Introduction

Here is an overview of our daily-driven 2014 ATS+4. We put this car together just as a reliable driver—maybe run mid 12s—and just enjoy it. Things, as they do, kept progressing, but the main heart of the car hasn’t changed.

Teaser

• We have 35k miles on this build, with 25k of those miles on our XDI injectors.
• The car ran 11.77 @ 117 mph in the ¼ mile using the same tune we daily drive year-round in Michigan.
• Averages 21–22 mpg on full E85. Only maintenance has been spark plugs once, plus regular oil changes.

Below, we’ll dive deeper into the parts used, lessons learned, and what we might do differently for our next build.

2. Engine Components & Strategy

2.1 Overview of Engine Goals

We wanted an engine that combined good reliability with affordability. At the time, we were between garages and had ZZP build/install the long block. It’s a fairly basic build using their components, and as of this writing, I have nothing but positive feedback on what we received.

2.2 Short-Block & Internals

• Pistons: ZZP pistons (4302 forgings). We like that we can run a tighter piston-to-wall clearance, ideal for a year-round driver. Our end-gap measured .023–.025. (In our other car with JE pistons, we set them at .029–.031.)
• Rods: ZZP rods. They appear physically more robust than Molnar rods, though we use Molnar in other builds as well.
• Crank: Stock.
• Balance Shafts: Retained, since we don’t spin above ~6700 RPM.

Lessons Learned: The short block has been extremely solid. I wouldn’t change anything—just a basic forged engine build that’s worked great.

2.3 Cylinder Head & Valve Train

• Springs & Retainers: ZZP springs and titanium retainers. They add spring pressure, which helps control the valves under higher cylinder pressures. They aren’t cheap, but until a beehive-style option is found, these have proven effective—even on stock cams.
• Camshafts: ZZP fuel cam (a stock cam reground to ~30% more stroke on the fuel lobe). We haven’t upgraded the HPFP, yet we haven’t run out of headroom.
• Valves: Stock. They’ve been perfectly fine.
• Head Studs: ZZP 8740 studs. With this turbo size, they’ve been sufficient; no issues so far.

Lesson Learned: We plan to add a ported head and stronger studs in the future, but that’s for performance expansion, not reliability concerns.

2.4 Turbo Setup: Z54

• Turbo: Z54 (ZZP’s version of the BW 6758), featuring a journal bearing instead of the lightweight turbine. Given its cost and potential output, it was ideal for our goals.
• Manifold: Stock GM.
• Downpipe: ZZP catted.

Lessons Learned: For the cost, we wouldn’t change a thing. Our Z54 has outperformed similar 20G, MHI, and Z57 setups. If budget allowed, we’d consider a BW supercore or ZFR. We actually have a BW supercore ready, but can’t justify swapping it out yet since this setup runs so well.

(Call-out): Looking for custom injectors or advanced calibrations? Our Tuning Services can help with bigger turbos, fueling needs, etc.

3. Fuel System Upgrades

• Fuel Pump: 5th Gen ZL1 pump. Contrary to popular belief, this is the same pump used in later ZL1 and CTS-V models. Our version doesn’t require extra lines for the aux side, making installation easier.
• Fuel Cam: As above, we’re using the ZZP intake cam with an enlarged fuel lobe. Perfect for our current power level.
• Injectors (Stock): Initially ran these on full E85 for ~9k miles. Combined with the fuel cam and ZL1 pump, we could push to ~400 HP levels. We were cautious about aftermarket injectors at that time.
• XDI Injectors: Once XDI released LTG injectors, we gave them a shot. After dialing in the tune, they became a no-brainer upgrade. We dropped 0.3 seconds in the ¼ mile and still have plenty of headroom—where stock injectors were nearly maxed out.
• Flex-Fuel: ZZP flex fuel sensor. If E85 is accessible, use it! It makes better power than race fuel, costs less than 87 octane, and lowers LSPI risk.

Promoting Our Injector & Tuning Business: We spent lots of time perfecting injection timing and rail pressure to optimize fueling on Gen V platforms. XDI injectors are now almost plug-and-play. Still, fine-tuning fuel pressures and pulse width is critical—especially on bigger turbos and E85 setups.