Okay, I'm going to double post as this is getting no replies in the drive section.

I'm going to do some upgrading to my drives this spring and I'm looking to get some advise. As of now, I'm running the blunt nose bravos ('89) on my Formula 292 SR-1. I'm not experiencing any blowout yet but I know I'm at the limits of this drive. Currently I'm getting 71 mph GPS with my boat, and last summer I had it tuned VERY conservatively, so I am sure I can get a few more MPH this summer with a more aggressive tune. That said, I want to upgrade my lowers. I've been looking on this site for a couple years to see if anyone has installed -2 imcos on either a 292 or a 311. Lots of talk about it, but I can't find anyone that has done it. So with that said- does anyone know of anyone that has put -2 drives on one of these two boats or a similar hull?

Now with all that said- does anyone think I would see any improvement with a standard length IMCO vs my old school bravos? I know the case is longer, so that is going to create more drag, but the imco is also streamlined which may negate that. I've also been reading that some guys have sharpened them and sanded them with 600 grit to further reduce drag and improve the speed. So drive experts, what are your 2 cents on this topic?

I had a 1990 292 sri with 365 mags, I was getting blow out at 66-68 mph, so I'm sure those old style blunt nose cones are costing you speed. I installed Bob's nose cones and improved speed 2-3 mph. Also, I hope you are running full hydraulic external steering, that is a must for that boat at speeds in excess of 60 mph IMHO. I wanted to install stand-off boxes and raise the x dimension on my 292 when I had it. I don't recall imco having the -2 lowers back in the day. I did set up a 357 that I converted from a KAMMA drive to bravos. I had formula send me the stock x dimension and raised the drives 2" with the standoff boxes. The boat ran great and saw speeds in excess of 70 mph with 500 hp, which is not bad for that boat. I would definitely try the -2 lower IMCOs. Remember, you can always add spacers to bring the drives back down for very little additional $$$$. Also, Fountain has achieved some pretty amazing speeds with their 35's significantly raising x dimensions, but more importantly going 5 or 6 blade herrings. From what I'm seeing in the industry, propeller technology has improved drastically since your boat was constructed and you should take advantage of that new technology, even on an "old school" boat. Good luck and let us know how it goes.

Thanks for the info- I've been reading about some boats having issues not being able to carry the bow with shorter drives. It seems that most if not all of them were single engine boats. Do you have any thoughts on this?

I have thought the same about doing shorties on my boat and there not very many who have said they tried it, and it appears that when they did they may not have tried the right props or stuck with it long enough

I think the idea of getting spacers is a good one. Be ready to run 4 blade props and even 5 blades.
Be prepared to spend some money experimenting since there are not a lot of others who have tried that combination

I'm currently running Bravo props so my props should be close to what I would need. I called Bret at BBlades Monday to get his take, but he wasn't in and I haven't got a call back yet.

Definitely apples to oranges, but I used to run a blunt nose '88 bravo on a 24' baja in the low 90's with no blow out. I am sure that it would have been faster with an imco style lower but never got around to it. I did raise the x-dim 3.5" on the boat which made a huge difference in handling and I'm sure it helped the speeds. Those 80s boats had drives in the basement.

I think propellers are the key to the set-up. I am currently converting my 38EC from bravo 3's to bravo 1's. My pocket book kept me from getting imco or merc -2 lowers. That will be the next step. A while back I tried the bravo 1's off my 419 formula fastec and my 38EC ran about 4 mph faster (61 mph to 65 mph) as compared to bravo 3's. I know slower speeds, but it is interesting how much speed gain with just a drive change. I think if you raise x-dimension you will definitely want to look into 5 blades or maybe even 6 if your budget allows which I'm thinking would help carry the bow. I recall my 292 being a little bow light in the first place, so I don't think you would have an issue. Also, you should have a wedge built into the bottom just above the first strake. The wedge extends from the transom about 12" to 18" towards the bow. Just take a 6' straight edge and check. Removing the wedge would be a low cost item to restore the attitude of the boat if you lose bow height with the -2 lowers. I'm guessing that from what wfo1 experienced, the blunt nose bravo doesn't come into play when you raise the x dimension 3.5"!!!!! That's damn near a surface drive. Also, with 2 drives, you should have enough lower in the water to maintain high speed control of a 29' boat.