How much can the heat & humidity rduce power on a blower motor?
 

I was out last weekend with 4 people, one extra large, full of fuel and boat ran up to 5300 rpm with 6.5 lbs of boost. Temp was low 80's and low humitidy. Went out yestarday 4 people, full fuel. Temp was mid to high 80's and high humidity. One motor ran up to 5000 rpm with >6lbs boost and the other at 4800 rpm with 3.5 lbs boost. Is this normal?

One hell of a lot...
I lost 7 mph last weekend.

I just got in from causing hate and discontent up and down the lake.:D
Pulled 7 lbs of boost and 5800 rpm`s both motors.

This boat seems to run the same every time out.

Kurt.:D

Fuel injected gets affected the lest , carb motors moderately and blowers the most. I did prop testing on my boat in 90 + degree weather and very humid. not to good of results. Between the water in the oil from the leek in the block and the weather I would say I was 60+ hp short at least.

Affects it big time. Three weeks ago ran the boat in the evening
62 degrees 60% humidty ran 108 on both gps. Next afternoon
less fuel 90 degrees 90% humidty 102 on the same flat water.
The Sterlings have so much cooling capacity that I never really
see any engine/oil temp. changes.

Early in year got to 102, now lucky to get to 94. I am fighting few issues. First is under cover temps, when air temp 91-98, undercover temps 125-130. Other issue is I do not think I have enought vents to get motor air. In the process of checking there items.

Hotboat is dead on. Blower guys get killed by the NA nitrous motors on hot humid days in drag racing.

Hey fauker......dont talk about my girlfriend like that.."extra large"
wait til I tell her what you said on the board about her :D

Actually I will have to assume you are talking about a mutual friend that does hilarious Tommy Boy impressions over the Nextel.

No disrespect to the GF. Yes, you know who I am talking about.

My cat running a blown 510 with 10# of boost would run an easy 105 mph in the winter and early spring at Havasu when it was cool. During the summer when the temps were 110-120 it was a 95 mph boat.

The new Cig with 500 efi's runs almost the same rpm and speed in the Havasu heat as it does in the Pacific ocean. It does not seem to be noticably effected.