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Performance expectations with new engines

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Old 10-03-2003, 11:12 AM
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Default Performance expectations with new engines

Anyone have a good idea of what I can expect performance/speed-wise from my '85 35' Cigarette Mistress with 600hp@5500rpm, 675ft lbs @ 3500 rpm T-540's with TRS drives and weighing in at ~8500#? I know there are other similar Cigarette's out there with similar setups.

The boat was originally equipped with 330hp 454's and was good for 60-62mph. The speed predictor at go-fast.com says 80-82 mph with 1100 combined hp and 8500#, but I think that is probably overly optimistic. I'm not looking for the highest top speed possible, just overall respectable performance. 75 mph would be nice though. TIA.
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Old 10-03-2003, 11:24 AM
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Monty,
Remember that the speed calculator at Go Fast is based on Prop shaft HP not crankshaft. For example a Merc 500HP has 470 at the prop. That calculator has always been pretty accurate when all the information is fed in.
Good Luck.
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Old 10-03-2003, 11:25 AM
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Also are you positive about your wheight #8400 seems light for a 1985 35' Cig mine is a '94 and is #9400 Dry.
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Old 10-03-2003, 11:50 AM
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GLH,

That's a good point about crank vs. prop hp. My 540's should make 590-600hp, so I used 1100 combined as the hp input, figuring a drivetrain loss. I based this drivetrain loss on my automotive experience knowing that automatic transmissions and drivetrains generally lose around 15%. But that's with a 4 speed automatic tranny, driveshaft, differential, and rear end. I figured that was a conservative drive loss. Maybe I'm wrong, but I would have thought the loss would be less on the boat as a result of the much simpler drivetrain( 1:1 Velvetdrive's w/ TRS) compared to a car.

I could also be wrong about the weight, but I was told 8500# was about what it weighed.
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Old 12-22-2004, 10:33 PM
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Default Re: Performance expectations with new engines

my mistress is closer to 10,500. i'm ready to freshen or repower this winter. the engines are already out & stripped.i'm considering 540's anyone want to gues about top speed???
trs drives
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Old 12-22-2004, 11:33 PM
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Default Re: Performance expectations with new engines

You may want to get in touch with "Stalkin" (James) from the boards. He just sold his Mistress and replaced it with a sweet T/S Tiger. But he'd have all the info you'd want since he built the motors in his Mistress I believe. He lurks every once and a while on here but just PM him, he's approachable and a super cool guy.

Tank
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Old 12-22-2004, 11:35 PM
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Default Re: Performance expectations with new engines

74-75
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Old 12-22-2004, 11:42 PM
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Default Re: Performance expectations with new engines

It's probably a kevlar boat, do you have a picture of it inthe water? Wasn't this Fred's old boat? I'm sure he would know. We had a Kevlar Mistress w/330s ran about 62. With 500hp it ran 70mph.

LS JR.

Last edited by lucky strike; 12-23-2004 at 12:01 AM.
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Old 12-23-2004, 09:01 AM
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Default Re: Performance expectations with new engines

Originally Posted by lucky strike
It's probably a kevlar boat, do you have a picture of it inthe water? Wasn't this Fred's old boat? I'm sure he would know. We had a Kevlar Mistress w/330s ran about 62. With 500hp it ran 70mph.

LS JR.
Hmm, this is an old thread, I'm surprised to see it come back up. I ran the boat this past summer with the 540's, which ended up making about 675hp@ 5600, and ran a best of 68.9 mph on the GPS with 21p Mirage's. These were the props that came with the boat and the 330's, but I never got around to replacing them with props appropriately pitched for the 540's. I'm doing that this winter, my wife is getting me a pair of 25p Mirage Plus's for Christmas. I'm hoping for 75mph, but most importantly an increase in cruise speed. I was only getting 40mph at 4000 rpm.
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Old 12-23-2004, 10:22 AM
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Default Re: Performance expectations with new engines

My 1977 Mistress has twin 650 hr with trs 71 at 5500 using 24 hydromotive.
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