This is what your completed engine could look like. We took the time to make some billet inserts for our valve covers and paint the engine a nice shade of sinister-looking gloss black.
For those just joining the fray, we are knee-deep in the teardown of a GTP and are looking to increase horsepower to 400 at the flywheel by installing a set of Thrasher heads that flow 211 cfm on the intake side, and 182 cfm on the exhaust side, and a bumpy Comp Cams stick featuring .520/.536 lift with 1.6:1 roller rockers, duration of 212/224 at .050 and a lobe separation angle of 116. The Other Guys Performance headers with 1 5/8-inch primary tubes will also be installed and topping it all off will be custom programming to make the most of the new parts.
So read along as we plod through the nuts and bolts of this top-end buildup. In our next installment, we'll tackle dyno tuning and making this engine live in a restrictive OBD2 environment.
PARTS LIST Component Part Number Thrasher Engineered Performance ported/polished heads N/A Comp Cams camshaft "X-P Hot Cam" 76-000-9 3312S/3314S HR116+2 Comp Cams LS1 valve springs (105 lbs.) 26915-12 Comp Cams steel LS1 valve spring retainers (12 needed) 744-1 Comp Cams chromemoly pushrods 7937-12 The Other Guys L67 FWD headers 380021 Front cover gasket GM P/N 12539092 Supercharger gasket GM P/N 24503911 Balancer to crankshaft bolt GM P/N 24504736 Cam to sprocket bolt GM P/N 24501366 Upper head bolts (8 needed) GM P/N 25533811 Lower head bolts (8 needed) GM P/N 25527831 Head gasket set GM P/N 12539091 Rocker arm bolts (12 needed) GM P/N 24503515 GM Assembly Lubricant GM P/N 1052367Special thanks to Tim Cole from Comp Cams, Bob Weiland from Motorsports Performance and last but certainly not least, Duane Dodson from The Other Guys Products.
