Drop in Top speed

[Nmocean]

Over the winter I installed a hydromotive nose-cone on my bravo1 and a cfm carb spacer on my 454 I ran the boat friday I picked up about 150-200 rpm's but the boat slowed down about 4mph everything is the same prop etc. I can't believe a nose cone would slow the boat down and the rpm's come up. What gives? Also. the boat is very loose at top speed but it seems to carry the bow more, the boat feels faster but according to gps it is not

[VDRIVERACING]

Possible the nose cone is causing prop cavitation?

[jmherbert]

For what its worth, I've always heard that above 80mph a nosecone helps. below that it hurts. Something to do with the flow behavior of water at 80 mph changes from laminar to turbulent.
Unfortunately, my boat doesn't come close to 80mph, so I have no direct experience with this. Just passing on info I've seen others post.

[DMOORE]

Adding a nose cone can really change the hydrodynamics of your drive. This can cause a host of other changes as you can see. It could be causing more prop slip than before. You may have to experiment with props once again. BTW what boat and prop are you running.
Darrell.

[Nmocean]

I am running a 93 wellcraft nova spyder 454-420; When I talked to Hydromotive in the fall I was running 66mph and they told me it might help that it would be close I am also running a labbed bravo 1 prop 24 I have run a 23 pitch mirage last year the boat ran 62mph. I am going to go today since the weather is good and get a good test on this.

[cfm]

What are the exact mph before and after ? RPM before and after ? Note any differences in fuel, weather, water conditions. Notice any difference in trim vs ride attitude ?
Which spacer and what engine - especially intake manifold and carb ?
Who's that CFM guy ? LOL.

[Nmocean]

I am running a eldelbrock performer rpm air-gap and a 1 inch spacer my trim settings are the same at full trim the engine will now turn 5300rpm (no rooster tail) speed is 64.1gps if I trim down a tick motor will drop to 5200 speed will pick-up 65.6. Water conditions and temps were about the same as last year. My motor has picked up my prop slippage has had to increase due to the nose cone. Maybe some prop tuning I might be able to run a little more prop and get a little more speed. The boat with the nose cone does carry the bow more.