Posts Tagged ‘Comp Cams’

Motor Progress

Tuesday, September 1st, 2009

Today I stopped by CLC Auto Machine in Lynchburg VA to see the progress on my Pontiac 400. The majority of the machine work is already done. The cylinders were bored .030″ over and honed. Mains were aligned and valve seats cut for 2.11″/1.77″ valves instead of the stock 1.96″/1.66″ valves. Valves will be replaced with new stainless valves and the crank is to be balanced. I ordered a roller cam that I’ll drop off by the shop next week. The cam is Comp Cams roller XR276HR-10 ordered from Summit. Duration is 224/230 at 0.050″ and total lift is .502/.510. Combustion chambers in the head measure in at 75cc and piston to deck height will be 0.020″ to bring the compression to around 9.5:1. The motor should be ready to be picked up in about two weeks.

Dyno Software

Friday, December 19th, 2008

Today I finished experimenting with engine, cam, and intake combinations.  I bought some software from Ebay that I saw featured on Horsepower TV on the Spike channel.  The software is called Desktop Dyno 2000.  It allows the user to select from a variety of engines including Pontiac, big block, and small block Chevy’s.  It has factory bore and stroke combinations built in but allows adjustments in both.  Once an engine is selected, the user can manually input compression ratio or allow the software to calculate based on bore, stroke, gasket thickness, cylinder head volume, and pistion setup.  Other inputs include headers, exhaust manifolds, carburetor size, and cam configurations.

The hosts of the show tested some import that I don’t remember, but what I do remember is how accurate the software was when compared to the actual dyno results.  The software was suprisingly cheap, around $20, as it was an old version.  The calculations in the old software haven’t changed and are based on laws of physics that will always be the same so spending the extra $70 is pointless.  I’m sure there are new features and better user interfaces, but for me this software works fine.  The beauty of this software is that you can try out experimental combinations without costly and time consuming component swaps which previously have been cumbersome trial and error in the abscense of a personal dyno at your fingertips.