Any benifits to drilling a bravo one to lower time to plane out?
 

292's are dogs out of the hole. This is where you miss the torque of a big block but as soon as she gets on plane it's great ride and acceleration. Has anyone ever drilled vent holes in the props of one of these applications with through hull exhaust? In theory the vents would give it some slip like a loose torque converter to get it up in the rpm band where it make more power. Once up on plane the vents don't do much at all. Anyone tried this?

I had a revolution 4 that had the adjustable vents on a different hull that responded well to it.

With the thru hull exhaust I doubt you'd see much benefit.

That's what I thought with the other boat but with the vent plugs pulled it had considerable slip on take off. Same set up with through hull. I would just pull the plugs if it was that easy but the bravos don't have the vent system like the revolution 4 has

there is different versions of the mercury bravo 1 props have vent holes
lower hp/ heavy hull boat set ups do benifet from them

If you have just thru hull exhaust and not silent choice that goes thru the prop hub, check to see if the exhaust bellows (attached to bell housing, lift drive to trailer position to see it) has been removed, it is not needed with just thru hull exhaust and it is only held on with 1 hose clamp, 5 minute job to remove. It made a big difference in one of my boats. http://www.mercstuff.com/exhaustbellows.htm 2nd pic in link.

COOPS

Do you have 28" or 26"

I have 26" and dont have much issue getting on plane, still not a rocket but much better than the owners with the 28's say. I do bang my limiters hard and can only touch 70 in perfect conditions.
I have the 350 mags.

The 28's from formula were the lab finished props from merc.

The drives don't have the bellows

28's yeah I know 26's would be better but I am stubborn in liking the 74mph I am seeing now top end.

Just thought I would ask around and see if anyone has tried this before since this and hydraulic steering are the biggest complaints on the 292. I bought an imco system this weekend so 1 ish down one to go.

I love the boat but always want to tinker to make it better

Hey Loose,,, whats your prop shaft height

We can install a Mercury PVS system or un-closable vent holes of any size. Or, best case, our CAP (Controlled Aeration Port) system.
Our CAP system uses much more manageable hard rubber plugs with a larger 7/8" hole.
And yes, even with through transom exhaust, venting the propellers does make a difference.
Call me anytime and I'll explain the differences and options you can choose from.

Brett

Have you ever had a customer try this with a 292 with any success?

You really don't have much to lose, if you don't like them just plug them.

I believe we have but I can't tell you the exact customer.

The physics of the operation are sound on any application. If you need to vent the propeller to get on plane, put in the largest adjustable holes you can.
BBLADES CAP system.

Brett

What ever formula installed. Rather high.

Brett,
I have a 29 Scarab twin 383's 400hp/420tq tuned & dyno by Full Throttle Marine. I have pulled the Y-pipe off and blocked with plate. The exhaust bellows on Bravo's are still in place. Do you think I should take them off or have holes drilled like you said for Cap System

OK Thanks loose

Trying the CAP system is a obvious choice since the holes can be adjusted.
I would start with the wide open 7/8" hole to determine the amount of venting you get. You can always down size the holes with the plugs as needed.
Here is a link to our CAP system offering.

http://bblades.com/vent-holes-pvs-system-installation/

Let us know if we can help.

Brett

Anyone ever try to vent bravo drive like a #6?

Just thinking outside the box.