Exhaust Manifold - Update#4
Turbo Mini Forums

Just finished my exhaust manifold design.

Based on Sched. 10 316L stainless weld elbows. 1" nominal bore, actually approx. 28mm.

I cant get hold of 321 stainless fittings so have to use 316. The schedule 10 is 2.77mm thick so should be quite strong.

I've had to curve below the inlets as they need to be quite straight to get the two injectors in line.





Now I've just got to order the materials, TIG and Plasma Cutter!

Edited by Paul S on 10th Jun, 2007.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Im not sure, but. Iv heard that stainless stell crack easy so its not good to use whit alot of heat.

TBH stainless is prefered

321 stainless has the best properties for dealing with high temperatures, but I cant find any weld elbows in 321.

I can get 321 straight pipe and a tube bender, but the radii would be too big for fitting it all in the tight space.

316 is the next best grade and I can get them easy - about £3 each.

Searching round a lot of the other tuning/welding furums, a lot of people have succesfully used 316, so I think its worth the risk. Maybe on a race car then use 321.

In using the weld elbows at 2.77mm thick, I'm hoping that the additional strength will help the crack resistance.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Can you get 304 elbows? These are what many consider the 'minimum' grade to use for a turbo exhaust manifold.
That said - If you watch the EGT's (especially on the Rolling road) and tig them up with a decent rod, then you will probably be fine.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Axel - nice piece of cad work there! - just a thought, would it be worth bringing the branches from 1 + 4 up over the top of the inlet tracts to give a more direct feed into the back of the turbine? - I'm not a great fan of exhaust branches pointing at each other - reads backpressure to me? - only a thought

JK

If Carling made Mini engines
it would probably be like this one!

http://www.snstainless.com/index.php

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

On 16th of Apr, 2007 at 07:38pm Mini Sprocket said:
http://www.snstainless.com/index.php

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

It's never straightforward is it! - flow dividers sound like a good idea.

If Carling made Mini engines
it would probably be like this one!

Alex try Milner Offroad they might do the bends you need.

http://www.milneroffroad.com/PIPE.HTM

Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe.

you prob know this axel , but make the holes ,for the manifold to bolt to the head , big enough to grow a bit as it gets hot .
looks good
robert

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

It's starting to come together:



Cut and machined the flanges from some 316 stainless, 50 by 10 bar.

Edited by Paul S on 29th Apr, 2007.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

:cool: 8)

Done a bit more:



Needs tidying:



Should I put some dividers in there?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I'm thinking no,

IMO without the dividers the pulses should still be quite divided and will have a good radius to turn into the turbo.

with the dividers i think the turn will be too sharp.

hopefully these shitty pics will show what i mean :$

if there was a more complete/straight path turn into the turbo from the outer cylinders i'd say the dividers would pay off.

this is of course just an opinion

Mini13,

Thanks, I think you are right.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I think you need to consider the shape of the turbine you'll be bolting upto it aswell when considering dividers?

This pic shows the gasses coming out nicely, but actually hitting the side of the turbine for example


I think some turbines (T2 certainly) have a big offset- so the lh tube would have a nice flow right into the turbine, the RH one would have a 'sharp turn' about halfway into the turbine housing.

(difficult to explain - look at a housing and you'll see what i mean). If you take a look at the metro manifold, you'll see how BL made the entry pretty straight (easier with a casting than tubes of course)!

Edited by TurboDave16V on 9th May, 2007.

Edited by Paul S on 9th May, 2007.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

End of the day - the mirage one does the curly wurly's as proven by nic - this should in theory encourage more pulses from the outer branches into the turbine than the mirage, so it'll probably be cool.

What is the wall thickness on these btw? 28mm ID sounds perfect!

The pipes are quoted as 2.77mm wall thickness. OD is 34mm.

To my mind they may be a bit small for high hp but they are the same csa as the 12G295 ports that I'm using.

The turbine needs energy to drive it, by the time the gas hits the wheel the energy has all been converted to velocity. Why slow the gas down in the manifold when the turbo will speed it up again in the volute.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Yep - same potential argument for why makign the exhaust ports larger than the (factory) manifold tracts is probably going to be of minimal benefit.

It's coming together well. Get them outer runners on now :)

I'm hoping to start mine in the next two weeks as I'll be $4K richer on friday (after selling the subaru), and probably $3.5K poorer on saturday after buying a Miller Dynasty DX and a plasma cutter!

Edited by TurboDave16V on 9th May, 2007.

Good point on the turbo inlet TD, i was forgetting they come in odd shapes, like you say the mirage one works well, but as i've said before i suspect it would be better if the outer 2 pipes didn't face each other.

which reminds me, found an interesting site today, check out the flange.

http://www.momentummotorparts.com/store/diy_parts.asp