The time had finally arrived when GMHTP and RaceKrafters Automotive Machine Inc. were able to get back to work on our project TPI 355. As mentioned in our update on the series that ran in the January 2006 issue of the magazine, even though metal shavings were not flying, we were busy at work lining up the additional services of cryogenic processing and coatings to our research exercise.
In the update we touched on a problem that we discovered with the cam that we had chosen. In reality the camshaft supplied by COMP Cams, a roller hydraulic grind, was made to perfection and the bad readings we received from the Cam Pro Plus was from a batch of faulty stands that were production out-sourced by Audie Technology. Company owner Audie Thomas worked feverishly to determine his supplier had machined error into the cam holding stand and the problem was not with the manufacturer's cam grinding machine. As a matter of fact, the COMP Cams bump stick was made to such exacting standards that it looked as if it were custom produced for a NASCAR team, not an off-the-shelf part! COMP Cams has invested heavily not only in research and development to create the most efficient valve events, but also in advanced manufacturing processes and quality control. We are excited about the contribution this camshaft will make toward reaching our performance goal and thank COMP Cams for its effort.
The Probe Inc. forged piston and the Manley connecting rods were also masterpieces of quality and engineering. The piston is very light and features metric ring grooves for the lower-than-standard friction rings we wanted to use. Likewise, the Manley connecting rods just dripped of quality and not only measured exactly to standard, but were also light and strong. When held in the palm of your hand, both the pistons and connecting rods had the feeling of quality. There is an intangibility to quality that cannot be measured, but can be felt and seen. The Manley and Probe products definitely posses that attribute.
Bob and Craig Wise worked alongside the author during the machining steps that were used to prepare our engine. The most common mistake made by enthusiasts is that he or she does not understand the necessity for quality machine work and its impact on the end result. The machining is not only the result of the equipment employed, but more often the skill, finesse, and edict of the operator. I know with certainty that at the end of this series when all is said and done, a number of readers will try to duplicate our results with a local machine shop that may be very good, but is geared both physically and mentally toward general rebuilding. Or as we like to say in the industry, taxi cab-style work. The attention to detail that RaceKrafters gives to a project such as ours is the intangible difference that not only produces the extra horsepower, but makes the engine run better, smoother and longer. Engine machine work is akin to brain surgery. There is no place to save money or eliminate a step.
Since it is very hard to capture the true dynamics of proper machining procedure with still photos, extended captions will be used as we tell the story of how our little 355 is coming together. As was stated in Part I, not many street TPI engines are built to the standard that GMHTP and RaceKrafters Automotive Machine are establishing on these pages. We hope this series starts a Tuned Port revolution!
Extensive flow testing of...
Extensive flow testing of the cylinder head was performed by Bob Wise on the shop's computer-controlled bench. Bob is very intimate with the Vortec design, but likes to document the flow on each cylinder so any manufacturing deficiencies can be corrected. Without the final valve job, the "roughed-in" ports flowed 265 cfm and 185 cfm, intake and exhaust, respectively. This was at 28 inches of water, 0.500-inch lift, and with a radius inlet. That is approximately 35 cfm to 40 cfm better than stock. A complete flow sheet will be published as part of our next installment.
The cylinder head was then...
The cylinder head was then flow tested with the induction track attached to document flow loss. When completed, Bob did some minor hand porting and scribed the gasket openings on the intake base and runner in preparation for shipment to Extrude-Hone for abrasive flow media porting. Once the parts return from Extrude-Hone, the improvement in air volume will be measured on the flowbench.
The Manley stainless steel...
The Manley stainless steel valves were dressed to the desired angles on a traditional Kwick-Way valve resurfacer.
Bob spent many hours re-contouring...
Bob spent many hours re-contouring the bowl and combustion chambers of the Vortec casting. Much attention was paid to increase low-lift flow on both the intake and exhaust ports. The combustion chamber work was centered on increasing median burn velocity without disturbing the high level of mixture motion, and thus, octane tolerance the Vortec head is known for.
While "sneaking up" on the...
While "sneaking up" on the desired results, the cylinder head constantly goes from the head shop (used to cut the angles into the valve seat), the porting bench, and the flowbench. This is the difference in building an engine like a race motor or just grinding in the ports.
While "sneaking up" on the...
While "sneaking up" on the desired results, the cylinder head constantly goes from the head shop (used to cut the angles into the valve seat), the porting bench, and the flowbench. This is the difference in building an engine like a race motor or just grinding in the ports.