Whats everyone.
Just wanted to share my experience with those who are interested in doing the same. First I want to thank Mike( racerXtreme7 ) for getting me started in the right direction and his great input.


Here it goes!! This all came about because I purchased one of those ss manifold off of ebay for my 1993 R1, which was recomended to me by the guy i bought the turbo from. After trying to make the manifold fit the car, I gave up out of frustration with the lack of professionalism in who makes the part. You'd figure that a part that is mass produced would have greater tolerences, to allow the differences that may occur. Such as worn motor mounts (That would sit the block closer to the cradle) or even..... Anyway.
Moving on.

I looked into haveing a custom made manifold for my AF61 turbo, but was shock at how much people wanted $800+. So after speaking with racerXtreme7 I decided to take a shot in fabricating my own manifold to the specs that I wanted. I realized that this would be a REAL challenge since I have never before design a manifold. Believe me its not as easy as it sounds!

I bought the parts from McMaster which came to a total of $172, I believe with shipping. Now this is 1/8" thick SS 304 tubing. As for the flanges I had a company waterjet cut them out of 3/4" thick 304 SS to help in resisting warpage.( I know an over kill to some, but I had acess to the material for FREE).

I has taken me a while to come up with the right design after comparing some that are out there. Well I don't know if its the right design, but will see how it performs. What i found difficult was keeping the two length as equal as possible. Mine is about 1.5-2 inch diffence. That and keeping the flow smooth. One detail that Mike told me to try and keep was the straightness coming out of the block. To at least 3" straight before turning. Also right before the flow goes into the turbo. Now that was hard to keep straight because of clearences between the cradle and the bottom of the manifold. I think it looks cool but you let me know.

As for the welding I did the tack welding with a mig welder that I have and a friend finished it for me.
I still have to send it out to get coated and then finish my end tanks for the up grade intercooler that i bought.

This started out to be a 3 week project and turned into a 4 mth project. We'll at least I'll have a sense of accomplishment!! After all its what I love doing!!! (Don't tell my wife)

I'll up date this thread when i have the car running. Enjoy the pics!! Would love the feedback, good or bad.

Thanks
Diego

 

More pics

 

looks good....i plan on doing the same this winter.

 

Thanks Bro

 

Nice job man. Glad things worked out for ya!! Nothing like the feeling of accomplishment and pride when you make your own stuff! Looks like you rushed the wastegate runners a bit (not same length) but i seriously doubt you'd be able to feel the difference in the butt dyno anyway. The most important part is the long runners, divided T4 flange, and runner diameter. It should spool up quick and have good top end to boot.

~Mike................

 

looking good, I'd just dremel/sand off the inner weld spots, where the flange and tubes meet so that the air flows smoothly into the turbo, but otherwise nice work!

 

Now that is pretty damn cool, big kudos to you. You should start producing them and selling 'em

 

looks like that's going to be one bad-*** manifold. overkill-schmoverkill! i love the thickness of the flanges.

 

I'm with you on the thick flanges. 304 warps like a bastard.

 

Looks great, i have a bunch of pics of my header build and was going to make a thread too but i got lazy. Which coating do you plan on going with?

 

looks nice

 

Yep!
The only cavaet you need to worry about is I hope the bolt / stud holes aren't too tight toleranced!
304 (hell, almost any SS) heat expansion rates are pretty crazy, and some have claimed to be able to *shear* fasteners due to it's expansion rate from heat.


-Ted

 

Thanks Guys for the positive responses. I'm going to get that black coating, not sure of the name but i have it written down somewhere. As for the size of the hole on the flanges, there is enough room for expansion. Worse case I can always make them bigger.

Hey mike, the WG runners seem to be off but there actually pretty close, like a 1/2 or so off. If you notice one of the runners wraps around and the second one comes off the side, so one looks shorter than the other.
I still have to clean up the inside welds before sending it to the coater.

By the way does anyone know which is the coating that actually impreganats itself to the metal, rather than staying on the surface like a paint??? I believe the black one that I've seen on line is the one that becomes one with the metal.

 

You've given me hope! This is cool man, I'm subscribed to this as I really look forward to seeing the finished product. If you have more pics of the build process, let's see them. I think I'm sort of in the same boat as you -- I have a crappy OBX manifold that I really don't want to use, but I also can't see forking over the $800+ for a custom job.

I'll be interested to see your final price list when you have it.

Thanks for posting this -- keep up the work and please keep us posted!

 

Your runners ends as soon as another terminates to it (generally at a merge collector). So your front wastegate runner comes off the first (front) main runner and does a bend right? Then your rear wastegate runner comes straight off the rear main runner. Were the front is spliced into the rear is were they BOTH end. Your not going to notice any loses or gains by doing this the most proper way. Its when you add tons of little things up is when their noticed. Good job none the less, I'm not nick picking, just making sure you understand the basics of these things and that your rear wg runner effectively termminates were your first one is spliced into it.

~Mike................

 

I see mike, thanks for the feedback. I'll use this one as a stepping stone for a better one. Not that I'm going to attempt to build one again! lol As for a list of parts, just get 45 deg and 90 deg pieces and I would of gotten a couple of 30 deg to make it easier on me. Other than that two legnths of 1.5" and 2" tubing.

 

I can't quite figure it out from the pictures, but how did you make the transition from the round tubing to the rectangle T4 flange holes?

 

https://www.rx7club.com/single-turbo-rx-7s-23/manifold-tube-turbo-flange-transition-592836/

^^ he answers you in a thread dedicated to your very question.^^

Simply squish it either in a vise, or hammer it. If you use heat it'll be easier. You can also make a inlet shaped matrel and press/hammer it into the tubing also, but this requires quite a bit more work and sometimes getting the mantrel out is a bitch.

~Mike..........

 

What Mike said and this added detail....Actually to make a precise shape I had to cut a small wedge out of each side of the tubing the sqeeze the tub to confine better to the shape I was trying to achieve.

 

Thats why I bought the tapered cone tubing sections . Takes your main runner diameter and tapers it smoothly to the correct circumfrance to make a 1 piece square shape.

You can also just make it slightly bigger then the inlet flange, then port the flange smootly into the runner too.

~Mike............

 

aaaa Thats what happens when I rush things!

 

You still got the desired shape and its smooth!

I also used these cones on the engine flange too. The main runner diameter is slightly bigger then the exhaust ports, so I matched up the manifold flange to the exhaust ports, then used a taper section of tubing then full diameter runners, then back down to a taper cone that was squished to the final T4 square shape.

~Mike..............

 

Hey Mike do you have any pics??

 

^^^what he said.

I'm feeling inspired! Maybe this isn't as out-of-reach as it first seemed...

 

Naw, sorry guys no pics. The ones I had of the build got lost. I still need to finish welding it, its just mocked up right now. It looks pretty much like coolrotaries except the wastegate runners are a little different and I managed to get all the runners withen 1/8" to being equal. I have too many hobbies and not enough time or money for them!!

~Mike................