Building a manifold
 

Been looking for a used BEGI or FM manifold to no avail. I'm not adverse to building my own. I have a metal bandsaw, grinders and a nice Miller TIG at home, so equipped to do so.

I have a couple of questions.

1) Has anyone cut up a stock exhaust manifold for the flange plate and used it in a turbo manifold? Does anyone know what kind of steel it is?

2) The stock manifolds get by without expansion cuts between ports, but all of the turbo manifolds that I have seen have been separated with a saw cut. How do the stock ones get by without this? Is it because they are tubular and can handle the movement from expansion? It still doesn't answer the stud shearing question on the stock one.

3) I have an extra head from a 96 that I was going to use for a fixture for holding/clamping the manifold while welding. Is the exhaust side of a 96 head exactly the same as a 99? I'd hate to build it up and have an issue.

4) Would I be completely wasting my time building a mild steel weld el manifold or do I have to go to stainless? I'm not set up to back purge stainless, but could probably rig someting if I have to. Also, if the stock flange can be used and is stainless, I guess I have answered my own question.

Uh, I've seen it somewhere where a guy cut off the flange of a stock miata header and used it for his turbo manifold. Hmm, might do that...

Pretty sure the exhaust ends are the same. A turbo manifold that fits a 1.8 fits them all, though I suspect the ports *could* be slightly different. I'm port matching my flange to the head.

It wouldn't be a complete waste of time. I was gonna build one from steel, but then decided to use stainless instead. Hell I may end up using steel, I dunno. I need to do more research but I think I read the SS is more resistant to cracking.

maybe turbo manifolds get a bit hotter because of all the restriction of the turbo and thats why they need expansion cuts. wouldnt hurt to add them in once the manifold was finished.

Short, cast manifolds are brittle relative to tubular. When a manifold heats up, it expands. A tubular manifold like the stocker isn't affected by this much but a stubby cast one like a Greddy is, so relief cuts are made. That's my theory anyway.

I don't think you would need to backpurge all the way. May be only when you will weld the 4 into 1 coupling but even there, you will weld surely sch 10 pipe so if you pass through that and make sugar you sure have welded too damn hot! What you can do is welding a quart of the radius of the pipes, cool it with air, weld, cool, weld, cool. If you absolutly want backpurging, just tack the entire manifold, and make you a block plate for the head flange and one for the turbo flange with a hole with threads and put a plug with a hose connected to your bottle of argon. At least, that's the way I would do it, but I never did it myself so i'm not much a good reference for it!

Stein,

I believe all 1.8 manifold flanges are the same. You can buy premade flanges a few places though (JGS, ETD, maybe more).

Also check around either mcmaster or a local plumbing supply store for some pipe weld elbows. Those are going to be the right thickness ( to build your mani. It's also what most shops build them with. Vibrant also has them.
http://vibrantperformance.com/catalo...df6970ba11d1f9

You aren't wasting your time with mild steel. I've had mine on the car for years and 10s of thousands of miles and it's been solid as a rock. get the outside ceramic coated though. it looks much nicer and will better manage the heat.

I'd probably start by talking to TurboTim about components...

Matt

If you go with mild getting it coated is recommended but for minimal cost increase you can use stainless weld-els and be better off in the end.
WEIR makes cheap flanges ($24) but the OEM flange will work just fine. The 99-00 cast iron manifold obviously doesn't have a flange you can use though. WEIR can be found on the forum but you can also reach him at homemadeturbo.net.
ETD racing doesn't cut their flanges between runners and doesn't recommend that the buyer do it either for some reason. Apparently they've had more issues with cut flanges than not cut ones.
You can use SCH10 of SCH 40 1.5" pipe, SCH10 is lighter and strong enough for turbo manifolds though.

The cast iron used in turbo manifolds has (or should have) a high nickel content, giving it good corrosion resistance at temperature. Mild steel or non-nickel cast iron has very little corrosion resistance. Basically, it will begin rusting instantly in fresh water if it's not coated with something, and in air only slightly slower. If you have to go with mild, go with Sch 40.

I'd stick with the 316L weld-els for a manifold, as they're only 10-20% more than 304 and have better corrosion resistance. Sch 40 might let you get away with not bracing it properly. Sch 10 is plenty strong if it's braced right.

Cutting the corner and failing to back purge stainless will let you put something together that will work for a while, but the oxides that are formed have very little corrosion resistance, so you're asking for cracked welds over the long haul.

If you're a perfectionist, using mild steel els and PVC straights would keep the costs way down for mocking it up the first time. You could replace the PVC with mild straights and practice welding some of the trickier access spots without having to back purge, and with low scrap costs if you f(*& it up the first time or two.

zabac can get you a flange for sure if you need one.

a manifold with PVC pipe? interesting.

I was talking about just a mockup. It's easier to cut and costs almost nothing, so you can play with it until you get your straight lengths perfect and not run out of patience and hate yourself later. If you were going to weld up the mild, you'd of course replace PVC with steel. Gosh...

As cjernigan mentioned, this guy makes flanges for so cheap, it doesn't make any sense at all to go through the hassle of cutting the stock one off. Might as well sell the stock one to recoup the cost of the flange:

http://www.homemadeturbo.com/forum/i...?topic=83018.0

yeah, i've got lots of the bp flanges as well as b6t's in stock. they are $22 plus shipping. as you can see i've got quite a variety of flanges:
http://i47.photobucket.com/albums/f1...h/DSC09846.jpg
http://i47.photobucket.com/albums/f1...h/DSC09848.jpg

coincidence, i've just started mocking up a bp manifold this weekend. i'm probably going to make a jig for it as well. i don't really know the miata market a whole lot though, so i'm not sure who would really be interested in something so elaborate, most miatas i know are ripping around cones, or a road course, not a drag strip. this manifold isn't even for the owner of the car, i was just doing a dp for him with his edt manifold (crappy design imo) and thought since i had the car in the shop, i might as well use it to rip off a mock up quick.
http://i47.photobucket.com/albums/f1...h/DSC09911.jpg
http://i47.photobucket.com/albums/f1...h/DSC09914.jpg
http://i47.photobucket.com/albums/f1...h/DSC09917.jpg
http://i47.photobucket.com/albums/f1...h/DSC09918.jpg

If you can make a manifold that will work easily with powersteering and A/C while having good clearance to fab a downpipe then you will have a product that sells.
If you can make a manifold and offer a downpipe for both T25s and T3s then you'll really have a product that will sell.
Make a combo that will sell for less than $1k and you'll get some interest from people looking for big power off the shelf.
There are currently a couple companies offering mani/DP combos, FM and BEGI, so it would be nice to have another in line.

The DP for that manifold is going to be interesting.

I am late for this thread, but Aaron(weirtech) makes flanges for $22+shipping, that's worth it to me to leave my OEM mani in one piece if I need to go N/A...
As far as weldes go, acestainless.com is pretty damn good. (stainless or mild)
A flange from weir and your sch40 from ace beats the crap out of the JGS kit as well in case anyone wandered...

Stein, what I did is order a (mild) flange from weir and plan on getting (stainless) weldels from ace and mocking up my own mani, and since I cannot weld nor have the means to try it and teach myself, I will find someone (proffesional) to TIG it all up.
Good Luck to ya.



PS-does that Miata have a GS rad in it? lol

actually, the ac compressor isn't in there, so when the customer comes to pick the car up i'll ask him to bring it. i know where it goes, just not sure what it looks like.

do you think the manifold will clear it? the runner that will be closest to it is the one towards the front of the car. the one incomplete is going to #2 up behind the collector...

as for the dp, you can see the runners that are going to #3 and #4, pretty straight forward, so basically all the room you see in the third pic is what you will have for a dp and a wg dump tube... i think it is quite a bit of room... certainly more than the etd manifold!

Hey weiRtech, do you sell the weld ells too? I was going to buy the flanges from you guys, and some weld ells elsewhere, but as the multiple shipping charges add up the JGS kit begins to have its appeal. I basically need everything to build a log style manifold. Thought about sending you a PM instead but I'm sure everyone else wants to know too.

Thanks.

For $22, it doesn't seem worth it to do the stock hack job. As for the earlier post about the 99 being cast, I have stock 95 and 96 manifolds to work with.

Zabac:

You said you were getting a mild steel flange and going with stainless weld els. Aren't you worried about dissimilar material compatibility?

This was one of the reasons I considered an all mild steel manifold, plus the backpurge issue, plus the extra cost, plus tougher to keep the stainless from cracking.


Weirtech will probably see an order shortly as soon as my turbo and DP arrives so I can get a look at everything. I'm going to check around locally on the weld els just in case I can save the hassles of shipping, but acestainless has good prices.

See if you have a Fastenal around you, I know they can order them if they don't have any in stock.
As far as different materials go, I'm not too worried as a friend of mine just did this and has had no issues thus far. Plus Sch40 is pretty damn thick, I am not worried about it cracking. I will brace the flange properly when welding the runners to the flange so it should not warp much due to the higher heat required for welding SS.
I could go horribly wrong with this and waste a bunch of money on all the weldels, but as I have seen this done, I am not too worried.

Welding stainless weldels to mild flanges is common practice. Stainless flanges are super expensive and supposedly warp easier when welding. You bolt the flange down and resurface it anyway but you understand. You just use the correct rod when tig welding and there are no issues with cracking or dissimilar metals.

If you want to be sure that your manifold won't crack, chamfer the pipes that are gonna be welded to the flange. Because even if you weld very hot, TIG is not the champion in penetration. The welds can seems damn good but have no penetration. Where I work, from 3/16 and past, we chamfer every pieces that we weld.

when tig welding 304ss to mild steel, it is best to use 309L filler. i also weld the inside of the joint as well as the outside on all flange to pipe joints (head, turbo and wg).

schedule 40 is too heavy imo, i use schedule 10 for manifolds, plus they are cheaper.

as far as warping goes, even when bolted down, you are going to get some mild warp in the head flange, it is pretty much unavoidable. but if you heat cycle the manifold a couple times on the car and re-tighten the head studs in the proper sequence while it is still hot, it will flatten out. i've done this with 1/2" flanges that were warped 1/8" and by the end of the summer it was glass flat.

I just received 2 BP flanges from Mr. Weirtech. Very nice pieces. Better quality than the ETD flange and MUCH cheaper. I haven't started welding to it yet but there should be no problems.

I have used sch. 40 1.5" weld ells from mcmcaster (I can pick them up will-call so no shipping) on all my manifolds mostly because the ID matches the port size almost exactly. Plus it makes a nice solid manifold and I've never had any cracking issues; I don't saw in between primaries on the head flange.

I have never tried schedule 10, but maybe on one of my next manifolds I will. The larger ID shouldn't hurt. It would take less time to build, that's for sure.

Nice looking manifold Wier.

This is all good to hear, I am glad you proffesionals are joining in to advise.
Dark dude, chamfer means to grind down at an angle the ends of the pipes where they meet, right? Kind of like weldels come when you buy them...? I assume that is it.

Aaron, only reason i wanted sch40 is because that's what my friend used and that mani is bulletproof. If you really feel that sch10 is sufficient enough and that i should not worry about it cracking with a bottom mount turbo, then that's what I will use as I do trust your judgement. Right now is the time I need as much input as i can get as D-Day is approaching.

Tim, I found that 1.5" weldels from Acestainless are really 1.610" ID or something close to that, is this the case with the McMaster ones as well? Or is this maybe the norm?

i think most if not all of the ace stainless stuff is schedule 10... i am going to see if i can get a good source for elbows locally and start offering them, although i don't think i'll be able to sell them as cheap as ace.

if you are more comfortable with schedule 40, go for it. i've repaired a ramhorn manifold that was made with 10... i won't mention company names though, but i've never had problems with my own. i haven't had any manifolds crack where i used schedule 10, although i did have a wg pipe coming off the collector crack at the joint because i used a different stainless tube instead of the matching sched10 stuff.

imo, for short runner manifolds it isn't going to make much of a difference in the material that you use... it is more with the bigger and longer runner manifolds when weight comes into play and vibration due to lack of proper bracing is when you start to see cracks.

My runners will not be nearly as long as the ones in the mani you are building, my only concern was because I will have a bottom mount, I don't know if that will make a difference or not.

Ace has sch40, in the 1.5" diameter.

If you're really worried about it, you can make a quick and dirty adjustable heim support (or cheap nonadjustable) to keep some of the weight off. I would make a plate that bolted through 3 valvecover bolt holes so you don't strain just one and run the heim to that plate. Parts from mcmaster for the heim adjustment would be cheap. I think they're around $10 a piece there maybe more like $7 if i can find the part number.

Good to know that compatibility isn't an issue, and thanks for the tip on filler rod. Looks like stainless els and mild flanges FTW.

Yep Zabaz it's that!

Yeah I was going to do that, for better penetration just wasn't sure that's waht you meant.
I can't effin wait to start the damn thing.

Just ordered my flanges from weirtech. Good prices and good price on shipping!

Parts shipped two hours later with tracking info! Customer service at it's best!

thats my car :)

maybe i'll ditch the etd for that manifold, looks great

yeah, marlon, your dp is done, i'm just doing the wg/dumptube. sorry for taking some time to do the mock up... surprisingly it didn't take me all that long to do. the wg is going to be tight in the new location, but it will fit. i can't remember if you wanted me to do that charge piping section or not. i remember talking about it, but couldn't remember if it was something you wanted done now, or after you got it back on the road. lmk, aaron.

pm sent
in a couple of weeks ill killing my friends sti :)

It would be sweet to just be able to buy a manifold made from weld els for a 1.6 that looks like a BEGI S4 and allows the use of a T25 or one of its many variants with a Nissan RWD SR20 turbine outlet pipe, which is commercially available for dirt cheap. And with a compressor inlet position that lets the power steering and A/C stay in place. Mr. Wier?

Two more manifold questions:

Are fittings available to weld in the manifold for the EGR tube fitting? IIRC, the 94-97 was a male thread on the mani and the 99 is a female, otherwise I would hack one off of a 94-97 stock mani.

Second, can someone give me a general dimension for a flange-to-flange distance and centerline of exhaust port to centerline of turbo flange port for a BEGI/FM cast manifold? Because I have a BEGI downpipe, I'd like to best replicate these dimensions to help ensure everything will bolt up without having to mod the downpipe.

10+k and still goin strong.

http://www.aemfic.com/images/turbo/mani1.jpg

http://www.aemfic.com/images/turbo/manifold1.jpg

http://www.aemfic.com/images/turbo/manifold2.jpg

http://www.aemfic.com/images/turbo/turbomounted.jpg

Stein, can't tell you distance, but the best way to do it, if you have to, is to mount your turbo to DP and secure it in place (like let it hang off of something, like a stick maybe) and then build the mani up to that

Yeah, I considered that, but took the car out of service. Not a biggie, because it is a third car, but it would have been nice to build everything in advance and go from there. Once the turbo arrives, along with the flanges, I'll take a look at everything.

It will be hard to do it ahead of time...at least without turbo there to test fit etc.
if you find someone with the skills to take accurate measurements and is willing to take their mani of the car and help you out, you could do it...i guess creat a jig to hold flanges in place and then just make the runners work

I guess I'll build to the test fit.

I just assumed if the BEGI mani, turbo, BEGI downpipe would all bolt together without mods(supposedly) , if I matched the dimensions, it would do the same.

Easier said then done...lol
But yea, if you can get the right dimensions, even if they are not spot on you should be ok as long as you are not too far off

it is pretty hard to copy a manifold and have the turbo placement exact without building a jig.

here is one i did a replacement for of a greddy manifold:
http://i47.photobucket.com/albums/f1...h/DSC08475.jpg
http://i47.photobucket.com/albums/f1...h/DSC08479.jpg
http://i47.photobucket.com/albums/f1...h/DSC08480.jpg

here is the downpipe replacement and how i jigged it up... i clamped the existing downpipe in place bolted to the turbo, then just basically replaced the cast elbwo section of it.

http://i47.photobucket.com/albums/f1...h/DSC08468.jpg
http://i47.photobucket.com/albums/f1...h/DSC08469.jpg

new:
http://i47.photobucket.com/albums/f1...h/DSC08472.jpg
http://i47.photobucket.com/albums/f1...h/DSC08487.jpg
http://i47.photobucket.com/albums/f1...h/DSC08488.jpg

the entire new downpipe weighed less than the cast elbow.

very nice

Awesome, those piecuts look like they would be a PITA right next to the flange. Your skills with a tig torch are pretty sick.
Now start making affordable stainless pieces for the miata. How much for the manifold you just showed us that you had on the miata?

Pretty cool. Any dyno info of the differences between those two elbows?

the owner also changed the compressor wheel and ported the turbine housing as well... so it really wouldn't be a fair comparison. i don't think he put it on a dyno, but was very pleased with the outcome.

it was a pita to weld...actually, it ended up cracking right at the tightest spot to get at... i ended up re-welding it and also reinforcing that area with a second layer of 16g tube.

the top mount manifold i'm mocking up... i'd have to finish it first, but it wouldn't be cheap. i still have to add the wg.

Very nice work!!! I wanna spill my semen all over those welds!!! lol

I think if Stein gets close enough he should not have an issue as the DP has a little wiggle room. Worst case scenario, mod the DP as well, he has the skill.