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So, 93k original miles on the truck with near perfect compression. All I did was a new coil, wires, plugs, MPFI injectors, K&N drop in filter, and a true dual 2.5 inch cat back with Thrush Turbo Mufflers. Truck is a K2500 with a 4L80, and 14 bolt rear.
The end result, 183.7 hp on a Dynojet 248. The graph is pretty messed up cause you can't lock a gear with the 98 black box ECU, so the truck down shifts and then up shifts trashing the curve. Even so the dyno helped with cleaning up the tune with EFI-Live. The torque graph was useless but if you do the math it looks like it peaked in the 240-250 range based on the horsepower to rpm. You can really see how badly the stock intake and manifolds choked this as the rpm climb considering the horsepower curve is flat.
End of the day, I'm pretty happy with 183.7hp as a starting point considering lifted 1500 4x4 trucks with the early 5.3 are in the 200-220 range. Installing long tubes, a marine intake, and a small cam from comp. It will never make the power that my Suburban does but if it breaks into the 240-250hp range I'd be really happy with it for what it is.
been looking at 2 different grinds for this. Comp sells a series of torquey "4x4 Cams" as they call them for the 305-350 OE roller blocks. Figure that with a new set of lifters, pushrods, LS-Locks, and LS6 springs would be the extent of it. Unsure though which on to purchase between the smallest one or the 2nd smallest one.
2 concerns with the bigger one are whether or not the engine will have enough flow up top with the marine intake and headers, and secondly how tight the valve guides will be with the larger lift. No real experience with the old small blocks cause millennial problems.
I just don't want to play it save only to learn I could have gone bigger. Truck is basically a daily/highway-cruiser, but a little lope and solid 1st gear kick downs would make it more fun.
unless you are referring to the retainer to guide clearance at full lift....however in that case it should be retainer to seal clearance........right??? I'm a little confused.
06-22-2016, 04:32 AM
Dyno'd my 1998 Vortec 5.7
