Yes, Bill assures us that if people want further increased power levels out of these engines, it's definitely there for the taking. If you want to start really getting serious, there's Hahn Racecraft's so-called Hi-Boost Engine System for 2.4L engines that Hahn says "enables people to take advantage of the very robust LE5 bottom end (which features forged rods, oil-jet piston cooling, and the like), but corrects the aspects that prevent these engines from being readily exposed to very high boost numbers." The basics: heavy-duty valve springs, head studs, and a thicker MLS head gasket that drops compression from the stock 10.6:1 to 9.1:1-enabling a claimed 18-20 psi on 93 octane! Also included are associated doodads to get it to work with GM's sensitive factory VVT system.
It doesn't end with the LE5, either. As to other Cobalts, Hahn has products in development for the '08 SS Turbocharged, and right now offers complete turbo systems for '05-'07 LSJ-equipped cars that replace the factory supercharger system with a turbo system. This kit will produce 320-360 whp on the bone stock LSJ engine with pump gas. Plus, there's a Hahn kit for 2.2L Cobalts-check out the company website for more info.
Hopefully, you're starting to see that the Ecotec is a power-potential-rich engine family-it can do a lot of the same things our V-8s can, though admittedly with a far less gnarly exhaust note. Still not convinced of the worthiness of an I-4 GM, and its suitability to create a badass, fuel-sipping daily ride when turbo'ed? Don't worry, because Hahn Racecraft assures us it has kits for the RWD LS-powered GMs we know and love in the works as well. And since you're reading GMHTP, you already know where to look for 'em!
The BoostFueler adjustments are best performed on a dyno-here we double-check Hahn's work back at TTP. A boost gauge is hooked up (none is provided with the Hahn kit, but feel free to mount one in the cockpit so you can get thrills out of seeing its 8-9 psi). The large Allenhead atop the unit is adjusted until the fuel pressure gauge reads 25-30 psi at idle. Then, during a full-bore pull, the small brass control valve we've mentioned earlier is twisted to yield 70 psi. Be careful not to turn this latter knob too far or you'll prevent the fuel pressure from bleeding off when you let off the throttle. In this way, the BoostFueler system can be easily adjusted to match the exact setup of a given vehicle (no ECM tuning required or allowed here-Hahn mails it back to you in a "locked" state, i.e., its calibration cannot be altered.)
 Our power increase comes out...  Our power increase comes out to damn near 50%! Hahn says reports from the field indicate as much as 265 whp with this system on manual trans cars, 245 on automatic. Torque made a similar jump, up over 70 lb-ft (or 75 against our exhaust-only situation). This is just about stock LT1 territory! While its graph is not shown here, we also verify a safe AFR (under 12.0:1) with TTP's wideband O2. |  Getting the newly-boosted...  Getting the newly-boosted 'Balt off the line is pretty straightforward. After a quick spin to clean the tires off, the launch basically entails footbraking the car to about 1,600-1,800 rpm, then rolling to full throttle within the first two seconds of the run (anything more will set them spinning hard). Also, one needs to start out in "L" to prevent the traction control from coming on, then shift to "I" or "D" at the top of first gear. |  While Hahn's engine control...  While Hahn's engine control methodology is not designed with end-user adjustability to the ECM calibration in mind, we nonetheless decided to pick up a scan/tuning tool to evaluate our LE5's new operating characteristics. A great source is HP Tuners, whose VCM Scanner and VCM Suite tools are some of the most popular in the business, with myriad vehicle support and extensive user-friendly features for novice and professional tuners alike. You can get a scan-only unit for as little as $349, or the full VCM Suite like ours for $499 (standard) or $649 (professional)-all with the latest MPVI Interface hardware. |
In addition to showing us DTCs (like the intermittent P0300 code we've already mentioned), our VCM Scanner software also allowed us to see (and log) parameters like knock sensor behavior. Truth be told, a few degrees of knock retard is now more or less standard fare on our LE5 when in the boost, but Hahn explains that this is typical for a forced-inducted Ecotec: the engine family's knock sensors and characteristics are such that it's actually one indication of optimized ignition timing, and one must resist the temptation to draw hard-and-fast comparisons to what knock retard indicates on an LS or other GM V-8s. Plus, we've never actually heard the slightest smidgen of any unusual combustion events from underhood, so that's great news.