BBC 540 performance upgrade ?'s
 

Hi, I'm running the first twin screw boat I built this year and was just looking for some input or new ideas on what everyone thinks would be the best idea for next performance upgrade. My boat is a 32' hustler with twin 540 bbc's topped off with 250 b&m blowers and nickerson 1075's. The motors were just rebuilt at East Coast Offshore, and are set up for boost with good crank, ross blower pistons ect. The boat is only running about 5 lbs boost with no intercoolers. Also running trs drives with BW trans. My biggest question is how much boost can I squeeze out of this set up without intercoolers or should I think about intercoolers to help. The drives are rebuilt by speedmasters and should handle whatever I throw at them for now. Im new to the blower motor world and just looking for and input ideas on what to try next. Thanks, Josh

You may not want to hear this but those blowers are pretty weak and small for a 540...they are even small on a 502. I would think you would be spinning them pretty fast the way it is to reach 5psi boost on that displacement. What is your compression ratio? If you spin the blowers faster you will make even more heat. Chillers would help but for the price of the chillers you could bolt on B&M 420s and have a more durable package capable of more efficient boost. They should bolt rite on your current intake. How much hatch clearance do you have?

I have 509bb with 250b&m blowers. 5lbs of boost and 850 carb. 605hp. at 5500rpm. From talking to my engine builder, he said that 5lbs is all you want to push the 250b&m. They are too small to create more boost as they generate too much heat. An intercooler would give you more HP, but if you really want a lot more that is going to make a huge difference, then you need to go with a larger blower. My advise: If it is NOT broke , don't fix it.