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[7808]

ive been screwin around with my "project car" for going on 3-4yrs.. ya ridiculous. anyways I have an e46 bmw I wanted to turbo . true to my hmt roots doing it the cheap way and best way. I swapped in a iron block 97 motor and converted it to obd1 and im running dual ECUs, the stock one for all the can bus shit and the obd1 dme just for the engine, easy to tune. but that I mean I can buy a tune.  whatever.  car is swapped and running great right now.


heres the situation. i want top mounted turbo. for some reason i just don't like bottom mounted turbos in these cars. look it up and see why.  i bought a rather bulky borg warner s300sx3-60 88 a/r turbo. there is really no manifold i can buy exactly for my setup that the turbo will forsure fit. if there is, i probably cant afford it.

so i am handy with my mig welder, located the flanges needed for a reasonable price (not easy) and am planning to build a log manifold.  this is where you guys come in.  i think i should "neck it up" at least once or twice, and probably just feed the farthest runner from the flange right into the end of a size up of tube. i think what i want to use is sch 40 mild steel butt weld elbows and pipe.

what would you guys use - exact pieces - and how would you design it?

heres a cast manifold for reference



heres the turbo, as you can see its FAT. i got a good deal on it and should work good for my goals with room to play



ya im probably going to have to cut my hood up.  don't care, already has hail damage

[92CXyD]

Hail ya!!!! 

[DSharp]

you could always just use steel plate and make a squarish- tapered plenum with short runners.  Not Ideal, but easy to make.

[HiProfile]

If firing order is 1-5-3-6-2-4, you don't have to neck it up much IMO. At the very least I'd give it more volume for cylinders 4 to 1. After 4 fires, it clears out of that half before 5 fires, and same before 6 fires. Exhaust gases from 6 have the longest to travel, that's why I say make it larger between 2 & 3. A bit more volume for 1 & 2 wouldn't hurt either. A divided log wouldn't really require much, since the firing order alternates between each trio of front/rear cylinders. Feed 4-6 as direct to the closest volute, then 1-3 under that pipe to the farthest.

[7808]

Ya thats the firing order. Good point. My other idea was make two 3 runner logs out of two 90s and a T and join them at the flange, but space is gona be pretty tight and a need room for the downpipe.

I think a plenum type manifold would probably work fine, but it wouldnt really be much less work .

Trying to picture how id cut elbows to join the main runner without using straight short tubes or cutting 90s so short to merge them that it makes welding hard and puts it too closeto the head. Ialmost need long 45s

[DSharp]

plenum style would be so easy.  you could make something like this with a welder and a few basic hand tools:  and if you want to make it real easy, get the flat parts cut for you by a shop. 

[ratcityrex]

I vote squarefold

[7808]

that's pretty cool.. can you just hit the print button to your cnc waterjet machine now lol

that would make for much easier cutting and welding with no real curves

stick a throttle body on the end of that thing and it looks like some intake manifolds ive seen for this motor

here is my rendering



i figure joining them all into one pipe log style i can avoid attempting to build a collector and easier to add pipe to position the flange exactly where i need it

i included another design i liked, chopped stock manifolds joined with pipe, strongly considering this, but id have to get a spare set of manifolds (money i could use to build one from scratch) because i like to keep my stock exhaust just in case. also id need to build a jig or get a spare head, and cant use a gasket to make one because they are not one piece

[Minor Threat]

Keep your stock manifold in case you get a case of the faggots and want to go back to stock? Homo.

[7808]

My stuff is always forsale and i dont keep interest in one car very long, i find returning cars to stock usually brings a faster sale. People tend to be scared of heavely modified cars.

[highroller54]

Modded stock manis ftmfw!!!!!!!

[DSharp]

My stuff is always forsale and i dont keep interest in one car very long, i find returning cars to stock usually brings a faster sale. People tend to be scared of heavely modified cars.

So you enjoy wasting your time and money?

[7808]

Ya good one.. isint that kind of how turboing our cars usually turns out? I dont see people earning money turboing there own cars and later selling them for a huge profit really, and ive never had a car i loved so much i wanted to keep it for 10yrs,  thanks for the worthless reply.

[crxvtec91]

Ya good one.. isint that kind of how turboing our cars usually turns out? I dont see people earning money turboing there own cars and later selling them for a huge profit really, and ive never had a car i loved so much i wanted to keep it for 10yrs,  thanks for the worthless reply.

1 car, my crx i have had for 11 years!

[7808]

Crx dont count. Wish i wouldnt have sold mine kinda

[DSharp]

Ya good one.. isint that kind of how turboing our cars usually turns out? I dont see people earning money turboing there own cars and later selling them for a huge profit really, and ive never had a car i loved so much i wanted to keep it for 10yrs,  thanks for the worthless reply.

Your welcome

[ohisofly]

Is tuning obd1 really that much easier with these? I have a 95 318i sitting around that needs a turbo, but I figured everybody just goes obd2 for tuning these things

[7808]

To have your oem ecu tuned is about the same price obd2 vs obd1 now but swapping my motor to obd1 and using the less restrictive obd1 manifold was just easier because i already needed a intake manifold and engine harness for my mostly bare longblock . The 4cyl 318 is a whole different thing i dont know alot about

[7808]

ya so im going to just make a manifold. ordered a cheap cast one but theres no way im making this fit easily by flippping it and making an adapter like I did last time.

I can get the flanges and elbows in stainless or mild steel

but all I have is a mig with c25.   should I make it out of stainless anyways or is there no point? going to order up parts soon

[ratcityrex]

I would go mild steel and Just mig that shit.

[Minor Threat]

I would go mild steel and Just mig that shit.

x2

You are obviously not worried about selling it so highly modified so why bother wasting money on nice manifold materials? Especially if it's gonna be mig weld madness.

[7808]

I found mild steel sch40 weld els stupid cheap, if anyone is interested. like 1/3 the price of ace stainless. I don't think many people make MS manifolds though.

I might make cyl 123 and 456 there own "logs" that merge at the collector.  I don't think this turbo is going to fit, probably use it anyways.

[JohnHandcock]

Where? I cant find any that jewish

[ratcityrex]

Link on weld els?

[7808]

I think they were $2.49.  but when I added them to my cart, they were on sale for like $1.50, not sure if they still are. either way still the cheapest I was able to find.

http://www.kingmetals.com/Catalog/ItemContent.aspx?ItemNumber=6057&CatalogId=c39&CatalogDetailId=733&NSM=Y

[7808]

making the fixture to make the manifold, test fitting, its going to be a tight fit. probably going to have to cut the hood.

heres what im dealin with

[ratcityrex]

Holly fucking shit. I just registered for a account and they are only $1.43 each.

[JohnHandcock]

50pcs @ 1.22 that's the 1.25" really wish the 1.5" was cheaper. Most manifolds are made from the 1.5"

[7808]

your welcome. I had to use my skills on the googleweb to find that. I didn't think the $5 or whatever they were on ace seemed right once I figured out they use them to make fences lol


you sure most manifolds are made from 1.5?  that's almost 2" OD, i ordered 10 90s and 10 45s  in 1.25 (1.66" actual OD) and a couple 1.5" 90s in case i step up the main runner/s to 1.5.  never seen a turbo manifold with runners that big.   

feels stupid then im welding dollar elbows to this $110 flange.  only thing i couldn't find cheap

[JohnHandcock]

1.5"refering to hondas but its the both same OD.