Originally Posted by Unlogic
Have you found a way of cooling the rear turbo without disturbing the rest of the airflow in the engine bay?
Looking at a couple of different approaches. I'm starting with the reasonable expectation that the front of the hood is a low pressure zone but the rear of the hood (close to the windscreen), is a high pressure zone. I plan to validate that with testing.
I'm going to add a hood vent at the front to vent from the radiator and front turbo. I'm also looking at deleting the fog lights and mounting two 4" air feed trumpets and ducting where the fog lights would be on a '99.
So the two approached I'm looking at are:
1) modeled off the EXO X which has a rear mounted turbo. That has a scoop at the rear of the hood to take high pressure air from outside the engine bay to cool the rear mounted turbo. I'd pair this with a hood vent for the front turbo and ducting to route air from the rear turbo out of the front hood vent. The downside of this approach is that hot air exiting the front vent may end up feeding the rear scoop and it will probably make the hood look messy.
2) ducting air to the rear turbo from the front of the car similar to what you did for the air filter.
I think 2) would make a cleaner install, so my initial plan is to route the passenger side air trumpet to the air filter and the driver's side air trumpet to inside the splitter/undertray to the rear turbo and then use ducting from the rear turbo area back to the hood vent at the front.
The general idea is to manage the flow in the engine bay so that cold air enters through the radiator and the two new air trumpets - goes to where its needed and all of it exits through the low pressure zone at the front of the hood. However, I may also add venting at the rear of the splitter/undertray to suck hot air from around the rear turbo.
Its going to be a work in progress. Managing heat from a transverse mounted twin turbo V6 is a PITA - probably why nobody uses this configuration any more. With the levels of HP we are making, there is at least 2x the heat to remove.