So been a lot happen since last year, original engine blew with the cams, company who supplied them paid out some money. Gary build my new engine up as I brought the rest of the parts I needed with the money. Engine is now a 9.5:1 comp ratio and is over bored slightly to 2044cc. I ran the engine in before Xmas then went for some bigger power and this is where some issues have arisen.
I want the car to be responsive so don't want a large turbo like gt35 but we have found with lots of testing the back pressure in the manifold is getting too high and causing the car to flatline from 7k onwards. This was at 1.6 bar but it still made between 460-500bhp by then. As I like things to be right i can't live with this and i can't live with a gt35. I now have a 1.06 turbine housing and the back pressures have dropped from 3.2-3.3 bar to 2.7bar. I hope this is enough to give me another 100bhp with more boost. Once my wheels are powder coated I will be going back to the dyno to find out.
I do have a backup plan if this doesn't work......I will compound charge the engine. I will run a tts rotrex supercharger and my turbo. As this type of supercharger builds boost as you go up in the revs the turbo will have to do less work at topping up the boost so the wastegate will be open more thus reducing the back pressure in the manifold. We had no issues of power dropping off when at 1.1 bar so I would plan to have the supercharger make 16psi at 9k then the turbo will only need to boost it up by 12psi to get to the 2 bar target boost. I will lose ac with the bottom mount tts kit but I believe I can run a toyota Prius electric ac compressor and just put a 12vdc to 200vac inverter in the car to power it, this means the compressor will always run at its optimal speed and I can move the compressor out of the engine bay.
I did think of a compound turbo set up with a gt28 and a gt40 turbo but it's the weight and heat that will cause issues. It would make more power but the supercharger is so simple to map and install.
The tts kit I am thinking about....
http://www.tts-performance.co.uk/#!hond ... -diy/c11r8
Any other ideas are welcome!