CHEV SILVERADO L5P 6.6L V8 DURAMAX PROJECT S300 TURBO UPGRADE

Stage 1. ECU & TCM Remapping Results

There is so much misinformation on the internet about tuning these L5P Duramax’s. Still to this day, the only way of tuning these properly is to exchange the ECM and TCM with HPTuners Modified ones. I just buy new ones for customers because the cost difference is not that great and you don’t have a truck that wont run while the controllers are away getting modified.

The TCM is easy to replace. The ECM on the other hand is a little harder to get to. We found pulling it out from under the wheel arch is easier and quicker.

The gains shown in the graph below and on our L5P Tuning Page shows awesome gains from just tuning the ECM and TCM and leaving everything else stock. And if it were my truck again, in hindsight, I’d consider leaving it here. But it still sounds like a muffled 6 cylinder in this state. Pretty crazy gains of 174HP and 462Nm!

Stage 2. Tuning With WCFab Turbo Back Downpipe & Dump Back P1 4″ Race Exhaust

Now this is where things start getting crazy with the L5P – the sound and jet turbine acceleration is worth every cent. More on that later.

We installed WCFab’s 3.5″ Intake Horn, 3.5″ Dump from the back of the factory turbo and hard piping both hot and cold side of the intercooler. The Kingsport Grey powder coating is just immaculate – we also did the top coolant pipe for aesthetic reasons only. But it kinda looks factory in a cool way. I’ve seen lime green etc but it just spells trouble during any sort of roadside “inspection”.

Without a topside crawler, which is kind of like an elevated work bench you lay on whilst working, this job would be nearly impossible. If you attempt this in the drive way and you have not done this type of thing before – I would seriously reconsider getting a workshop with experience in these trucks to do the job. Its full on, you will lose grams of skin from every joint, from your broken finger nails, to your shoulders. And without a heavy duty hoist I couldn’t imagine getting it done in a weekend. And you will need a GM diagnostic tool to relearn the immobiliser – you will actually need to do this for the previous stage also.

As you can see from the graphs, this is an awesome upgrade. It will spin the 33 x 12.5 tyres as it changes gears through the 6 speed Allison Transmission. But a word of warning, you will hurt the trans even with moderate abuse with this amount of torque and power. The TCM will detect slip and start to ask the ECM to begin to pull torque to protect itself.

The sound from the MBRP 4″ Full Exhaust is truly satisfying, quiet with just hint of turbo spool when lightly cruising, it wont grab the wrong attention. But let it rip and it will bark so loud people will shit themselves and look around in a panic to see where that sweet growl is coming from.

Fuel consumption is also so much less. It will easily cruise in single number territory, the best I saw in a 100km/hr zone was 7.8L/100k’s. Down from 14’s. But I drive it pretty hard all of the time so normal people would see better numbers.

Towing is just so easy with this upgrade. I mean it loved towing stock, but with 1724Nm now, it would pull a caravan past a tuned 200 or 70 series Toyota with nothing on the back of them.