Measured with a scanner the inlet air temp while running. Around 113 degrees inlet. Ambient temp was 80. This was twin 575sci. Is 30 degree difference normal for boat?

You mean inlet, as in the air going into the flame arrestor?

I don't think the 575 runs an intercooler, right? I would say your numbers are normal. I run a 3.3 whipple with IC and my intake temps are low 90's. If I lean on it, I may see 100. Thats with 65 ish water temp (lake)

I'm not in the same class as most with OSO - we have a stock 7.4 mpi (2000)- but I know this for fact the cooler I can without doubt that the cooler I keep the air in the engine compartment the better speed I can get. WOT at 60 F I easily hit 63 mph (GPS) However, when this summer the air temps in the high 90's and warmer water- I was hard pressed to get into the high 50's. Now I'm not a performance boat owner - 226 Cobalt. But I wish there was some cheap easy way to "Really" lower the temps going into the air intake -- too bad dry ice is CO2-- a chunk in engine area for sure would cool the air!!

3pointstar

The IAT sensor is in the flame arrestor in the 575, so it's basically going to be reading the incoming ( to the throttle body)air temp.

Before I built my fresh air system, I measured engine compartment air temperature with a digital thermometer and a probe and it was 20-30* more than ambient air.

2 of these things are emanating 140-150* worth of heat in a confined space.

Before jumping the gun, are you having a problem with your 575's? If so, please explain.

jaay teee got any pics of the fresh air system you made?

no issues with engines. This is measured by the IAT. Just wanted to know what is normal for a performance boat without dual hood scoops in hatch.

yes. reading IAT with a renda scan tool

I don't have many pics, but Eddie took a few when he listed it
http://m.powerboatlistings.com/photographs/44770