Boat question

[Bill Sampson]

Just remember that once jetted for 5280 altitude if you drive it back to where you came from it will run very lean (maybe burn valves) unless you rejet before going.

I am keeping the jets in a separate location so I can reinstall them if I go to lower elevation. The engine is not smoking black from a rich condition, but has quite the hesitation when I go to full throttle. Thanks for all your suggestions and information regarding altitude.

 

[Bill Sampson]

Camaro?

Oops, so much for spell check.

 

[TR.]

Density is directly related to air pressure. Less air pressure affects carburetor performance. The following chart shows how elevation affects pressure.

View attachment 6204View attachment 6204

Just a thought, I believe that Latitude, seasonality and weather would affect this chart? Winter and low pressure front should make felt barometric pressure drop by over a thousand feet...not that it matters at all to a boat engine at that small change. My point is that while the chart is awesome and a good start, barometric pressure is not static, there are variables that impact it.

TR

 

[Cliff]

In the full computation for Density Altitude a computation for "Pressure Altitude" is input first before Density Altitude if finalized. Therefore changes in barometric pressure are accounted for in the full density altitude computation.

Don't conflate the Hg pressure of each of the altitudes that you show in your chart with "barometric pressure" . The pressures you show are generally refereed to as "density altitude" pressures under ideal conditions. Those "pressures" will vary with temp and barometric pressure to get the true Density altitude.

Latitude, in among itself, has no affect on Density Altitude.