Are you sure your not over trimming? What do you have to determine you trim angle? If you were running a 23 before gear change, a 24 or 26 bravo one should do the job if nothing else was changed.

something else is wrong. That is a heavy boat but with the prop that deep - NO WAY - is the prop blowing out. I ran a Bravo to the mid 80's without a nose cone and never had any blowout. With the drive ratio change your not spinning the prop as fast as you were before. On your boat that should not change anything except engine RPM. Something is slipping and it isn't the prop.

I had a problem with my prop blowing out very bad. It turned out it was from a halo style drive shower which has the water pick ups on both sides. One side was pushing water and the other side was sucking air down to the prop when rotating. Switched to a single pick up drive shower and problem was solved. Also make sure the pick up is located on the same side as the direction of which the prop is turning. Hope this makes sense. Jeff Wurl

Jwurl - was it blowing out at speed or just getting on plane. He is saying it is blowing out at speed. I wouldn't think that anything mounted behind and above the prop would have any effect at 4000 RPM.

Is it the early style bravo lower with the drain plug on the side of the bullet?

The drive is a '98 with low water pickups only. I do have a drive shower, it's an Eddie Marine style with a single pickup on the LH of the drive (opposite direction of prop rotation).

It's possible that I'm over trimming, at least with the Rev 4. The Bravo runs fine, just too much slip to get back to the 70s. I have been thinking about a Hydro P5X.

At 6.5" prop depth the last thing you need is a 5 blade. I don't even consider one until 3" or less from the bottom

I am running a 4 blade BRAVO at 1 inch above the lowest point of the hull and I am not blowing out at speed. He is probably over trimming because the prop is so deep. Is the bow of your boat bouncing up and down just before it blows out?

No, it runs straight as an arrow. I'm stumped as to why the 3 blades blow out if my prop is buried, I would think everything would have no problem hooking up.

Did you have this drive shower on the drive with the 1:36 gears ? If so, you you absolutely positive the pick up is in same exact position ?