Kento

I wouldn't exactly call it "trivial" when you're talking about turbos of equal size, and their relatively small rotational mass. The tension drag of the oil on an oil-film bushing does multiply as the rpm increases. It's the reason why engineers are always trying to balance the bearing journal sizes and clearances on crankshafts to reduce these losses, while keeping the surface area large enough to handle the stress loads.

Trivial compared to properly sizing the turbo for your needs so that efficiency is maximized, yes.

EpitrochoidMan

Check it out, I'm working on a 3d model that should make more sense, but Bryce 5 is the only program I have and it's a PITA. But the idea is if you got a couple of quick spooling turbos, you could mount them on this eliminate the rats nest, and still run sequential, using minimal controls.

Here:
https://www.rx7club.com/rotary-car-performance-77/improved-sequential-turbos-344247/

cloud9

iTrader: (4)

Thats affirmative Jim.

Flybye

The manfifold holds:
1) The turbos (obviously )
2) WG
3) Secondary Turbo control flap
4) Secondary Turbo control flap actuator
4) Turbo Prespool flap
5) Turbo Prespool flap actuator

If anyone has ever taken apart the stock exhaust manifold, you know it is a huge restriction............and heavy as hell.

A SS manifold designed to accept the entire stock setup would not only be difficult but time consuming. If you think about it, it's actually pretty easy to come up with a design for it. The measuring and making of it would be the worst part.

As a guy who autocrosses (although not lately due to school, finances, etc) I would LOVE to have a SS manifold. Coated, it will produce a LOT less heat under the hood since the exhaust won't be going through a maze in the manifold, and it will allow the engine and turbos to breathe a lot better. Paired with BB turbos........................

I have to practice a bit more with Autocad. Once I master the 3d aspect of it, it won't be too difficult to put in a rough sketch of it.

jimlab

Mounting the turbos would be the easiest part, and while you were at it, you might as well eliminate the internal wastegate and actuator and use an external wastegate. However, the main problem would be integrating the pre-control gate and actuator into the system. If you were willing to give up sequential operation, it would be much simpler. However, we considered doing something like this back in '97 and gave it up as a waste of time, because what's the point in creating a more efficient turbo/exhaust manifold for a pair of fairly inefficient turbos?

If you were going to the trouble of creating a stainless turbo manifold, you might as well reduce cost and complexity by going single, or get rid of the sequential system and use two somewhat larger turbos in "non-sequential" configuration. Look at what the Japanese tuners have been doing for years... not one of them has tried to reinvent the wheel by making a new manifold for the stock twins.

One idea that has some merit is adapting a set of MKIV Supra twins for use on the FD. They're set up to be mounted front and back like the stock twins, have a simpler configuration, and can flow into the 21-22 psi range on a MKIV before they're horribly out of their efficiency range. 17-18 psi would be a breeze, and they spool very quickly. Something to think about.

Flybye

I don't think anyone in their right mind would use the stock turbos with a SS manifold. Slightly larger than stock turbos, sure, but the idea would be to be able to keep the stock sequential system.

An external WG would certainly simplify such a setup. It's all a mess anyways. You would still have the precharge control to have to worry about and the charge relief.

Str8Down

I think it sounds like a great idea. I would love a SS manifold and some sweet ceramic BB turbos.

pianoprodigy

1. Are Supra twins sequential?

2. Has this ever been done to anyone's knowledge?

3. What all would be involved? I would think at least:

• Some kind of adapter plate for the exhaust manifold
• Oil Lines
• Custom Y-Pipe

In my head, it doesn't sound that hard, but I really know very little about what I'm talking about. I had thought about asking about adapting 300zx or Supra twins in the past, but this post sparked my memory. Of course, before any work was started, it would be nice to see compressor maps for the stock Supra twins.

jimlab

Yes.

Not to my knowledge, but the idea has been kicked around a few times.

Toyota (like Mazda) has never published the compressor maps for the MKIV turbos to my knowledge. This map is actually for a Garrett T3 45 trim, but it's fairly similar to the Hitachi CT12B turbos used on the MKIV based on horsepower potential.

widebody2

"i'll bet there aren't any remaining oem cast iron manifolds existing that don't have large heat cracks. "

I actually own one of these and it was on the car for 75k miles....I guess mine is very special. It doesn't even have a small crack in it.