Just curious how underrated inboards are compared to IO engines if they are at all. Boat is a 91 fever. thought they came with 7.4 365 mags. Bought 7.4 blue waters out of a 1994ish sea ray. NEVER were opened up, untill 3 weeks ago when I had to fix a stuck exhaust valve from sitting over the off season. Was told that this boat in 91 came from Fountain with 25' mirage props. These engines will twist these to 5200 all day long, turn out 55-600 once the boat gets running. I know it is not good, so I do not do it, jsut wanted to see how far it would twist. I I need more prop for sure. That was with 3/4 tank and 2 of us 225lbs. Engines are stone stock down to water pumps, exhaust. Any thoughts or more info would be great. Just kinda got me thinking..


John jr

Free speed!!!

I would look at the props. They could have changes in pitch that you can't even see.

It appears not to be the case but Searays often came with the non-mag version of the 454 and those really can't handle 5,600 rpms.

they are usually just base 330 mercs, some were down to 310's but the engines were the same as base I/O's in inboards the 330 were 340's..less H/P loss that a I/O

What is the chances the props actually de-pitched ? Guess I will try some 27's out and see if it is the ticket. I was assuming, from reading these 7.4's were 330-340 hp.

John jr