Intake Manifolds

Runner length matters to optimize cylinder filling. Remember, the cylinder fills in pulses, so runner length is tuned to use that pulse for good. Read the linked article about half way through this thread.

Those dual plenum manifolds are pretty trick when they're done right. I've seen a few CFD analyses of various setups, and they work very well.

Just some images pulled from Google. This should give you a basic idea of what's going on. Pay attention to the colors of the lines/velocity of the air in the intake runners:

Standard intake:



Dual-plenum:




Edited 1 time(s). Last edit at 01/28/2013 11:28PM by b00sted.

Interesting, the "swirl pattern" on the dual. It appears as if one could almost "go back" to a wet manifold, if this modeling is accurate. A set of injectors aimed down the bellmouths might could give one heluva mix to the fuel.

I wonder what the pattern might look like were one to extend the trumpets proud of the plenum-wall a bit.

---

Parfois, on fait pas semblant!

I am:
I know:
I am from:

Nobody.
Nothing.
Nowhere.

I see it done both ways, but have never seen any sort of analysis comparing the two designs. Not sure how much it matters on a forced induction application.

Aiming injectors down the runners gives fantastic atomization and would add to the consistency across the cylinders...Check this out:

That's a pretty picture. Wonder what engine its for. Some fancy thing that has all four valves open at the same time obviously.

---

Grant Hughes

From the no coast engineer.
problem with that cfd that was done, from what i can tell is that all valves are open. i've done something like that before. but! sure it looks cool and stuff and you may think that it works well with whatever design you have made, but you have to consider the opening of each valve, closing of each valve, duration of intake, and the intake curve. i've looked at videos of doing cfd on stuff like that where you map the intake curve of each cylinder to a plot/iterative spreadsheet that the program reads and does calcs based upon, but its a lot of work to do and i've never thought that there is much benefit from it. i could sit there for days working on learning it, then working on making up an intake, then soooooo many days doing the simulation. all of that time is contingent upon the simulation working too. but once you have that, how do you verify results? is one going to make it? and if so, are they going to test it for flow either through bench testing or dyno? doubtful. which seems to make it a mental crank. i don't doubt that some people have done it, or could maybe maybe maybe get something that seems to work better, but the time involved and the unknowns and the software you need and the testing seems like minimal returns for a lot of time and work.

---

Grant Hughes

do a search and you can see it. i think i could set it up in solidworks. parametric. its really neat, but you have that constant problem of "is my mesh fine enough, is my delta t (time) period between iterations short enough, do i need to account for heating or cooling, does this converge and are my parameters for convergence acceptable, etc." it could be way way cool to do, but doing it by ones self, pouring through documentation on how to get it to work, get it just right to give accurate results, and the convergence (which crashes your results if it doesn't converge). it takes forever to run through the comp. i ran a static one through a turbo, not spinning (couldn't figure out how to get it to spin), constant in and out, and nowhere near being sonic speed, with a really fine mesh and it took all 8 cores a couple hours to solve.
>
> cool, but i don't want to do alone without guidance or help or never being made or tested.

---

Grant Hughes

very interesting info in here.

---

I be sorry as a muthafucka I did, still sorry I did n' hustled ta peep what tha fuck I holla'd a lil' bit better, or at least try to.

Here's a cool setup an FSAE team designed. Not ideal packaging for a rally car, but interesting none the less:

Here's some decent videos...
Initial/static setup:




Now let's get real:

---

Grant Hughes

Those simulations are cool and all but like flowbench results they don't seem to simulate what is actually going on when the engine is running and in Davids case how boost will effect it..

When a turbo is added, everything else drops in importance (or so I'm told by the boffins). Intake runner tuning, and plenum volume still effect the tune, but to a lesser degree. I could see that minimizing pressure drops, and maximizing flow would be the areas to look at.

Quote
sidewaez
Those simulations are cool and all but like flowbench results they don't seem to simulate what is actually going on when the engine is running and in Davids case how boost will effect it..

Exactly...
But he should probably build something from scratch using some general theories that are oversimplified for the problem at hand?

---

Grant Hughes

Quote
NoCoast

Quote
sidewaez
Those simulations are cool and all but like flowbench results they don't seem to simulate what is actually going on when the engine is running and in Davids case how boost will effect it..

Exactly...
But he should probably build something from scratch using some general theories that are oversimplified for the problem at hand?

Exactly! Just think, there might be 2-3 or maybe 4 ft/lbs of torque awaiting one after spending hours anhours reading and playing at the keyboard, and sawing and welding and running the car on a rolling road...
MONEY IS NO OBJECT!
And time isn't money it's Horse powerz at stake here, even 1 or 2 is worth thousands!

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.