Building a Turbo Manifold

[Duk]

I'm looking to build a turbo manifold in (hopefully) the near future as part of my intended twincharger set up for my AW11 MR2.

The eternal turbo manifold questions are:
1 Tubular or log?
2 Thin wall stainless or thick wall mild steel (what everyone calls 'Steam Pipe')?

I can weld both materials with minimal fuss, but which material is better?
Stainless has good corrosion resistance but a reputation for fatigue cracking. It's also easier to get stainless mandrel bends and straight pipe.
Steam pipe/butt weld fittings bends can be bought from place's like Blackwoods, but getting straight pipe normally means buying a 6 metre length of the stuff

Design wise I'm leaning towards a tubular set up. More work than a log design, but ultimately it's going to give better top end flow.

I'm not looking to make stupid power, probably will be limited by injector flow more than anything. Haven't settled on a turbo yet, but it will more than likely, at this stage, be from an RB25 (good for 180-200rwkw).

Thoughts and experiences preese

[feral4mr2]

you can browse through here if you havnt already done so for some ideas.
http://toymods.net/forums/showthread.php?t=17307

as for manifold design and material? there have been some very good discussions in this section of the forums in the past. a search should bring them up and i'm too lazy to look for the links for you.

[Duk]

Cheers Feral I did a search and came up with pages of stuff but found no 'how to make a turbo manifold'. Have you dyno'd the lil feral? What's it like compared to just a supercharger?
Your twin charger set up was my motivation, just thought i'd do the manifold differently.

[feral4mr2]

no havnt been on a dyno, i'll wait til i'm 100% happy with completion of it. i still need to do the st205 w2a i/c, the 2.5" s/c outlet pipe and inlet pipe to inlet manifold and hopefully wire up the MegaSquirt. though i'll be getting on the dyno as soon as the other stuff with-out the MS is done. then all will be posted in my thread.

at ~3500rpm when the turbo comes in the feel of extra torque is awesome, plus at that stage i'm on 15 odd psi and it raises to my max of 18 not far after that. on a wet road it just starts spinning all over the place at that ~3500rpm point. i like spinning my tyres, but when your already doing 60 odd k's it gets a little scary for me.
last week i put my 175mm crank pulley back on, man what a difference that made, and helps down low with the auto having a slightly too large turbo. i still have to play with the max boost setting as it was doing 25psi when i went for a test drive!


i was sure in the threads on here there were good links to different turbo design and build sites.

[Duk]

[QUOTE=feral4mr2]

at ~3500rpm when the turbo comes in the feel of extra torque is awesome, plus at that stage i'm on 15 odd psi and it raises to my max of 18 not far after that. on a wet road it just starts spinning all over the place at that ~3500rpm point. i like spinning my tyres, but when your already doing 60 odd k's it gets a little scary for me.
last week i put my 175mm crank pulley back on, man what a difference that made, and helps down low with the auto having a slightly too large turbo. i still have to play with the max boost setting as it was doing 25psi when i went for a test drive!
QUOTE]
Well you have just given me something to keep me awake all night , and I have work in the morning
Your manifold design looks straight forward enough. Have you had any problems with it (cracking, signs of uneven heating)? Would you recomend it to someone looking to make 1?
http://www.turbobygarrett.com/turbob...tech102.html#c

[feral4mr2]

i built that turbo manifold in 2002 and been useing it since. good ol steam pipe.

depends on what your fabrication skills and patience is like i spose, a log type manifold is very simple to make.

[6BOOST]

Steam pipe is the only way to go for a long lasting manifold, its also far more forgiving to design, you can fill gaps easier and everything isn't so critical, and lastly its heaps cheaper, especially if you make a mistake, bends are $3 not $7-10 each. If you can weld both, you obviously have a tig, use "super steel" welding rods, and about 8L/min gas flow, and make sure you bolt the head plate down when you weld otherwise expect at 6mm bend

Oh, and pipe should be able to be bought by the metre from most steel places, its only the real big ones that won't sell offcuts.

6BOOST

[witte reus]

I made a log manyfold from thick walled (3,6mm) stainless.
I'd like to have made an tubalar, but I don't have enough space .

Here are some pics;
@ the left you can see the wall thickness of an E-bay manifold. @the right the tubes i used.
http://memimage.cardomain.net/member...1_424_full.jpg
http://memimage.cardomain.net/member...1_426_full.jpg
http://memimage.cardomain.net/member...1_427_full.jpg
http://memimage.cardomain.net/member...1_429_full.jpg
http://memimage.cardomain.net/member...1_451_full.jpg

[Talasas]

I built a manifold using the butt weld cast bends from Blackwoods and the straight sections from heavy mild steel. I've been running the manifold for 8 months now without any hassles. One key thing you should do to prevent cracking is to brace the turbo, I made a bracket from aluminium which bolts to the engine block and provides adequate flex. So many people don't bother bracing the turbo hence why their manifolds crack.

As for type, I've seen log style manifold perform well and they are great for tight spaces. The only other niggle I had with my design is that the turbo sits a little too far away from the block. This made the oil return angle a little less desirable. Doing it again I would sit the turbo closer to the block and as high as possible to allow for better oil drain.

Pics/info here:

http://www.toymods.net/forums/showthread.php?t=24096

[Hengsta]

Are you willing to make another one? If you make one for your self.

If so how much are you looking at?

let me know

Thanks, Heng

[big wad]

talasas. you took the words right out of my mouth ,even the place of purchase. plus rep for you, cheers bigwad

[Duk]

Cheers to you guys for sharing designs and photo's . The log manifolds look nice and simple to make so I'll probably go down that path using butt weld fittings. But I'll also make a jig and in the future I'll make a nice tubular manifold with a nice collector design. It will be interesting to see if there is a meaningful power/response difference for the power I'm hoping to achieve. I believe there will be, but how much improvement for the extra effort...... 6boost?

[mr2gze]

... But I'll also make a jig and in the future I'll make a nice tubular manifold with a nice collector design. It will be interesting to see if there is a meaningful power/response difference for the power I'm hoping to achieve. I believe there will be, but how much improvement for the extra effort...... 6boost?

Its going to be hard to quantify how much extra power/response/torque v's rpm etc etc, you are going to get, from the effort you put into making a manifold.

http://www.toymods.net/forums/showth...420#post557420

Pointy end of the spectrum, but its food for thought.

cheers

[6BOOST]

Cheers to you guys for sharing designs and photo's . The log manifolds look nice and simple to make so I'll probably go down that path using butt weld fittings. But I'll also make a jig and in the future I'll make a nice tubular manifold with a nice collector design. It will be interesting to see if there is a meaningful power/response difference for the power I'm hoping to achieve. I believe there will be, but how much improvement for the extra effort...... 6boost?

There would probably be a fairly sizable difference in spool and hp, I have seen claims from various people saying they have back to back tested a log manifold vs a proper collector style manifold with no gains, all I can say is they did something wrong if thats the case, I even see 200rpm gain in spool and 5% more power back to back against most TUBULAR manifolds against mine, let alone a log manifold.

Tell me, race teams have endless budgets, if a log manifold spooled earlier and made the same power, what do you think they'd be using??

6BOOST

[medwin46]

Steam Pipe FTW! Heavy, maybe, but strong. Make sure you put a support onto something on the engine block, number 1 problem people see with manifolds (in particular stainless ones) is cracking due to thermal expansion and contraction, fatigue etc. Steam pipe tig welded and have the mounting plates machined after welding to ensure flat surfaces.