[ TECH] GOING FASTER PART 1: PREPPING OUR C5 FOR A FAST LSX INTAKE MANIFOLD JAMES MILES WORDS PHOTOS Now that we ve sorted out all of our 02 C5 s minor mechanical issues, it s time to get busy with some basic performance modifications. The intake tract is usually a good place to start if you re looking to strap on some extra power without delving into your engine s internal components. Based on numerous positive reviews and an eminently reasonable price tag (around $950), we decided to start with one of FAST s 92mm LSX intake manifolds. For our baseline dyno testing, we contacted Enhanced Street Performance Inc. (ESP) owners Dave Brady and Greg Gemme. Their shop had been mentioned on the Corvette Forum in an extremely positive light, and, coupled with its proximity to this author s house, it seemed like the natural place to go. Getting right to work, ESP performed some pulls, suggested a few fuel-system-maintenance items (see Fuel for Thought, Sep. 10), and followed up with another round of testing once our LS1 s FI setup was back in peak condition. Brady and Gemme were great to work with, and even took the time to explain what kind of power gains we could expect from our new intake. (As we ll see in our next installment, they were spot-on with their prediction.) This month, we begin our installation with a look into what it takes to remove the OEM parts and prep the engine for its new mouthpiece. Believe it or not, the install itself takes very little in the way of time. And while it may look daunting, anyone with a set of GM Service Manuals (available from Corvette Central and other large Vette-parts retailers) and the correct tools should be able to have his or her car up and running in a weekend or less. With that, let s get our C5 going faster and breathing easier. EDITOR S NOTE: Since this story was written, FAST has replaced the 92mm LSX with a 102mm version. This new intake is also compatible with the LS1 engine and should perform at least as well as its predecessor in that application. 1 We started by getting our pre-install baselines at Enhanced Street Performance Inc., or ESP for short. When our C5 exhibited fuel starvation at high rpm, ESP owners Dave Brady and Greg Gemme suggested a fuel-filter replacement. Once that was taken care of, the 02 put down 268 hp and 272 lb-ft at the rear wheels a bit less than the Pro Street Camaro in the foreground, but about average for a stock LS1 automatic. 8 6 VETTE 11.10 VEMP-111000-FAST.indd 86 6/17/11 4:30:33 PM
[TECH] GOING FASTER Begin the process by siphoning the 2 pressurized fuel from the Schrader valve. My method uses a reinforced PVC tube, a tool stuck through to act as a trigger, and a bottle on the end to catch the waste. 3 Next, use a disconnect tool to remove this fuel-feed tube. This item can be found at most parts stores. 4 After that, disconnect the MAF sensor 5 and remove the air bridge. 6 Now, disconnect the throttle-body wiring on both sides 88 VETTE 11.10 VEMP-111000-FAST.indd 88 6/17/11 4:30:47 PM
along with the throttle body tubes. 7 8 With those chores done, remove all three retaining bolts 9 and pull the throttle body off the front of the manifold. VETTEWEB.COM 89 VEMP-111000-FAST.indd 89 6/17/11 4:30:55 PM
[TECH] GOING FASTER The fuel injectors receive attention 10 next. In this photo, we ve begun disconnecting the wiring. 11 Afterwards, it s time to loosen the fuel rail and manifold-retaining bolts. 12 Keep in mind that there are eight slightly expanded injector O-rings keeping everything in place. As a result, removing the rail might take a little elbow grease. 13 The rear manifold bolts are under a lip and can t be removed. We decided to cut a couple of spacers from plastic tubing to keep these bolts from falling back in their holes. This worked perfectly and kept us from scratching the engine. 14 The final step involves removing a few rear harness connections. After that, the manifold can be lifted up and out of the engine bay. 15 And there you have it: one slightly dirty OEM intake manifold. 90 VETTE 11.10 VEMP-111000-FAST.indd 90 6/17/11 4:31:12 PM
16 The stock MAP sensor located on the back of the manifold will have to be removed and reinstalled on the FAST LSX unit. 17 Now is a great time to address other issues such as an ailing PCV system or oil-pressure sensor (see Under Pressure, Aug. 10), both of which require the removal of the intake. 18 With those problems solved and the valley thoroughly cleaned, it was time to install our LSX intake. Join us next month as we begin the fun. VETTE Ë Sources CORVETTE CENTRAL (800) 345-4122 www.corvettecentral.com ENHANCED STREET PERFORMANCE, INC (888) AWD-DYNO www.enhancedstreetperformance.com FAST (877) 334-8355 www.fuelairspark.com VETTEWEB.COM 91 VEMP-111000-FAST.indd 91 6/17/11 4:31:20 PM