403 rwhp LS1 using exh manifolds

[Atilla the Fun]

I found this on LS1Tech, but I feel it belongs here in case anyone ever wants to build an LSx Fiero using these exhaust manifolds, now that I've shown how excellent they fit. This was a '99 Z28. I assume it had the manual trans and synthetic lubes in the trans and axle. It baselined 332 rwhp at 5400 rpm and 347 rwtq at 4300 rpm. First, they kept the stock air box, which caused 7 kpa of vacuum at full throttle at the 403 rwhp level. I assume it was the "SS" version. Anyway, the build includes #243 heads, (which may have been on for the rather strong baseline) an LS6 intake, (same possibility) COMP 26918 valvesprings, and a cam from Geoff at Engine Power Systems. The cam specs are 218/230 int/exh dur at 50, 115 lobe sep, ground 4 deg adv and lift of .595/.600" This gave 403 rwhp at 5900 rpm, and 392 rwtq. It was said to be good to 6600 rpm, with no sewing machine noise like most other LSx cams. So, we don't need headers to get good results. Well, when corrected to sea level. Up here, this would have shown 330.5 rwhp. lame.

[Aaron]

With headers, welcome 440rwhp!

That is a relatively strong stock baseline for a 99-00, but the newer models (02s specifically), routinely lay down 330+ if they have the LS6 intake and SS options. Although I haven't thrown our's on a dyno, I'm positive it'd beat 330. I'll run it next time they have a dyno day (3 runs $50). The LS1 is no slouch, I've taken down some numerically superior cars:

LS2 Corvette Auto (400hp)
2010 Camaro SS 6-speed
2001 Cobra 6-speed

[Honest Don]

218 duration and .595" lift? That's gotta be an agressive ramp..



Those 918's aren't going to live very long