Technical Theory : Plenum Design

[v6h.o.]

the link only shows up as barely visible lines. hard to see the measurements.

i'll have to look at it at home on my monitor.

[Corpse]

The image was probably downsized for your browser. If you look at it full size it is at perfect clarity. It appears asthough there are a few more measurements that could be thrown onto this diagram aswell. I haven't yet had a chance to take a look though. (All my stuff is at my garage.)

That is the measurement of the Plenum's flange, correct? Eventually it would be ideal for someone to measure the other side of the flange aswell. For matching purposes, then it would be possible to do the math easily to do even a rough port match.

I can't be of much assistance at the moment...

-Dave

[bszopi]

Go ahead and list whatever measurements you'd like to see. Its all in AutoCAD, so getting any dimension takes all of 5 seconds. I can get whatever measurements people desire.

And yes, I will eventually do both sides for proper placement and such.

[RednBlack]

Worked great! Going to transfer it to Smartcam. Just in case. Just curious. Can't you just mirror it for the other side?

[bszopi]

I'm trying to think off the top of my head... I think you'd have to mirror and rotate it. I wanna say the spacing is opposite on the opposite side. But I could be wrong. Maybe I should look at some of the pics I have...



Yeah... mirror and rotate. But it wouldn't be hard. Just have to figure out the spacing between the 2 sides. I will hopefully eventually be putting the entire plenum into AutoCAD. But that's when I get some time off.

[RednBlack]

Wish I had a spare to put on the comparator. Makes it a breeze. And I doubt if you are wrong unless they moved a cylinder! When you check it, let me know. Correct me if I am wrong, but aren't all V engines mirrored?

[CNCguy]

I am in the process of building a UIM and had a '99 3400 intake measured on a CMM. The locations of the ports, UIM mounting holes, gasket alignment holes, fuel rail mounts, vertical mounting holes and the (4) unused bosses have all been mapped out. Measurements are of the front and rear banks and thier relationship to each other.

I will try to get the drawing dimensioned so it can be posted this weekend. Currently it is only a CAD file without dimensions.

Marc

[bszopi]

Well that is just cheating! But I'd be happy to look at it...

Started messing with my design alittle more, rounding edges and such. Here is my latest modifications (although there are more to come before its done).

[Maetrix66]

I've been thinking about designing a new upper and lower plenum for a 3100,
but my application is forced induction, so it's a little different. I've been working up some designs in 3d, just to get a picture of them, even started to setup a particle emitter to "flow"particles through the intake to test different flow patterns, but I don't have that up yet. They're at home on my home pc, and I got stuck working on a Saturday. LOL

What are the "ideal" conditions for a 60v6 intake manifold?
For a NA one?
For a FI one?

Should the runners be longer, shorter, larger at top, smaller at bottom, other way around??

Oh yeah, I have a full machine shop, a TIG, a MIG, an exhaust mandrel bender that can go from 1.5" to 3", a plasma cutter that will cut up to 1.5"steel, and a stick welder with it's own trailer at my displosal.

It's just gotta fit under the decklid of my Fiero, LOL

[CNCguy]

Regretfuly I have not had time to dimension the drawing, spending time on building my headers. I dont know how to post a file on the forum.

Brad, if you PM me your email addy, I will send you the CAD file and you can post it if its possible.

Marc

[bszopi]

Ok, here is Marc's CMM drawing with dimensions. I was pretty damn close except for the position of the bolt holes with respect to the ports. So I'm glad that I got the right dimensions, cause that would ahve sucked to have the bolt holes off....

http://www.60degreev6.com/hlperf/3400plenum/3400CMM.jpg

EDIT:

And here is a pic of what I will probably end up getting machined for the plenum plates...

http://www.60degreev6.com/hlperf/3400plenum/3400plate.jpg

[Corpse]

"Correct me if I am wrong, but aren't all V engines mirrored?" - Nope. In gerneral, it is easiest if it is identically mirrored. But, since the making of newer and newer technology, R & D has found it better in some ways to just use whatever design is deemed necessarey for the application. Which means, if a non-symmetrical engine is cheaper to build, so be it...

"What are the "ideal" conditions for a 60v6 intake manifold? For a NA one? For a FI one? " - Ideal conditions? Not to sound mean but, there is no such "ideal".

Due to the way the internal combustion engine works, the tuning of an intake manifold's runners is very dependant on other factors. Such as, Air Temp, % of Fuel/Air, Fuel Temp, Fuel atomization, intake runner length, intake runner width, runner turbulence/runner wall resistance to flow, Int valve timing, cylinder pressure when the intake valve opens/closes, air pressure, RPM level (for scavenging), etc..

And if you are actually going for Hi-Perf you need to accurately setup all the stuff I just mentioned in relation to your exhaust setup. ie: Exh Valve timing, runner length, runner size, charge temperature, Collector size and dimensions, charge left in cylinder (neg or pos), need I go on more?

As you can see, there is no ideal unless you do the math. but, the math will be wrong unless you do it all.

Sorry to babble, realistically though, I would tell you to shorten the penum's runners. I know for an N/A engine the runners are a bit long for the upper RPMs. I do not see any reason for extending the runners unless you are able to seriously widen them so that the engine isn't sucking air through the "straw" of an intake runner as hard. I would only widen the ports to a little larger than the intake valve though, as that is what will help promote peak torque creation.

If you want an idea to start from, custom make a plenum and cut out the plenum's runners. With the right modifications, that will help the engine breath quite a bit better in the higher RPMs.

I would shoot out some actual ideas but, I don't like to use 8 pages... But, I can tell you how to make an easy dual 56MM TB intake, hehe. Just don't expect to use an egr or vacuum based equipment. (althoguh it IS possible, just dirty, MAP is not a problem though. Because it is vital)

-Dave

[bszopi]

Well, I couldn't sleep tonight, so I decided to mess around in AutoCAD some more. Now that I have the following piece drawn up, I can maybe start working on drawing the rest of it in AutoCAD as well... The following is what the base plates of the plenum will look like. It could also possibly be what some phenolic spacers could look like

[v6h.o.]

looking good brad.

hey you'll have to shoot me a PM with your address so i can send you out those header flanges eh.

[bszopi]

Yeah, I can do that. I'm almost done with your head stand. All I have left is to mount the studs and then tie the 2 ends together with some plate or angle. And then it will be ready to ship to you.