Water and Air temps impact on speed

[mach351]

I noticed big differences on top end as a result of different outside Air and Water temps, sometimes up to 4mph - I know 2 stroke motors are really affected, but this much? What are your experiences?

[spanky2002]

cold water has nothing to do with performance improvement, it's all in the air. colder air has more oxygen thus stronger burn. there is a table where you can punch in air temp, humidity%, and barametric pressure and it gives you a % of your engine's performance. i think the ideal conditions for a motor to run 100% of it's potential is 75 degrees with 75% humidity and 29-30mb of barametric pressure. 35 degrees and 31mb of pressure will give you about a 10% increase.

[H2OPERF]

Thats true but cold water allways has a layer of cooler dense air, depending on wind and how far you are from the shore it will be well below outside air temps.The same is true down here in miami where we have 85+ deg. water in the summer it allways drives up air temp along the coast especially at night.Run down here with 95+ deg air and 87deg water and your performance sucks.Dave

[Ray Neudecker]

The air density can make a difference of up to 3/10 second in a quarter. We carry a guage to help with set up at the races. The big boys have a computer program just for judging this. I have seen reports of as high as 20 percent loss of power in a two stroke because of air conditions. Listen in during the middle of the summer when the Bass boater wants to know what is wrong with his motor that he bought new in the spring and has lost 4-5 Mph during the hot humid weather.

[BarryStrawn]

Read this

http://kinsler.com/56pg_hand_HTMLs/pg39_H.htm

http://kinsler.com/56pg_hand_HTMLs/pg40_H.htm

[jrpromax]

http://wahiduddin.net/calc/calc_hp_abs.htm