First thread as a member, yay!
I have been wanting to work on my IAT charge cooling for a while now. There are many ways to do it, all with different results (no, the usual "get a FMIC" won't cut for me). My goal, as usual, is to get the best possible setup for my application. No cutting corners, no compromise, just straight up business. I went back and forth with what design would work best and finally decided on something I think would complement the rest of the setup.
Before I dive into it, just to bring those not familiar with my car up to speed, I have an 01 225Q roadster. Stock turbo, manifolds and internals with the exception of drop-in IEs. Full 3" straight turbo back and Velocity stacked intake (downpipe and intake courtesy of my sponsor and kick ass company 42 Draft Designs). I run 33 psi boost tapering to about 25 psi on E85 ethanol and water injection on 630cc injectors. Tuning tweaks are done with Unisetting over a generic GIAC flash.
The goal for this project is to bring IAT down as much as possible while removing as much restrictions and pressure drop from the system.
Part 1) Intake manifold
To get to the level of water injection I needed, the basic single or dual nozzle wouldn't be enough. I already had a single directly ported nozzle (aiming at supplying the problematic first cylinder runner that usually starve for juice). I decided to go full direct port water injection. As the name suggests, each cylinder will get equal amount/distribution of water through a nozzle plumbed and dedicated to each runner.
Ports aiming at each runner ( didn't want to port the runner to avoid spraying at a wall )
I also decided while I'm at it to delete the annoying vacuum ports under the manifold and side ported it
Part 2) Heat Exchange
I ran dual SMIC for a while, then experimented with great results deletion of one of the SMIC (gained 3 psi from boost onset to redline where a 3 psi gain is awesome on a chocking small frame turbo). Please don't attempt this if you have a 225, I did it because I have an elaborate water injection system to back it up.
Now it's finally time for air-to-water intercooling! I thought long and hard about what core to use and what design. The barrel types are nice for fitment but trails in terms of performance over the square tanks. I also didn't want a core that doesn't have the inlet/outlet facing each other (straight through is the name of the game whenever pressure drop is important). I decided to go with a 550 cfm rectangular unit rated at 0.1 psi pressure drop. I feel that it would be ideal for the space available in the TT's engine bay without major surgery. The short route plumbing is also pretty sweet and with water injection to back this up, I feel that it would be an ideal setup for lowering IAT close to or even sub-ambient, without hurting pressure from turbo to manifold. The rest of the setup would consist of a side mounted radiator and a trunk mounted water/ice box. The TT 3.2 auxiliary radiator is the choice for now and maybe something aftermarket later if it is struggling to keep the water cool (I will have decent volume). I haven't decided on what pump to run and is open for suggestions. Now some pictures!
Lower support bracket fabricated and core mounted
Pipe mock up
Part 3) Pre-turbo injection
The process of injecting before the turbo has its specific advantages when done properly. On a turbo that is running past its efficiency range, like my poor K04, a wet compression will reduce adiabatic loss and bring the compression closer to an isothermal compression. What that does, without turning this into a thermodynamics class, is shift the compressor map to the right and giving you the effect of a bigger compressor by a certain percentage.
We have been going through design ideas in the 1.8t technical forums since we are dealing with an extremely small turbo inlet that leaves limited room for mounting nozzles without creating substantial airflow restrictions. I want to spray as close as possible to the compressor blade but with 2 miniature jets that will guarantee instant atomization and keep volume high. I will be fabricating a nozzle mount next week and continue to update the thread.
A few ideas below but I want to reduce flow restriction over these designs to a minimum.
Please feel free to discuss, critique and give inputs as long as they are intelligent ones (this forums in desperate need for intelligent and technical discussions )