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.
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.