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

[RarlyL8]

As many of you know I have assembled and built a mule motor - the EVIL ENGINE - out of spare parts, many of them given to me by generous Pelicanheads. I can't thank you guys enough. The plan is to use this mule for fitment purposes so that the engine in my car can stay there as long as possible. With a mule we can try many configurations and fiddle with this and that with no worry of time constraints. No idea is too wild and pictures of what others have done are a big plus.




Right now I have 3 exhaust systems to work with:
- Early Heat Exchangers from a '73T
- 993 Bishoff Heat Exchangers
- Shorty Headers

We need to pick one of these systems as a starting point - unless you can convince me otherwise. Price is a factor. This may be the worlds only twin turbo conversion on a budget. I have a garage full of parts and a good welder, we can make it happen.

Here is the 993 Exchangers vs Shorty Headers. Pros/Cons?

[MattAlpha]

One question, are you looking to hook up the heating system too? Or are you only concerned about the twin turbo install.

If only the twin turbo install, I would say the shorty headers hands down. I feel its a huge space saver under the engine and you won't have needless items collecting dirt and muck. There will also be a smaller number of things preventing your hands and so forth from working under the engine.

Just my very humble thoughts,
Matt

[WydRyd]

Agree. If you don't want/need heating, go with the shorty 993TT style headers. They'll spool the turbo up a bit quicker too

What type of oil drain system will you use? Gravity drained to the valve covers (u'll need to raise the turbo a bit with a short J-pipe), or using a scavenge pump?

[mb911]

the 993 HE would work nicly for multi use but the shorties would work best for quick spools. but that said you are doing twin turbo so who really is worried about quick spools?? either way 2 little J pips some falnges and your done. pretty straight forward. I would think the HE may be better due to them keeping heat in the tubing which drives a good portion of the turbo anyhow!

[RarlyL8]

Heat is a factor but I can fabricate some small enclosures for the shorty headers if need be.
What about flow and header design? The 993s have larger ID primaries that taper to a large collector. The shorties collect at the same ID as the turbo inlet (1.5") which is very small.

[klaucke]

If heat is a factor, definately use the 993 heater boxes/headers. The shorties won't provide enough heat even if you do box them in. As Ben said, quick spooling shouldn't be a problem even w/ the 993 units.

[tsuter]

Can you take a picture looking down into the flange of the shorties. That'll tell a lot about how well they'll work.....

And I guess you run a turbo integral wastegate with those????

[RarlyL8]

The turbos are K16s with internal wastegates.
The shorty headers are exhaust port matched and also match the turbo inlet (a very tiny 1.5").

[tsuter]

You mean about this big???



I took this one off my 1.8T VW turbo. It was spooling too fast and out of gas by 5500RPM.

[RarlyL8]

Yes. These are stock 993tt turbos. The exhaust inlet is surprisingly small.

[Facey]

I've been wanting to see someone high mount the turbos.

makes gravity feed much simpler, and if placed propely i believe it can be made to start with colder air... i guess this is pointless if your planning on intercooling.

i guess part of my idea, comes from my thinking of clean air above, dirty air below.

ps- i like the shorties....IMO turbos can never spool to fast.

[sand_man]

Man, I love the simplicity of the "shorties"!

[RarlyL8]

Should not have to gravity feed anything, this is a 930 engine. The plan is to use everything 930 and adapt it to twin turbos. The oil drain lines from both turbos will route to one collector to be pumped back to the engine.

[WydRyd]

What about a muffler? Are you planning to use a muffler, or just straight dump pipes? If you plan to run a muffler, it'd be easier to plumb one in with the side mounted configuration IMO.

[RarlyL8]

Good question about the muffler(s) - that is an issue to be discussed here as part of the exhaust "system". Side Mount vs Rear Mounted Turbos.

It would appear that running a couple of cherrybombs on side mount turbos gives an advantage to that configuration. Rear mounted turbos leave little room for a muffler.

Here is a picture of Mark Hargett's beautiful side mounted turbos:



And here is a picture of Amac's bad-ass rear mount turbos:



Vastly different designs. Here are the turbos I will be working with:




So what are the pros and cons of each configuration?
What engineering obstacles do you see for each configuration?

[Facey]

maybe just a noob observation.

your turbo are the same, whereas the ones in the above picturs are mirror images of each other.... this is gonna make your engine aysemtrical... dunno if that makes a problem

[beamonk]

If you need any turbo rebuilding or parts, the best guy around is right here in Tuscaloosa. Let me know if you want to cantact him.
John Brasfiled

[WydRyd]

RarlyL8, I'd be going side mounted turbo's plumbed directly into a Magnaflow dual in/out muffler. Get the biggest Magnaflow you can find to fit the space available. They are a cheap muffler and are also of a very high build quality.

You don't it TOO loud, so I'd shy away from dumping straight out to atmo. Just my 2c worth

[sand_man]

Hey Rarely, another thing to consider: which turbo arrangement provides for the easiest access to other engine parts that will need servicing - i.e. valve adjustments, spark plugs, etc. Though I said I like the simplicity of the shorties (side location), it looks as though you'd have a helluva time adjusting the valves without removing a bunch of ***** (referring to Hargett's engine...maybe it's just the photo angle).

The rear mounted turbos look like you'd only loose access to the chain covers, and that's not something you typically mess with anyway (barring a leak or cam timing adjustment).

Just food for thought...

[RarlyL8]

My turbos are a matched set from a 993tt.

Engine access is paramount. I fiddle with my engine a lot and engineer everything for quick access. That is one reason I considered rear mount turbos - they are completely out of the way. Spark plug #1 is a real PITA to get to on a 930 and that IS complicated by rear mounted turbos due to the plumbing involved.

On the other hand you only need to adjust the valves every 15K - about 2 years for me.

What do you think about using the shorty headers AND rear mount turbos? Pipe lenght should be about a foot on each side.