Well I did this a couple of days ago for Chris, and I don't think that there is an actual write up for it so I decided to give it a shot. Now this is a Racing Beat header as you can tell, which is good as it will most likely apply to most of the people looking at doing this. All you need is a welder, a pipe with the same outer diameter and side wall as your existing header size, and a band saw.

First thing I did was cut the flange out , now I know this part takes a bit of time but it need to be done. When cutting this what you can do is just hold the header flange perpendicular to the table and cut it straight down. Now if your band saw isn't that big you'll most likely have to cut it from both edge and maybe finish the center with a cut off blade on hand grinder, or just do the whole thing with a hand grinder. One thing that I did notice was that as soon as I cut that piece the pipe moved back about 1/2" on me so the pipes were in tension when placed in.

Now this is where it might be a bit different from the collected vs uncollected headers. This is an uncollected one, and I just proceeded to cut the pipe leading to the front rotor. I did the cut in a straight section are as when I increase the length it would move in just a straight line. Doing this also allowed the back section of the exhaust system to remain in the same position as before.

I then placed the gasket on the table, and then overlaid the 2 header pieces on top of it while making sure that the bolt holes were centered with each other. From there I took 3 clamps and clamped the whole thing down to the table. You have to ensure that your clamps are on there as tight as possible and that the flange is as flat as possible. Any bit of unevenness will most likely cause an exhaust leak at the gasket.

Now you have to measure up length of pipe needed. I measured my gap to be about 12mm so i cut a piece close to that. You might say "hey wait I thought the difference between the 2 engines is only 10mm? Where is the other 2 going to?". That's when I would reply, well genius you forgot the width of the material you cut. I would assume that a band saw would achieve the smallest gap difference ( i'm assuming the second more favored thing to use would be a grinder possibly and that might be about 4mm.

Now I have snugged ( and yes it was snug) in that piece in between those 2 pieces of pipe for the front header and tack welded it in place, make sure you tack it up in at least 8 spots 90 degrees apart. Also you want to do most of the welding while you're still clamped in. Once I was all welded I noticed that the pipe still relaxed in the same spot as it did before when I cut the flange. Now I could of left it like this, but this really makes it a pain when installing. So what I did was toss the headers in vise, and pulled them together till the bolt holes matched up again. Once lined up, I just cut a piece of 1/8" steel plate small enough to fit on the flange top and welded it across the 2 parts. This now made it hold itself together.

Once installed on the engine it lined up perfectly to everything, and didn't even struggle. Here's the pictures of the stuff.

 

Very nice Sam.

Welding is one of those things I always wished I had learned, but it seems like once you've got a wife and kids, there's no time for anything else anymore. Not that I'd have it any other way, of course.







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I give your header mod three thumbs up.

 

Lol ... there's a reason why I like to stay single for the time being All in due time ... the rest will fall in place.


Thanks Jeff for the compliment

 

Nice, even nicer having the tools to the the job and the welding skills to complete it. Since I did not have the bandsaw, welder and welding knowledge I was stuck buying another header even though I had a 12a roadrace header to play with.

Great job!!!

 

He did a great job, on this as well as my battery tray. Fit perfectly and you can't even see the welds from the engine bay.

 

Lucky bastard

 

Looks good man! Anyone made a 13b header fit a 12a?

 

I would asume its just a reverse process

 

This would make a 13BT manifold work on a 12A - and that would be SERIOUSLY AWESOME!!!

 

That requires quite a bit more work. The turbo manifold is first of all cast iron, welding that for some is already a pain. secondly, try to make sure that after you chop it in half and take out some material, the inside might not line up as you'd like. Really if you're into doing that much work, you might as well make one from scratch as it will most likely take not as much time to do.

 

I was thinking an aftermarket mani but yeah I know what youre saying. I will most likely end up making my own manifold if I decide to go that route.

 

Wow, you really really REALLY overthought it...





There's still a beneficial amount of port mismatch - the headers are MUCH larger in ID than the exhaust ports, so it doesn't take much to make up the 5mm difference per port plus a little extra.

I guess Aussie guys have been ovalling out 13BT exhaust manifolds to fit 12As for quite a long time. It's absolutely nothing new.

PS - This header is now on its third 13B. Well, second, if you don't count the two incarnations of the current engine. It also saw a 12A in post-modified form.