Dyno Software

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.

I knew right away that I wanted to go with a roller cam setup since there has been many concerns about the lack of anti-wear additvies in modern motor oils than have been used in the past.  Apparently this is due to federal requirements that newer cars have to meet.  Modern catalytic coverters have to last around 120,000 miles up from 100,000 years ago.  The anti-wear additive is known as zinc dialkyl dithio phosphate (ZDDP), which contains phosphorous as well as zinc and manganese.   The phosphorous has been found to cause early catalytic coverter failure/loss of efficiency.  Modern cars with roller cams typically require far less of this additive than do flat tappet cams.  There is still ongoing debate on how much effect this has on a flat tappet engine, but I’d rather be safe than sorry while enjoying the benefits of the increased horsepower.  Roller cams are expensive as I’m sure most of you know, so there is an alternative.  A motor oil made by Shell called Rotella is supposed to include all of the additives needed for a flat tappet cam.  A good source that goes into far more detail about the additive problem than I do here can be found on the Hot Rod website.

The pictures below compare the theoretical dyno results at the flywheel between a single and dual plane intake.  Both results are with specs taken from Comp Cams’ Xtreme Energy XR276HR roller cam. The rest of the stats can be seen in each picture to the left of the window.  Also remember this is at the flywheel and not at the wheels.  To get hp & torque at the wheels, you would have to reduce these values by about 15 or 20% to account for frictional losses in bearings and gearing.

As you can see, the dual plane yields a broader curve and more low end torque which is usually a good thing.  Since the single plane Tomahawk intake (described in Nov 11 2008 post) requires no modification to the shaker scoop that’s the one I’ll use.  With the amount of ratio I have in the transmission and rear-end (which now I’m second guessing), a little less low end torque may be a good thing.  Accounting for loss of efficiency, with my single plane manifold I should peak out somewhere around 376hp @ 5000 rpm and 427ft-lbs @ 3500 rpm.

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