A bigger turbo is not a power upgrade. It's a commitment.
Get the supporting work right and the power comes. Skip it and you'll be shipping us a destroyed cartridge wondering what happened. We've seen it enough times to be direct about it.
Start With Your Target Number
Before anything else, know what power level you're actually building toward. This determines everything downstream: turbo sizing, fueling, supporting hardware, and whether your bottom end can handle the load.
A turbo that supports 400 wheel horsepower is a completely different unit than one sized for 600. Going bigger than your fuel system, tune, and internals can support doesn't gain you power. It gains you surge, heat, and bearing stress.
Pick a realistic number. Build to that number.
Turbo Sizing: The A/R Ratio and Wheel Diameter
Two specs control turbo behavior more than anything else: wheel diameter and housing A/R ratio.
A larger compressor wheel moves more air but takes more exhaust energy to spool. That means lag. A tighter turbine A/R spools faster but chokes out at higher RPM. A looser A/R extends the power band but pushes spool further up the RPM range.
Neither is wrong. They're tradeoffs. The right combination depends on your engine displacement, rev range, and how you drive the car.
A performance street build on a 2.0L four-cylinder has different requirements than a built 2JZ making 1100hp on the track. If you're not sure where to start, talk to someone who maps compressor maps for a living, not whoever answers the phone at a parts warehouse.
Oil and Cooling Feed: Non-Negotiable
A performance turbo runs harder and gets hotter than a stock unit. Your oil feed and drain lines need to be sized appropriately. A restricted feed line starves the bearings. A drain line that can't keep up with return flow causes backpressure and oil pooling in the center housing.
Ball bearing turbos are more tolerant of oil supply variations than journal bearing units, but they still require clean, pressurized oil from the moment of startup.
If your build involves a relocated turbo position or a significant change from OEM routing, get the oil lines done properly. This is not where you cut costs.
Water-cooled center housings are standard on most modern performance turbos. Make sure your cooling circuit is connected and flowing. A dry CHRA on a hot engine will damage bearings on the first heat cycle.
Boost Control
A bigger turbo needs a matching boost control strategy. That means an external wastegate or an electronic boost controller, a wastegate port sized for the flow, and a tune that accounts for the new turbo's spool characteristics.
Running an upgraded turbo on the stock tune is a common and expensive mistake. The ECU doesn't know what it's talking to. Boost will spike, fuel will go lean, and you'll find out the hard way.
Budget for a tune. It's part of the build.
Intercooler and Intake
More air means more heat. A stock intercooler that was marginal at OEM boost levels will be completely overwhelmed at elevated pressure with a larger turbo. Charge air temps directly affect knock threshold. High intake temps kill timing and with it, power.
A front-mount intercooler sized appropriately for your target power level is one of the higher-return investments in a forced induction build. Don't ignore it.
What MIC Turbo Can Do
We rebuild and upgrade IHI, Garrett, Borg Warner, Holset, and Mitsubishi applications. Whether you need a cartridge swap, a compressor wheel upgrade, or a custom housing configuration, we work with what you're building, not off a generic parts list.
We're in Miami. We ship nationwide. If you know your target numbers and want to talk through what makes sense, get in touch.