OIL: YOUR ENGINE'S LIFEBLOOD
We've already discussed the importance of accelerated engine oil change intervals and the use of conventional oil during an engine's first miles. What we have not covered is the viscosity of engine oil to use, as well as the advantages of eventually swapping to a synthetic oil.
Oil viscosity--or more commonly, "weight"--is an important fluid characteristic that needs to match up with a particular engine's physical needs. In the interest of not getting too technical on this subject, let's just say that the controlling factor in oil viscosity selection is how the engine's bearing clearances have been established. Recall from the first installment of this build our sidebar on "The Lunati Friction Package," where we went through and explained the reasoning behind Lunati's bearing clearances being set somewhat greater than GM does from the factory: basically, Lunati engineers prefer higher viscosity oil because of its inherent protection in severe situations. Because of this, our 383 stroker will need oil a good bit thicker than the 5W-30 that GM recommends for the LS1. Lunati's Mark Chacon instructed us that at least a 10W40 should be used to ensure the minimum 10 psi per 1,000 rpm oil pressure, with a 20W50 or similar heavier weight oil optional as well.
That said, why swap to synthetic oil after break-in? The short answer is that it offers more protection via the likes of reduced friction, corrosion, and wear. But not all synthetics are created equal. Texas-based Royal Purple, Ltd. is one of the leading manufacturers of premier high-performance lubricants for both consumer and industrial applications. Unlike some other companies that manufacture engine oil, Royal Purple's resources and talents are not diluted by expenditure of time and money on other petroleum products like fuel, enabling the company to focus exclusively on developing lubricants that outperform other synthetic or mineral-based oils. We spoke to Royal Purple's Jared Martin on the advantages of synthetic oils in general, as well as those of the company's "XPR" line of oil that we've chosen for our 383 LS1.
"First, it may be good to clear up a common misconception about the origin of synthetic base oils," says Martin. "Despite the common thinking that they are completely man-made--evoking visions of a mad scientist creating a Frankenstein fluid out of exotic materials--the most widely used synthetic base oil in automotive applications is actually derived from crude oil, just like mineral base (conventional) oils. The huge difference is in how the two are refined. Synthetic base oils are completely broken down, stripped of virtually all impurities, and then are essentially pieced back together, hence their man-made or synthetic nomenclature."
"This costly refining process yields significantly greater performance than conventional oils in a number of ways," continues Martin. "Because synthetic base oils have a long-chain, uniform molecular structure, they have higher viscosity indices (VIs) as compared to mineral base oils. The higher the index, the less change in viscosity over a given temperature span. In addition, synthetic base oils naturally possess lower pour points due to their purity and molecular structure. The contaminants found in mineral base oils (wax, paraffin, silicone, etc.) are removed, thereby increasing resistance to the effects of heat, yielding far greater oxidation resistance. Also, the inconsistency in molecular size and shape of mineral base oils significantly reduces their shear stability; and synthetic base oils have a higher specific heat, meaning they carry and dissipate heat more efficiently."
"While synthetic base oils do provide performance benefits over mineral base oils, keep in mind that base oil is a mere starting point. Engine oils are typically made up of 15 percent to 25 percent additives, which are used to tweak performance. Because additives essentially define the performance of a finished product, it could be said that a well-formulated mineral-base oil may outperform a poorly-formulated synthetic. However, if equal or greater focus is placed on the additive formulation when used in a quality synthetic base oil, the lubricant can reach a whole new level. Such is the case with Royal Purple and our Synerlec additive technology. Synerlec amplifies many of the inherent benefits of the synthetic base oil, particularly film strength and oxidation resistance, both of which have been found to be multiple times that of even other synthetics of the same viscosity," says Martin.
For this project, Royal Purple recommended its Extreme Performance and Racing (XPR) line of engine oils, which is a new marketing twist on an existing and proven formulation. Previously referred to simply as the "Racing" line, Royal Purple has renamed this line of oils to better project the products' viability in high performance street applications. "This LS1 stroker build is an ideal candidate for such a product," says Jared Martin. "The XPR line differs from our other products primarily in that our Royal Purple SAE engine oils are API/ILSAC licensed for OEM warranty approval, and this licensing process limits us on what we can do with certain additives to tweak performance. In contrast, the XPR line is designed specifically for customers that have no warranty--or have already voided it 100 other ways--and are looking for maximum performance! While it's true that thanks to our Synerlec technology (which is not API/ILSAC regulated) our SAE oils already outperform most other "racing" oils, the XPR line redefines the class. I usually recommend stepping up to the XPR line when a customer has either installed a power adder, stepped up the boost on a factory blower or turbo car, or has made internal engine modifications. Such is exactly the case with GMHTP's project LS1 stroker."
When Jared first mentioned the fact that the XPR line of oils is not approved for use in new vehicles under warranty (you won't find the API approval starburst on an XPR bottle), I was a bit skeptical of its suitability for a street driven vehicle. However, I was assured that what this approval process all comes down to is an emissions issue, and not even a proven one at that. "The main two elements the API is concerned with are zinc and phosphorous, which are used to form the compound zinc dialkyl dithio phosphate, commonly referred to as ZDDP," says Martin. "These have been the cornerstone of anti-wear technology since additives began being used in lubricants. What the API and EPA are concerned with is the potential effect of phosphorous on emission control devices like oxygen sensors and catalytic converters. It is speculated that higher degrees of phosphorous will lead to an early demise of these devices, though I have yet to see conclusive evidence of this. So rather than placing the burden on the manufacturers of these emission control devices to better withstand the effects of these elements, the regulatory agencies instead choose to reduce the upper limitation of these elements in engine oil. While I'm not at liberty to get too deep into what separates the Royal Purple SAE and XPR oils, I can say that due to our Synerlec technology it has very little to do with the ZDDP issue. Rest assured that foregoing any API licensing with our XPR line gives us the ability to design a lubricant from the ground up, enabling us to make a better product."
While engine mileage was insufficient to enable us to install this oil prior to our dyno and track testing, we'll be doing so at the next oil change--endowing our 383 Gen III with long life and more power.
TUNE AND TEST
But wait; we just got ahead of ourselves. The observant reader might realize that we've glossed over a critical area--one that must be addressed whenever an engine is anything more than mildly modded. He or she would probably ask, "Hold on... is my new stroker motor really going to run with a stock computer?" The answer, roughly, is no. With a heavily modified engine like this one--more cubes, big-lift cam, high-flow heads, etc.--stock or near-stock fuel and ignition maps simply won't cut it. Though the engine will likely start and run on a factory tune (assuming stock fuel injectors are being used), parameters would likely be so far off that even if the car were able to be driven, it would probably be a bad idea even for break-in purposes. Therefore, the home engine installer will need to make a choice with regard to tuning. The first option is to completely learn a PCM tuning program and construct all engine maps from the ground up--a daunting task. Another is to get a local shop to perform a full custom tune, which is viable, provided you have a trustworthy and affordable tuner in the area. The final route is to take the middle road.
Middle road, you say? This third option, which is the one we have chosen to pursue (at least for the time being), involves having the PCM flashed with a customized mail-order calibration. Though often this will not result in a dead-on tune, the enthusiast can use what limited tuning abilities he or she might have to dial it in using commercially available scanning and tuning software. See the sidebar on the Thunder Racing tuning we chose for this build, and follow along below as we take steps to evaluate the suitability of this calibration, as well as make fine adjustments to match it more closely to our vehicle. Although we won't purport to supply all-encompassing analysis and instruction on how to tune your vehicle (as PCM adjustments are, by and large, beyond the scope of this story), we'll fill you in on a few tips and tricks to help you evaluate whether you can handle such a task yourself or would rather leave it completely to the pros.
THUNDER RACING: PUTTING YOU ON THE MAP
Louisiana-based Thunder Racing is one of the country's larger retailers of aftermarket parts for late model domestic performance vehicles. These folks carry virtually any part from any manufacturer that you'd want for your late-model GM ride, including most of what we've used in this engine build. Thunder obviously knows its customers like to buy go-fast goodies, and so its computer tuning service is the perfect complement to the company's extensive retail product line.
Available for virtually any 1994-later GM V8-powered ride, Thunder sells basic tuning for mild mods, which includes adjustments to the rev limiter, shift points, speedometer recalibration, torque management deletion, and performance fuel and timing curves, among other things. This service can be had for $150. If your ride steps beyond what this basic tuning service can address, don't fret: Thunder offers a custom tuning service for vehicles with more serious hop-ups. Designed for heavily-modded engines with goodies like an aftermarket cam and heads, the custom tuning service (which goes for $450) includes all of the features of the basic service, but adds highly customized spark and fuel tables tailored to a customer's specific combination of parts-optimizing power and drivability. This is the service we've selected for this project.
Though the company's personnel are extremely experienced in their tuning capabilities, having tuned many vehicles on its in-house dynamometer, Thunder's Geoff Skinner had some honest commentary for us regarding not only his capabilities, but the capabilities of mail order tuning in general. "Some mail-order tuners claim to be able to wave a magic wand and send off a perfect tune to a customer for every possible engine combination," says Skinner. "While we're able to get at least 90 percent close to an ideal tune for engines with known parts combos that we've also built in-house in the past, the huge variety of aftermarket parts available on the market means that being able to get a completely perfect tune in every single scenario for everyone is simply not possible. The simple fact is that every car is different, even two cars that have the exact same aftermarket parts installed on them. So a good portion of the time, our custom tuning service will not be an end-all solution, but we can at the very least get you in the ballpark of your ideal PCM calibration."
That said, would the PCM tune Thunder provided for our 383 LS1 prove adequate? You'll see in the main text how pleasantly surprised we were at how well our vehicle drove and performed--not wanting to leave well enough alone, however, we decided to try and evaluate and further dial in this tune. I'll also show you some of the things I learned in playing with our EFILive tuning software (unlike some other GMHTP staffers, this author is not an expert tuner), as well as pointers from Thunder Racing and buddies more knowledgeable than I. See the main text for this information.
OXYGEN SENSORS: GOIN' WIDE
PCM tuning is not a task for the faint of heart, and that's why there are so many shops available around the country who can help you out. But when trying to do at least some of it yourself, the single most important tool you can add to your arsenal when dialing in the computer calibration on your newly stroked ride (other than the tuning software itself) is a wideband oxygen sensor. By being able to monitor the engine's air-fuel ratio in real time, tuning status and changes can be accurately evaluated. Now, it's true that all vehicles sold today come with oxygen sensors already on board--but almost without exception, they're "narrow band" units that can only accurately read AFRs near stoichiometric 14.7:1. Full throttle AFRs need to be significantly richer than this for optimum power and safety, and only a wideband can accurately monitor these. From helping verify that a typical enthusiast is in the ballpark with a mail order tune, to assisting more experienced persons in customizing fuel and spark maps from the ground up, tuning simply can't properly be done without a wideband.
For the novice and expert alike, the absolute best way to evaluate and adjust PCM parameters is to use a chassis dynamometer to put the vehicle through its paces. As fate would have it, most of us don't have dynos in our garages; so unfortunately money will most often need to be spent renting one out. And while it's true that many dyno shops already have wideband O2s hooked into their equipment, chances are you'll want to use a scan tool to acquire some information via street logging before spending dough on a per-pull dyno roller romp.
Follow along as we install an Innovate Motorsports LC-1 wideband on our project Firebird. The LC-1 can be used both as a standalone product--with real-time readouts being displayed by the provided LogWorks software--or in conjunction with tuning software such as EFILive. We'll be hooking up for the latter option, but take note that even when so wired (which configuration differs only slightly from standard wiring), the unit's multiple outputs mean that the Innovate LC-1 can still be used as a standalone product simultaneously--a convenient feature.
TUNING: DIALIN' IN
We'll admit it: we were a bit apprehensive about how well someone could tune a vehicle from well over 1,000 miles away without having ever even seen it--particularly a heavily modded car such as ours. After weeks upon weeks of engine assembly and installation, the success of the entire project still hinged upon proper PCM calibration. A poorly tuned engine yields a poorly-running and poorly-performing vehicle--and I'll be the first to admit, even though tuning was coming from folks as reputable as those at Thunder Racing, I was a little worried.
But I'm happy to report that, all things considered, Thunder did a great job on our tune. It was a pleasure to find how well our Trans Am ran and drove; throttle response was excellent, no noticeable burbles were present in the powerband, and fuel mileage was decent (though of course off from stock a couple mpg thanks to our big cubes). Before we knew it, we were cruising local car shows and turning heads, unable to resist the urge to open our QTP electric cutout and let onlookers better hear the lopey idle provided by our Lunati cam and the deep rumble of our 383.
Very few drivability issues emerged during our first few miles on the road, and we'll hit the highlights of them and how they were dealt with in the photo captions. Along with talking to Thunder Racing for help and insight, I also had a GMHTP contributor experienced with EFILive tuning have a look at the maps; based upon the readings seen using EFILive's Scan Tool and our Innovate LC-1 wideband, these folks were able to point me in the right direction with respect to some minor tune adjustments. Check out the photo captions for more information. (And note in the accompanying screenshots we're only showing a portion of each screen for clarity.)