Arranging turbos for better flow.

**Quint** · 05-03-2009, 05:35 PM

This topic is spread over the internet as i'm trying to find the answer. So please excuse me if you've read it before.

Have a set of ct12 C2s that i'm upgrading to from the CT12 series 3. i'm wanting to fit to my supra but also wanting to arrange them in such a way to maximize flow, i've seen this done once before but can't remember the specifics. Engine is in a middle of a re-build and i'm hoping to re-power the old girl, hoping to make 190kw (not big hp, just a little extra)

Anyway, the basics, shift the front turbo so its kicked out 30 degs from the block, have the front 3 clys powering the front turbo while the back turbo is on the same angle just sitting further back from the first turbo and is powered by the rear 3 cyls. Does anyone have any ideas of how to maximize the efficiency of this design?

The main problem i can see occurring is feeding the turbos with air, as i'm still running the AFM system. Does intake length matter? Will i have to balance the length to each turbo. If this is the case, i may have to upgrade to a map system also.

EDIT: Engine is a Gen1 1G-GTE

**celicapain** · 05-03-2009, 08:27 PM

Unless your building completly new exhaust manifolds there isnt much point changing the standard orientation of the turbo, all youd be doing is adding volume and turbulence to the exhaust manifold increse lag if anything. What would be worthwhile is fabbing up a proper twin feed dump pipe(into a reasonable exhaust obviously) as the standard dump pipe is pretty poo.
Theres someone running around here with an ra28 making just under 200rwkw with gen3 tubos and the standard piping feeding the turbos so its probally not worth changing the plumbing for your needs.
When you say 190kw do you mean at the engine or the wheels? at the engine shouldnt be too hard on the standard twins with maybe a modded(piggy back or something) computer, at the wheels is possible but most people seem to do a turbo upgrade once they start going for over 180kw@w.

**Quint** · 05-03-2009, 08:45 PM

190 at the wheels (at the engine is just cheating

).

Hmm i hear ya, do you have any details then on the dump pump? pics etc. Just to give me a good idea of what to aim for. Cheers.

**Duk** · 05-03-2009, 10:34 PM

Originally Posted by Quint

The main problem i can see occurring is feeding the turbos with air, as i'm still running the AFM system. Does intake length matter? Will i have to balance the length to each turbo. If this is the case, i may have to upgrade to a map system also.

Length isn't a big issue with vane/flap type AFMs, I've seen twin turbo V6s with a single AFM.

**abently** · 05-03-2009, 10:45 PM

I agree, unless you can decrease the exhaust manifold volume compared to the factory one, then all you are doing is wasting time and money. Even more so on such responsive Turbos...

The single AFM isn't an issue running twin Turbo's inlets either.

**celicapain** · 06-03-2009, 02:38 PM

i dont have any pics of the dump pipes, but if you have a look around this site there are some standard twin turbo 1jz dump pipes which are basically the same design. the issue with the factory dump is that both the turbos basically blow towards each other and the exhaust gas has to swirl around and find its own way out which faps with the flow and creates back pressure. what you want is a dump which smoothly merges both the turbine outlets together compared to the factory one. if you wanted bonus points you could run a full divided system to each turbo(seperate pipe for turbine exit and wastegate) and then merge them together down the line.

p.s intake length tuning is usually only somthing youd bother with on a N/A car, turbos kill the harmonics that make tuned length manifolds work, so all you really want is minimal restriction, anything else is pretty much a waste of time(not talking about inlet manifolds)