Re: Proper Performance Engineering
thought i had edited my post earlier, must not have taken, Last nite, after thought, the 19 pitch Mirage is probably a better prop for your set up, its a large blade surface wheel with much lift, either bow or stern, this prop is extremlly efficient, i had a customer that had one on a performance boat, we calculated it was within 7% slip at 101 MPH, that type of efficency is allmost unheard of. We ran 21( it had been worked on) pitch on my old roommates boat, it had a 3.7l Mercuiser 4 cylinder, it was rated at 165 hp and has simular torque band as the I-6 250 GM engine you have, we got that 4 cylinder pushing a 17 ft boat to 52 mph( on radar), not bad for a 4 cylinder. The original Mirage had too much blade surface for an outboard( Mercury only recomended its use on the 3.4L 275), it was designed for the 454 sterndrives. most smallblocks wont even turn like it needs to be, but some engines, due to gear ratio in the drive( I-6 like yours, I-4)and their low rpm torque curves are able to make use of this prop. Some of the go fast crowd(Fountain for one) was trimming 1/4 inch of diameter to get a little less bite, to allow their engine to turn up in the rpm band they wanted it to be in, Mercury saw what they were doing and applied some fine tuning to the Mirage, allowing a litle less bite, making it an excellent prop for outboards.
Mercury has a prop selector on their web site, i have never used it, but several people i know have and have had excellent results with it.
Improperlly set up trailers can ruin a boat, they can warp the hull ( especially if it has set a long time), putting in excessive hook or pockets. This keeps the boat wet, it won't let the hull lift like it was designed to, roller trailers will do the same thing, just not one hook or pocket but several, at each place a roller contacts the hull. Of course it depends on how good of a hull you're talking about, there are some old trihulls out ther that you could'nt warp if you parked a truck on them.
As far as Volvo goes, they make the best sterndrive availble, they also have some of the most expensive( yamaha may have them beat), hard to find parts around. they now offer 2 day deliverd parts out of the wharehouse in Chesapeke anywhere in the continental US, it just seems the parts i order are allways nla
Was down at the ramp where Cummins Mercruiser test their boats, they have a new 150 hp Diesel that looks good
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