GTM Performance Engineering: MHI Twin Turbo Official Release

Originally Posted by SPOHN

And for the two guys that asked about the Garrett turbo oil return line. No you will not have to tap the upper oil pan. We will still be using the GTM oil baffle pan for our source of return.

Originally Posted by SAM@GTM

Yes, it is possible and will be available for sale separately. You can mount the pan with the Garrett kit to get more volume. However, we don't recommend using the returns on the oil pan with the Garrett kit since the Garrett turbos are a lot more sensitive to oil return line. We have extensive experience with Garrett turbos and even per Garrett's recommendation, the oil return needs to be above the oil level.

Bear in mind that we didn't wait until now to do an oil pan out of laziness or to make installing the original turbo kit harder. There is a technical reason for requiring drilling of the upper pan for the oil returns on the Garrett kits. Putting the oil return in the lower pan drastically increases the chances of developing a smoking issue. Basically, the oil will go out the turbine shaft seal into the exhaust instead of into the pan. Keep in mind that ball bearing turbos require just a fine mist of oil to lubricate the bearings and when it comes out of the bearing section that is spinning at 50,000 - 130,000 rpm, it is very frothy and does not flow very well compared to liquid oil. This is why the return needs to be above the oil level: to give the return oil enough room to flow out of the line and calm down.

This is not an issue with the Mitsubishi journal bearing turbos since they require much higher oil volume and pressure to support the journal bearing riding on a film of oil. That is why we can use the oil pan on this kit.

Sam