Hey everybody..

Time to start the planning stages of a new intake manifold. Figured this would be the best forum for the brain dump.

My planned goal is to have an intake manifold that is modeled after the OEM manifold complete with the changeover valve and resonance port but with larger runners.

Lets try to keep the thread on that topic. I do not want a short runner nor the CVP.

The end result should be a manifold that fits the stock mounting points and plumbing that just kicks up the dimensions of the runner area to allow the engine to breath easier hopefully allowing a respectable gain up top while trying to minimize losses down low.

At this point, the all motor guys on the 3.2's are making +25% more power out of the engine than it came from the factory with and seeing rev limiters set 800+ RPM higher than stock.

I'm pretty sure the engineers didn't have this in mind when they designed the stock intake manifold. Below is a picture I took of a stock intake manifold I cut up to show the runner cross section. Yes, that is a water bottle cap sitting on the runner.. they are tiny!!!!

Packaging is going to be the biggest challenge here.

Due to the coil packs the runners will not be able to be wider so they will need to be taller. The upper plenum 'ceiling' will be raised to match the runner height so this will increase it's volume by default.

The stock manifold sits soo close to the engine that it rubs the valve cover from the factory. It literally rubs off the paint and makes a smooth spot. That will need to be a major spot to watch in addition to the spark plug wire cap clearance.

The changeover port barrel tolerance is critical. Look at the picture I am posting below.

Anyone who is not familiar with the manifold design in detail, study this as well- https://acrobat.com/#d=YyIcQzOsQ7SsDus9OUNeWg

Here is a dyno overlay of the short runners only VS the long runners only (Credit Jeff Atwood)

How much clearance is under the hood?

Work
http://www.robocopywriter.com

To start off with, I will look to INA for their ability to supply an intake to head flange and TB flange, both of which should be available with no issues and appear to be of fine quality.

If I am not mistaken, that flange is sized to accept the oval tubing available from Ross Machine racing. Issam?

We'll have to find a way to bend it.

RMR also makes matching oval velocity stacks which will be implemented in the upper plenum.

Here are the runners as they come into the upper plenum (I cut off the plenum)

Due to how close together the 6 runners are in the plenum, the velocity stacks will have to have the flanges cut to butt to each other as such-

Hard to believe that we are pushing 300+ HP through those huh?

Unsure on hood clearance at this point, I think we should be OK though.. just measuring the section I have sitting here the runners (at this point) are only 1.75 high, that oval tube is 2.37. Should be small enough to clear, big enough to make a difference in flow.

But I'm not opposed to finding a spare hood and running an older school muscle car style bulged hood if I have to..

No idea why the prototype had the indentation on the bottom of the upper plenum. I ran both on my car with no functional differences. Weird..

3.2 N/A people COSWORTH will make us a manifold with enough interest check it here
http://forums.vwvortex.com/zer...53413
300BHP CAMMED R

-Oval bells lose flow (power) compared to even the simplest round bells.

-The oval to square transition in the INA flange is very quick and changes the direction of the air away from the port sides. I am not sure if this is good or not, just an observation.

-Good luck bending that oval tube along the long axis.

-Get a lighter car so you don't have to worry about torque

That all being said, I would go from the head and transition to round as quickly as possible and then fab everything from there up in round. This will make the bells harder to fit, but from a flow point of view you're up from the bells all the way to the head flange transition. You might want to CNC a plate for the plenum wall with the stacks integrated. Sure, off the plenum floor is better, but it's a lot less to fab. For the area near the plugs just 'vice' the round into an oval in those sections to clear the coilpacks.

That's all for now, I'll think more and post later..

Yea,..but look at the stock setup above..tight fit to cram 6 runners where we need them to be.

I think we are looking at something like this-

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Make sense?

Quote, originally posted by need_a_VR6 »

-The oval to square transition in the INA flange is very quick and changes the direction of the air away from the port sides. I am not sure if this is good or not, just an observation.

I think there is not much of a choice here.. I'm not going to create a whole new flange, and there has to be some sort of a transition regardless unless each runner was shaped to it's corresponding port.

Hopefully in my wishful thinking the transition in the INA flange will serve to increase the velocity of the air into the ports which if it did would be a good thing.

Quote, originally posted by need_a_VR6 »

Good luck bending that oval tube along the long axis.

Won't be..my idea is to squeeze a transition in the tubing to make it go from tall and skinny to short and fat before the bend starts.. the stocker does the same thing.. which will make the bend easier and allow more room for clearance.

Quote, originally posted by need_a_VR6 »

Get a lighter car so you don't have to worry about torque

Yea yea.. I know you welcome the TQ loss Mr I disable the manifold valve.. there is only so much FWD can handle.

Quote, originally posted by need_a_VR6 »

I would go from the head and transition to round as quickly as possible and then fab everything from there up in round. This will make the bells harder to fit, but from a flow point of view you're up from the bells all the way to the head flange transition. You might want to CNC a plate for the plenum wall with the stacks integrated. Sure, off the plenum floor is better, but it's a lot less to fab.

That may be easier, not entirely sold on the idea of better though. The factory probably had a reason why they stopped making round runners like the old 16v's and started making them square. Maybe it was just packaging issues as well.. but have you seen the 3.6 VR head ports? They are crazy..

Quote, originally posted by need_a_VR6 »

For the area near the plugs just 'vice' the round into an oval in those sections to clear the coilpacks.

Yea, We will have to do that even with the oval tube as it is a little too wide anyway.

For those that need a visual, HPA did the same thing here-

I'm not following you.. can you sketch it?

Quote, originally posted by Issam Abed »

Josh, have you looked into the manifolds like what ABT did for design inspiration?

Is that even functional? Where are the plug wires?

Looks like they are starving the # 6 cyl something awful.

About the only thing I like about it is the fact that they made the runners removable from the lower section so I would be able to swap cams without having to put the front end into the service position. That is what I *really* like but it would be difficult to do and still incorporate the changeover valve and resonance port.

So basically this is what will happen (modelling off only 1 port)
CNC flange ---> (2) CNC'ed 180* tight bends which will be welded together to form 1 part ----> flange tapped for M6 bolts -----> gasket ----> flange welded to RMR circular tubing which will now span OVER the valve cover ---> CNC'ed plate with 6 holes for each runner ----> Plenum ----> Throttle plate.

make sense? Essentially a 2 piece manifold.

I think this is the key right here, do a curved runner out of CNC'd halves that integrate a slight taper in them and a gradual transition from the port shape to round. Then you would end up with 6 round outlets (technically inlets) facing back at the firewall. From that point I would use standard trumpets that can be purchased in many diameters and run them into a plenum located where the OEM plenum is.

Yea..gotcha.. just like above.. but I'm stubborn and am not willing to give up the resonance port.

It can still be done, the changeover valve might just need to be moved higher.. which would effectively lengthen the 'short' runners which we don't want.

The only way around that (which gets convoluted) would be to make the section containing the short runners/changeover valve/resonance port removable which would uncover the bolts holding the main runners to the lover section. A 3 piece manifold.

Yea.. I'm crazy.

I see what Issam is saying about the lower manifold transition, it's going to be interesting for sure.

There's a difference between disabling the changeover and just not using it. I would have had to use it in the first place

Anthony's ITB'd car has the 6 bells on almost stock 12v spacing with just crushing the short three bells down a bit to clear. The 3.2 port spacing can't be that far off.

Also you could give up the stock style COPs for remote mount and plug wires.

I have more to say but limited on time.

There is a reason this is titled the OEM+ project. This isn't a race car. Nobody is going to get rid of the coil packs , nobody is going to remove the radiator, fans, etc.

Besides, can you see a del sol radiator cooling a 300+ hp engine effectively? 90+ degree weather, stop and go traffic?.. no thanks.

I know there are sacrifices that could be made which would simplify this, compromises that could be made, shortcuts that could be taken.. but that is not what this is about. I could easily slap a plenum on 6 runners and call it a day. I think I can do better.

You should use the changeover ports (and cam timing).. there is a reason they are there.

As for Dowd's 12v.. there is a difference between the splayed out spacing off the head and the space constraints inside the upper plenum.

We need to fit 6 runners with decent transitions into a space of 12 inches-

You had the original VW prototype intake manifold on your car? Do you still have it? While it would be a shame to cut apart something like that, why not just have that extrude honed and with a little fabrication you could add to the plenum volume? That should get you where you want to be.

Yea, I had it.. was made an offer I couldn't refuse to sell it.

Josh, great thread. I can't wait to see what you guys come up with.

Quote, originally posted by ElevatedGaze »

take that 17yr-old-handi-acura!

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Quote, originally posted by PowerDubs »

Actually it went from her to her ex. He sold it to me then I sold it to a guy in Canaduh who has it on his turbo R.

Ahh, my mistake! Thanks for the correction, I thought you had it first. Just went back & found the thread, sorry!

Quote, originally posted by ElevatedGaze »

take that 17yr-old-handi-acura!

Im no expert, but why would round have better flow than oval/vw square? If anything, there is more turbulence in a round cylinder vs an oval/square that "channels" flow......(yes there would be more turbulence if there was an "exit", but its all sealed and vacuumed with no "spouts/openings" to speak of)

This is not a statement, its a question....

I believe VW did switch to oval/square for a reason, and as more people on these forums study, the more they "discover" how everything VW does has a reason and how advanced it is, to me, this is no different. I do realize sometimes its cost plus efficiency plus space that influence the shape of some of these designs, but if you read some of the programmes, you can tell VW makes engine performance/efficiancy a priority over anything else, so i think that this design was intentional.


Modified by howzit-eksee at 3:37 PM 1-21-2010

Its hard to study the R36 for this application since its FSI no?

Modified by howzit-eksee at 3:44 PM 1-21-2010

Exactly with the R36 being FSI don't think that we can use that manifold.Not sure how the set-up works with the FSI works.Since we are needing the change over for the low end.Hmmm gonna have to read into it

3.2 N/A people COSWORTH will make us a manifold with enough interest check it here
http://forums.vwvortex.com/zer...53413
300BHP CAMMED R

No, but here are the only pics I could find.

It looks like the Intake Manifold is very similar to the 3.2