Ram air scoop for our cowlings that increase mph and rpm?

[zyphyon]

3B098123
2021 300r

Found this one a performance page on facebook that I am apart of. The designer of the part claims you'll gain 300-600 rpm and 2-6 MPH, he claims these engine cowlings do not have great airflow and by forcing more air into the cowling itself he is getting these results.

I for one am not about snake oil, so I asked a ton of questions and to my surprise many people that have installed one of these all claim it did exactly what is advertised even the folks over at doug wright powerboats chimed in and told me the same thing. What are everyone else's thoughts on air scoops or ram air for our outboards? Does anyone here have anything like this that can attest the similar results?
d

[mactlman]

looks cheap and aftermarket but might work ok?

[Robby Moser]

Looks to me like the 450s in the photo already have air scoops on either side of their respective cowlings. I would be concerned for the add on scoop in the bottom photo,as that is the access door to dipstick,oil fill,and cowling unlock lever.I wouldn't want that

door to come flying off.

[Capt James]

If you want to try something like this. Just remove the oil fill door, or the cowling itself and run the boat and see if you gain anything.

[mike464]

Here's another vent, I saw a test with them on a 450R, and showing an increase in speed and rpms. https://www.riverdavesplace.com/foru...-vents.232338/

[fly by night]

Interesting to say the least! Provide more feedback as you learn more information.

[fishnfireman]

Story as I understand --- it helps the 450R with super charger -- but not so much with the 300R.
There's a lot more professional looking one out there that River Racer has some good tests with.

[zyphyon]

Story as I understand --- it helps the 450R with super charger -- but not so much with the 300R.
There's a lot more professional looking one out there that River Racer has some good tests with.

One photo is of a Doug Wright boat, the other with the aluminum scoop is a 300r. A lot of the people that commented on my post on the page were either 300r's or the pro xs with a few 450r's mixed in but the majority were 300's.

[fishnfireman]

Check out Fastbass marine TV .
Geoff (River Racer) has some good data on some good looking vents.

[Fishshooter]

The real question is " has anyone tried this on a 250 ? " or are the intake systems completely different ?

[2dwoods]

How much mph you figure to pick up a 10th which is good if you race but not much fishing

[EuropeanAM]

A Supercharged Model could indeed potentially benefit from this as it's PCM programming is designed for MAP pressures in excess of ONE ATMOSPHERE.

Any others: PCM is not programmed for barometric pressure or manifold pressures that exceed 15 psi (technically 14.7).

That's going to create a very fine line at which the engine will run lean and very likely detonate. Additionally, the added air and pressure will likely induce emissions-related faults when the fuel trims are unable to bring O2 into proper parameters within the allowed "normal" range of trim.

Just because someone did it to a 450R doesn't mean that any other model will live: and before you start making this type of modification, be sure to review the Warranty EXCLUSIONS section of your Engine Owner's and Warranty Manuals for any "Modification of/to the product".

And of course- it is also illegal.

[Pulsare2020]

Looks to me like the 450s in the photo already have air scoops on either side of their respective cowlings. I would be concerned for the add on scoop in the bottom photo,as that is the access door to dipstick,oil fill,and cowling unlock lever.I wouldn't want that

door to come flying off.

I doubt you can pressurize the cowl much over atmospheric pressure with that tiny hoodscoop or even a large one at that. At 80 mph (117 ft/sec) if you do the math, you might gain 0.1 psi over atmosphere. Remember the velocity of the air going into the engine is higher than 117 ft/sec so if anything there might be a slight negative pressure (vacuum) in the cowl, which the scoop might reduce a bit. The cowl also has factory vents, so air will escape through those factory vents as you try to pressurize the cowl. Now the temperature in the cowl could be 30*F - 40*F above ambient? I am only guessing, to make a point, it would have to be measured. If the scoop could lower the air temperature by 20* - 30*F, that would result in a performance increase just like running your boat on a 60*F or an 80*F day.
At sea level the air pressure is 14.7 psi. At 1000 ft (I live on a lake that is close to 1000 ft) the pressure is 14.17 psi, so I think the ECM can take care of close to 0.6 psi less air pressure since that occurs to many of us in the summer and often much lower psi. Sometimes in the fall the baramoter is high and the temperature is low, which makes the air density the same as being at negative 1000 ft. (we called that "mineshaft" conditions when we were drag racing). At -1000 ft the air pressure is 15.24 psi or almost 0.5 psi higher than sea level. That happens to boaters up north often and I think the ECM takes care of that as well. Most 200 mph Pro Stock cars claim close to 0.4 - 0.5 psi increase in the hood scoop pressure over atmosphere at 200 mph. I have no idea of their is a vacuum in the cowl and if there is, how high it might be. If it is high and you eliminate it, perhaps that would be more than the ECM can handle? If you run the engine with no cowl, there is no vacuum around the throttle body intake, just perhaps behind it. I doubt running a cowl with a scoop can add more than 0.1 - 0.2 psi over having no cowl. I personally still would not do it for the reasons Don mentioned, but any performance increase I would think is more likely due to an intake air temperature reduction, rather than a "supercharger" effect as in pressurizing the cowl.

[zyphyon]

A Supercharged Model could indeed potentially benefit from this as it's PCM programming is designed for MAP pressures in excess of ONE ATMOSPHERE.

Any others: PCM is not programmed for barometric pressure or manifold pressures that exceed 15 psi (technically 14.7).

That's going to create a very fine line at which the engine will run lean and very likely detonate. Additionally, the added air and pressure will likely induce emissions-related faults when the fuel trims are unable to bring O2 into proper parameters within the allowed "normal" range of trim.

Just because someone did it to a 450R doesn't mean that any other model will live: and before you start making this type of modification, be sure to review the Warranty EXCLUSIONS section of your Engine Owner's and Warranty Manuals for any "Modification of/to the product".

And of course- it is also illegal.

He isn't forcing more air into the engine itself, he is just allowing more air into the cowling as it was explained to me to give the engine the ability to have access to more air.

[EuropeanAM]

He isn't forcing more air into the engine itself, he is just allowing more air into the cowling as it was explained to me to give the engine the ability to have access to more air.

If you're forcing it into the cowling, you're forcing it into the engine.

PulseAre2020: The factory air vents are covered in the above photo, and replaced with forward-facing slots with scoop in the center. Pretty sure that's not pulling a vacuum...

[Farmerman99]

The 250 needs something to make them run

[fishnfireman]

The 250 needs something to make them run

My 250R has a better hole shot and midrange than my old 300XS 2 stroke did on the same boat. Not to mention this 4 stroke gets better fuel mileage and no oil to mix.
Only place the 300 was better was top end and I think that was mainly due to it turned more rpm.
Not sure if it's just the R motor or the hull .. After hearing the early reports I was elated with the 250R...It's able to turn the same pitch props that the 300 did.

[Farmerman99]

Im having trouble getting mine to turn rpm, i installed wedges yesterday and that helped a bunch

[Welaka]

Im having trouble getting mine to turn rpm, i installed wedges yesterday and that helped a bunch

Not sure if it applies, but I have seen most running too much pitch on the new 4 strokes. Also seems like most boats are shipped with a pitch or 2 high.

[Farmerman99]

He isn't forcing more air into the engine itself, he is just allowing more air into the cowling as it was explained to me to give the engine the ability to have access to more air.

If tou pull the cowling it has on air inlet on the port side about 4” diameter, i know at 1550’ elevation these motors are dogs, they do need more air I believe