Freshly squeezed

I am picking up a 1999 fountain lightning 42 in 3 days but there is one thing thats bothering me the engines are dyno d at 825 hp 540 blocks with prochargers but they have bravo xr drives, can anything be done to them to hold that much power? I am afraid of getting taken if any body can help i would appreciate it.

mike38scarab

It’s not if the drives will break, it’s when the drives will break.
What size boat? How many engines? What are the size of the props? How much slip in the props? Standard lowers or speed masters? You really have to factor all in the equation. They are only rated for 600 hp by Mercury. Your dyno’d 825 hp engines should be just under 800 hp at the prop. Flying the boat and the re-entry is what kills the drives. MDC makes couplers that have their proven drive guard technology which takes the jolts down to reasonable torque numbers. Here is a cross section of a bravo XR.

JaayTeee

That picture looks to be of an outboard lower, it has a dog clutch in it

XR’s
can and do fail behind 525’s FWIW, if you don’t want to worry about it,
you need SCX uppers at the minimum

AllDodge

No expert by any means but I don't see someone that knows putting that much HP on a XR. Might be that the dyno sheet could be suspect

Brad Christy

AllDodge,

ProCharger advertises their 496HO 3lb Kit at ~615HP. I don't know what we've actually got, but I do know I'm pulling 2" more pitch than any PQ280 with a NA 496HO and running 8-10MPH faster.

I don't know which ProChargers he's got, but I could definitely see 825 with the right one.

Thanks. Brad.

Brad Christy

Freshly,

I'm running a 496HO with an M1 ProCharger through a stock B1 drive on a PQ280. The drive is rated at 425HP and ProCharger advertises my combo at ~615HP. The boat has ~300Hrs on it, and the drive oil is still clean as a pin. The thing you have to realize is that the ProCharger is actually a belt driven turbo charger, with its detriment of low-end lag, but not the benefit of top end boost. While our boat planes off easy enough, and even pulls my fat ass out on a slalom, the boost doesn't actually come on until we hit ~3500 RPM or so. I was all excited to be buying a "supercharged" boat, but, after running it for a few years, I'm not overwhelmed. I'd much rather have an appropriate sized Whipple. But, then, I'd probably have to swap the drive, so.....

Unless you hammer it out of the hole all the time, or air it out and let it reenter without dumping the throttles, I'd say you'll be OK. That said, I'd also be inclined to agree with the suggestion for SCXs. It never hurts to address an Achilles heel. Determine which props are typically run on your combo without the power adders and compare that to what yours is actually running. If there's a large difference, you may need to address the drives.

Thanks. Brad.

underpsi68

Prochargers claim of 615hp on a bone stock 496 at 3psi is a little over zealous. It's probably closer to 500hp.

Brad Christy

UnderPsi,

Possibly/probably. That's why I stated "advertised". That said....

What kind of HP does it take to push a 4800-5000lb, single-step boat to 78MPH? How much extra HP does it take to reliably pull a 28P prop instead of a 26P on said hull? Genuine questions.

As I said, I'm not all that impressed with my ProCharger. It's OK, and there IS output gain, but the torque curve is WAY too top-ended for a boat, in my, admittedly anecdotally experienced, opinion. Which is why I don't think the OP is going to have any real issues with his rig that aren't self-inflicted.

Thanks. Brad.

SB

Those motors will eat those Bravo’s like i eat mashed potatoes.

Freshly squeezed

Thank you for all the responses, I am looking forward to being a member here, I was informed today that the drives have all Teague parts and they have all documentation looks like I am heading out Thursday to survey and pick up boat pictures will be coming soon, hope its not pics of me building drives
the boat is a 42 lightning orange named freshly squeezed with 540 blocks, if anyone knows anything about this boat let me know, I heard previous owner was named Lou and passed away he was part of this community I think