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1989 272 big block questions

Hi All, recently purchased a 1989 272 sr1 with 454's, alpha 1's, and 25p mirage props.The boat was repowered in 2008 with new longblocks. I do know who installed them but i don't have a spec or horsepower rating or any info where they came from other than 2 of part # "CH454m-01 gm marine gen IV long block w/cam upgrade". When I google this info it leads me to a Promar Engine out of New Jersey. Anyone know if thats who would have built them based on the info and IF that is correct anything about Promar or the specs of these motors?

The boat does NOT have k planes, it has what looks to be homeade aluminum squares (bennett style) with a cheesy cylinder that are air locked or don't work. The most i have been able to get is 63 mph @ 4500rpm on gps only twice with 4 people on the boat and 1/2 tank fuel with drives trimmed up, and the other time was with 2 people on board with 1/2 tank of fueland drives trimmed up. Usually i only see about 62 mph. I thought, or understood from reading the forums that it should be a 65-67 mph boat especially with fresh repower. the props look good, drives are good. any advice? Will k-planes help me that much? i really don't go out in rough water although i know of a complete set of 280's with pumps that i can pick up for $400.

thanks in advance, sorry for the long post

Quote:

Originally Posted by AJH391 (Post 4199021)

K planes will help with the ride, speed, ahh not really, unless there making more then the 330hp from stock you are in the range, 62-65, also some chop will help the heavy azz get outta the water, 1/2ft chop is best,

65ish was a good max. Also fresh or salt? There is a speed difference.

Lake Erie, fresh water

It has alpha drives? Are you sure, if so been switched out from small blocks to big blocks.
I run 64 with 330s. No tab. Worst 63 with full fuel and 4 guys, best 66 low fuel 2 people and cold real cold like 45. Usually 64mph

Quote:

Originally Posted by AJH391 (Post 4199054)

Lake Erie, fresh water

Saltwater is denser and therein faster. Your numbers sound about right.

Quote:

Originally Posted by Mr Maine (Post 4199287)

Big blocks had alphas. Primarily 87. Bravos came out in 88. Wouldn't be far fetched to have an alpha big block in 89

I knew they did in 87. My 89 big block has bravos.

My mistake! They are bravo's, my last boat had an alpha 1 and it's habbit for me to say it. I appreciate everyones input very much.

I had a 90 292 sr1 with 365 hp magnums and older style bravo 1's. You may have the bravo lower units with a shorter case. I would get blow out in the low 60's. Added Bob's nose cones and it really helped the boat run straight at speed. Also, adding external hydraulic steering will help the control at speed. When I purchased the boat it would run about 66 max on a gaffrig speedo/70 on the stock VDO speedo. Added stainless marine exhaust and picked up about 4 mph. Ended up a 70 mph boat on a good day with the gaffrig speedo. Loved that boat, it was a blast to drive. Good luck with yours.

Thanks 38fountain, obviously im right where i should be then assuming i have 330-350 hp in the rebuilds.

Quote:

Originally Posted by AJH391 (Post 4199448)

Thanks 38fountain, obviously im right where i should be then assuming i have 330-350 hp in the rebuilds.

Your numbers are spot on, I did add stainless marine exhaust on my 272 with custom long risers (330's) and gained 0 mph , always got 64mph 65 mph with mirage 25p @ around 4500rpm , with that said stainless marine is a great upgrade, my idea was to eventually go with 540's but ended up selling it . Great boat

Thanks Diego, i was going to start making changes thinking i wasnt where i should be.

Well I finally got a chance to talk to the guy who build the boat. The motors were ordered from Promar Engines out of New Jersey and they had an upgraded cam in them. They were ordered to be 380hp each. With that being said, I still feel like i should be 5-6 mph faster being that theres 100hp more in the boat than i originally thought.

I really don't think 100 more HP will give you 5-6 mph in a 272. They have a small "hook" in the hull in front of the tabs that helps the ride but works against you when it comes to top speed. Enjoy your 272, they are a great boat.