How to: Turbo Manifold design, need your thoughts

[RAd28]

Hey guys,

i've been consdiering re-designing the stock turbo manifold on the 1G 'cause i really hate the stock setup. but don't have the money to go for fresh turbos...

option a) typical twin turbo design, much the same as the nissan GTR, nothing special.

option b) and this is where i need yor thoughts, i was flicking through a HOT4's, and noticed a turbo set up one one car, single turbo, 4cyl, the unique thing about this setup was the fact the turbo flange was parallel to the head flange (instead of parallel with the ground in most set ups). i think this would be easier to set up in the case of the 1G, what i wanna know is reguarding to runner lenght. i would be aiming for short runners, which would be almost dead straight (only enough deviation to allow for equal lenght runners). i noticed on JOEL'S RA28 he has really long runners, how much difference is there in turbo engines? i understand some basic concepts abot runner lenght... but how much should i worry? what shold i consider?

many thank in advance

[Hydra]

I guess that depends on the car, but I would say the less bends you have on the intake and exhaust sides, the better.

I can only imagine that in the case of a 1G-GTE you want to keep things pointing almost straight ahead.

[brett_celicacoupe]

I guess that depends on the car, but I would say the less bends you have on the intake and exhaust sides, the better.

as long as you arent pointing cyl 6 runner straight into cyl 1 runner.... ie log spec manifold.



you'd want to get all 6 pointing into the turbo as perpendicularly as possible. having turbo flange parallel to the head might not permit this as easy?

[RAd28]

was planning on keeping one turbo with cyl 1-3, and the other turbo using cyl 4-6, exactly the same as the stock manifold, but re-designed, main point isn't to improve the manifold so much as the dump, and intake side of things.

i can understand the idea of keeping the flow as laminar as possible, the main question was in the effect of runner lenghts... is there any benefit in keeping runners long? or short?

[brett_celicacoupe]

for memory there is shit all room in the foward-aft direction of the car for the turbos. one end is the firewall, the other is the dizzy. allowing more room in the middle for the dump would mean compromising the radius of the turbo inlets.

better off channeling all that manifold building energy into making a manifold for a nice 2nd hand single turbo. dont think many gains would be seen for the twins

[Hydra]

I know I am going off-topic a little, are you keeping the CT12's? It seems wasted on those to be honest...

[jonra23]

No real effect on long or short runnners in a turbo setup like there is in a naturaly aspirated engine, where you are trying to getas much scavenging as you can from the pulse generated when gass exits pipe.

Try and keep runners as equal a length as possible to get greater pulsing into the turbo to increase turbine accelration.

regards
jon

[RAd28]

will be keeping the CT12s, i'm a tight arse.

as for the space, if i roate the turbos so the dump points toward the rear center of the firewall, will allow for better use of space, i really just wanna make the turbo setup more efficient, i've seen kirks car, putting out 200+ KW, with stock turbos, that would be plennty for me, but if i can reduce lag, and wind on some more boost, would be great.

[brett_celicacoupe]

if your that keen to make something useful..... make a dump pipe collector. now ther is a challenge.

exhaust gases hitting each other square on at 7000rpm cant be to efficient?

[RAd28]

exactly why i'm re-arranging the turbos... both turbos will be facing inlet foward, and exhaust rear-ward.

[JustenGT8]

Mate, best bang for buck option is to ditch the twins. Keep the stock 3 cyl sections and make a simple collector from those two into a singlethe single. Will flow sweet and a heap of mega cheap turbos out there these days that'll make great hp.

Manifold mod will cost you bugger all. I would suggest a KKR turbo or a cheap Garret from the US. 200+rwkw and great response with nice simple plumbing.

[RAd28]

well as for bang for buck, i'm hoping to do the work myself, so cost will be limited to materials, and hopefully i won't need to try more then once

[JustenGT8]

Even easier then as the setup i described is pretty simple to make. On the flip side, getting a 6 cyl manifold to flow, fit and not crack is a bitch and not a job for the faint hearted.

[RAd28]

yeah, that's why i haven't tried a traditional manifold where the flange is horizontal... 'cause the extra curves and joins would make it more difficult, i'm HOPING that if i can keep it simple, i can prevent some of the problems...

ya gotta start somewhere... not expecting a work of art, just something that works...

[Hydra]

I reckon it'd be easier to make up the collector, and save up for a single

But if you do go ahead with this design, we want pics!!