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Anyone over 500 HP in a Formula 382??

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t500hps

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Discussion starter · #1 ·
Looking to build motors for my 382. Currently running 500EFI's with 8 psi Prochargers. While it's fast, I don't want the blowers and plan on rebuilds this winter. The article about the 382's in the new Powerboat mag has me concerned.
My plan is to build 540's, keep the EFI intake system, roughly 9.5 to 1 compression and aftermarket heads. This should get me in the 620-640 HP range. Magicfloat claims a new 382 with 600's runs 84 (but that might be with boxes). The Powerboat article claimed 79.XX.
Anyone with 500+ hp willing to provide me with your real world cruise and top speeds? I'd hate to drop this kinda money for just a few MPH.

Russ C.
 
#2 · (Edited)
I PM'd you and will post JMHO here......
540's will not get you what you want
575's are closer to what you need to move a boat as heavy as yours.
The 575 is only 1/4 longer stroke.
There are other issues with the 575....but I do not think the 540 will do what you want.
Magicfloat's 600's? Is that Merc's 600's???
If so I think they are different than a N/A 540 by about 100 HP. The 600's from Merc have more HP than a 540 N/A
Like I said ...........
JMHO
 
Discussion starter · #3 ·
PM'ed back....Thanks.
Magicfloat was refering to a new 382 with the new 600sc running 84 WOT. (Possibly with boxes???) The Powerboat article claimed 79.X. I figure my XR's will live behind the torque of the 540's, anymore than that and I may start loosing drives. If I get low 80's with this package I'll be happy as I hear stock 500's get a best WOT of 74.
(With the Prochargers right now I spin heavily cupped 34's to 5,500. 5,000 RPMs showed 86 on GPS and the bottom/hull needs a little work.)
 
#6 ·
What dont you like about the blowers? if theyre done right they should be safe. And probably get better gas milage then the 540's or 575's at cruise speed. maybe put bigger pullies to bring the boost down if reliability is your issue. i never really liked the idea of superchargers but bought a boat with an M1 and now that I understand how it works and know it was done right I think its a great way to make horsepower.
 
Discussion starter · #7 ·
Maybe these aren't set up correct but I need to go into the motors anyway (overheated before I bought it). Mine are set REAL rich and blacken the transom in 30 minutes of running. They get lousy mileage and we do alot of long range cruising. I am around .8mpg and should be closer to 1.2.

BTW: Do you get the "blower wine"? I can hear the thing spinning at idle pretty well, can't quite hear it when running unless into the sticks.

DagaH2X said:
What dont you like about the blowers? if theyre done right they should be safe. And probably get better gas milage then the 540's or 575's at cruise speed. maybe put bigger pullies to bring the boost down if reliability is your issue. i never really liked the idea of superchargers but bought a boat with an M1 and now that I understand how it works and know it was done right I think its a great way to make horsepower.
Click to expand...
 
#8 ·
Yeah it does whine but I like it. :D
Mine gets black too but not much worse then my stock 454 in my last boat. It was probably just setup real conservative. Best thing to do is have the fuel set correctly on a laptop by someone who knows WTF they are doing. Have it done on the water not on a dyno if you can, only way to really get them right. Usually when you send the computer out somewhere they set them up rich to be safe.
How hot did they get? if a leakdown is OK and oil pressure is OK and everything seems to run good I would probably leave them alone.....
At cruise not in boost my boat seems to be real good on gas, I would think a higher compression N/A motor would be worse atr cruise. Deep into the boost is another story though....shes a PIG!
 
#10 ·
T500HPS,
You may want to consider 557's. These are 4.375" stroke by 4.500" bore. A little more stroke and cubes maybe a better choice for your application. Gen 6 blocks which is what you should have will take this stroke with minimal grinding.
 
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