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Audiofn
05-16-2004, 08:28 PM
I just purchased a 1981 18 2+3 with a TRS and 454 (330hp). I am wondering if anyone has done any extensive prop testing with these things. I am wondering what the best prop is with a slight compromise to speed for handling.

Audiofn
05-18-2004, 05:32 PM
Mad thank you very much for the offer. I have a right hand rotation I believe. Still have to check that but I would bet it is. I do have a friend up at the lake that has one hell of a collection of props. I have heard that you should stay away from 4 bladers with the TRS but that may just be on heavier boats.... I am not sure what a good top end will be with this boat, do you or anyone have any ideas what is a number to shoot for?

Jon

Ranman
05-18-2004, 10:48 PM
Audio,

The problem with a BBC in an 18 is all that weight at the transom.

For example, I know of a certain 18 BBC pushing 425+ HP with an OMC King Cobra Drive that'll run 72-73 MPH.

I also know of a 97 18 Classic with a 300HP Merc tied to a Bravo One that'll run 70-71.

Why is there such a small difference in top speed you ask? Well the Bravo and KC are pretty close (the B1 may have a slight advantage over the KC hydrodynamically). This really only leaves one thing...weight. The transom of those BBC 18's sit loooowwww. The motor fights to get all that weight up and out of the water.

Anyway, I'm not bashing BBC 18's, I just feel a SBC is a better choice as you can get the same speed with less HP along with better fuel economy. The 22 Classic is a different story. BBC all the way.

That's one hell of a cool boat you bought though if it really is a factory BBC regardless of weight or speed. They are rare indeed and thus have a high cool factor. :shades:

As for top speed on a 330HP TRS 18, I'd say if you hit 62-64 MPH you're doing good.

Audiofn
05-19-2004, 09:10 AM
RanMan I have no doubt that the SBC is probablay a better engine for this boat. I was told that the weight difference btwn the Big Blocks and small blocks was 150 pounds? One of the things I was thinking of doing was to take out the Log style manifolds and get/make one of the high rise hatches so that I can get a alluminum or header system in there. I have even been toying with the idea of pulling this motor and saving it and dropping in a 350 fuel injected motor into it. This will get rid of most of the weight issue. However I am going to waite to drive it and see how it does before I make any of those decisions, plus I have to finish the Formula first.... As for top end I have heard people say anywere from low 60's to low 70's so I guess we will see. It currently has a 27" blade on it. So depending on the slip numbers we are in that range. Clever style props and hydromotives sound like they may be the ticket as they give more stern lift.

Madpoodle let me run it with what I have first and get some base line numbers and see if my buddy up in Maine has any props for me to try and get more base line stuff from. Then I may take you up on that :D:D

Since the wife will be driving it also and she likes to cruise we will probably look for the fastest cruise speed prop that offers good predictable handling. I know props are like magic with boats and I actually enjoy trying all kinds tell I feel I have the best one.

Jon

Ranman
05-19-2004, 09:32 AM
Don't change the motor. The original BBC 18's are sweet. So what if they're dtern heavy, they're cool. Plus you get to enjoy that distinctive BBC sound. :D

THe Hydromotive QIV 4 blade props work wonders on the 18 classic hulls. THey are not the fastest, but dramatic improvment in handling cannot go unnoticed.

I run a Mirage+ for speed and a Hydro QIV for rough water. BTW my boat is an 18 Classic 350/Bravo.