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C5 Power Pack
A five-step program to 40 horsepower
This article appeared in Corvette Fever
September 1999
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No doubt about it, the C5 Corvette is a world-class car; arguably, dollar for dollar, the finest car on the road today. You've read it in all the magazines, seen the tests, and know the specs. Even better, you might be lucky enough to experience this impressive performance first hand as a Corvette owner. Having said this, you might surmise the LS1 performance is as good as it gets. Well folks, that's not the American way. Everything can be improved!
For example, suppose we told you there is another 40-plus horsepower hiding in you LS1? Suppose we told you it was easy to find and you don't lose any of the drivability? Suppose we told you the work could be done right in your home garage? Sound interesting? We thought it sounded real interesting so before you could say Zora Arkus-Duntov we were on our way to Vinci Hi-Performance to check out their Stage II Power Package for the LS1 engine.
Upon our arrival we were greeted by Roger and Joe Vinci. A bench-racing session ensued and it didn't take long to understand the Vinci philosophy. First, they recognized the LS1 in stock configuration is an excellent and very sophisticated platform. The stock engine is rated at 345 hp at the flywheel, and generally produces between 268 and 290 horsepower at the rear wheels. A very nice power band supplies ample power on demand, although some feel the low-end torque is a bit light on the LS1. Now "ample" is a relative term and in the Vinci camp, they were certain more power was hidden within the LS1, and it was their job to release those extra horses.
The subject of these modifications is a '99 black convertible that just happens to be the "shop car" for Vinci Hi-Performance. We followed along as Greg Warner performed the installation and associated testing. Greg has been at VHP for 10-plus years and is key in development of new products. Finding horsepower is his game.
The modification process is that of a super-tuner, searching for performance through improvements on the existing platform. No mega-inch motors, no radical surgery, no loss of "manners" on the street. It's more like a massage and it can be done in increments. Let's take a look at some simple modifications that will net around 50 hp and 50 lb-ft of torque for the LS1 - a worthwhile effort, and a difference that is easily detectable from the driver's seat.
The fact that you can do this in your own shop is a bonus. All Vinci Hi-Performance products come with a full set of installation directions, making it possible for the home mechanic to install these items. Basic automotive hand tools are all that's required for installation. When you have completed the project you'll have a Corvette that sounds better, looks better and above all, performs better. The car remains emissions legal with these modifications, making your C5 mean and green.
An impressive thing about Vinci Hi-Performance is that they put each car through the automotive equivalent of a lie-detector test - the dyno. Prior to installing any products, the car is run on the dyno to determine baseline performance figures as the car arrived. Let's face it, rear-wheel horsepower and torque are what matters in real-world driving. These ratings are recorded on a graph printout. After modifying and tuning the car, it is once again run up on the dyno. The before-and-after comparison tells the tale of exactly how much power the car is producing.
The associated charts illustrate the performance improvements on the C5. Arriving in stock form, the car was pretty strong - 275.9 horsepower at the rear wheels. After installing the VHP Stage II kit, the C5 produced an impressive 324.5 rear-wheel horsepower, a 48.6hp gain.
For those of you seeking even higher levels of performance, consider the "Ultimate LS1 Power Package." This extensive Vinci Hi-Performance kit involves changing the camshaft, heads, and exhaust manifolds, but that's another story and another hundred horses. For now, let's see what it takes to uncover 40 extra horsepower in your C5.
Step one in the search for power is replacing the stock thermostat with a new Powerflo thermostat.... (Edited)
The second step is to replace the stock fan controller with a VHP Constant Monitor Fan Controller.... (Edited)
Step three involves the ECM (aka computer - brain).... (Edited)
Step four involves a simple oil change. The Vinci Hi-Performance dyno shows several free horsepower by using Amsoil Series 2000 synthetic lubricant. Change the oil filter too, but we shouldn't have to say that, should we?
The final step involves a little more work (Come on, you didn't think you could get 40 horsepower without some real work, did you?) Replacing the exhaust system from the catalytic converter back will provide lower dynamic backpressure.... (Edited)
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