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Thread: Cadillac Big Block jet boat project planned

  1. #1
    Yvettefan25
    I'm thinking a Talor jet boat, but would really like room for four, and want to use it for para-sailing and skiing as well as drag and crusing. The Cad 500 I'll use will be a replica of the Street Rod magazine 500 stroker build up, and will pull the same numbers 611 pounds of torque at 3200 rpms, 450 HP at 3600, and would be able to twist at 5500 rpms if needed. I'll get better numbers if I use fuel injection and move up to 10:1 compression, and get a cam built for higher rpms. 650 pounds of torque, 500 HP at slightly higher rpms is very realistic on pump gas. The engine is 85 pounds lighter than a big block Chevy-correction, an extra 35 pounds lighter than that with aluminum intake. My question is this: Is there a pump designed with the gears I need for the low RPM operating Cad motor, or it there a way to over drive it? How about a way for one engine to twist two side by side pumps? My goal is do regular crusing at 85-95 mph safly, and with top speed runs well above 100 mph. I was in a Cobra bass boat w/Merc 300 out board running 80 mph, and loved the speed, but did not like the way the boat tended to get air born with all the weight in the back like that. Any one got any Ideas or know anyone who went the Cadillac rout in jet boats? I'd love to get a picture.

  2. #2
    Jungle Boy
    Originally posted by Yvettefan25:
    I'm thinking a Talor jet boat, but would really like room for four, and want to use it for para-sailing and skiing as well as drag and crusing. The Cad 500 I'll use will be a replica of the Street Rod magazine 500 stroker build up, and will pull the same numbers 611 pounds of torque at 3200 rpms, 450 HP at 3600, and would be able to twist at 5500 rpms if needed. I'll get better numbers if I use fuel injection and move up to 10:1 compression, and get a cam built for higher rpms. 650 pounds of torque, 500 HP at slightly higher rpms is very realistic on pump gas. The engine is 85 pounds lighter than a big block Chevy-correction, an extra 35 pounds lighter than that with aluminum intake. My question is this: Is there a pump designed with the gears I need for the low RPM operating Cad motor, or it there a way to over drive it? How about a way for one engine to twist two side by side pumps? My goal is do regular crusing at 85-95 mph safly, and with top speed runs well above 100 mph. I was in a Cobra bass boat w/Merc 300 out board running 80 mph, and loved the speed, but did not like the way the boat tended to get air born with all the weight in the back like that. Any one got any Ideas or know anyone who went the Cadillac rout in jet boats? I'd love to get a picture.
    Cuising at 85 - 95 MPH?? Good acid. 500ci Callilac engines are heavy. There are some people working underdrives out there but I don't think you'll ever see a Caddi engine in a Taylor with 4 people in it cruising at 95 mph unless it's on a trailer.

  3. #3
    Unchained
    I don't think you need the parasail, you're higher than a kite already. http://free.***boat.net/ubb/biggrin.gif

  4. #4
    coolchange
    My brother put one in his truck. 514, lighter, lower power band, built a sheet metal FI intake. Very expensive to build. Everything will have to be custom fabricated. Unless your trying to gain some notoriety stay away from it. Just my .01.

  5. #5
    froggystyle
    In contrary opinion to everyone who has posted, I think it is a phenomenal idea. I owned a Caddy as my first car, and back then there was an outfit called "Cadillac Motorsports Development" who was making an intake for it, and made really good power stock. Similar to the numbers you are describing. The block was the 504, not the 492 found in later models.
    Reliable, strong lighter power will be in your future. Bolt it right up to a Berk 12JG style pump and run a "A" or "AA" impeller and you should see power where you want it.
    Now, back to reality. In a 18-19 foot Taylor you will see around 73-74 mph with this motor. If the planets align and a ray of light shines down from heaven you will run 79-80 in a good following sea with a tailwind. 450hp does not get you very much speed, although the 650 ftlbs is formidable for low rpm pulling. Should work great for everything you are describing, short of 80+ runs.

  6. #6
    SSTSleakcraft
    Why not a caddy? You won't set the water on fire but Variety is the spice of life. A rear engine mount for an Olds will work. Remember, Chevy was the odd man out. Buick, Olds, Caddy, and Pontiac all shared the same bell housing bolt holes. Ford big block have similiar exhaust port spacing. Someone out there makes spacers to use BBFord exhaust, more readilly available than marine Caddy stuff. Good luck with the project!

  7. #7
    coolchange
    CMD is still around. They used to be in Ventura, are now back east somewhere. Off the shelf prices are higher for caddy stuff. just price a piston. But if your going to Arias etc. for parts pistons rods etc. the prices are the same. They don't care what it's goin in. Valves my bro ran a big Pontiac valve, justhad to shortin it up a bit. 2.35 I think. Hey old rigger, do they actually have inventory of those manifolds?

  8. #8
    Aduner2
    This set-up is screaming "Dual Jet Drives"!

  9. #9
    SPECTRABRENT
    OLD RIGGER,
    Did you see who made a post on the Spectra site. The guy with the Spectra 18 out in Camarillo is still trying to sell his boat. I know that you already got a boat, but you should go make him a really low offer.
    Brent

  10. #10
    CoastGuardSteve
    I talked with that guy in Camarillo last summer and he didn't seem like he was too worried about selling his boat. I would suspect that after a year of trying to be clever on the net he might take whatever he can get now.
    Steve

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