[N0DIH]

An interesting find!

A 3.0L engine with 2 turbos and 16 psi boost @ 6600 rpm uses the same turbos as a 5.0L engine at 5000 rpm and 6 psi boost. BOTH with 2 turbos. You need to step up to the 301 Turbo's .82 A/R on that turbo to get enough airflow to run it at a single turbo level.

Hmmm.....

The 5.0L engine (@5000 rpm, 6 psi boost, intercooled and 1 turbo) will run around 36.5 lbs air/minute, where the 3000 engine with 2 of them will run around 41 lb/min. According to my calculations adding an intercooler will only add around 30 hp. It really complicates installation. Might not be a good choice for Phase 1. Now, Phase 2....Muhahahahahahaha. If it is easy to install, go for it, but might be an option on the requirements.

In reality, Pontiac picked dead on the right compressor side for the 301. With too small of a exhaust side (around the 231 CID size). It could flow the air, but the restrictions everywhere were terrible. It is an oil cooled turbo, no water lines to it.

Run a HD oil for sure, you need every help you can with heat of the oil soaking in the compressor during shutdown. Or some way to cool the oil to it, make a small oil cooler for the oil going to the turbo itself.

Oil drains from the turbo are critcal. Make them big (like 3/4" to 1"). And get them into the oil pan or somewhere that can get to the oil pan quickly, do not ever dump them into a valve cover! This will overload the head and it will not drain quick enough. Pontiac dumped it into the lifter valley though the lifter valley cover. Pontiacs and Chryslers (B and RB) have had "Air Gap" intakes forever. So it was easy. If there is a place on the intake on the 4.9L that you can drill through to make a clean dump into the valley, I would consider that.

Oil pressure. Pontiac installed a 70 PSI pump into the 301 Turbo. I don't know on the GN and turbo 3.8's. You will have a large oil "leak" on the main oil galleries with the turbo on there. Upgraded oil systems will be needed. Increased capacity can't hurt, being we already have an external oil cooler we have a good start already. Even a catch can with oil that can "store" it will increase capacity. Diesel semi's have 30+ qts of oil, so capacity galore. At the minimum, a RotellaT/Delvac 15W40 is already designed for HD diesels with turbos. It would likely be a good choice.

More thoughts brewing....

Next? ESC....

Tom