EVIL ENGINE goes Twin Turbo - Your Chance to Design the 930tt Exhaust System

[midlife]

Very interesting. The siamese turbos could cause high stress due to thermal expansion. Convention is that the turbo is fixed by the hot side, and the compressor is allowed to float. International 7.3 diesels had the turbo mounted by the center section, but that was considered an oddball.

[Craig 930 RS]

Yeah, pretty goofy setup.
It obviously has EFI, so you'd think with that you'd also have a well-thought out turbo/inlet setup....

[copbait73]

Originally Posted by midlife

Very interesting. The siamese turbos could cause high stress due to thermal expansion. Convention is that the turbo is fixed by the hot side, and the compressor is allowed to float. International 7.3 diesels had the turbo mounted by the center section, but that was considered an oddball.

When I first saw this it looked like the compressor inlets were welded. On closer inspection I think there is an o-ring connection. Still there is a problem because I see no hanger for either the bearing housing strap or the turbine housing inlet flange.

Could be the turbine outlet flange (not shown) carries the weight. That's how I'm supporting my K16s. CAC looks too narrow to handle the flow of a 3.6L.

[RarlyL8]

What do you guys think about that siamese turbo intake specificaly? What are the flow issues and are they significant for say a 400WHP engine?

[Lukesportsman]

The fact that the silicone hose continues with this oval shape makes me wonder if there is a divider inside the "V" to keep the outputs separate until parallel. It seems to be similar in mind to the 996TT aftermarket designs and I actually wonder if its something adapted from such. The 996TT market seem to have several alternatives in getting the dual inputs to converge together. The OEM version certainly looks "rougher" than this.

[midlife]

This does not look like a typical one-off custom set up. The turbo inlet looks like a casting. The transitions and intercooler ends are very elaborate. It looks like someone was developing a kit.
It will be interesting to find out more.

[Craig 930 RS]

Let's not forget that one of the main benefits of a 2 turbo setup on an aircooled motor - not only for better response but a sizeable hp INCREASE.

Twins ought to produce more than my 438 RWHP.........I'd venture closer to 475-500.

[copbait73]

Here is my two cents, setting aside the only natural desire to make your installation appealing by symmetry your problem is easily solved. Your CIS motor already has one turbo location.
One option is what I did years ago installing twin Garrett T25s with intregral W/Gs on a 3.0LSC. It retains the factory heat exchangers (nice for kit cost) and keeps the compressor inlets and outlets on the same side. There's lots of space in that cavernous wheel well and doesn't intrude on heating, A/C or oil tank.
Place one turbo in the existing single turbo location. Mount the twin turbo along the driver side valve cover. At the existing triangular flange split the exhaust into two head pipes.
At this stage you can decide to siamese the compressor inlets or the exhaust outlets or leave them separated. I say there is less risk in separate for intake and exhaust but it really is a matter of what the parts are showing you. Two medium diameter tubes carry more flow and are easier to package than one larger tube (same principle as four-valve head vs two-valve). On my install I faced the compressor inlet of the twin forward and plumbed two separate intake (joining at the water couple CAC) and exhaust .

[copbait73]

Originally Posted by RarlyL8

What do you guys think about that siamese turbo intake specificaly? What are the flow issues and are they significant for say a 400WHP engine?

Don't think flow is a problem but need you to cut up the body in a stressed location to install the motor or the casting is too restrictive.

[RarlyL8]

Where can I get the plenum assembly that unites both turbo inlets?

I think that would be a good part to modify for my intended use. It looks like the routing can be improved upon so that nothing short of the tin would need modification.

[copbait73]

Originally Posted by RarlyL8

Where can I get the plenum assembly that unites both turbo inlets?

I think that would be a good part to modify for my intended use. It looks like the routing can be improved upon so that nothing short of the tin would need modification.

Ok, if you can't be discouraged by the casting being forced into a very narrow cross-section, how much blockage to you think can go in front of a tip type axial cooling fan before it's effectiveness is seriously compromised?

One consistent theme on all Porsche installations, regardless of all the stuff they have crammed into their engine compartment over the years, they never placed components in front of that fan.

[red9]

Have you resolved preferred set up yet?

[RarlyL8]

The project was abandoned when I started the exhaust business. No time.
The Evil Engine became my build fixture and test bench.
Looking at the above photo now with different eyes, that engine layout is atrocious. I would lay it out completely different. All of the plumbing needs to be under the engine tin.

[drmatera]

Originally Posted by RarlyL8

what are these? I thought they were the thermal reactors at first but they are not... wanna sell them?

[RarlyL8]

Darin, those are thermol reactor replacements. The ones pictured are cracked so no good. There was a set for sale recently in the classifieds. You can still buy them new as well I would think. They did make a very tight package for twins. Problem is the passenger's side turbo hit the oil tank.

[drmatera]

thanks Brian. The shop next door just pulled a stock 930 motor out for a quick refresh, clean and a couple bolt ons and i thought his "manifolds" were the same as your pic. upon closer inspection they are NOT. yours have a much better "flow".

thanks for the info

[RarlyL8]

There are 2 versions. One version is a "log" type with very squarish tubes. The one pictured has a more flowing appearance. They are both very small ID so take a look at that before you buy.

[drmatera]

i'm not real concerned with the small diameter tubes. I've seen some turbocharged V8's make well over 1200hp on 1 1/2" primary short tube headers. There isn't one part on my car that is tuned, modified or built to produce 100% efficiency as it's just not practical to acheve on a street car. So if i'm leaving alittle top end power on the table but gaining quick boost response i'll be more than happy.

[kenikh]

Abandoned project or not, this was a great read. Kudos.

[RarlyL8]

It was a great learning experience, I tried about every configuration and set of headers imaginable. Have learned a lot since then and will add twins to my car someday using my equal length headers as the bassis. I plan to make a kit afterward for others that want to do it.