prop selection 2550 sx
#1
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I am restoring a 91 Chaparral 2550 sx. the boat had 250 orig hours equipped with the 330/454/ bravo. Reading the posts i decided to do the top end and replace the heads with 71 vette heads. The compression should be about 9.2 to one. The ports are 262. I installed a crane marine cam with 529 lift. added crane gold rockers and 3/8" push rods. The motor looked almost new in the holes. Being fresh water cooled , i decided to use the performer rpm intake and a 770 holley street avenger setup for marine use. The boat weighs about 4400 lbs. it spins a 19' quicksilver prop. can I go to a 23" pitch?
#2
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I had a '88 2550 with the same motor that I bought with a 19" mirage prop. I installed a Crane Commander cam with .536"-.553" lift, large ovalport GM heads with 1.88"and 2.19" valves, Edelbrock Performer RPM intake, a Holley 750 DP and Stainless Marine exhaust. I ended up spinning a 23" mirage that was tweaked to about a 22.5" pitch at 4900-5000rpm. I spun an untouched 21" mirage at 5200 rpm. Over all I went from 58mph to 65mph.