After sitting for several years, we are getting off of our asses and are working on getting a decent bump in power on Project Mitsubishi Evo IX. In our last story, you probably read about the modernized Link plug and play stand-alone engine control unit that we will be running. In this edition of Project Evo IX, we will be adding some engine parts to enhance our car’s power while keeping its great driveability intact.
When we were young, we were always looking to make the maximum amount of power, this usually meant big laggy turbos. These turbos were happy at higher boost levels which required race gas. At boost levels that were safely obtainable with crappy pump gas, the big turbos were both sluggish and soggy without that redeeming rush of power when in the powerband.
The stock Evo IX turbo is pretty decent, it is quick spooling with a twin scroll turbine section with a pretty efficient compressor. Our car was able to make pretty decent power with the stock turbo with little lag, the car would pull well from 3000 rpm to its 8000 rpm rev limit without any drop off in power. In fact, the car’s knock limit was what seemed to be holding the car back from making more power as we tapered the boost to reduce knock at high rpm.
Our car was zingy and responsive making it very fun to drive. We wanted more power of course but we didn’t want to give up any of the cars fast spooling nature. This is especially true when compared to modern direct injection high compression turbos! Modern turbo engines spool really fast thanks to higher compression ratios and the ability to take a lot of boost at low rpm without detonation caused by the cylinder cooling of direct injection. So we are going to proceed but we are not willing to give up bottom end or response for more top end power.
The first order of business was to get rid of the stock intake manifold. The stock 4G63 intake has a really small plenum with the runners close to the plenum walls. This is not a good way to make power whether it be in a NA or turbo motor. We are not sure why Mitsubishi designed the manifold like that, perhaps for packaging reasons.
Based on results with other engines, turbo engines seem to like a larger plenum volume, we decided to change our intake manifold. We obtained a Hypertune 4G63 intake manifold from Australia having formed a relationship with them when we were there for WTAC with Team America a few years back. A few emails later, we had a beautiful Hypertune intake manifold for our Evo IX in our hands.
The Hypertune intake manifold has CNC machined billet aluminum flanges and intake runners with a hand fabricated tig welded sheet aluminum plenum chamber.
The Hypertune 4G63 intake manifold has a large plenum that is at least 2x more volume than stock, this gives plenty of room around the ends of the intake runners for better air distribution and less interference of wave tuning. The ends of the runner have velocity stack trumpets for good flow.
The CNC machined runners have a perfect fit to the flanges and intake ports. CNC machining assures a perfect match with runner length and volume. The Hypertune manifold has runners that are straight and significantly shorter than stock. This might cost us a little bit of bottom end but should help top end power. Turbo engines are less sensitive to intake manifold runner length than NA engines so this should not be much of an issue.