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To maximize "Inertia Ramming" at the end of the intake period, you want to always be accelerating the air from the plenum to the valve pinch.
Here the flow speeds up through the runner inlet, slows way down through the first half of the runner expansion and then has to speed up again after the turn to the manifold inlet.
Lost velocity is lost boost.
But the test was to prove/disprove that the turn was what is choking of the air flow through the TPI intake.
My giant increase in runner area at the turn is just an extreme version of what a trapezoid or flat bottom D-shaped runner is trying to do.
Slow down and even out the velocity around the turn.
Even this extreme version doesn't seam to improve the flow very much?
I think if you want to flow more through a TPI intake you need bigger or shorter runners with a nice inlet radius
... but not much room in the stock plenum to go much bigger.
When I was playing with all these different TPI runners, my printer broke 48 hours into a 52 hour print and I just was just sick of TPI stuff ... so I walked away
But there was one runner that I always wanted to test.
Since way back in the 90's, TPI guys have talked about slowing the airflow down to help it flow around the 180 degree bend, but no one ever tried it that I can remember?
Didn't even imagine 3D printers back then
For this test I decided to slow down the airflow by increasing the area around the curve.
Started with the AS&M 1.66 diameter at each end, stepped up to 1.70 diameter about an inch in and positioned an oval at the peak of the curve as shown.
Quite a bit of increased area in the whole runner.
Printed out the prototype.
Setup and retested the AS&M runners on my bench.
Then tested the new "Oval" runners.
The results where kind of a bummer ... #$@&& TPI stuff
With all that extra area, I expected a little more of a gain.
Keep coming back to the fact that the smallest CSA in the intake path dictates the flow, the 1.66 Diameter ends?
This is going to take some more thought ... don't know if it's worth another try
The more I read about this stuff, the more clueless I feel. Not my educational background. not an engineer. I built the stuff engineers developed. but still drawn to this. feel like a greenhorn apprentice asking the most basic questions.
found this college project, optimized elbow design. I guess I'm trying to understand how engineers come up with designs. some wild stuff to me.
The more I read about this stuff, the more clueless I feel. Not my educational background. not an engineer. I built the stuff engineers developed. but still drawn to this. feel like a greenhorn apprentice asking the most basic questions.
found this college project, optimized elbow design. I guess I'm trying to understand how engineers come up with designs. some wild stuff to me.
That's the kind of paper you have to print out and read to understand what's up
Maybe there is something we can use?
In a way it is interesting that we are all trying to do the same thing ... slowing the air down and evening out the velocity around a bend.
My wide runners.
The guy's designing and porting cylinder heads.
My elbow adapter design.
The concept is the same.
I tried one last 1.8 inch inside diameter runner and I'm getting pretty frustrated that all these runners bench results are packing up together ... they should be further apart?
As always, you have to backup and look at what you are testing.
I think I'm testing the pinch at the injector on this TPI base and not the runners.
It's very tight in that one spot.
At some point it needs to be ported bigger but I decided to go back and test just the different runners alone on the bench.
I tested some runners way back when my bench was new and changing with only three pumps.
Now that it's stable with six pumps (600+ cfm) it's probably a good time to retest all of them the same way.
Plan out and fabricate an adapter that's makes it easy to swap runners.
When I was playing with all these different TPI runners, my printer broke 48 hours into a 52 hour print and I just was just sick of TPI stuff ... so I walked away
But there was one runner that I always wanted to test.
Since way back in the 90's, TPI guys have talked about slowing the airflow down to help it flow around the 180 degree bend, but no one ever tried it that I can remember?
Didn't even imagine 3D printers back then
For this test I decided to slow down the airflow by increasing the area around the curve.
Started with the AS&M 1.66 diameter at each end, stepped up to 1.70 diameter about an inch in and positioned an oval at the peak of the curve as shown.
Quite a bit of increased area in the whole runner.
Printed out the prototype.
Setup and retested the AS&M runners on my bench.
Then tested the new "Oval" runners.
The results where kind of a bummer ... #$@&& TPI stuff
With all that extra area, I expected a little more of a gain.
Keep coming back to the fact that the smallest CSA in the intake path dictates the flow, the 1.66 Diameter ends?
This is going to take some more thought ... don't know if it's worth another try
your runner is more efficient than a first tpi intake manifold with1.75"id runner 234cfm. so, the design works.
Will test the Siamese and my short runner designs next.
Tested two runners (#2 & #4) for each type of runner and averaged them together.
Tested with and without a clay radius on the inlet, because I've seen test data both ways floating around.
There are all kinds of dimensions floating around as well, so measured the ID about one inch into each runner inlet and exit, horizontal and vertical and averaged them together.
Also measured the inside and outside runner length and averaged those.
Made a fixture for my bench with 1.75 inch holes.
Test #1 was the stock runners with and without clay on the inlet.
Test #2 was the AS&M runners with and without clay.
Test #3 was some straight runners that I had made from PVC pipe a while ago.
The ID was 1.65 inches but for some reason I was a little confused when I made them and they are long at 11 inches?
Test #4 where 3D printed runners that taped from a 1.8 inch inlet to a 1.70 inch outlet.
Test #5 was the 3D printed "Wide Turn" design with 1.66 ~ 1.70 inlet and outlet.
The results.
The stock and AS&M runner numbers compare pretty well to what I've seen posted on the net.
Surprising ... maybe not ... difference the clay inlet radius makes on the results.
That 25 to 30 cfm makes me want to put nice big radius's on the inlets in the plenum somehow.
Even though the straight, tapered and wide elbow runners flow more than the AS&M, it's not an earth shattering difference.
Maybe that 180 degree bend isn't as bad as we have been led to believe?
Will test the Siamese and my short runner designs next.
Tested two runners (#2 & #4) for each type of runner and averaged them together.
Tested with and without a clay radius on the inlet, because I've seen test data both ways floating around.
There are all kinds of dimensions floating around as well, so measured the ID about one inch into each runner inlet and exit, horizontal and vertical and averaged them together.
Also measured the inside and outside runner length and averaged those.
Made a fixture for my bench with 1.75 inch holes.
Test #1 was the stock runners with and without clay on the inlet.
Test #2 was the AS&M runners with and without clay.
Test #3 was some straight runners that I had made from PVC pipe a while ago.
The ID was 1.65 inches but for some reason I was a little confused when I made them and they are long at 11 inches?
Test #4 where 3D printed runners that taped from a 1.8 inch inlet to a 1.70 inch outlet.
Test #5 was the 3D printed "Wide Turn" design with 1.66 ~ 1.70 inlet and outlet.
The results.
The stock and AS&M runner numbers compare pretty well to what I've seen posted on the net.
Surprising ... maybe not ... difference the clay inlet radius makes on the results.
That 25 to 30 cfm makes me want to put nice big radius's on the inlets in the plenum somehow.
Even though the straight, tapered and wide elbow runners flow more than the AS&M, it's not an earth shattering difference.
Maybe that 180 degree bend isn't as bad as we have been led to believe?
A lot going on here to think about
radius the plenum inlets. could put clay on inside of plenum. sure you already thought of that.
That's the flow results for the 1205 runners vs. runner length.
Have to take those numbers one more step towards generic and get cfm/in2.
Reminder quote from John Baechtel, keeping in mind he says this about cylinder head ports and not intake runners directly.
I added the cfm/in2 to my runner tests.
Any design that have multi diameters, I used the smallest in my calculation.
It's interesting that the stock runner with clay is the most efficient.
The 3D printed runners are less efficient than the smooth tube runners.
Is it surface finish?
That 180 change in direction doesn't appear to be hurting very much either?
I was wondering about the 3d surface and if it affected the cfm.
at some point I want to test the effect of tapering the entrance of runner with no clay. on crossfire runner, a smaller runner with tapered entrance flowed the same as a hogged out non tapered entrance. there wasn't enough wall thickness to taper larger runner. truth is that tapering wasn't done in isolation. I didn't take the time to test that.
found an old article giving length of runners and flow numbers.
Extrude-Honed ACCEL Hi-Flow intake manifold with 3/8-inch radiused inlet
275.83 cfm
Extrude-Honed ACCEL Hi-Flow intake manifold with ACCEL runner
266.94 cfm
Measuring the smallest CSA around the injectors on the stock Edelbrock base in somewhat subjective, but I am getting...
1.121 x 1.661 = 1.862 in2 CSA
After my quick porting...
1.218 x 1.720 = 2.095 in2 CSA
The AS&M runner, down in the tube is...
1.62 ID = 2.06 in2 CSA
So I wouldn't port any bigger without a larger ID runner.
If you could keep the entire assembled intake averaging 260 cfm, that would be pretty good for a long runner intake.
The hard part would be modifying the plenum inlets.
Bead blasting and then epoxy ... maybe?
I like the idea of printing something out and fastening or gluing them in.
I keep saying that I'm done with this TPI stuff
But one last go
Realized that I didn't subtract the corner radius's from my intake runner CSA comparison.
They are about 1/2 inch, so minus 0.196 in2.
That would make the stock Edelbrock 1.666 in2 CSA
The first porting would be 1.899 in2 CSA
Compared to the AS&M 2.060 in2 CSA
So room for just a little more porting.
Made a template (1.28 x 1.774) and ported the intake runners out to a 2.075 in2 CSA
There was such a large improvement after the first porting, interested to see what happens as the intake runner approaches (equals) the AS&M runner CSA?
Roughed out ports after attempt #2
A little increase, but as might be expected, as the intake runner CSA approaches the AS&M runner CSA the improvements diminish.
Getting very thin in this area, so if your porting one of these ... watch out
Plenty of material everywhere else.
Not fair to add this modified TPI to the chart until all the runners are ported and clayed.
But if I could maintain the 263 cfm average of these two runners the second red arrow is where this TPI combo would move up to.
Realized that I didn't subtract the corner radius's from my intake runner CSA comparison.
They are about 1/2 inch, so minus 0.196 in2.
That would make the stock Edelbrock 1.666 in2 CSA
The first porting would be 1.899 in2 CSA
Compared to the AS&M 2.060 in2 CSA
So room for just a little more porting.
Made a template (1.28 x 1.774) and ported the intake runners out to a 2.075 in2 CSA
There was such a large improvement after the first porting, interested to see what happens as the intake runner approaches (equals) the AS&M runner CSA?
Roughed out ports after attempt #2
A little increase, but as might be expected, as the intake runner CSA approaches the AS&M runner CSA the improvements diminish.
Getting very thin in this area, so if your porting one of these ... watch out
Plenty of material everywhere else.
Not fair to add this modified TPI to the chart until all the runners are ported and clayed.
But if I could maintain the 263 cfm average of these two runners the second red arrow is where this TPI combo would move up to.
I think thats the max. no more wall thickness left
05-07-2024, 11:28 AM
