Engine Air Intake

[Dolphon35]

We recently purchased a P30 Dolphin with a Rule 240 marine inline blower installed in the engine air intake line? Has anyone ever heard of this before?? It has the Banks Ram air intake and exhaust system installed. We drove it 5000 miles last year with no issues. I used the blower going up long hills and in the mountains. It appeared to help with a little extra power.

[LJowdy]

Several years back some enterprising person decided that putting a marine bilge pump in line with the engine intake throttle body would act as a 'cheap' Supercharger (or blower in the vernacular) In reality it caused some minor problems in that more air was introduced to the engine but no extra fuel was added which was needed to keep the proverbial 14.7 to 1 fuel air ratio thus, the engine was running lean.

My advice is to remove the bilge pump and forget you ever had it. Most of the 'claimed' improvement was mostly between the ears of the user.

[twinboat]

First thing you would need to know is if the CFM ( Cubic Foot per Minute ) of the blower is more then the CFM that the engine can suck in without it.

If it can't push more air in then the engine can draw in on its own, with the pedal to the floor, then its just in the way and not helping.

Once you let off the gas, and close the throttle plates, its just blowing against them. If more air goes past the throttle, you will let off the pedal more, to find the happy opening for your speed.

All of the air fuel mixing happens after the throttle, so blowing air in isn't going to change that, unless your blowing it in at full throttle and overwhelming the controls.

Having bilge blowers in all of my boats, I don't think they have enough CFM to make a difference in an engine intake.

Try taking it out, clearing the possable intake restriction, and run it. You may see better performance.

Did a bit of research.

The blower in question can flow 235 CFM of air.

A 5.0 Ford V8, stock, throttle body can flow 500 CFM.

Your engine is much larger and needs lots of air.

[LJowdy]

Twin boat, Yes, the fuel isn't introduced into the system until after the throttle plate however unless the system has been mapped to enrichen the fuel supply then the engine may run lean if more air is introduced.

[speed racer]

Not knowing what year it is I would assume it's not a mass air controlled fuel system. Saying that the fuel system is probably controlled by throttle position, RPM, And MAP sensor. In any case if the blower doesn't flow as much as the valve body it just becomes a restriction after a the RPMs get past the flow rate of the blower. and if you can turn it on and off in the off position it is a restriction at all times.

[Dolphon35]

Thank you for your responses. I was also thinking it would restrict the air flow especially with an idle fan blade. I fly little airplane's as a hobby and the propeller is like a big air brake if your engines not running and its not feathered. Parts on order to remove one Rule 240 marine inline blower.