tips for turbo manifold design

[6BOOST]

SOme tips for the learners.

1" steam pipe is called 25nb pipe, or nominal bore. It actually measures 28ish mm from memory. When you buy it, its comes in 3 thicknesses, think medium and thick walls. These are red, blue and yellow respectively. This also works for all diameters, not just 25nb.

You want to use the medium wall pipe, the ends are usually painted "Blue". This matches the ID and OD of the bends that are used for building manifolds.

1 1/4" steam pipe is around 36mm ID, despit the pipe being called 32NB. ALso use the medium wall blue pipe.

1 1/2" stema pipe is 42-43mm, once again despite the pipe for it being called 40NB.

I have personally made 430rwhp from a 1GGTe with stock bottom end, stock camshafts(NA), 600hp GT30/40 and my own intake and exhaust manifolds, all using 1" steam pipe for the tubing. This was on pump fuel and 28psi too, and not a bullsh1t dyno figure. If thats any indication of the power possible through small pipes, I'd say 1" is heaps for a 4 up to 280-300rwhp, and 1 1/4" should support anywhere up to 600rwhp. We have made 860rwhp no gas through 1 1/4" pipe no gas in a 6 cylinder application. The only time I have ever used 1 1/2" is a 1200hp Methanol RB26/30, and 800+hp 4G62 mitsubishi 4 cylinders.

6BOOST

[FATMR2]

Lastly, short pipes and long pipes don't effect spool as much as people think.

Join that with this.....

Ok, so I picked up a t25 for 100$

And i think you'll find it wont really matter how long your runners are........


Its a t25.......its going to spool up straight away on a 4age. It wont matter if its a log or a tuned length manifold.

I say just make one up that suits you engine space that you have and be happy with it. Trust me, you will be.

[feral4mr2]

Its a t25.......its going to spool up straight away on a 4age.

well not exactly.

[myne]

I dont really plan on sticking with the shitty t25 I got. I just wanted something of the right dimensions to play with. 100$ and it's in a potentially working condition - I call that a score.
I'd like to play with something bigger in the future


Anyhow, here's attempt #4

http://www.users.on.net/~jvizard/myn...old/4-left.jpg
http://www.users.on.net/~jvizard/myn...ld/4-right.jpg
http://www.users.on.net/~jvizard/myn...fold/4-top.jpg

I know the equal length might not make any difference, but just knowing that it could make some difference makes it hard to ignore.
Especially since this is a make-once item. I may as well do it right.

ROFL! I'm sitting here and I hear a strange noise + movement near my hand. Naturally I flinch. Bloody camera parking the lens after a timeout.

[4agte]

Here is a pic of the one i made for my 4agte. I tried to keep all the runners the same length. It worked quite well so i was happy.







Oh, i just looked at the rest of those pics you have......If you sit the turbo that low you will have problems with the oil return line to the sump. The way mine sat was a little on the low side as it was but there's not much you can do in an aw11.

it does sit a bit low but its a nice manifold i need to get it re ceramic coated

[FATMR2]

well not exactly.

AS IF IT DOESNT......!!!!


HAHAHAHA

[feral4mr2]

^^ remember i had the revs up before the clutch was dumped.

myne, # 1 runner you might want to run low under # 2, it may get a little close to the dist/cas going over the top. re: look at the pic of fat's.

[ReQuieM]

I'd copy the design on teh first page, yours looks good but the turns on the dark green pipe (#4?) look a too tight compared tot eh white (#1?)

[BrianRA23]

In my opinion I would use the smaller diameter pipe. I have heard of an old 2L escort engine making 400hp with 3/4" pipes going into a turbo. This is a bit small for me so I would go with the 1".

Smaller pipe results in higher air velocity for the same flow. If only mass airflow was required then a log style collector would be fine, but its not. Performance manifolds are designed to get the air to the turbo and loose the least amount of energy. Bigger piping is used due to fear of creating too much of a restriction, but if 6BOOST (well done!) and others can get impressive figures with these small pipes then maybe it is not a problem.

If the collector is well made (assume smooth 4 into 1) and I wanted the same air velocity as in the runners (which I do) then the maths say for a 4 cylinder engine the collector ID should be double the ID of the runner tubes.

To maintain the air velocity into the turbo I would also extend the collector through the turbo flange down to where the turbine passage narrows to for an even flow. If this is not done then the exhaust gases will slow down and become turbulent behind the flange, in the turbo itself, thus loosing all its velocity and force.

A certain horsepower requires a certain amount of air and the smaller the pipe the higher the velocity, but how fast is too fast and is there an upper limit?

In the turbo / exhaust manifold the combined smalllest ID is where it is reduced just before it hits the exhaust turbine to cause increase the force of the air on the wheel through a velocity increase. Is this the best place to do it or should it be much earlier to assist with scavenging of the combustion chamber?

6BOOST have you compared the boost response from idle between two manifolds made from different sized pipes with the rest of the system unchanged?

["Z" UTE]

Great thread, lots of idea's from all levels of knowledge.
Some excellent designs.
Uniformity on a 4A-GTE is hard to achieve, mainly due to the CAS positioned on the exhaust cam side of the head. Yep right above No1 exhaust. That being said, I have seen 4 different designs in use in Canberra, and all of them work. Which one works best? Not a clue, as all the engines run different ECU's cams injectors etc.The only way to see which one has best flow and velocity, would be to put 'em all on a flow bench. Guess that is not going to happen any time soon.

Velocity = energy. ( in the case of a gas turbine, it is kinetic energy)

Heat = energy. (Thermal energy)

Keep the velocity up, and keep the heat in the manifold before it gets to the turbine.

Exhaust pulse may not be so important, as at 8,000 rpm, each exhaust on a 4 Cyl will pulse 16 times per second. So the turbine inlet is recieving 64 impacts per second.

Positioning is always a compromise, you dont want to fry your bonnet, but you need effective oil drain. Heat shielding is your friend.

Keep up the good work guys, cheers Chuck.

[myne]

These are some really bad pics(different, older camera), but here's the near final mockup
Plan is to use 1 3/8" pipe. It has the same internal diameter as the port exits.
I figure it might not be ideal, but it it's good enough for the ports, surely it's good enough for the runners.

http://www.users.on.net/~jvizard/myn...d/IMAG0001.JPG
http://www.users.on.net/~jvizard/myn...d/IMAG0002.JPG
http://www.users.on.net/~jvizard/myn...d/IMAG0003.JPG
http://www.users.on.net/~jvizard/myn...d/IMAG0004.JPG
http://www.users.on.net/~jvizard/myn...d/IMAG0005.JPG


Plan is to bring the turbo flange out a further 30-50mm and rotate the turbo 5-20* towards the block.
like this : http://www.users.on.net/~jvizard/myn...d/IMAG0007.JPG


Slightly funny thing, after finally giving up on the idea of a 1342 collector entry order, it turned out easier to do it that way in the end.

[actionDAN]

i made this 4-2-1 turbo manifold with a hacksaw, angle grinder, file, and tig welder. you dont need any expensive tools or machines (even a cheap tig will do fine) to make a turbo manifold! also your runners dont merge in the firing order.

clearance issues - its very simple to mount a turbo in the engine bay without having to move or relocate the radiator or even the air-con pump!!! so many ppl do it but i never do. the only real issue you should have (if desined propperly) is the radiator fan. i just remove them (on ae101 fwd) and wire up the air-con fan at the front to replace it.

[jono]

here is the steampipe manifold i had made:






**plug** It was made by Road & Race Exhaust Technology in Hornsby, (02) 9987 1278
Gary (owner) is mostly into rotary race cars but did a great job of making this for my 4agte ke20.
lol, I had a $100 t25 which was used to mock this up. it was leaking oil so badly i got an HKS2540 which spooled up instantly on the 4age.