1970 GM 350 Small-Block Engine - Clash of the Small Block Titans

The 1970 LT1 Takes On The 1996 LT-1 In A 350-Cube Throwdown

Richard Holdener Jun 8, 2010 0 Comment(s)
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Demon Engines supplied an 11.0:1-compression short-block consisting of a combination of a forged crank and rods from Pro Comp, along with a set of forged aluminum pistons from Probe Racing. These were used in conjunction with a set of 492 Fuelie heads featuring 64cc combustion chambers to produce the desired compression ratio. The 492 heads came from L&R Automotive and were treated to set of 2.02/1.60 valves from Pro Comp, along with minor surfacing and a factory-style valve job. We wanted the heads to represent what would have come from the factory back in 1970. They were treated to a set of valvesprings from Comp Cams, to ensure we could safely rev the motor to 6,000 rpm.

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Our reproduction LT-1 solid cam and lifters came from Elgin. We also sourced an original LT-1 aluminum high-rise intake, but topped the dual-plane manifold with a Holley 750 HP carburetor in lieu of an original (and very expensive) or reproduction 780 Holley. Both the LT-1 and LT1 were run with 13/4-inch headers, and both were optimized in terms of air/fuel and timing. The EFI LT1 was run with a FAST management system, while jetting and distributor advance took care of tuning on the LT-1. The LT1 was run with the factory water pump (meaning a slight drop in power from the parasitic loses associated with driving the pump), while the LT-1 could be run with an electric unit. Neither motor was run with an air filter of any kind.

Run on the engine dyno, the LT1 produced 350 hp at 5,700 rpm and 379 lb-ft of torque eat 3,800 rpm. This compares favorably with the factory rating of 300 hp and 340 lb-ft. Torque production exceeded 350 lb-ft from 2,600 rpm to 5,100 rpm, while the horsepower curve flattened out past 5,000 rpm. Despite a factory (gross) rating of 370 hp, the LT-1 produced almost exactly the same peak power as the LT1, with a peak of 353 hp at 5,600 rpm. In the torque department, the '70 LT-1 offered 292 lb-ft at 4,100 rpm, bettering the LT1 by as much as 13 lb-ft. Torque production from the LT-1 exceeded 350 lb-ft all the way up to 5,300 rpm, but like the LT1, power output from the LT-1 fell flat past 5,000 rpm. Given the wilder cam timing, this seems unusual, but it's hard to argue with the results of direct, back-to-back testing. Despite the sizable differences in rated output and more than 20 years of technology, the two LT small-blocks are more alike than different, at least in terms of power production. From the results of this test, it's obvious that the later LT1 carried on the tradition of performance offered by the original and can proudly wear the name.

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