Header flanges? (Now ready for Sale!!!)

[xtremesunfire]

can somebody send me some flanges for the 3400 so i can start getting them get cut so i can start selling them at work.

[bszopi]

I edited the file last night for Geoff... He will be making me 4 total test flanges: both designs as seen in the DWF, each design with either a round port or a D-shaped port. I think he was going to try to get them cut today or tomorrow and then send them to me for a test fit. I will bolt each test flange up to a head and take pictures for everyone to see. Once the flanges are tested, I will make any changes to the design necessary, sent the new file to Geoff and he'll start getting some produced. I would guess a max of 2 weeks time until the flanges are available.

[SappySE107]

No not at all.

This coming from a guy that is keen on port matching.

I think you need to explain yourself on this. When have I EVER said it is best to port match the exhaust.

[xtremesunfire]

dude i wanted to start making them 2 so can you please send me the updated dwf file to me at xtremepcconcepts@gmail.com

[SappySE107]

are you going to post every hour about this? Calm down!

[geoffinbc]

dude i wanted to start making them 2 so can you please send me the updated dwf file to me at xtremepcconcepts@gmail.com

Quit trying to cut in on our project :P

[Guest]

No not at all.

This coming from a guy that is keen on port matching.

I think you need to explain yourself on this. When have I EVER said it is best to port match the exhaust.

You've never said to port match the exhaust, at least I'd hope you wouldn't, but to put a round port (header tube entry) over a D-shaped port, you just lost all benifits of a D-shapped port.

Also the fact that the bottom of the port seems to be just as important as the top as indicated by the improvment of flow over a round port, would tell me that the primary also needs to have a D-shaped primary entry, with a transition to round, not just from D-shaped to round in less than a .001".

The flange/primary entry shape should be consistant with the exhaust port shape, only slightly larger.

[bszopi]

If we were getting these CNC machined, I would make a flange with the transition inside the flange. Marty and I were discussing it the other night, but since a laser or waterjet can't limit the depth of its cut (at least not one I've seen), its kind of a moot point. And I'm guessing that getting these CNC machined would at LEAST double the cost.

[SappySE107]

Why would you bring up port matching then!?

Where have you read any credible information stating that the D shape is what you should run on D shaped exhaust ports. Does this mean that D shaped exhaust flanges on a round port will give you a benefit? No, it does not. The transition and shape of the bowl and port are what are important, along with tube diameter. How are pressure and sound waves going to travel through a D shaped primary tube? Im not making any sense of this.

[tejohnson]

I was always under the impression the flat space in the D was to assist in scavenging. Flows slightly faster "curving" over the flat space. But I could also be fabricating this in my crazy head

[SappySE107]

http://www.rbracing-rsr.com/SAHeadTech.html

"You can see the pronounced "D-Shape" of the SA exhaust port. Remember that we have a 1.750" exhaust valve that has almost a staight shot out of this raised port...but the vertical height of the port is only 1.675". The "D-Shape" flattens out the inside radius to increase flow on the exhaust cycle and provides a shelf to prevent reversion on the overlap phase of the camshaft timing."

[Guest]

Ben, I brought up port matching more for the shape than the transistion, it was a poor choice of words, but easiest way to state it at the time.

If a D-shaped port is of no benifit, why do most engine builders end up with D- shaped ports in the end for high flow, high HP street engines (and some race engines), like the LS1s, the more desirable LS1 heads use the D-shape port, though due to the non splayed valves the LS1 uses, the flat spot is not turned like on the genIII 660, and yes the flat bottom helps in port velocity, which helps with scavenging.

What you were proposing or at least how I read it is that the flange opening could cover the jut outs that create the "D" shape, since in your words "as most of the flow is coming off the top rounded part anyway". So maybe we should just have a port that will utilize the top of the port, who cares about the rest of the port, or even how it effects where the rest of the flow happens.

The transition from D-shape to round should be longer than 3/8" (Thickness of the proposed flange) from what I have seen, probably closer to 1/2" or 3/4" transistion.

I stand by what I say, the opening in the flange needs to match the same shape of the actual port, just preferable larger, by between .050" and .100".

[tejohnson]

Out of curiousity, if you have a turbo, why does it matter Or are you thinking of others?

[Guest]

Out of curiousity, if you have a turbo, why does it matter Or are you thinking of others?

I take it you're asking me that question?

Every aspect of the engine matters, even moreso IMO with a turbo.

With the higher exhaust restriction that comes from placeing a turbine in the exhaust system, the anti-reversion is still just as important, if not moreso than an N/A application. But I don't expect anyone to agree with me, so I'll just build my stuff and be waiting for y'all at the finish line.

[SappySE107]

wow...just wow.

I didnt say 1 thing you are saying that I implied. I did not say the D shape was worthless. You said the D shape was worthless if you bolt a round pipe up to it. I said that is incorrect because it is the port shape and bowl transition that matters. The primary should not hang into the port. I did not say this either nor imply it. Yes, there should be a larger flange/primary right at the exhaust port, but it should then immediately resize to the proper primary diameter. THere is no reason to keep it D shaped at the flange or first 1/2" of the primary tube. Have you done any analysis on the port design? Sure, it could be beneficial if it turns out that the port runner needs x amount of legth to get the most effect from the D shape. I have no see this number for the length and as such, still believe that there is no reason to reshape the primary tube to a D just for the sake of doing a D.

1 5/8" primary will be larger than the D shape on the exhaust port. No way is it going to overlap be it a D or O shape.

If you think you read me wrong so that I look like a retard...you probably did read it wrong.

On my flowbench, the majority of the air coming out is at the top, mostly the top corner biased by the port shape. Did I said we should just block off the bottom corners? No I did not.