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Forced Induction EFI or NA with a Carb

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Forced Induction EFI or NA with a Carb

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Old 06-14-2018, 04:17 PM
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Default Forced Induction EFI or NA with a Carb

Ok how much additional expense and headache is it worth to go forced induction?



I currently have an HP 500 Carb motor and am wanting to bump it up to around 650ish. Anymore than that and Iím assuming Iíll start running into start running into exhaust and drive issues(have an standard bravo with XR gears and a sportmaster -2 lower). I donít drag race around or anything just looking for a little more pep in the few evening hot laps I make.



Iíd like to keep everything under the hatch witch eliminates a roots blower and leaves me converting to EFI and going with either a whipple or procharger. Iím assuming by the time I get the kit and whatever Iíll need to convert over to EFI this will be a decently sized bill.



As Iím only wanting to go to 650 Iím reasonably sure I could get some nice aluminum heads, a bigger cam, maybe a bigger crank and go to a 540( I donít think I would really need this either), and a bigger carb and that would get to the same HP for a much cheaper price



I know blowers pack a much better punch with better torque curves but in my case Iím thinking the price difference wonít be worth it. Iíve never owned/driven a blown boat before so I donít know. What are the groups thoughts ?
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Old 06-14-2018, 05:06 PM
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How heavy is your boat? Single engine? Use of the boat?

In my research the centrifigal chargers make so much power up top needing a huge prop that can be tough to jump out of the hole with. For my purposes of family fun and wakeboarding it just wasnít the right fit for me.

Last edited by Baja Rooster; 06-14-2018 at 05:32 PM.
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Old 06-14-2018, 06:15 PM
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650hp is going to be tough out of a 502 NA. It would have to be pretty high compression, the perfect camshaft and some really nice exhaust. I would recommend going to 540 CI or bigger if you want to keep it NA, but I am a blower guy. I say Whipple it and be done with it.

https://whipplesuperchargers.com/ind...&product_id=55

Last edited by snapmorgan; 06-14-2018 at 06:24 PM.
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Old 06-15-2018, 05:05 PM
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Originally Posted by farmo83 View Post
Ok how much additional expense and headache is it worth to go forced induction?



I currently have an HP 500 Carb motor and am wanting to bump it up to around 650ish. Anymore than that and Iím assuming Iíll start running into start running into exhaust and drive issues(have an standard bravo with XR gears and a sportmaster -2 lower). I donít drag race around or anything just looking for a little more pep in the few evening hot laps I make.



Iíd like to keep everything under the hatch witch eliminates a roots blower and leaves me converting to EFI and going with either a whipple or procharger. Iím assuming by the time I get the kit and whatever Iíll need to convert over to EFI this will be a decently sized bill.



As Iím only wanting to go to 650 Iím reasonably sure I could get some nice aluminum heads, a bigger cam, maybe a bigger crank and go to a 540( I donít think I would really need this either), and a bigger carb and that would get to the same HP for a much cheaper price



I know blowers pack a much better punch with better torque curves but in my case Iím thinking the price difference wonít be worth it. Iíve never owned/driven a blown boat before so I donít know. What are the groups thoughts ?
I'm a big fan of EFI. its a computer who who job is to keep the motor within a programmed spec. Cabs don't have that, no way of pulling timing if it hears knocking/pinging no way of increasing or decreasing AFR based on sudden load changes.

Originally Posted by Baja Rooster View Post
How heavy is your boat? Single engine? Use of the boat?

In my research the centrifigal chargers make so much power up top needing a huge prop that can be tough to jump out of the hole with. For my purposes of family fun and wakeboarding it just wasnít the right fit for me.
This

while this is pretty generic, its close.


if your going to run your motor at WOT all the time then CF. CF also takes less power to spin. if your gonna be all down low then Twin Screw or Roots. Twin Screw > Roots because you get lower discharge temps, a CF will get you lower discharge temps then both of those but don't produce the volume at low speed
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Old 06-15-2018, 09:00 PM
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I built a Procharged engine for my boat..

It's 555 cid with an M4 Procharger
Used a fairly small cam. 8.5:1 compression. AFR heads, Eddie Marine manifolds, and Holley EFI
Dyno'd in full marine dress.. made 629 hp N/A 1020 hp blown.
Have the blower set up for 10 Lbs of boost at 6000 RPM...

It's in a 29' Velocity. Running a 1.35:1 ratio XR with a 26 pitch P5x prop
Boat jumps out of the hole and accelerates HARD at any rpm It's a absolute BLAST to drive !
I NEED a shorter drive at this point (next year) but have hit 99.7 MPH..
I am NOW addicted to BOOST..







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Old 06-15-2018, 10:39 PM
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Originally Posted by farmo83 View Post
Ok how much additional expense and headache is it worth to go forced induction?



I currently have an HP 500 Carb motor and am wanting to bump it up to around 650ish. Anymore than that and Iím assuming Iíll start running into start running into exhaust and drive issues(have an standard bravo with XR gears and a sportmaster -2 lower). I donít drag race around or anything just looking for a little more pep in the few evening hot laps I make.



Iíd like to keep everything under the hatch witch eliminates a roots blower and leaves me converting to EFI and going with either a whipple or procharger. Iím assuming by the time I get the kit and whatever Iíll need to convert over to EFI this will be a decently sized bill.



As Iím only wanting to go to 650 Iím reasonably sure I could get some nice aluminum heads, a bigger cam, maybe a bigger crank and go to a 540( I donít think I would really need this either), and a bigger carb and that would get to the same HP for a much cheaper price



I know blowers pack a much better punch with better torque curves but in my case Iím thinking the price difference wonít be worth it. Iíve never owned/driven a blown boat before so I donít know. What are the groups thoughts ?
I ran a modified .060 over 454 MAG that was injected and ProCharged M3SC. Made 720 HP and 727 TQ 685TQ at 2800 RPM. Ran 6 years turn key with a B-Max Drive, Changed oil.
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Old 06-22-2018, 06:27 AM
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for what you are looking for a M1 procharger, blow thru carb will do the trick BUT need to tune with wide band to get it right...ran a setup like that for 5 years
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Old 06-22-2018, 07:05 AM
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Originally Posted by farmo83 View Post
Ok how much additional expense and headache is it worth to go forced induction?



I currently have an HP 500 Carb motor and am wanting to bump it up to around 650ish. Anymore than that and Iím assuming Iíll start running into start running into exhaust and drive issues(have an standard bravo with XR gears and a sportmaster -2 lower). I donít drag race around or anything just looking for a little more pep in the few evening hot laps I make.



Iíd like to keep everything under the hatch witch eliminates a roots blower and leaves me converting to EFI and going with either a whipple or procharger. Iím assuming by the time I get the kit and whatever Iíll need to convert over to EFI this will be a decently sized bill.



As Iím only wanting to go to 650 Iím reasonably sure I could get some nice aluminum heads, a bigger cam, maybe a bigger crank and go to a 540( I donít think I would really need this either), and a bigger carb and that would get to the same HP for a much cheaper price



I know blowers pack a much better punch with better torque curves but in my case Iím thinking the price difference wonít be worth it. Iíve never owned/driven a blown boat before so I donít know. What are the groups thoughts ?
If 650HP is your goal I'd vote finding a used roots 8-71 and keep it carbed. It's not the most efficient supercharger out there but at 5lbs of boost it will make the power you're looking for and have a lot of torque down low to help with planing performance. We've run one for 4 years now and love it. It starts and idles better than our old 454MAG EFI. I say buy used because you'll see complete systems for sale at reputable marine engine builders for half the price as a new system. Because it is considered "old technology" performance boaters are taking them off and going to more efficient forced induction (whipple and turbochargers). You may have to modify the hatch and add a scoop but in most cases it adds to the performance appearance of your boat and it will do a nice job aerating your engine compartment. You'll love the supercharged mill-power is substantial all over the operating range and they sound and look great.
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Old 06-22-2018, 07:12 AM
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Idles all day, no loading up.

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