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EFI Connections LS1 PCM/Ignition Conversion - Bridging The GapEFI Connection's Trick LS1 PCM/Ignition Conversion Adds Power And Driveability To A 10-Second TPI From the February, 2010 issue of GM High-Tech Performance By Scott Parker Photography by Justin Cesler, Scott Parker
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Ever since the LS1s came out, many have dismissed TPIs and LT1s, mainly for two obvious advantages the Gen III has over them: a distributorless ignition and a powerful, easy to tune PCM. The only solution to either of these problems was a crank trigger and aftermarket EFI-both of which are pricey, not street-friendly, and a pain to install. Thankfully this is no longer the case now that EFI Connection has developed its 24x System, allowing troubled Gen I and II motors the ability to run an LS1 PCM and coil-per-cylinder ignition. Why, you might ask, has no one managed to do this before? Well, it certainly wasn't easy, as its creator and EFI Connection owner Mike Noonan will attest. A tremendous amount of R&D went into developing kits for these applications, and quite honestly the man must have cajones the size of watermelons. So it came as no surprise that when I asked him about his kit he described it with a smile on his face like it was his son that just pitched a no-hitter in little league.  Byron Jay's home-built nitrous...  Byron Jay's home-built nitrous 383, while not pretty, was certainly functional, running a best of 10.76. His '89 GTA was originally equipped with a MAF-based "165" computer, but Byron had since converted to a Speed Density "730" ECM. We thought it was time to stop burning chips and take a flying leap into 2009, so that he could not only go faster but improve driveability as well. When the GTA arrived at our Tampa shop, the EFI Connection crew started to drain the coolant and get to work.  As anyone familiar with LS1s...  As anyone familiar with LS1s knows, the 24x crankshaft reluctor wheel is an essential part of the PCM's operation, so in order for EFI Connection to build an LS1 PCM conversion it would have to fabricate a similar aperatus. The pieces you see before you are the result of countless hours of R&D, working closely with a machine shop and the tightest of tolerances. The wheel works in concert with a 24x sensor in the timing cover to detect crankshaft position.  To get started on installing...  To get started on installing the reluctor wheel, the crew started tearing down the front of the motor including the alternator, water pump, and front accessory bracket to gain access to the timing cover. A puller is used to remove the balancer.  On the Gen 1 it is necessary...  On the Gen 1 it is necessary to unbolt the front of the pan and...  ...drop it down a touch to...  ...drop it down a touch to remove the timing cover.  The reluctor wheel is simply...  The reluctor wheel is simply slid onto the crank snout as seen, and the dowels (for the old timing cover) are removed. Two different wheels are available, one designed to fit with a double roller timing set and one for a single. It is worth mentioning that the reluctor works only with a 0.525-inch thick crank sprocket, and some double rollers have a 0.550-inch. We switched to a single row HD unit to be safe. The key components that allow the late-model SBC and LT1 to run using an LS1 PCM and ignition are: the 24x crankshaft reluctor wheel, custom wiring harness, and dummy distributor that acts as a cam sensor. Sounds surprisingly simple, doesn't it? Other supporting components will also be necessary such as an LS1 PCM (obviously), ignition coils, plug wires. and coil harnesses-all of which are available through EFI Connection ($1,500 or more for a complete kit). The slickest part of the whole endeavor is that nearly all of the parts used are OEM. We hope to take a look at the LT1 system in the future, but for our first experience we decided a highly modified TPI motor would make the best test subject. Big cams and forced induction can give a PROM computer fits, no matter whether it's MAF or Speed Density-based, and we were determined to do right by one lucky TPI. Enter Byron Jay, who hails from St. Augustine, Florida, and frequents (our new home) Gainesville Raceway, and his 1989 GTA. Byron built the GTA all himself, including a changeover from MAF to Speed Density and the subsequent chip burning to dial in his stock block 383 with ported AFR heads, big hydraulic roller cam, Mini-Ram intake, long-tube headers, MSD ignition, and 175-hp shot of nitrous. With a fortified 700-R4, Yank converter, 3.73 gear, and slicks the GTA has managed to go 11.87 at 113 mph on motor and 10.76 at 126 mph on the bottle. Though these times are quite impressive, it was immediately apparent when we first heard its 1,000 rpm idle that the 107LSA cam would definitely feel more tame with the LS1 PCM and ignition. Byron and the crew from EFI Connection were happy to meet us at GMHTP world headquarters in Tampa for the installation and testing on our in-house Mustang chassis dyno. Follow along as we bridge the gap between old and new technology.  A Vortec timing cover (an...  A Vortec timing cover (an OEM piece for another application) is used with the 24x System, which has the crank sensor built in. It's hard to beat OEM quality and durability, so why bother. The side benefit is that it makes this piece (as well as other OEM pieces in the kit) easy to replace.  A generous helping of high-temp...  A generous helping of high-temp black RTV is applied to the cover before installing since the pre-'96 blocks have a few thin sealing areas. The oil pan can be bolted back up being careful to align it with the cover. With the cover bolted up, it is important to turn the flywheel to ensure a proper installation of the reluctor and that there are no clearance issues with the timing chain.  One important note, we were...  One important note, we were not able to reuse Byron's previous aftermarket balancer. However, EFI Connection's Mike Noonan assured us that a trip to the machine shop could have easily fixed this by milling the thickness of the crank reluctor, but it was just easier to use a Vortec balancer (from a '96-02 Vortec engine).  With the crankshaft position...  With the crankshaft position sensor removed you can see the reluctor wheel through the timing cover. As we found out, if you are having other mechanical issues-improper location of the reluctor wheel in relation to the sensor can cause a poor running engine. But the crafty crew got our issues squared away, and should have no problem troubleshooting if you should run into the same problem.  The factory computer is unlugged,...  The factory computer is unlugged, the fenderwells unbolted, and the harness is pulled through for removal.  The keeper that seals the...  The keeper that seals the firewall where the old (and new) harness feeds through is reused, so a heat gun and a flathead are needed to separate it from the old harness.  The distributor cap and plug...  The distributor cap and plug wires are removed, and neither will be reused. Good riddance! The rest of the distributor is left in place for the moment, it will be necessary to install the new one in the same orientation (cam sensor position). Tip: to save money, you can easily reuse your plug wires, though, by shortening them and installing MSD (PN 3304) coil boots and terminals.  The wiring harness is modeled...  The wiring harness is modeled after the stock piece, in terms of location and how it is routed in the engine bay, and uses only high quality connectors and wiring as well as plenty of loom for protection. With prices starting at $1,500; EFI Connection will include an LS1 PCM as well as all of the other supporting components needed to complete the conversion (coils, coil harness, timing cover, reluctor wheel, distributor, etc). There is also a slick new electronic throttle version that runs about a $1,000 more.  The new harness is laid out...  The new harness is laid out on top of the motor loosely at first then the crew starts plugging in the injectors, charcoal canister purge, etc. Byron chose to go with a MAF-based custom operating system for better driveability (though EFI Connection recommended Speed Density in this application for ease of tuning and less intake restriction), a few wires had to be cut, stripped, and threaded into a connector once the MAF sensor location was established.  EFI Connection sells these...  EFI Connection sells these LS2 coils as part of its kit, along with these slick coil brackets designed to fit a variety of valve covers, which are compact and produce ample output. This makes for a very neat and tidy mounting solution that keeps the coils close to the plugs for a better spark.  Using the supplied (longer)...  Using the supplied (longer) valve cover bolts, the brackets bolt right on without any interference to the fill cap.  One down side is that you...  One down side is that you will have to cut your own plug wires, though you may find an off-the-shelf LS wire is sufficient. Mike opted for MSD's 8.5mm Super Conductors.  This aluminum Vortec distributor...  This aluminum Vortec distributor with sealed cap has a built-in 1x cam sensor,...  ...which is also essential...  ...which is also essential to running the LS1 PCM.  The LS1 PCM is plugged into...  The LS1 PCM is plugged into the new harness, which will be mounted in the passenger footwell like the previous computer.  Surprisingly, very little...  Surprisingly, very little is required to satisfy the stock gauge cluster:  a few wires were spliced into...  a few wires were spliced into the vehicle speed module for the speedometer, which runs to the PCM, and a Dakota Digital signal converter box was used for the tachometer.  The best part of the conversion...  The best part of the conversion is that you now have an OBD II connector under the dash, which you can connect your laptop to for datalogging, tuning, and diagnostics.  Two heated four-wire O2 sensors...  Two heated four-wire O2 sensors are required with the LS1 PCM for closed loop operation, so if you haven't already upgraded from the standard single wires, you better factor in another hundred bucks for a set of quality sensors.  The knock sensor will also...  The knock sensor will also have to be replaced with one compatible with the LS1 PCM such as the '96-97 LT1 or '96-02 Vortec truck unit. Some may require two knock sensors, in this application we only used one.  Since Byron was interested...  Since Byron was interested in possibly upgrading from his current 700-R4 to a 4L60E to better take advantage of the PCM's capabilities, and rid himself of the scourge of GM's overdrive transmissions, EFI Connection provided a harness with the necessary plug, which for the time being will go unused.  Topside, the engine bay was...  Topside, the engine bay was tidied up and a Z06 MAF was clamped to the homemade cold-air intake and plugged in.  A base tune was uploaded using...  A base tune was uploaded using EFI Live software and Moates.net's Roadrunner LS1 Emulation hardware.  On our in-house Mustang chassis...  On our in-house Mustang chassis dyno the GTA baselined at 347 hp and 323 lb-ft of torque (on motor), which at the time was thought to be a bit low given the combo. When we strapped it down again, post-install, we found out why ... the tranny and/or converter were on the way out. Despite having more than 10 (yes, 10) less degrees of timing in it, the car was making near identical power before the trans gave out. But tuner Jamy Lippencott did get the idle down to 650 rpm without stalling, definitely a testament to the new PCM. He later raised it up to 800 rpm to get better vacuum to the braking system. We plan to get final numbers from Byron's GTA as soon as we get the trans situation squared away, and maybe even utilize that extra plug for the 4L60E, so stay tuned.
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Camaro ZL1 Morphs into “Freedom Fighter”
In a post-9/11 world, there are a multitude of organizations and individuals dedicated to helping veterans, both human and canine, adjust to life back home and aid with their health problems --...
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