Hey all! Im 21 but have been involved in turbocharging and fabrication for quite a while and am continually trying new things. I cant stand "cookie cutter" builds, so I always strive to be different, even if it means more work. (which it usually is ) I have turbocharged hondas, suzuki samurais, Nissan 350z's, and I have have had at least five different setups on my dodge diesel including a holset he551ve variable geometry turbo off of a 15.0l ISX cummins with a piggy back computer to control the valve. yada yada yada haha.

My latest project is a 2003 Mitsubishi Evo 8. I bought the car and threw a rod bearing 5 days later . So it gave me and excuse to do a complete build. Ive built a 2.4l 10.5:1 compression longrod stroker motor that I would now like to compound turbocharge. (stock is 2.0 8.8:1comp) Based on the parts in it, Im confident that it will hold anything I can throw at it.

Currently Im planning on using the factory 16g twin-scroll turbo and then feeding a .91a/r holset hx40 in compound configuration. For the time being, im going to use the internal waste gates on each of the turbos. (ported a bit) My biggest question is, when I feed the exhaust from the small turbo to the large, should I divorce the main exhaust outlet into the large side of the t3 inlet of the hx40, and the waste gate dump outlet into the small side inlet of the hx40, or should I open both into the same pipe and both into the t3 inlet at the same time?

My theory with the divorced idea is that it will act kind of like a spool valve, spooling the hx40 quicker on the large side until the waste gate on the small turbo opens and it sees full flow. I hope my question is clear enough, but Im sure I will need to clarify. (I have trouble explaining things sometimes haha) Thanks in advance!!

Heres a pic to illustrate

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IF you were serious about doing a compund setup from the start, why raise the compression? What octane fuel do you plan to run? That compression is going to limit the amount of boost you can run on pump has which kind of defeats the purpose of a compund setup.

 

That's not a bad idea to use the wastegate exhaust to propel the large turbo. Utilize that heat!

 

Do alot more research. The HX40 isn't big enough IMHO to be the bottom turbo on an EVO 16g setup.