CNC Header Flanges

[RallyBob]

Originally Posted by Geek Somewhat related: What are you going to use to get the mill scale off? A (very) little experience has proven to be miserable.

I believe he said he would mill it off.

I previously had mine sandblasted, very efficient method!

[Geek]

Actually, he said:

I'll be facing both sides to get the correct height.

Did you do the sand blasting, or was it professionally done? My neighbor is putting together some very large, very heavy, metal working tools - scale has been a problem.

[Gumby]

Originally Posted by RallyBob Other than the center divider, I basically just cleaned up the stock design and made sure it fits aftermarket intake manifolds. I tried all the ones I had in my possession to make sure. I did enlarge the ports a bit compared to stock (2.4's have bigger exhaust ports for example), which allows for almost any header tube size. Bob

Ok so having the "half circle" for the bolts isn't important. I copied a 2.4l manifold so it should be larger than a 1.9 already. I still plan to compare my digital model against the one you sent to me. Hopefully it will be here today.

I have three manifolds I can test it with, stock 1.9l, 2.4l, and a cut down 3.0l.

Originally Posted by RallyBob The problem with copper is the lack of 'crush'. So the head's surface, the header, and the intake must be perfectly flat (no corrosion or warpage), and the intake and exhaust flange must be the perfect matching thickness. The intake/exhaust bolts also need to be perfectly torqued to spec, and checked frequently. There's no 'sprung' gasket to take up the slack here! It's been done before on race cars, but conditions must be perfect. The alternative is a car burned to the ground. Especially with a turbo!!!!! Still, the thought of fuel leaking past the intake flange gasket onto a hot exhaust does not thrill me! Bob

What series copper alloy are you talking about? Either way you make good safety points. In the past did you use a stock gasket for your tubular headers? Personally I plan to use a regular gasket since I doubt the gap between the two ports will cause much issue.

Originally Posted by Geek Somewhat related: What are you going to use to get the mill scale off? A (very) little experience has proven to be miserable.

As Rallybob said I plan on milling it off. It's nasty stuff so that is all that particular carbide tool will get used for. Sand blasting isn't a bad way to go for the vast majority of people but I already have to face the material down to the correct thickness so this takes two steps down to one. If you do go about removing the scale via milling I'd recommend a fly cutter with a brazed carbide tool since they are cheap and can be reground with common equipment. Modern high performance end mills require cnc grinders to properly regrind. Indexable tooling is the other way to go but that is more expensive.

I have these "Gorilla Mill" variable helix end mills I am looking forward to trying out.

[Gumby]

Originally Posted by Geek Actually, he said: Did you do the sand blasting, or was it professionally done? My neighbor is putting together some very large, very heavy, metal working tools - scale has been a problem.

What size is very large/heavy?

[Geek]

Much thanks!

[Geek]

Very heavy = three interlocking pieces, each weighing ~100(ish?) pounds. That's just the buiness end though, stand and handle/monkeybar extra.

[Gumby]

Originally Posted by Geek Very heavy = three interlocking pieces, each weighing ~100(ish?) pounds. That's just the buiness end though, stand and handle/monkeybar extra.

I don't know how they are shaped but sand blasting may be his best bet because any contours or odd angles are going to be a pain to do on a mill.

[RallyBob]

Originally Posted by Gumby What series copper alloy are you talking about? Either way you make good safety points. In the past did you use a stock gasket for your tubular headers? Personally I plan to use a regular gasket since I doubt the gap between the two ports will cause much issue.

Not sure what copper alloy specifically, to be perfectly honest. But once annealed it was 'dead soft' for sure.

I have used custom header gaskets (1.9 and 2.2 type) on all performance applications. I used to have them made when I owned C & R. They have the divider between cyl #2 and #3. Not doing so skewed the ability to jet each cylinder correctly. Not sure it's much of an issue on a street engine, but for racing it's rather important. Plus not having the metal port 'surround' means I can port the gaskets (they were graphite with metal core) to match the head's port shape. Again, very critical for racing, as stock gaskets hang into the intake port tract!

Bob

[RallyBob]

Originally Posted by Geek Did you do the sand blasting, or was it professionally done? My neighbor is putting together some very large, very heavy, metal working tools - scale has been a problem.

I had it done professionally, cost me $2 per flange as I recall. Besides the ugly appearance of the mill scale, it makes proper TIG welding very difficult from contamination.

[Gumby]

Originally Posted by RallyBob Not sure what copper alloy specifically, to be perfectly honest. But once annealed it was 'dead soft' for sure. I have used custom header gaskets (1.9 and 2.2 type) on all performance applications. I used to have them made when I owned C & R. They have the divider between cyl #2 and #3. Not doing so skewed the ability to jet each cylinder correctly. Not sure it's much of an issue on a street engine, but for racing it's rather important. Plus not having the metal port 'surround' means I can port the gaskets (they were graphite with metal core) to match the head's port shape. Again, very critical for racing, as stock gaskets hang into the intake port tract! Bob

Copper is a soft abrasive metal by definition but the difference between a 400 series alloy (common) and a 1700 (harder alloy) series is pretty big. The nice thing about copper is the coefficient of thermal expansion is almost exactly the same as common stainless steel (304B).

Most so far seem to be for street vehicles so I am honestly not worried about the gaskets. If the few racers who said they wanted the flange and/or turbo header need a gasket made they can contact me. Otherwise I still plan to run with a regular gasket.

I am considering running boost on the 2.4 I aquired… what kind of realistic gains from a stock engine would I see at 9 - 14lbs? If a 1.9L can hit 160ish with 8 - 9lbs of boost O_o I'm a bit worried that even during normal nonabusive driving I'd see reliability issues out of stock torque tube and rear end with a turbo or supercharged 2.4L.

[Paul]

Once upon a time... OGTS was selling the Intake/Exhaust manifold gasket with a center divider in the #2/#3 hole. I believe they are in the process of having a new batch made...

[Gumby]

Originally Posted by Paul Once upon a time... OGTS was selling the Intake/Exhaust manifold gasket with a center divider in the #2/#3 hole. I believe they are in the process of having a new batch made...

I just got off the phone with Dennis. They have them in stock, item number 10012.

[RallyBob]

Originally Posted by Gumby I am considering running boost on the 2.4 I aquired… what kind of realistic gains from a stock engine would I see at 9 - 14lbs? If a 1.9L can hit 160ish with 8 - 9lbs of boost O_o I'm a bit worried that even during normal nonabusive driving I'd see reliability issues out of stock torque tube and rear end with a turbo or supercharged 2.4L.

Please don't even consider ANY boost on a stock 2.4 shortblock. The stock pistons fail (ring lands) under high rpm naturally aspirated use. They won't tolerate forced induction for long, even at modest levels. You'll need custom forged pistons. Rods and crank are strong enough however.

HP depends on breathing, rpms, and turbo size. If you choose the same size turbo I did, expect about 15-20 more HP than me, but a heap load more torque at the same boost levels. At 150 hp with a turbo 2.4 I'd expect 200+ ft lbs of torque. More than enough to shred stock Opel parts!

Bob

[Gumby]

O-o Well it looks like I need to get searching on a solution for that problem!

The flange didn't arrive today so hopefully it will be here Monday.

[Gumby]

Update:

The flange didn't arrive yesterday. Maybe today!

Rallybob - I measured the distance between the #2 and 3 cylinder exhaust ports on my 2.4L. It is a few 10ths over .2". Do you know how thick they made that on your design?

I'm in the process of removing the manifolds from my 1.9 so we can get ready to do a mockup of the piping. I'll have the mild steel for the flanges this week so they could begin shipping as early as late next week. The turbo manifolds are still a ways off.

I'm going to be gone three out of the 4 weekends in July for various military trainings so I am not sure how this will affect the timeline to completion yet.

[RallyBob]

Originally Posted by Gumby The flange didn't arrive yesterday. Maybe today!

So much for 'priority' mail! Thanks USPS....

Rallybob - I measured the distance between the #2 and 3 cylinder exhaust ports on my 2.4L. It is a few 10ths over .2". Do you know how thick they made that on your design?

Very thin. I allowed for insertion of the tubes into the flanges, so they would be able to be welded internally. Wth bigger tubes you can weld to the face of course.

http://farm4.static.flickr.com/3077/...a21724e4_o.jpg

This shows it pretty clearly!

[Gumby]

That looks to be less than .1" - I'll wait to get your sample before I mess with the model in that area.

What are your recommendations on the tubes inner diameter at the individual exhaust ports and when they come together for the turbo?

[RallyBob]

Originally Posted by Gumby What are your recommendations on the tubes inner diameter at the individual exhaust ports and when they come together for the turbo?

I've used 1.25" weldable cast steel 'Schedule 40' pipe fittings for most manifolds. Enough for 400+ hp, anything bigger and you'll just get more lag. I'm going to use 1.5" pipe fittings for my Dad's GT, but that's a 600+ hp turbo and a 2.6 litre engine with a lot of headwork and a hot cam, so it can support it.

On my wagon turbo header I used 'Schedule 10' fittings made from 304L stainless. Dimensions below.

[markandson]

Originally Posted by Gumby Stainless is an option since the jigs would be the same. Cost will obviously be higher. My guestimate is $80 for 304 but let me get back to you on an exact price. If you are ok with sending me your flange that would be great. I was planning on using the CAD file I posted a link to in another thread and comparing that against my stock exhaust manifold to make sure it was dimensionally accurate. Personally I'd rather use your design. This isn't really applicable to you Rallybob but I know a skilled welder who is hurting for work. He may be willing to make complete headers for cheap. I plan on having him do the welding on my header but if anyone else is interested I'll talk to him to see if he is willing to do more than just one.

I'm jumping in kind of late here, but if the CAD file I did is the one you are referring to then you can trust it. It was done using Bob's old template and a vernier on my 2.2 head to tweak it just a bit. I was originally going to have them waterjet cut by one of my vendors but there was not enough interest.

[Gumby]

Originally Posted by markandson I'm jumping in kind of late here, but if the CAD file I did is the one you are referring to then you can trust it. It was done using Bob's old template and a vernier on my 2.2 head to tweak it just a bit. I was originally going to have them waterjet cut by one of my vendors but there was not enough interest.

Another member here mentioned that there were some fit issues with the flange when they made from your template. I can't get Inventor to open the darn thing so I am not really worried about using the other CAD file since I've already created one based off of the 2.4 exhaust manifold I have. If you could send me an IGES file of the model so that I can compare the three designs that would be great.

[markandson]

Originally Posted by Gumby Another member here mentioned that there were some fit issues with the flange when they made from your template. I can't get Inventor to open the darn thing so I am not really worried about using the other CAD file since I've already created one based off of the 2.4 exhaust manifold I have. If you could send me an IGES file of the model so that I can compare the three designs that would be great.

It is a .dwg file from AutoCad 2004, no 3D model exists, I believe I posted it as a .pdf, maybe the other members did not use mine, I printed a full size one on my plotter and then cut it out with an xacto knife and it fit perfectly. I would have to search for it myself, I don't recall what the thread was. I still have the original Acad drawing, PM me your email address and I will send it to you.

[Paul]

The problem I found was interference with the thermostat housing. The other tweaks were very small adjustments with the bolt clearance holes to improve the ability to get all the manifolds bolts in easily. We're talking .020 to .030 nothing major.

I cut mine on the water jet at work. First, I cut it on 18 ga sheet metal and kept making very small adjustments, checking against the 3 heads I have.... and then cut one out of 3/8 hot rolled plate. I made mine so it would fit a head modified to Bob's street porting article, which should still work okay with the stock head.

[Gumby]

I received Rallybob's version of the flange today. The divider between the two cylinders is about .1" and I also noticed that the thickness of the flange is actually less than 3/8"... The sand blasting removed about .004" from each side.

A few other things I noticed.

This flange has a 1.22" width for each exhaust port but the 2.4" manifold I have various from 1.38 - 1.42". So it is a bit larger. Is there merit to using one size over the other? In either case the width is larger than the exhaust ports.

I can faithfully copy Bob's design or just as easily make any improvements. Is there any census as to which way to go?

[RallyBob]

Originally Posted by Gumby I received Rallybob's version of the flange today. The divider between the two cylinders is about .1" and I also noticed that the thickness of the flange is actually less than 3/8"... The sand blasting removed about .004" from each side.

Finally! That took forever to get there.

This flange has a 1.22" width for each exhaust port but the 2.4" manifold I have various from 1.38 - 1.42". So it is a bit larger. Is there merit to using one size over the other? In either case the width is larger than the exhaust ports.

Well, even with extreme porting on Gregg's 2.4 head, the header flange I used on my most recent header fits with no issues. I can't imagine having to make the flange holes any larger.

I can faithfully copy Bob's design or just as easily make any improvements. Is there any census as to which way to go?

Whatever is easier for you. If you can make some improvements, I say go for it! Maybe widen the center partition a bit? The fabricator/end user could always grind it away 'if needed'.

Bob

[Gumby]

Originally Posted by RallyBob Well, even with extreme porting on Gregg's 2.4 head, the header flange I used on my most recent header fits with no issues. I can't imagine having to make the flange holes any larger.

I couldn't think of a good reason either. The corner radius on your flange is much closer to the stock ports on the head… the exhaust manifold is more than twice that size!

Originally Posted by RallyBob Whatever is easier for you. If you can make some improvements, I say go for it! Maybe widen the center partition a bit? The fabricator/end user could always grind it away 'if needed'. Bob

That isn't a bad idea. The stock 2.4l ports are more than .2" way from each other. That would give more material to weld to and make it less likely to warp.

I'll get cracking on the updated model this week.