Part 2
In last month's installment, Texas Speed and Performance (TSP) used a brand-new GM L92/LS3 block as the foundation to build a high-performance 418ci stroker engine. Sunset Racecraft in Lubbock, Texas, bored the block to 4.080 inches (4.065 is stock) and stuffed it full of such heavy-duty components as a custom Eagle 4.00-inch stroker crankshaft, Eagle connecting rods, and Diamond Racing pistons. TSP then completed the engine build with its own Texas Speed/Precision Race Components (PRC)-prepped cylinder heads and accessories.Because a stock '01 LS1 computer...
Because a stock '01 LS1 computer and Superior Harness wiring harness were used for testing, the fly-by-wire 90mm LS2 throttle body was replaced with a Precision Tool and Machine (PTM) 92mm cable-driven unit. Although rated at 92mm, this throttle body mates to the L76's 90mm intake opening as well as to the FAST LSX 92mm piece.
Dyno Results
With our 418 fully assembled and ready to rock, Sunset's techs strapped it down on the shop's Dynamic Test Systems, Inc. (DTS) model 4000G engine dyno for a series of pulls. The engine was tested in three different configurations: with stock heads and a mild Comp hydraulic roller cam, with the TSP/PRC heads and the same cam, and, finally, with the TSP/PRC heads and a more aggressive Comp grind.
Baseline numbers checked in at an outstanding 608 hp at 6,300 rpm and 561 lb-ft of torque at 5,200 rpm. Torque exceeded 500 lb-ft from 4,100 to 6,300 rpm, while average power and torque (measured from 4,000 to the 6,500-rpm redline) checked in at 531.5 and 532, respectively. It's clear that even in its least radical form, the TSP 418 is a serious performer across the rev range.
Baseline testing was conducted...
Baseline testing was conducted with an SLP 85mm MAF designed for the '01-'02 F-body. The factory 85mm MAF from an LS2/LS3 Corvette would have worked just as well.
The final test involved swapping out the baseline Comp cam for a hotter stick and installing one of TSP's own 100mm MAFs. The end result was a towering 641.2 hp at 6,400 rpm and 578.5 lb-ft of torque at 5,200. Average hp and torque rose by 6.6 and 6.3, respectively, while the peak numbers jumped by 10.9 and 8.0. Although the peak and average gains were modest, the larger cam and higher-flowing MAF added both power and torque from 4,900 rpm all the way to the redline without sacrificing on the low end.
(From left) Trevor Doelling,...
(From left) Trevor Doelling, Joseph Potak, and Jason Mangum of TSP work to complete the wiring, throttle-body cable, and coolant system in preparation for the first dyno pull.
According to Doelling, "The redesign of the Gen IV block from the LS2 into the larger-bore L92/LS3 allowed builders to offer stroker engine packages of up to 427 cubic inches without resorting to expensive cylinder liners and machine work. It's now possible to sell a top-quality 418 or 427 short-block or long-block at a budget price. Since enthusiasts have their choice of cams, we can work with them to build L92/LS3 packages that offer anywhere from 500 to 675 hp, depending on their intended use."For owners looking to make even more power, both engines are rated to take up to a 200hp shot of nitrous. Custom pistons are available to take the compression from 11.1:1 down to 8.5:1, allowing a forced-induction 418 to achieve over 1,000 hp. In fact, other than the camshaft and dished pistons, our twin-turbo street car-which makes 1,063 horses at the rear wheels-uses all the same components as this build. That shows just how robust and powerful the package is."