make the ID the same as the port or as close as reasonable, having the right turbo will do the most for making it come on and not be laggy. yes the diameter has an effect too, but using the correct turbo helps too.

i would like to see all this bulk manifold making happen but i think alot of you guys are trying to make too much of a complicated thing out of the design and the types of flanges etc.
if you are trying to keep the cost down its not as though everyone is going to be able to ask for different orientations of turbo position, different flanges, ability to run stock intake. you will all have to agree on one type if you plan on getting a bulk order discount .like dodgeman said the key is standardisation. from the sounds of it most people want to make a final product that uses close to standard motor with well sized turbo and most using a carby setup. i beleive that it should be very simply designed and you should not worry too much about flow and that sort of thing because the fact is that the manifold itself wont matter that much (as long as it is made with common sense and not scientifically) because the limitations of the engine will b more in the port sizes and carby sizes intake manifold size etc.
it probably sounds like im critisizing this idea but ive been there before and i know what its like i applaude sidedraught for trying to organize something like this because it will help so many people, but i think you all have to put alot of thought into it if you plan on doing the rest yourself, making a turbo system isnt a case of hoseclamps and cableties there is alot of other little bits and pieces that need to be made/modified and unless you have access to machining and welding machinery youre going to have alot of trouble.
i hope this doesnt put a stop to andy's idea but everyone needs a bit of a wake up call from someone who has done this before to say that an exhaust manifold isnt the only part of a turbo system that has to be made.

So far this manifold below is the simplest and cheapest design I have found, some members may find it crude, but its all close to the block for strength,and has short runners for speed of spool up.




With a few more curves like Keg's, and a TnP flange it could be the one.

Also when the time comes if the definates could supply say a paper template of the flange of the turbo they wish to install (if its not going to be a T25), it shouldnt add to much to the cost of production, (say $25ish).

Please tell me what you think, as you guys are the ones who will be buying it.

Yep, that manifold suits me. Put me down as a definate.

Write me down too

If anybody is concerned by its lack of equal length pipes I urge you to read this quote as taken from story linked below.

"If you look at many custom manifolds you

if they're as simple as the last one pictured and the $$ are reasonable i'd be interested

I haven't read all the post here as there are so many, but must say it appears that everyone wants something different... and everyone has a different idea as to what will work best...

I am working on a "Basic turbo setup" now...

I am working a system that would suit 1000's, 1200's, 120y's and sunnys...

I am not going to make an exhasut manifold, Im going to make a "J-pipe" setup and use both the std inlet and exhaust manifolds. People here have used them and they work. I know in a "perfect world" there not the best, but they work... I have 2 reasons for doing this...

1- Cost of developing a manifold, testing a manifold properly, then mass producing is very expensive...

2- A J-pipe is easier to produce and would be much cheaper...

I would design to hopefully not need to pull the manifolds off the car to fit the kit. I have already brought the turbos... The reason I say "turbos" is I brought a pair of turbos off a "Subaru legacy" 2 litre twin turbo engine. They are small enough for a small 1200cc engine AND they where $150 FOR THE PAIR... $75 for ONE!! The oil feed can come from the oil pressure switch side of the oil pump, but im not sure where to feed the oil back with out having to pull the motor out or apart yet..? I welded a fitting in my sump for the oil return. You will also need to lock the distributor so it has no vacuum or mechanical advance...


After doing my first setup with a "STOCK OLD A12" with an old TD04 (I did make the manifolds) it made 100kw atw with a suck through stromberg carbie on 14-15lbs... I was impressed and surprised!!

With std manifolds, J-pipe set up, an SU carbie off a 180b SSS motor (cheap!), small Subaru turbo(cheap) on a std 1200 motor (not stripped or rebuilt, but also not stuffed!). I believe it should make around 70kw+ at the wheels on about 10-12lbs (130 engine hp... conservatively), be on full boost at 2500rpm and be good to drive on the street...

With a std A14-A15 probably about 90kw+ atw, about 160+ engine hp, and be on full boost at about 2000rpm...

The Subaru turbo "MIGHT" be to small for the A14-A15 but until I try I wont know...

My A12 setup with TD04 wasnt on full boost till 3500-4000 which feels laggy to drive on the street and would become annoying to drive everyday.... was great once up and running though...

Some people might disagree with what im saying, but I think for what it would cost and on low boost (10-12lbs) it would be good "reliable" hp...

Im not doing to mass produce to sell, unless there was huge demand???... its more R&D to see how it works and what sort of HP it would make...??

The cost of doing all this might be as follows-

1- J-pipe & inlet manifold- $300-500??
2- Subaru turbo- $75??
3- SU Carbie- $75??
4- Oil feed line- $120??
5- Oil return line- $50??

That works out to around $820, if you said $1000 round figures with hose clamps etc you be pretty close....

Like I said im not doing it to make and sell (unless im pressured to ) but can give others an idea of what it might cost them to do and what hp they would get...

Dont take this the wrong way sidedraught, what your doing is awsome and I take my hat off. I just think everyone has to agree on one std ex manifold. In all honesty, I think if you made it to suit a std inlet manifold (people could make there own special ones if they want), with a turbo everyone knows is a pretty good size, and the price was respectable... everyone will buy them Even those who dont agree wont go to the trubble to make one if there is one thats good and works

I would have thought this

In original post there were 2 pics
The one with the lower mount turbo looked the goods
It looks like it would suit a twin weber manifold
It would have flange for T2

I thought this would be a basic setup thats easy to make and fits most purposes

I plan on running a weber manifold and single TB for mine.This will go on my race motor that already makes 100hp atw with 9.0:1 comp
I should hopefully be able to run this at 10psi without hurting anything.. I hope

I'm not a big turbo nut and know very little about them
Thats just my thinking

The last manifold pictured... the black log one... is the manifold here in Perth that pops up every now and then for sale but the guy never gets back to me
Otherwise I would have paid him his $250 and have it hanging from the shed wall already.

Let me know what you guys decide and then I'll tell you how many I need

Oval port by the way... oval port.

boof i could make up that last one, with pipe not rhs for pretty much the cost of bends

what do you want a tubo manifold for any way...only so much stuff can fit on your garage wall