lower runners on 2 piece = bottleneck

[glhs875]

Well I was looking over my parts while I have the head off my engine. My head is heavily ported, and I already had the runners welded and removed the bolt dimples on the runners. But the runners neck down basically to stock port area well before where the bolt dimples were. So just removing the dimples will help but really won't do a whole lot if more than stock port area is wanted. It's hard to port that far back and measure things, but I'm slowly getting it. This could explain why although my combo was pulling great to around 7200rpm, the HP was basically staying level above 6500rpm, according to the track times anyway. And the stock port area is a long ways from working well to 7200rpm on a 2.2. I've had to open the runners up a ton to more closely match the ports on my head. I can't wait to try it out. A whole new intake from scratch needs to built for my combo before I will be satisfied though. But this will have to do for now! I've been shooting for a 1.8" + area that far back in runners for now. A 1.49" diameter exhaust valve that has an area of 1.74" will now easily slide all the way down the runner with clearance to where the runners squeeze down on the sides while getting taller on the roof and floor and start to become oval. The runners definitely have a taper as much larger back towards the plenum as cast to from what I'm measuring in the 2.0"+ area. It's really hard to get a real accurate measurement.

[Directconnection]

A few years ago, I did my own flowtest on 1 piece and 2 piece intakes. I tested 4 in all (two 1-piece and two 2-piece) and the results were submitted to Barry for the SDAC newsletter. Basically, the flow between the 1 dn 2 piece were pretty much the same with the exception of the 2 different style intake having runners that flowed differently (another story on it's own). For $hits and giggles, I decided to try and flow just the bottom half to see how badly the top half restricted flow. I was suprised to find that the bottom half alone attributed to 2/3rds the flow losses of the whole intake! I backed this up by flowing the other 2 piece bottom half and same thing! I used a large clay radius at the end of each runner I tested as well....

BTW... those "humps" attribute to a 2 cfm flowloss with it bolted to the head. doesn't sound like much, but 2 cfm here, and 2 there will add up.


Now... a couple months ago, I started in on the porting of my 2-piece bottom half. One thing to note: I made sure I kept the same taper all the way through. Hard to do on this as it's round, then oval, the rectangle and not to mention a long runner and very hard to see/reach with a cutter to keep things consistant and smooth. After I was done with a roughed runner I decided to flow it and see what I got. I was hoping to see that I reduced my flow losses by 8 cfm, and if 10 cfm I, would be pretty pleased.

Stock, unported 2-piece lower half with clay radius at end... 29 cfm flowloss bolted onto a head that flowed 181 cfm at .500" lift. Swap it out for my roughed out version and my flowloss dropped to only 13cfm. 16cfm gain ON THE HEAD! Let's just say I was pumped. Didn't expect that.

So... I did open up volume quite a bit, but could go a tad more technically but don't want to chance it (and put more work into it...allready have about 25hours just in the 4 runners. I opened up about .040 all around (.080" on the diameter, maybe a bit more .080-.100) When you hit both intakes with a screwdriver like hitting a triangle, the ported one is about 3 notes lower.

I also did somethign a bit different than what others decided to do... I treated the short turn like I would in a cylinder head... I widened the floor instead of porting and lowering it. The bottom half's short turn isn't very abrupt like in a head, but it startes to get that way right where they bolt together, so i chose that route. Did it work better? Not sure.

[glhs875]

I can relate to how much the runners needs to be opened up. Especially for a port in the head the size of mine (655 casting size and then some). I've been using a brake hone to keep things blended in after I port some. Works ptretty good. I also have been using exhaust valves to keep the taper and area in check. I have one valve with the sides ground down so I will go all the way through the ported runner. I'm also shooting for a straight shot into the head with the runners with as little bend as possible. I'm porting more for area, I probably won't have it flowed. It's gonna take a long time. But I feel it will be well worthwhile!! I'm glad to here such gains in flow from your work. :thumb:

[Mario]

Thank you both for your posts and information.

[glhs875]

[QUOTE=Directconnection;152738] Basically, the flow between the 1 dn 2 piece were pretty much the same


I had already decided that the 2 different style intakes had to have at least very close to equal flow as cast. Because I felt I was missing some pretty good HP from all the improvements I made to my combo and felt like there was a cork somewhere. One change I did make was going with a ported 2 piece ( had ported 1 piece). I just didn't port the 2 piece in all the needed areas and my flow stayed basically the same! Probably flowed a little better than the 1 piece I had, but couldn't be much more. I'm expecting a pretty massive gain in HP!!! We'll see!

[johnl]

What tools are you guys using to get at the mid part of the lower half? As said, tough to get in there. Good idea to use valve round and valve flat sided as "go/no go" gauges.:thumb:

The tricky part, conceptually, is that the short turn in the manifold becomes the roof of the port. That is, at the head we are raising the port toward the sky and not cutting the floor lower toward the ground while in the lower half of the 2pc we are cutting the part that is toward the ground while not cutting the part that is toward the sky - opposites!

Love the idea of a mild "flat flooring" of the short turn transition from the upper half to the lower half. :thumb: What are your ideas about tapering the diameter from plenum to head - larger at the plenum, smaller at the head? The flat flooring has to reverse/transition from the sky side in the lower half to the ground side in the port.:wow1:

[glhs875]

What tools are you guys using to get at the mid part of the lower half?

Love the idea of a mild "flat flooring" of the short turn transition from the upper half to the lower half. :thumb: What are your ideas about tapering the diameter from plenum to head - larger at the plenum, smaller at the head? The flat flooring has to reverse/transition from the sky side in the lower half to the ground side in the port.:wow1:


I'm using about a 6" long carbide cutter. The runners are naturally tapered from the from the head to the plenum, which is great in my opinion. But they taper down way too much about mid ways in the runner to probably in 1.4" sq. area and that's about what a stock head port has for area as well. The ports in my head are slightly tapered as well, and shaped like a venturi, and have ports in the 1.75" sq. area (smallest point in port). The entrance of the ports in my head are in the high 1.8"sq to low 1.9" range and then squeeze down slightly about mid ways of the port and then get larger again in the bowl area to about 90% of the 44mm valves outside area of 2.35"sq which is 2.11" sq. The ports start to get larger before the short side radius so the air can slow down a little to help make the bend. Based on the math for a 2.2, a 1.75" sq port is designed to work well in the 7200rpm range. A port or runner/pipe max flow can only be what the minimum area is, not the largest. And whatever the minimum area is, that will determine where that size port will operate well too (peak RPM's) for a certain engine size, which is based off of the max speed air likes to travel. A stock port area of around 1.4"sq. has a peak rpm of around 5800rpm on a 2.2 based off the math. And that is what pretty much happens in actuality on a well set up stock headed combo. I'm actually starting to think that when the air is compressed from being turboed, a port might need to be a little larger than what the formula gives for NA. Because compressed air is heavier than it normally would be. I'm still researching that. In fact, I'm still learning on port design in general, probably always will be. But here lately I've been getting some very good results. I don't have a flow bench, so I port based from port area vs. engine size and a target peak rpm, along with some other known to work principles. It seems to be working well!!Eventually I think the stock type intake needs to go, or at least have some very heavy mods done to it. I feel I will be leaving a little power on the table even after this round of port work!

[glhs875]

The tricky part, conceptually, is that the short turn in the manifold becomes the roof of the port. That is, at the head we are raising the port toward the sky and not cutting the floor lower toward the ground while in the lower half of the 2pc we are cutting the part that is toward the ground while not cutting the part that is toward the sky - opposites!





I've raised and lowered both the floor and roof in both the head and intake runner.

[John B]

So is it best to leave the top half pretty much as is except for the neck?

[Directconnection]

I'm about to find out. I have to work on my k-frame and front end along with redoing new brakes and lines and.... list goes on. basically, everything replaced under the car except for rear axle...actually, have a solid rear now that i think of it.

Trying to fit in the porting of the top half in between. Removing the neck on the 2-piece I think is not going to gain you much like people thought in the past. I am cutting my top half apart to creat the velocity stack type effect along with a few other tricks. I it works properly, I may see even a great reduction in flow losses to possibly a gain with the intake bolted on. We'll see down the road what happens.

[John B]

Thanks Steve. You logo suggests that you're a judokha?

[Directconnection]

judohka? No clue...you mean Joker?

[jonnyb]

Thanks Steve. You logo suggests that you're a judokha?

Now that right there is funny!

I guess looking at the picture, I can see how you might think that if you don't know the AGD cartoon, but if you do know the AGD cartoon, then thinking of all of the possibilities of what Rob Smigel could have done with them at a Judo match makes me crack up laughing.

John B - do a search on "Ambiguously Gay Duo" in Google and you'll find out what Steve's logo really is.....LOL!

[Directconnection]

Yes, the logo.... not me!

I am the ambigously straight married guy.

[John B]

Thanks. I need to get out more...

[2.216VTurbo]

Nice bit of inginuity using a cut valve for a gauge, however an el cheapo set of telescoping hole mics from Harbor freight will give you more consistant readings. There are 6 sizes in the set and you can inside measure just about anything on a motor:D

[mcsvt]

^ I bought the same ones. They work great and were cheap!

[Directconnection]

Nice bit of inginuity using a cut valve for a gauge, however an el cheapo set of telescoping hole mics from Harbor freight will give you more consistant readings. There are 6 sizes in the set and you can inside measure just about anything on a motor:D


Just make sure you don't count on them for measuring anything better than +/- .002" The cheapies are crap but in this case, awesome. At work, I have to play with telescoping gauges to get +/- .0005 or better. Not fun especially the Brown and Sharp ones I have which are supposed to be good. Starrett next time for me. Sorry for the rambling...........

[karlak]

Has anyone tried extrudehone. Probably a waste of time and money.

[glhs875]

Nice bit of inginuity using a cut valve for a gauge, however an el cheapo set of telescoping hole mics from Harbor freight will give you more consistant readings. There are 6 sizes in the set and you can inside measure just about anything on a motor:D


I would like to get one of those guages. But a valve works pretty good for now. The valve scratches, leaving marks on the places needed to be cut out. And I know exactly how much total area the valve has. I've also made templates to check things where the valve won't fit (where ports go from round to more of an oval shape). I have found that the runners were not equal in area. 1 & 4 tapered down smaller than 2 & 3. I feel when I'm done, the runners will be much closer to one another in total area than before and from the factory as cast. I have been bolting the intake to the head as I go, correcting alignment and the entrance of the runner into the head. With the valves removed, I can easily see what things look like. Things were off alot before. And although not as good as I would like, the intake is now matching the ports in the head way better. I eventually need to have more welding done to the runners so I can make things even better. I would like for the runners to have the same area as the entrance to the head ports then slowly taper larger all the way to the plenum starting at the injector throat area. The taper starts happening further up in the runner than I want, and I don't think there is enough meat in the runner to start the taper sooner. But this round of work should make a noticeable improvement, we'll see!! At least now the smallest part of the runners will be as large or a little larger than the smallest part of the head ports. This round of port work, along with a modest compression ratio bump up (from 7.7 to 8.2), and an external wastegate that will flow enough to control the massive boost creep problems I had so I won't have to use a BOV to bleed off excess boost, should provide a noticeable gain in HP!