SMIM Showdown! Lets figure this out once and for all!

[95talonracer]

This will cause uneven power and would that be hard on anything like bearings, pistons or just the total output of power and the equal power numbers made per cylinder.

[C3L1CA]

Cool to see some results. I have a stock 2g mani that you could use if you wanted a base line, could take as long as you wanted with it too.

[Halon]

Are you posting this on other forums? I'd like to hear what others have to say about this since, again, I'm far from an expert on any of this. I'd assume there's a lot more to IM performance other then what was tested here also.

Someone had mentioned something about this test being done with the manifold under vacuum, while it's usually under boost in our application, so are these results valid for our application. I have no idea, just like to see it put up elsewhere besides on here so we can get more input.

[iroc_g]

I'm honestly not an expert either, so I just have to trust what I have been taught by my boss, who is deffinatly an expert. Flow is flow, no matter if under pressure or vacuum. Intact, I remember reading a few things saying that a pressure situation would actually agravate the issue.

I want to hold off a day or two on spreading the link. I'm working with scheides on having it hosted here instead of my served (borrowed web space from ProKART!) once we get that worked out, then I deffinatly want to get this out!

And yes, baselines are hopefully coming very soon. If I can get some stuff done around the house, I'll pull my stock 1g tonight. And iceminion has offered his cyclone. Doing a 2g would be good to, so long as I don't have to modify my test fixture too much.

[JET]

Alright, I was holding off on saying anything about this until I saw how the test was going to be performed. I think there are a lot of people that are going to misinterpret this data. The test is NOT representative of the numbers that will be seen inside the engine.

One of the first things many people will notice is that there is no Heimholtz resonance taken in to effect because that can only be seen with the valves opening and closing. In a manifold with a straight back wall, this will not create a difference in flow balance between cylinders, but may change the flow numbers either plus or minus.

Another thing that is a larger issue is that there are no restrictions farther down line in this test (both sets of valves and turbo). This restriction downline from the IM will help to even out the flow of the intake manifold, so you will not see the imbalances to the degree that this test shows. Think of it this way, you have a 5" exhaust with a 1" outlet, will a 6" pipe with a 1" outlet flow any more? No, they will both be limited by the 1" restriction, the restriction is the valves and turbo. The degree of this can't be known unless a running engine is tested at a high flow rate.

I am not saying this test is not useful at all, but people need to be informed to really see what these results mean and I bet the vast majority of the people that will look at these results will not meet that criteria.

[Kevin 1G Drummer]

So one thing I was curious about. Did you number the runners like they would be numbered on the car? I.E. runner #1 being farthest from the TB?

[iroc_g]

Yes, runners are numbered as your sparkplugs would be.

Scheides got me setup to have this hosted on this board. Thanks alot! I'll get the change made tomarrow and we can start spreading the info.

[wheelhop]

Alright, I was holding off on saying anything about this until I saw how the test was going to be performed. I think there are a lot of people that are going to misinterpret this data. The test is NOT representative of the numbers that will be seen inside the engine.

One of the first things many people will notice is that there is no Heimholtz resonance taken in to effect because that can only be seen with the valves opening and closing. In a manifold with a straight back wall, this will not create a difference in flow balance between cylinders, but may change the flow numbers either plus or minus.

Another thing that is a larger issue is that there are no restrictions farther down line in this test (both sets of valves and turbo). This restriction downline from the IM will help to even out the flow of the intake manifold, so you will not see the imbalances to the degree that this test shows. Think of it this way, you have a 5" exhaust with a 1" outlet, will a 6" pipe with a 1" outlet flow any more? No, they will both be limited by the 1" restriction, the restriction is the valves and turbo. The degree of this can't be known unless a running engine is tested at a high flow rate.

I am not saying this test is not useful at all, but people need to be informed to really see what these results mean and I bet the vast majority of the people that will look at these results will not meet that criteria.
AMEN!!! I'm glad most havn't chosen an intake manifold based on constant volume flow. Resonance or not, the intermitant flow demand placed on the intake manifold will make a compressable fluid like intake aircharge act VERY different than a flow bench. The only way to tell which manifold flows the best is th put it on a motor with a known reliable maf like a 2g maf. If you want results for each cylinder, put a wideband on each cylinder and see how lean each is. . . Otherwise look at the whole picture like the real world has to :)

[Kracka]

I'd imagine this testing is at least a good starting point in the research/decision process, correct?

[iroc_g]

I agree that these tests aren't the whole picture. But, one has to ask the question, "why don't any of these manufactures flow test, or anything other than dyno test their parts."

I plan on showing the constructive critisisim comments to my boss, who will be able to much better answer these questions. One thing I can tell you though, at 30+ pounds of boost, we are forcing much more air through the intake than the flow bench is capable of. Makes you wonder how the incocsistency translates at those levels. I don't think that anybody can argue the importance of having each cylinder having balanced output, which will require balanced input.