Intake Manifold Design

If the plenum under the SC was one piece and the runners were one piece instead of 8 I don't think you'd see much difference.
 
renopker said:
If the plenum under the SC was one piece and the runners were one piece instead of 8 I don't think you'd see much difference.
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My runners do go into a single plenum but yes I think I agree with you. It's much much more noticeable naturally aspirated

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Perhaps we open runners up, providing a more 'mass' influencial CSA of the runner? Albeit if we do enlarge them we would have to shortern the length wouldn't we to keep a wave tuned and have the reflections still be effective in the cam duration of IVO & IVC?
 
Anyone give any thought as to how much of a radii can be employed nominally for our air charge entering the runner? I have heard around a 1/2" is stable.
 
The point of runner style manifolds, where the port is contiguous to the plenum is resonance tuning. This goes hand in hand with cam timing. With Late closing intake events and zero overlap you have to use the runner length and taper, along with plenum size.
I have seen nothing but gains with proper length and taper. The biggest problem I have seen with most diesel intakes is that the runners are not tapered or even worse there are not contiguous from the valve seat to the plenum.
On most diesel heads the intake port is extremely small, and even when flow is doubled through porting, the air flow speed is incredible. So when the runner is not tapered you create air friction.
Here are a few of what I consider proper manifolds, one for the Cummins and one for the Dmax . notice both are full runner manifolds the last is a 3500 hp Pro mod motor



newmanifold-3.jpg


mw_duramax20104_zps738b1008.gif
12v_ir_manifold08-002-1_zps3216db99.gif






PROCHARGERPROMOD1-1.jpg
 
Greg - fact is - no matter what the intake valve events - those intakes do not meet any kinda resonance tuning under about 10,000 rpm - the runners are too short
it is also impossible to make a tapered runner for a runner in the 15-18" range which would cover most 4th wave resonance tuning scenarios - and you are not making 1st wave at some 28 or so inches in length
air friction? every runner tube of any configuration makes friction - no way around it
so the real answer is - packaging, close enough, and the 1-15 or so hp you leave behind by being exact in configuration for runner length and cross section
 
duramaxsandwich said:
u mean something like this?
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Yes in the general sense. Lookin' sharpe on the base of that intake Dmaxsandwich! What are some more thoughts of yours on this topic?

I was thinking about the runners ends that protrude slightly into the plenum manifold though, sort of like a donut at the end with an equal & opposite radii meeting the intake floor to keep a transition smooth from the plenum floor as well.

Granted we have positive & negative pressure waves and rarefaction waves etc to deal with Greg you are touching on a subject that is of great importance. Friction from flow however I believe is very minimal when trying to reduce it further with different textures. Albeit it can be the decider between opponents. The shape of the plenum I have read plays a role in canceling out certain waves that may interfere with wave tuning at the desired rpm for peak power? Right?

I am not sure but wouldn't runner shape have a hand in this as well guys? I am just asking that since parameters are crucial in optimum cylinder fill.

:pop:
 
Fahlin Racing said:
Yes in the general sense. Lookin' sharpe on the base of that intake Dmaxsandwich! What are some more thoughts of yours on this topic?

I was thinking about the runners ends that protrude slightly into the plenum manifold though, sort of like a donut at the end with an equal & opposite radii meeting the intake floor to keep a transition smooth from the plenum floor as well.

Granted we have positive & negative pressure waves and rarefaction waves etc to deal with Greg you are touching on a subject that is of great importance. Friction from flow however I believe is very minimal when trying to reduce it further with different textures. Albeit it can be the decider between opponents. The shape of the plenum I have read plays a role in canceling out certain waves that may interfere with wave tuning at the desired rpm for peak power? Right?

I am not sure but wouldn't runner shape have a hand in this as well guys? I am just asking that since parameters are crucial in optimum cylinder fill.

:pop:
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thanks. to be honest my brother is the mechanical engineer with too much time on his hands and i infected him with the diesel performance bug. he has done a lot of the research about the waves from the valves opening and closing and designed the intake along with jason at wcfab for my motor. there is a lil more to that plate, but i dont want to put too many pics on here since they have a lot of time in researching stuff. i think he found alot of good threads about intake design on some turbo charged gasser forums. we tried some of their theories and it seemed to work out ok. we had the same turbo, injectors, headwork, etc... from last year to this year on the engine dyno and changed the intake, intercooler, and some little things and made +180hp/280 ftlb over last years numbers. i really think its about finding your motors limiting factor to gaining hp.... the guys that only gain 3-4hp from a different intake i would say that their intake design wasnt their limiting factor, but thats just my 2 cents
 
duramaxsandwich said:
...changed the intake, intercooler, and some little things and made +180hp/280 ftlb over last years numbers. i really think its about finding your motors limiting factor to gaining hp.... the guys that only gain 3-4hp from a different intake i would say that their intake design wasnt their limiting factor, but thats just my 2 cents
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My guess is the intercooler had a bigger play in it then the intake manifold. I know JSP just did some testing recently and 60F was worth 84hp in his setup. Not saying that the intake didn't play a part, but my gut is that the bulk of your gain was intercooler.
 
Proper end tank design on a semi decent intercooler core can make an "ok" intercooler a hero. It also gives the air a better shot at being cooled.
 
Yeah, I will agree with you on that, once someone changes the problem you hope your fancy intake keeps up or whatever it may be thats the lacking piece/system. With the manifolds, I can't remember exactly but, pressure, temperature and CSA all effect our tune. Longer runners give more ram effect at low rpm but how short can one go with the meat and potatoes rpm range most are running, 3,000 to 6,000 give or take.

Reading Smokey Yunick's autobio he mentions he was working with a variable intake manifold runner but it didnt make the cut I believe. Imagine that tunability with a dry forced induction system.

Even with forced induction we are tapering the runner it seems as Greg mentions taper and length. How much taper? Could a manifold with 1 or 2 less or more degree of taper make the killer difference in torque and horsepower production? Now with the first picture you posted the taper plenum is a gradual. The one I mention is quicker in terms of opening and transition into the air storage area. I have been thinking would a abrupt end such as mine with a 1/2 radii and equal transition into the floor produce a more pronounced reflection (positive wave) towards the intake valve and cylinder? See where I am diggin'? Would/could this, runner-end design, dictate the strength of our wave both in velocity and density?
 
dvst8r said:
Our current head is over 300cfm a port, and other then the expense would be at home on a dd.
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how much you charge me for a head, bare, ported to flow this kind of air? i will buy one right now. call or pm me. 812 229 1290.
 
lenahan05 said:
how much you charge me for a head, bare, ported to flow this kind of air? i will buy one right now. call or pm me. 812 229 1290.
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I don't do anything but turn some wrench's on the truck. Dave @ Passenger Diesel did the head. 604 630 6744
 
Anyone have thoughts to wether the wave itself changes between a N/A system to a forced induction system.......
 
Something has to change with air that is more dense. It has to move faster at a cooler temp and higher pressure than n/a with ambient temp.
 
Fahlin Racing said:
Anyone have thoughts to wether the wave itself changes between a N/A system to a forced induction system.......
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[ame="http://en.wikipedia.org/wiki/Speed_of_sound"]Speed of sound - Wikipedia, the free encyclopedia[/ame]

According to this the change in the speed of sound is more dependant on temperature than density, but will travel faster in pressurized air. How much I am not sure, still trying to find that info.
 
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I asked this question a few weeks ago on another forum. The answer was in response to exhaust gas temp. Rho (compressible fluid density) moves in direct relation to pressure and cancel each other out, leaving temperature as the biggest variable in speed of sound through air.

I dont know the calculation to answer this though.
 
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