Does this prove David Vizard's 128 lsa formula ?

Thanks for posting,

I don't think this table is great evidence that tighter LSAs will makes more power or accelerate the car more quickly. This is because the testing was not done fairly. This is not uncommon. It is hard, time consuming, and costly to do so. This will generally not happen in an article for a magazine. Also, they usually over simplify for the largest audiance interest. The details they often leave out can important.

First, take any motor and increase the cranking pressure and it will make more power. To be a fair test, the compression ratio for the 110 LSA cam should have been increased to match the 180 psi.

Second, the average hp under the shift-to-shift recovery rpm is the most meaningful. In the table, we don't know what the lower rpm is for the average through 7000 rpm. It could be well below the shift recovery rpm. The hp below the shift recovery rpm will favor the smaller LSA cam and will increase the avgerage, but will not representative of WOT operating range.

Finally, calculating the average hp to only peak hp rpm will always favor the smaller LSA cam. Hp above the peak hp will generally favor the larger LSA cam. We need to see the hp data to at least 7600 rpm, maybe 8000 and determine the best average for the shift/shift recovery rpm range for each cam LSA.

I don't know what the results would be if these items were addressed in the testing, but the average hp would certainly be much closer between the the three LSAs.


What is interesting is the math I’m using for cam timing doesn’t ask for air flow or valve size.