350hp wants more horse power
11-24-2003, 02:30 PM
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One thing to keep in mind regarding the drives - a 28' Sonic weighs a hell of a lot more than Travis Powerplay(quest). Travis, I think your boat is an 18' or maybe a 23'? That extra weight will put a lot more stress on that dinky Alpha drive.
Same deal with Bravos - they tend to live longer in a light boat with big power than in a heavier hull with equal power. All other things being equal, that is...
Same deal with Bravos - they tend to live longer in a light boat with big power than in a heavier hull with equal power. All other things being equal, that is...
11-24-2003, 02:35 PM
#14
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I what one of those engine programs woul predict for your '92 Mag or my '92 5.7?
Back to your original ?, my 2 cents are
1) pull the heads and have 2.02/1.60 valves installed,
2)use a thin head gasket (0.015 -0.018) so that your quench is around 0.040 (stock 0.025 deck);
3) hi-rise intake, if you don't have the z-28 cast iron one now;
4)Comp's XM262 (or 268, can't remember) roller cam;
5)jet the Q-jet to 068/041 primaries and CK or DA secondary rods. May have to enlarge the idle mixture screws bacause of cam duration
That should get you close to 300 crank. You could even stay with a flat cam.
Good luck
Back to your original ?, my 2 cents are
1) pull the heads and have 2.02/1.60 valves installed,
2)use a thin head gasket (0.015 -0.018) so that your quench is around 0.040 (stock 0.025 deck);
3) hi-rise intake, if you don't have the z-28 cast iron one now;
4)Comp's XM262 (or 268, can't remember) roller cam;
5)jet the Q-jet to 068/041 primaries and CK or DA secondary rods. May have to enlarge the idle mixture screws bacause of cam duration
That should get you close to 300 crank. You could even stay with a flat cam.
Good luck
11-24-2003, 03:21 PM
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Originally posted by dockrocker
One thing to keep in mind regarding the drives - a 28' Sonic weighs a hell of a lot more than Travis Powerplay(quest). Travis, I think your boat is an 18' or maybe a 23'? That extra weight will put a lot more stress on that dinky Alpha drive.
Same deal with Bravos - they tend to live longer in a light boat with big power than in a heavier hull with equal power. All other things being equal, that is...
One thing to keep in mind regarding the drives - a 28' Sonic weighs a hell of a lot more than Travis Powerplay(quest). Travis, I think your boat is an 18' or maybe a 23'? That extra weight will put a lot more stress on that dinky Alpha drive.
Same deal with Bravos - they tend to live longer in a light boat with big power than in a heavier hull with equal power. All other things being equal, that is...
Yes weight is a big factor. Mine is only 18' and weighs 3000 lbs loaded.
But if your up grading to bravos.. Let em rip
11-24-2003, 06:17 PM
#18
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Re: 350hp wants more horse power
Originally posted by sonic28
hey people i have twin 350 mags 1992 pushing out 245 hp at the motor not the drive. i would like to build it up to 300hp or better with out going to vortec i am running alphas which im up grading to bravo's can yo give me some good suggestions what i need i don't want to suck water back.im currently with gil exhaust 700cfm holly on the stock manifold.im running in salt water so ineed to stick with the stock maifold due to the bronze water jackets.the boat is 1992 sonic 28 my speed currently 60 mph on gps
hey people i have twin 350 mags 1992 pushing out 245 hp at the motor not the drive. i would like to build it up to 300hp or better with out going to vortec i am running alphas which im up grading to bravo's can yo give me some good suggestions what i need i don't want to suck water back.im currently with gil exhaust 700cfm holly on the stock manifold.im running in salt water so ineed to stick with the stock maifold due to the bronze water jackets.the boat is 1992 sonic 28 my speed currently 60 mph on gps
11-24-2003, 08:31 PM
#19
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I had 1987 20' Donzi Minx with a 270HP/350mag hooked to an Alpha. To my knowledge the only difference between the 260 and a 270 back then was the high rise intake and threw hull exhaust. The carb may have been jetted differently to, but I don't think so.
I made the following mods:
Changed the cam to the cam used in the 280TRS and the 300 Tempest engines; got the specs out of a Merc manual.
Re-jetted the carb to the jets in the 300 Tempest; again from the Merc manual.
Added a K&N filter/charger.
Labbed the prop.
The boat went from running 62-63mph at 4500rpm with a 23 Mirage to 68-69 at 5000rpm...
The following year, I bought another set of heads that had been machined for 2.02/1.60 valves.
Then changed the intake to an Edelbrock performer rpm Q-jet.
She gained another 100rpm and would crack 70...
Small Blocks are great to play with! A LOT LESS $$ than a big block!!!
I am learning this lesson the hard way.
I made the following mods:
Changed the cam to the cam used in the 280TRS and the 300 Tempest engines; got the specs out of a Merc manual.
Re-jetted the carb to the jets in the 300 Tempest; again from the Merc manual.
Added a K&N filter/charger.
Labbed the prop.
The boat went from running 62-63mph at 4500rpm with a 23 Mirage to 68-69 at 5000rpm...
The following year, I bought another set of heads that had been machined for 2.02/1.60 valves.
Then changed the intake to an Edelbrock performer rpm Q-jet.
She gained another 100rpm and would crack 70...
Small Blocks are great to play with! A LOT LESS $$ than a big block!!!
I am learning this lesson the hard way.
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Patrick
Patrick
11-24-2003, 09:46 PM
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Travis I ckd your specs on your first 383 and I compare it to my 377 and your engine must of had more hp than what you think. My engine is rated at 320 at prop so that should be around 350 or so. I think your engine has better or larger specs than my 6.2. Dwight
