Offshoreonly.com - 540 BBC Cam specs for water Reversion

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Quote:

Originally Posted by Tartilla (Post 4947266)

It's a factor of overlap. Duration and LSA. Also a factor of exhaust tubing dia...as well as intake port velocity.

Arcticfriends has the answer...mufflers.

Just a factor here, generally, you need 2.2cfm of exhaust airflow per 1 HP, IOT have unrestricted exhaust flow. If you have less...it just restricts it a bit until you develop sufficient backpressure to generate pumping losses that can't be ignored.

Mufflers would be a cleaner solution. Some can bolt on outside, under a swim grid...that is not really seen anyway.

Thank you. This still does not answer my original Question. I understand mufflers are an option but i would like to go from quiet to full open from a switch. If there is a cam in mind that you can suggest that is capable, please let me know. I am essentially looking for an engine builder to chime in that has done these setups before. Looking for a concrete answer. maybe my cams are fine?

Quote:

Originally Posted by articfriends (Post 4947167)

I personally think you WILL have reversion with that cam and water backing up from captains call going thru the prop. What about just adding mufflers? I had 5" tails on my Baja with water added at tips, hearing damage loud. I ran ggb mufflers then lost ine and put cheap Gibsons on. They looked extremely restrictive but boat really didnt loose any speed. Ran 99.5 with smallest pulley with them off and maybeb98.2 w then on fwiw

i have a 556 running dry to the tip exhausts, where i dump just a little water in. I am running gil switchable mufflers and i had some guys at the marina tell me last week how good the boat sounded.

I’ve also noticed that at 2900rpm, the motor pics up 100rpm if I close the mufflers. I also have external
dumps putting water on to the outside of the mufflers to
keep things cool.