well thats what i get for not paying close attention lol

 

Nice work. No concerns about thermal-induced movement of the head across that solid mounting flange? I've heard the flange should be split in a few areas. I'll be fabbing up my own headers, and that was the route I was going. Any issues with this?

 

Is that only a turbo manifold design concern or generalized for any solid flange? Only reason I ask is because every set of LS headers Ive ever used or seen, shorty or long tubes, have always had a solid flange rather than the split design of the factory manifolds. Forgive my ignorance, I've just never heard that brought up before with header or manifold design.

 

There are a few shops that will cut the flange. I personally don't because the ports & bolt holes will move around after you cut the flange. Might only be a little bit, but enough to where you might be drilling out the bolt holes and your ports might be off a little bit.

From what I've seen, most of that stress is taken out after you heat cycle the manifold a few times.

I've made maybe 70~80 manifolds and never cut one.

 

Some do it to take out stress from welding. everything relaxes a bit making it less prone to cracking. I weld on 2x4x24" aluminum blocks to keep the heat soak to a minimum from welding. Keeps the flange somewhat straight too.

If you don't keep the flange cool and bolted straight you can warp it 1/2" pretty easy.

 

lol, no worries. you're the second guy to make the AFC comment.

I love the AVCR. I've had it for about 12 years. Still doing its thing. I'm hoping to hook up the VSS soon so i can do boost by gear and all that jazz.

 

apexi stuff was huge back in the day, i rocked the afc's on a few turbo'd hondas in early 2000 or so

 

I have an LM7 in my truck and an LH6 on a stand in my garage getting rebuilt to take on the turbo. The one in my truck has aftermarket headers, and the flange is split. The stock manifold I took off the LH6 was split, too. With aluminum heads on both (the LH6 is an aluminum block as well), the thermal expansion differential between the stainless or cast of the headers vs. those heads is pretty big. I used to be a wrench for Caterpillar and Cummins, and both would divide the manifold into sections, with sliding joints joining them. Also, I read the pdf "Maximum Boost", and he brought it up in there, which got me thinking about it. It makes sense, but as this guy has pointed out, it doesn't seem to be necessary. I will probably still do it, after reading his comment about having to weld it on large blocks of aluminum. Maybe with shorter sections the likelihood of warping will be less (less welding per section). Dunno. But, I'll give it a shot. Obviously "boostedsl2" has a lot more personal experience than I do in this instance. Helluva manifold he built....the way he joined his tubes is very cool (something shown on that Maximum Boost document as well).

 

Yep, I'm in the same boat. I thought Apexi went bankrupt a few years back. I was surprised to see that they still sell the AVCR. Not sure about the AFC. For the price, it is a pretty good option compared to eboost 2, AEM or the other more complex boost controllers.

It's a pain to setup if you haven't done it, but I've setup a few of these and really like it.

 

You're correct. Most stock manifolds have a break in the header flange. This is for exactly what you're thinking. Cast is a different animal though. Much more prone to cracking than stainless tube header/manifolds.

If i were to build a mild manifold i would consider slitting the flange. The stainless pipes will allow for a lot of movement which cuts down on cracking. I also recommend using mild flanges over stainless in all conditions.

You can buy drops off of ebay for $40, which even if you're doing one set will help you tremendously.

Here's an example (little more expensive at $65). you can usually find these drops at a local metal shop/supplier too. You'll have to haggle with them on the price but, they'll match ebay usually.

6061 T6511 Aluminum Flat Bar 2" x 4" x 24"Long | eBay

I would not recommend welding a header flange without bolting it down. You can use a cylinder head, but it's a pain in the *** while you're trying to weld because you've got this huge base that you have to man handle. Makes it hard to be in a comfortable position which ultimately shows in your welds.

Here's a pic of one of the aluminum blocks I use.