrect, please reply to this post and I'll go about it to the best of my ability. One piece of "evidence" (or lets say interesting data) I might look to, to try and explain, is a reply to my thread about the stock manifold, referencing bent conrods.
Cheers :-)
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OK.
Introduction to fluid mechanics, 6th ed, Fox, McDonald, Pritchard. Chapter 12 - Compressible Flow - Subsonic Flow -
"In a converging section [a reduction in area, if you like] pressure must decrease, and velocity must increase" - This principal should be known to us all - like a venturi - a reduction in area of the pipe causes the fluid to increase in velocity and decrease in pressure (Bernoulli Principle). The reverse is also true - "a diverging channel must lead to a pressure increase and a velocity decrease" - a subsonic diffuser.
What does this mean for us? I'm still thinking about it now actually....but put it this way - try to keep that relationship in mind when you think about the fluid flow through transitions in cross sectional area, and what it might mean.
As for calculations, the time may come, but its not an attractive option for me as it means solving many many high order couple simultaneous equations... so i would need to write a matlab program at least....
All I can really say libby is that you've made me dig out my books, and now I'll have to do the bloody thing properly instead of just living in my happy little world of ignorence.
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Books on fan/ventilation engineering, rare, sometimes pricey, but a good read, cover much. Bernoulli never used a right angled elbow to demonstrate his theories did he?
I thought in trying to get the most out of the engine, creating inline resistances were things to be avoided.
Why not make the slot enormous and stick a coarse filter across to remove swirl perhaps like scotchbrite...
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ive got another to add question/idea..
why not add a intercooler directly to the runners and cone shape the end cap where the turbo feeds in?
reason...
mk1 jetta coupe, has ac and keeping ac with my tdi-m build. no matter what i have to make a hole in my hood to do a intercooler set up as is..
figure in a 2 piece design, add a flange at the runners going into the inter cooler, so can be removed easily so the valve cover can come off. there is enough 16v manifolds in junkyards for the flanges IMO..
you can also then have a factory gasket for the flange too, then add in the 45mm ish hole size of that to the runners you could build them into velocity stacks also.. aka big hole feeding into small hole..
yes i have thought it out.. just wonder why i see no one else try this
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for normal street driving, the charge air tubing should be made small enough, to get faster throttle response. 50mm or even 45mm tubing should be good for under 250hp. when planning the dual plenum intake manifold dimensions, the charge air tubingdimensions shoud be also considered. It's very important to avoid unnecessary increases/decreases in charge air tubing diameter.even the ic should have the right size inlet/outlet but sometimes it is not possible.about the dimensions of the first plenum: the diameter should be the same as thecharge air tubing, and the length the same as the second plenum.the area of the groove using 50mm tube should be 19.5-20cm^2, rounded up. In a 30cm tube this means about 6.6mm wide groove which is rounded up to 7mm.earlier it has been said that the groove should be smaller, but I disagree. The same size or slightly bigger.this applies to street-driven engines, racing engines have slightly differentdimensioning.
Hopefully this helps a little.
:D
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for normal street driving, the charge air tubing should be made small enough, to get faster throttle response. 50mm or even 45mm tubing should be good for under 250hp. when planning the dual plenum intake manifold dimensions, the charge air tubingdimensions shoud be also considered. It's very important to avoid unnecessary increases/decreases in charge air tubing diameter.even the ic should have the right size inlet/outlet but sometimes it is not possible.about the dimensions of the first plenum: the diameter should be the same as thecharge air tubing, and the length the same as the second plenum.the area of the groove using 50mm tube should be 19.5-20cm^2, rounded up. In a 30cm tube this means about 6.6mm wide groove which is rounded up to 7mm.earlier it has been said that the groove should be smaller, but I disagree. The same size or slightly bigger.this applies to street-driven engines, racing engines have slightly differentdimensioning.
Hopefully this helps a little.
:D
Aki,
if you use 50mmID tube, the area is 1963mm^2. If you have a 7mm slot width, that is 260 long (which is the length of the plenum on my design, and about the same on others of these 4 cyl vw ones) then the area is 1820mm^2. This is smaller!
Andrew,
Don't hold your breath on the book :-)... I may be a while
I don't have any hands on experience with solidworks, but I've never heard of it in the context of a flow dynamics program. There is however a VERY good program made by Ricardo (who would have guessed? hehe) but I don't know of its availability to the GP. I will look into the solidworks side of things, it might be interesting. I would be curous to see how what maths it uses.
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I have an older version of Solidworks as well, a semi functional student version. It's got CFD in it, but unfortunately I can't get it to work, my program keeps crashing. I was even trying to run a simulation on a dual plenum intake with it :D
It's fairly simple setting it up; there's a good walkthrough in the help files, so if you have a copy of solidworks, making the model of the intake will be the toughest thing.
I've been reading this thread from the beginning... I have a general understanding of fluid dynamics but have definitely learned a few things here. Somewhere on the interwebs, there is a 30+ page thread on someone designing/building a dual plenum intake for his car and having CFD simulations run on it all. The one reocurring theme I saw with every incarnation was that it was somewhat unpredictable; as is a lot of fluid dynamics as far as any of us can calculate. I'm not trying in any way to say it's a moot point that it shouldn't be discussed, but short of dyno testing (even with EGT probes on each cylinder?) and/or CFD running many simulations we can't prove anything and shouldn't get too worked up over it :)
I'm searching for that thread; IIRC, the guy running the simulations was a mech engineer working with fluid dynamics so there was a lot of good info in that thread. I should've bookmarked it!
One idea I had for an intake that was briefly mentioned earlier is running a proper merge collector near the injection pump, then running parallel charge pipes over the valve cover, each going into the middle of a plenum for two cylinders and runners dropping down from that. I'm still tempted to try to build it, that's the way I would most likely go if I was building an intake mani. It may not be the most perfect design, but I think it would be the easiest way of getting similar flow to each of the 4 cylinders.
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RadoTD - I agree, CFD is a bit of a dark art. There are applications where CFD works well, and others where it becomes more theoretical - mainly because of complexity.
The real world situation is so complex, with a variable frequency/position outlet port that has a transition from open->shut->open again, and on the inlet we have a more continuous supply....
Not only that, but depending on the design of it all, the the operational envelope, sometimes there may be some laminar flow, but mostly there would be turbulent flow. All these factors change the mathematics, and any model we make is ofcourse based on assumptions, that may or may not be correct.
When speaking on this subject with my associate, he said to me "just the shear fact that the plenum feeds to only one port at a time makes it difficult to get it really wrong - this is why VW can get away with such a seemingly thoughtless design".
There comes a point where you just throw your hands in the air and laugh at the the complexity of it all....
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the diameter should be the same as the charge air tubing, and the length the same as the second plenum.the area of the groove using 50mm tube should be 19.5-20cm^2, rounded up.
Aki, thanks for that. It's exactly how I will do it. you've also confirmed that whilst not 'scene friendly' my 2" pipework will be fine for practical applications.
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In that same thread I still can't find (but I swear it exists!) there was a chart that listed pressure drop given different sizes and airflow. I remember grazing this subject once, the name guy who came up with the law/equation started with a P I think
But anyway, I googled it and found an online calculator here http://www.engineeringtoolbox.com/pressure-drop-compressed-air-pipes-d_852.html
If you scroll to the second chart, that has 2" and 2.5" ID pipe listed with the flow values we're looking at. It's at 100psi initial pressure and 100m long pipe though, but it'll give you an idea. You can plug values into the second calculator up top to get reasonable values.
2" is probably the lowest I'd go; that's about where the pressure drops start climbing faster than you want it to.
For reference, 25psig, 300cfm, 10ft and 1.5" is 1.21psi, 2" is .29psi drop, 2.5" is .09psi. And 300cfm is about the most air you'll pump through these engines unless you're going nuts
I'm personally going 2.5", but you're not losing much with 2". 1.5" would be a different story...
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The tube diameter I don't look at as loss. I see it as how much extra air will the turbo have to compress to get it to spool with a bigger tube.
125.6 cubic inches is what I roughly figured for 2"
196.25 is same only 2.5" tubing
So you would have a little more cubic inches to fill up before the boost reaches the valve. That should increase spool time. From a daily driver stand point the smaller tubing should give better response, but all out racing or max flow you would probably want the bigger tubing. I think this is what AKI is refering to as well.
Same thing with the exhaust manifold. I am guessing if you had tubing the exact size of the exhaust ports and as short as possible to the turbo it would spool best. Not overall flow best but spool best. Then after the turbo the biggest tubing to make sure it doesnt' hold it back.
Just theories...like Andrew said earlier I probably am not helping clean the water, but muddy it more since I have no "proof positive" reference. Sorry guys just thinking out loud.
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but you're not losing much with 2".
depending on what else goes on, you might not be 'losing' anything at all. The pressure drop is greater than that of 2.5", but the gas velocity is much higher. Depending on a lot of different things, it might be better to have the higher velocity air.... Its all just so complex that the only way to say if one solution is better than another for a given application is to do a back to back test.
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Am I to understand that the consensus of opinion is that the larger the plenum the better? If that is so, why not start with a 1.6 N/A intake? If one boxed in the filter side one would have a very large plenum for the slot to feed. IIRC they have pretty straight parallel ports with a bell at the plenum end.
As for the tapered plenum dimensions, I think the photos have enough info to get us in the ball park. The length we know from the pics is just over the distance between runner 1 and 4. The inlet diameter appears to be the same as the inlet pipe diameter. It looks like about 3". The narrow end looks to be close to zero on the 4 banger and under an inch on the Audi motors. Some blown up prints and a protractor might help nail down the angle of the taper as well
If you used the N/A intake for a test mule you could fabricate the closure and second plenum to clip on like the black plastic N/A air cleaner housing. Probably not optimal but very quick to take apart for playing with slot dimensions while doing pulls on the "long hill dyno".
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Lots more photos here:
http://www.bufkinengineering.com/intake%20manifolds.htm
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I think im gunna try and make one of these for my AAZ also, only thing im not clear on is what size tubbing is going to be used for the runners?
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FWIW - the main reason most aaz users will want to go down this path is because the early intakes and gasser manifolds all mean you need to have the turbo mounted down low, which is a PITA on a mk3 with a T3 or other larger turbo.
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Remember the manifold I chopped up 12 months ago?
(http://i492.photobucket.com/albums/rr281/regcheeseman/Golf%20in%20progress/enginebits002.jpg)
well it got dragged off the back burner, cut open and filled with various detergents and put on the wok burner!
(http://i492.photobucket.com/albums/rr281/regcheeseman/Golf%20in%20progress/cookingmanifold.jpg)
That shifted all the clag out of the runners so I could get the bits welded on
(http://i492.photobucket.com/albums/rr281/regcheeseman/Golf%20in%20progress/P1030322.jpg)
Duel plenum inlet to balance boost across the cylinders.
(http://i492.photobucket.com/albums/rr281/regcheeseman/Golf%20in%20progress/P1030324.jpg)
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care if i copy the manifold for personal use?
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Sir, It would indeed be an honour.
:)
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THANK YOU!
im going to build one today.. i got plenty of gasser intakes..
im thinking the gasser manifold will probably work better right?
because i saw how dave cross built his, and he just used a stock 1.6TD manifold, but just the bottom half.. and then did just like what you did..
anyway, im gonna build me one!
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Well, lets see it..... ::).
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is the slot parallel or tapered? hard to tell from pic with my eyes
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Ok I was looking through this lot and thought I may be able to build one (not from 100% alloy, as the plenums would be thick steel) and I was wondering what are the real advantages of this design? at what point will an engine need one?
Looking at the design and Audi's inlets surely there wont be that much imrpovement, as on the audi it tapers down at one end??
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what are the real advantages of this design?
Take a look at the standard TD manifold. You couldn't design worse if you tried.
is the slot parallel or tapered?
Parallel - area equal to the intercooler pipe's bore area
I don't know what's up with the images....they were there?
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what are the real advantages of this design?
Take a look at the standard TD manifold. You couldn't design worse if you tried.
is the slot parallel or tapered?
Parallel - area equal to the intercooler pipe's bore area
I don't know what's up with the images....they were there?
Well I know what your saying, but vw must have had some design idea.
However I started having a look accross the tinternet and found some nice twin plenum designs arbeit not all for 8v application:
(http://www.usrallyteam.com/content/products/intake_manifold/cosworth/cossie_carbon_ports.jpg)
(http://www.usrallyteam.com/content/products/intake_manifold/cosworth/cossie_carbon_under.jpg)
(http://www.usrallyteam.com/content/products/intake_manifold/cosworth/cossie_carbon_inlet.jpg)
(http://www.usrallyteam.com/content/products/intake_manifold/cosworth/cossie_carbon_bottom.jpg)
(http://www.usrallyteam.com/content/products/intake_manifold/cosworth/cossie_carbon_back.jpg)
(http://i26.photobucket.com/albums/c112/leviplies/66.jpg)
(http://magnusmotorsports.com/wp-content/uploads/wpsc/product_images/intake_evo.jpg)
what does seem a common theme amoung alot of the manifolds for racing/high performance use is that they have a large inlet one end and the plenum, be one or two, seems to be tapered so the far end of the manifold is smallest.
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bottom manifold looks to be just a plain ol' SRI single plenum..
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bottom manifold looks to be just a plain ol' SRI single plenum..
It is a single plenum, but you can see the reduce size effect going on to even the pressure out even across a single plenum to even the pressure out.
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i played with this awhile ago. (kind hard to see).
rev1 no fins
(http://i34.photobucket.com/albums/d101/keatonstanley/junk/top.jpg)
(http://i34.photobucket.com/albums/d101/keatonstanley/junk/back.jpg)
(http://i34.photobucket.com/albums/d101/keatonstanley/junk/right.jpg)
Rev2 with fins(kind hard to see)
(http://i34.photobucket.com/albums/d101/keatonstanley/R2_Back.jpg)
(http://i34.photobucket.com/albums/d101/keatonstanley/R2_CUT_BACK.jpg)
(http://i34.photobucket.com/albums/d101/keatonstanley/R2_SIDE.jpg)
(http://i34.photobucket.com/albums/d101/keatonstanley/R2_TOP.jpg)
rev3 with fins (kind hard to see) and correct on center distentions
(http://i34.photobucket.com/albums/d101/keatonstanley/junk/4.jpg)
(http://i34.photobucket.com/albums/d101/keatonstanley/junk/6.jpg)
(http://i34.photobucket.com/albums/d101/keatonstanley/junk/1.jpg)
(http://i34.photobucket.com/albums/d101/keatonstanley/junk/2-1.jpg)
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Keaton I like the design of that!
Just a point though even though I am not an expert, would it not be better to have the end 25% of each end of the fin rows pointing outwards slightly? Or maybe the middle 50% straight and then the outer 25% of fines are all at slightly different angles, increasing as you near the end to truely direct flow to each port?
Is this something you could test? what software did you use?
Libbybapa, sorry if I had already covered ground covered by your post, even though I have scrolled through I obviously havent been paying attention!
I think for the most part I have been trying to understand the point of the manifold, followed by the gains achieved, I have a 1600NA that I was planning on bunging a Turbo on to create an 'ecoturbodiesel' which I have heard exists(apparently a turbo on whats effectively an NA engine) and because there is some time involved before I sort the engine out I thought it may be possible to build a manifold to increase effiecency further in the drive to build an MPG engine.
I think its probably better to copy an existing design from motorsport than guess! I can also understand how rather than a tapered inlet runner having a tapered slot may achieve the same idea. In some respects I also wonder if it would be as productive as to make a reverse of an exhaust header, where all pipes run together facing the incoming air rather than being 90deg to it.
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I have a 1600NA that I was planning on bunging a Turbo on to create an 'ecoturbodiesel' which I have heard exists(apparently a turbo on whats effectively an NA engine)
Your from the UK and this desire baffles me, the 1.6 ecoturbo as produced by VW was rubbish, as was it's 1.9 counterpart - there was nothing eco about it, you just had to drive it harder and thus use more fuel.
I've just fitted a 1.6 eco turbo in a caddy - thankfully I've now found a LDA pump for it
Why not go TDI if you want economy?
AS for the design of my manifold and the whole taper/no taper issue, I'd rather take a tried and tested design as used on a VW road car, than something designed for motorsport which has completely different requirements to mine.
Maybe I could have tapered the designs but I'm constrained by the reality of actually making the thing with hand tools alone and only basic material supplies.
As nice as the computer based hypothesising may look, I've had a Golf blocking my garage for 3 years now and would like to drive it !
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I have a 1600NA that I was planning on bunging a Turbo on to create an 'ecoturbodiesel' which I have heard exists(apparently a turbo on whats effectively an NA engine)
Your from the UK and this desire baffles me, the 1.6 ecoturbo as produced by VW was rubbish, as was it's 1.9 counterpart - there was nothing eco about it, you just had to drive it harder and thus use more fuel.
I've just fitted a 1.6 eco turbo in a caddy - thankfully I've now found a LDA pump for it
Why not go TDI if you want economy?
AS for the design of my manifold and the whole taper/no taper issue, I'd rather take a tried and tested design as used on a VW road car, than something designed for motorsport which has completely different requirements to mine.
Maybe I could have tapered the designs but I'm constrained by the reality of actually making the thing with hand tools alone and only basic material supplies.
As nice as the computer based hypothesising may look, I've had a Golf blocking my garage for 3 years now and would like to drive it !
well I want to find an LDA pump top, I have a good pump on my 1600NA and the engines alright (was in a caddy, a t25, then my bay van for a bit) now its spare and I want to have something that I can run on veg oil! I have a turbo kicking about which is a garret GT15 of a 1.7 astra van and from what I have read, you can just bung a turbo on and adjust the fueling as long as you dont go crazy, my fabrication is limited to grinder welder and steel fabrication. I was considering using the small White CO2 welding gas bottles to build the plenum from if there was an advantage.
Its more a case of not spending more than a gasket kit on my engine and building something thats efficient, doesnt have to be fast as such! I would say 1600TD would be fine for local driving and long distance cruising if running on veg. 1900TD would drop straight in my mk3, but then I'd have to go buy bits I dont already have :)
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I wanted to bump this topic as it kind of died off, I was wondering what software was used to generate the manifold and testing of airflow through it? The other curious question I have when generating a model like that is that based on natural air flow through it or a pressurised design?
The final thing on that model is do you have dimensions of it to build one?
I was also wondering, this slot in the manifold and general dimensions of building a dual plenum manifold, how do you calculate the sizes you need?
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how do you calculate the sizes you need?
you ask around, get a whole bunch of conflicting answers and then just do what you were going to do in the first place. ;)
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how do you calculate the sizes you need?
you ask around, get a whole bunch of conflicting answers and then just do what you were going to do in the first place. ;)
:lol: aint that the truth some times!
I mean I just figured I would work out the area of each inlet runner to the port (as they are circular on the inlet I am using) add all the areas together then divide that area by the approx length I want my slot which will then give me the height. I mean I just wondered if there was much more science behind it than that. I'm sure there are some answers on the internet somewhere.