Read this on the Rockbottom Designs facebook page (Air Intake)

[rocketmanjp]

The statement the OP pasted only mentions the 450R and it has been stated and tested that additional air does help the 450R quite a bit. It has been stated and tested that additional air does not help any of the other naturally asperated V-8’s.

[weevil]

Can 100 percent confirm it don't do anything that's noticeable other than more noise for 250proxs or 300r motors ( 50 rpm changes are hard to Cypher if the scoop did it or if it was condition changes) but there was absolutely not 200 or 400 and definatly not 600 rpm changes. These were test on a low 70's mph bass rig and a high 90's mph bass rig..
Close to what Don talked about in earlier post steve Williams has on YouTube about the intake from the mercury apex 360. Those boats run a 12-16 inch cowl induction plumbed to the sealed carbon fiber motor cowl via a 5 inch flex line. He says it was good for an additional 15 hp.. so keep that intake size and the fact F1 boats run 140mph and there cowls are sealed what it takes to make 15hp.

[Cbprov]

Too bad ,$1400 for more noise ,what about the venom vents ,snake oil too?? https://www.google.com/url?sa=t&sour...-E0z9zm57BlyD3

[weevil]

Never ran them but the guys at fastbass marine have. I think on a 90+ mph rig they think there was roughly 1mph gain on non supercharged motor (300r I think)

[Tim Powell]

Never ran them but the guys at fastbass marine have. I think on a 90+ mph rig they think there was roughly 1mph gain on non supercharged motor (300r I think)

250PXS, 250R, and 300R - Cowl on, service door removed = 1 mph and 100 rpm gain when compared to cowl on, service door closed. We have proven this on multiple 90-100 mph boats.

250PXS, 250R, and 300R - Cowl with Venom Vents Installed = 1 mph and 100 rpm gain when compared to stock cowl. Again ran this on multiple 90-100 mph boats.

LCB w/ 450R - Cowl with Venom Vents Installed = 6 mph and 400 rpm gain when compared to a stock cowl. This was done on back to back runs, same prop, same load, same propshaft height, same trim level, same conditions, same driver, propped to not hit the limiter. The venom vent cowl also out accelerated the stock cowl by 17 seconds and 2,359ft on 5-100 mph pulls. I think the biggest advantage on this hull was providing cleaner air to the engine with less water vapor running up the back of the cowl.



Ive been running a Venom Vent cowl on my Allison 450R, biggest improvement that I have noticed is the sound. The super charger gets to screaming quite nicely. However I will eventually do a comparison test on this boat but the issue is getting it over propped to not find the limiter . Steve Bishop did a great job on the design of the venom vent, they do have the most aesthetically pleasing appearance.


As for Da Skoopz, I can see it helping if the hull runs dirty and allows cleaner drier air into the engine but the claims are pretty wild versus what we have seen in testing. We would gladly give an independent test if Mr Keyes would like to provide a test scoop.

[EuropeanAM]

Tim- Thanks for sharing that. Here's an interesting observation or two:

-The 250's and 300's that are gaining 1mph and 100 RPM's would be running props that are right at 10% prop slip. Would that be a normal or target setup on these boats given today's wide-array of props?

-The 450's numbers (no doubt or argument there WOULD be a difference) are actually skewed because you would have to properly prop the boat for the CURRENT RUNNING engine configuration, then simulate as close to the same prop type and slip coefficient with the "scoop".

Running an engine 400 RPM's (3-5 pitch points) over-propped in one configuration is by no means a fair/scientific comparison, as it's simply not achieving it's full potential AT that configuration.

Be very interesting to see that 450 propped for the very top of it's RPM range, 10% or less slip under each of those configurations. THAT would be a true performance model.

[Tim Powell]

Tim- Thanks for sharing that. Here's an interesting observation or two:

-The 250's and 300's that are gaining 1mph and 100 RPM's would be running props that are right at 10% prop slip. Would that be a normal or target setup on these boats given today's wide-array of props?

-The 450's numbers (no doubt or argument there WOULD be a difference) are actually skewed because you would have to properly prop the boat for the CURRENT RUNNING engine configuration, then simulate as close to the same prop type and slip coefficient with the "scoop".

Running an engine 400 RPM's (3-5 pitch points) over-propped in one configuration is by no means a fair/scientific comparison, as it's simply not achieving it's full potential AT that configuration.

Be very interesting to see that 450 propped for the very top of it's RPM range, 10% or less slip under each of those configurations. THAT would be a true performance model.

Basically we are finding a prop that wont hit the limiter with the stock cowl, from there swapping the cowls on back to back runs.

For instance a Blazer 625 300R ran 96.5 mph @ 6200 RPM with a 31p prop. It was topped out and there was nothing left to gain. We swapped cowls and it ran 97.5 mph @ 6300 RPM. Same with an Allison, 32p wheel at 102 MPH at 6200 ran 103 MPH at 6300 RPM

The LCB/450R went to the moon at 115.xx MPH at 6400++ with a venom vent cowl.


We can prop to make either cowl run right at or on the limiter but we were able to keep a controlled environment by taking a setup that would not hit the limiter with a stock cowl and then push it to the limiter with a cowl swap. The ability to turn a bigger wheel more RPM will always be faster

[EuropeanAM]

Yes it will. If you're ever messing with that again on a blown model, would be very interesting to see with it propped peak-performance both with and without (can still back-to-back since it's cowl and prop change).

That would give a real-world measure.

[Tim Powell]

Yes it will. If you're ever messing with that again on a blown model, would be very interesting to see with it propped peak-performance both with and without (can still back-to-back since it's cowl and prop change).

That would give a real-world measure.

Its a struggle to find conditions that allow you to hit limiter on my Allison with the 450 Stock cowl with a 31p it is on the limiter at 110 loaded to fish. A 28p will run 100.1 at 6550 before it pulls it back.

[EuropeanAM]

Y'all must have some really fast fish up there! That's booking it.

[River Rocket]

We have wicked fast bass up here in the north. They have to be to beat the cold.... LOL

As Tim said, it is a struggle testing these things. It took me days and days of testing on the LCB 450R boat to get this captured on video. Same with the cowl and no cowl test on the Allison 300R. These boats are fast, and getting all the water variables out of the equation isn't easy. Then add in the speed the tests are run at and what the boat is capable of, you have to really work at it. I had to slow the LCB down to run this test. As you pointed out, perhaps too much, but on the flip side the venom vent cowl was just under the limiter. Changing props changes how the boat is carried so you have to account for that as well. As you know, when you are at the limiter mother merc takes over. After you hit the limiter and with no computer hooked up you don't really know what you are getting out of the motor. I really wish merc put that out for a gauge to read.

The 32 on that boat was all over the limiter and no props are awesome out of the box. They take months to get right. I had a 34 I was working on but sold the boat before I got it perfect. For this test, I added a windshield, 50 gallons of gas, and all the tackle I could find to bog the boat down off the limiter. This boat ran 111 with this prop, so you can see I had to load it way up and put a wind sail on it to slow it down. Then run the test. By just changing the cowl the boat clawed back a considerable amount of speed.

I loved the LCB for testing. It eliminated some of the risk of high speed testing. It was locked in stable at from 110-115.

Same prop, 20 gallons of gas, and no windshield below.

[River Rocket]

I made my own scoop and will be testing soon now that the ice is out. I'm really interested in how the design differs or if it does. I did design mine different and modeled the air flow.

I say this on the video and Tim mentions it as well. To me, my boat goes fast enough. This really isn't to get more out of it. This was about the look the vents added and the sound they allow you to hear. On a 450R that is worth the price of admission alone. The motor sounds amazing.

[Tim Powell]

I say this on the video and Tim mentions it as well. To me, my boat goes fast enough. This really isn't to get more out of it. This was about the look the vents added and the sound they allow you to hear. On a 450R that is worth the price of admission alone. The motor sounds amazing.

Long live the supercharger!!