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View Full Version : 1989 Conbrio Horsepower and prop clarification



firstdogriver
04-29-2010, 10:39 PM
I bought my first inboard last summer, a 1989 conbrio in great shape with low hours. I've heard conflicting reports on the horse power rating and the prop that should be used. The boat has a 351 with a 1.23:1 transmission. The prop is a RT 14 X 18 on a 1" shaft. First off I thought it was rated at 240 horsepower, but then I read in this forum that it if you have the 1.23:1 transmission that it was actually 260 horsepower. Secondly the prop that came with the boat was a 14 X 18 OJ and I was told that a 13 X 13 was the correct prop. I've been having a hard time finding the specs for the boat and was wondering it anyone out there could shine some light on these subjects for me. I've looking a getting a new four blade ACME prop for it and but I need to know what is the right prop is to start with.

mapleleaf
04-30-2010, 07:02 AM
welcome to the forum, Love those Conbrio's....If you call JT at Nettles props he can help you, he recommended a 3 blade acme 13 X 12 or 13 X 11.5 for my Conbrio. gives more lower end torque without sacrificing to much top end speed.
It's my understanding that the 351's are normally 240 hp, unless they have the GT 40 heads, which makes them 260 hp, but I could be wrong.....
Pics are always goood.......

firstdogriver
05-01-2010, 12:15 PM
I actually spoke with JT at Nettles Prop a couple of days before I posted my questions on the forum. He was surprised when I told him that the boat had a 14 X 18 OJ prop and that I thought it was the original prop. I am in the market for a four blade because I've always been told that four blades give the best hole shot. JT indicated that the ACME three blades performed just as well as the four blades, plus they were a little faster on the top end. Then we discussed wakeboarding and the fact that I plan to add a little weight to the boat to increase the size of the wake. I suggested the ACME 1490 or 1492 which was a something like 14 X 15.5 four blade and he didn't see a problem with it. Can anyone with a similar set up as my boat comment on props, hole shot, top speed and RPMs.

P.S. Thanks Mapleleaf for replying, I'll post some pics as soon as I get some.

87SunSportMikeyD
05-03-2010, 01:02 PM
Sorry to reuse my own post but it's a lot to type. Here are a couple tips to help you determine if you want a 3-blade or 4-blade. They both work, but one works better depending on your boat.

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As for the prop I talked to ACME and JT at NettleProps.com and they taught me a couple things. To tell if you should use a 3-blade or 4-blade prop, look at the trans and the stock prop. You generally want a 3-blade if the trans is 1:1 and the stock prop is a xx by 13" diam (pitch doesnt matter for this excercise). If your trans is anything else like 1:1.25, etc, and your stock prop is diameter greater than 13", then you will gain benefit from the added blade surface area and blade rpms. If not, you may experience cavitation or other issues.

The recommended prop for most '86 - 88 SunSports with 1:1 trans and 13"diam is the ACME#913 10.5 x 13". It is a great prop for a heavily weighted boat. Your max speed is reduced to about 35mph @ 4200rpm on my boat unweighted. Surfing with 1500lbs and crew of 5 she rips out the hole and is up to speed 11mph in about 5 seconds. Highly recommended and Nettles service and prices are great. Here is a link.

http://www.nettleprops.com/store/p/280-Acme-913-Propeller-3-Blade-13-X-10-5-LH-1-Bore-80-Cup-.aspx
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