Your Intake Manifold and You

Okay, so as some know I've been doing some flow testing of parts on a flow bench. Some of these parts are intake manifolds. The main reason why I'm doing this is because it's never really been done before. Flow testing parts is just like dynoing a vehicle. It gives you a good idea on how something is performing but it's fairly hard to accurately compare to results of others. Just like dynos, bench results can differ based on ambient conditions, bench calibrations, accuracy of the device, test pressure, etc. So when a company claims that their part flows xxx CFM it honestly doesn't really say much unless they can give more details, and most of the time they don't.

Before I get to my results I would just like to say, PLEASE do not compare my results to that of what others have posted. I have found little in the ways proper documentation for flow tested pieces and I really don't want this to turn into a, "well ______ said that their part flows xxx though". I don't care what a company has to say about their part, the point of this thread is to give an unbiased opinion, with properly documented results.


I'm going to start by covering some of the basics of the tests that pertain to all of the manifolds tested. The flow bench being used is a SuperFlow SF-600. This bench has a FlowCom computer attached to it which allows for great accuracy and ease of testing. All tests were done at a test pressure of 25" of H2O with a max variation of .3" H2O. The industry standard pressure for flow testing in the performance industry is 28" H2O. I chose to use 25" H2O because that is the pressure that the bench is calibrated for. I could have tested at 28" H2O but I decided I would rather have the most precise numbers I could get. The only real difference between 25" H2O and 28" H2O is that the test results would be a bit higher if the tests were done at 28" H2O. All results are in Cubic Feet per Minute (CFM).

To set a baseline I started with a totally stock intake manifold. The manifold was sealed with modeling clay to an adapter plate and sealed to the bench with clamps and a rubber gasket. I can't say for sure there weren't any leaks but if there were, it was less than a couple of CFM (aka mostly negligible). The VTCS was left intact and tests were done with the flappers open as well as closed. All ports not being tested were covered in tape so all air would be pulled through the throttle body opening. Lastly, every port was given a small exiting radius made of clay. This was done to help seal as well to keep variation of adapter plate placement a non factor.

Other ports sealed off:


The adapter plate sealed to the manifold:


Here are the results:


Next up was a gasket matched port and polished manifold. VTCS was removed but the holes were not sealed between runners. The same sealing methods were employed as before.

Manifold ports:


Sealed:


Here are the results:


The last stock variation of a stock manifold was a single runner manifold. Essentially a gasket matched manifold with a bit of throat porting and the runner divider removed. The same sealing methods were employed as previously.

Manifold ports:


Here are the results:


@Maisonvi; was generous enough to lend me two JMF manifolds. One is a single runner set up for Pi and the other is a split runner set up for meth. I was able to get the single runner manifold tested but not the split runner because I ran out of time but I will test the split runner when I return from my break next week. All of the PI bungs were taped off as well as the holes for the vacuum lines so all air would be drawn through the throttle body opening. The same sealing methods were used as the other tests.

Manifolds:


Here are the results:



So what are my thoughts on this? I discussed it with some of the IL Nator guys and I think that the reason for the flow imbalance between the runners on the stock manifold is because of the throttle body location. In order for air to go up the cyl 4 runner, it must make an almost 180* turn; that is something air does not like to do. On the other hand, to get to cyl 1 runner air has a mostly straight shot, not having to bend much. As to why 2 and 3 flow more than 1 and 4 I think is because of how the runners are connected to the plenum and the path they take is shorter than 1 and 4. Here's an illustration of what I mean:



As for why the JMF flows more on 1 and 4 I'm thinking it has something to do with this:



This flow imbalance was noted by SP63 on JMF's mani for the Focus ST. I believe that we are seeing the same thing on our manifold.

UPDATE: I've finished the testing for the JMF split runner mani by itself. Now that all the mani's I have have been tested by themselves I can finish testing with them connected to the head. The results for it are in the picture below. To my surprise the manifold flows ~15-20% less than the open runner manifold. I'm not really sure why the flow is so much less from this other than maybe it is causing turbulence in the port. Though I'm not really sure about that because the divider is CNC knife edged so it doesn't seem like it would really cause a lot of turbulence. Maybe the results with it connected to the head will tell a bit more.

Here is a more comparative view of the results. Please let me know what you guys think on this! If anyone has any non stock manifolds that I haven't tested yet and would like it tested please let me know!



EDIT (6/10/16): Here are the final results including the FoST mani with the DM spacer. As you can see, it flows EXTREMELY evenly. It's within 2% of all runners and flows 30-50% more than stock!

 

Excellent work.

Just need CS and CPE intake manifold to complete the testing.

 

That's awesome! Thank you, and thank you to the guys who let you borrow items.

Sent from my SP-G24627910574820P

 

This is awesome data, and really makes me glad I A: let you borrow my JMF's and B: am moving to a JMF over my ported stock one. The gains should be there for sure, not to mention better meth distribution.

Curious to see what the data shows for the divided JMF vs the non-divided. I have a feeling it wont be much difference.

@bRitzCrackers

 

Done in time to bring with you for the 12th?

 

I will not be able to make it on the 12th. Shooting to get it done the week after.

 

OP updated with JMF split runner results. Results were a bit more drastic than I thought they'd be. Let me know what you guys think. Both of the JMF connected to the stock head results should be done in a week or so. Been a bit slow recently, trying to catch up on school work since I'm back from break. Happy St. Pattys Day guys.

 

Thanks for the edumication... Great work!

 

@AYOUSTIN thanks for flow testing these for us.
@Chemmedic some numbers to ponder

 

@AYOUSTIN; I have something for you to test. @Maisonvi; pointed me to this thread after I received a far from perfect manifold from John Russell.

Sent from my SM-G928R4 using Tapatalk

 

In for lulz.

 

That's the only reason I'm willing to spend more money on this useless garbage. I need a good laugh.

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*paddy's

 

Hey, sorry to hear about the manifold situation. Glad to hear you got your money back though!

I can test that thing no problem. Testing the manifold by itself can be done in a day, it's not a tell-all sort of test but it's still useful for comparative purposes. If you'd also like it tested connected to a head with valves, etc it'll take me a week or two depending how loaded my schedule is. The only thing I ask is that you cover getting it to me and getting it back (when and how is up to you), being a college student doesn't exactly lend itself to me making a lot of money.

Also, my neighbor is a FANTASTIC welder. He used to be the head fabricator at a well known shop up here in MI and if you'd like I'm sure him and I could tweak it to not flow like shit (assuming it flows like shit). Probably wouldn't cost you anything, I'm already paying him for a lump sum of work so I can just toss it in with that.

 

I'm in for the testing portion of this. As far as "tweaking" this manifold. Once you see it, you will understand that it is just not possible without alot of design changes...etc

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Okay, cool. I don't live too far from Ken so if you want to hand it off to him at ENM and I can swipe it from him sometime after that works, if not I can PM you my address to ship it to. Oh shit, I just realized you're in WI, we might be able to work something else out if neither of those are convenient.

I was looking at the pics of where the runners meet the head flange. It's a bit cramped yes, and although that's terrible design, so long as the runner material isn't paper thin and the runners are fairly centered on their respective flange holes, it can at least be smoothed out a decent amount. It actually looks like he put a decent amount of filler material between the runners and flange (also shitty) but that could probably be turned into an exit radius. I've spent the past two semesters studying engine airflow and head design (I'm actually covering intake manifolds currently) so I'm pretty comfortable with altering stuff to make it flow better, it's also nice being able to quantify those gains on a bench. Anyway, it's all your call man, you just let me know.

 

Yeah at @REDMAN if you are going to ENM I can just bring it back to @AYOUSTIN for you. I can see about shipping it too if you wait for me to get it back from him. I get discounted shipping from work, and I know you are kinda in the whole on this. Im just curious to see how this thing flows. (watch, by some freak reason it flows better than everything out there haha)

 

I can't wait to see this thing in person at ENM. Are we doing nametags again this year?

 

--- Double Post Merged, Mar 22, 2016 ---

The runner material is 1/8" thick. I feel that this manifold flat out needs to be remade with major changes. I simply will not run a manifold that has the map sensor/brake booster on the bottom of the manifold. As much as I want to see this thing "cleaned up", simple testing is all this thing deserves. He welded a plate on the area where the throttle body bolts on. He broke a tap off underneath and was too lazy to fix it the right way. I will compensate you for any work you do. I appreciate the generosity, but as a college kid, nothing is free for you. I am already remaking this manifold as we speak. I will bring the original to ENM for all to see. I will hand it off to @Maisonvi; I have alot of the new one drawn up, but would love to hear your input on how to make this better when I start fabricating it.

 

Sounds good! As for modifying it, I'll give you my thoughts on how much it can be tweaked once I can check it out in person. What exactly are your goals in mind for your car? Different goals require different designs for best performance. If you're looking for best overall HP a design like the JMF that has a large plenum and short fat runners would be best. If you want really good low down torque, then you'll want longer runners, that are more narrow with a bit smaller of a plenum. If you're looking for something with a nice big powerband then I'd say you'll want something with long runners that aren't too big or too small and a plenum that isn't too big. Let me know when you start fabbing up the new one, there's a good amount of other design aspects that can be added on to any design to improve it. Wish I could make it down the ENM to talk with you in person but it's right around my finals and I don't have a car to take down there.