Max hp Rating

[andrewz9876]

What would you guys say max hp rating would be for an alpha Gen Iv magnum 350??

[Pismo]

Do you mean what can an Alpha handle, if so 400hp if you are easy on it..

[andrewz9876]

yes thats what I meant, thanks

[andrewz9876]

any others Ideas???

[maddad]

With Alphas, it's not so much the motor bolted to the drive, but the nut that holds the steering wheel.

[andrewz9876]

ive got 380hp

[realbold]

With Alphas, it's not so much the motor bolted to the drive, but the nut that holds the steering wheel.
:rofl::rofl:

[Planetwarmer]

Ive got a big block bolted to an Alpha, its lasted since 1987 just fine.

[Cuda]

If you keep good oil in them, I think an Alpha can handle anything a Bravo can. I don't think you could hurt it no matter how hard you twisted the tail on an SBC. Alphas will be faster than a Bravo also.

[Just Say N20]

With Alphas, it's not so much the motor bolted to the drive, but the nut that holds the steering wheel.

:lol9:

While there are design limitations inherent in all mechanical devises, how they are used has an enormous impact on longevity.

I believe the Alpha outdrive will survive if used wisely. It is not able to handle huge torque loads well, so driving in a way that reduces them is key.

Full throttle hole shots = not good.

Wave jumping, which leads to the outdrive getting air while keeping the throttle open when landing= not good.

If properly cooled, WOT running isn't a problem because it is a constant load on the drive. It is the LARGE, QUICK changes in torque applied to the drive that cause problems leading to failure.

[Planetwarmer]

Yep! Dont slam the throttle open, or chop it closed, and you should be fine. I know a guy that ran 700 horse power in front of an Alpha 1. Is that drive ideal for big power? No. But it can be done if you respect the fact the drive is the weak link. Ideally, everyone should be running a Merc #8 drive. You wouldn't ever have to worry about breaking a drive, even if you jumped over the moon.

I use the Alpha1, because that is what my boat came with, and I cant justify spending the coin on a conversion when the Alpha 1 is doing exactly what the Bravo would be doing for me. Heck, I may even be getting an extra 1 MPH and a little better fuel economy out of the deal as well.

[Planetwarmer]

I am knocking on wood. I sure hope my drive doesn't break now.

[andrewz9876]

Agree with N20 and his theories, more horsepower can create more torque so what would the reason be to bolt more horsepower to an alpha if it can handle alot of torque. As a mercury enthusiast what is a #8 :confused: I thought a #6 dry sump is the largest drive they make.

[Planetwarmer]

As a mercury enthusiast what is a #8 :confused: I thought a #6 dry sump is the largest drive they make.

Not as of the Miami Boat Show. There is a new 1300 (turbo) and a #8 now.

[Sweet Cheekz]

500+ on my Alpha. Throttleing with care :nilly:

I would love a #8 but I'm not sure it will work on a 16.:shocking:

Parnell

[Ghost]

Agree with N20 and his theories, more horsepower can create more torque so what would the reason be to bolt more horsepower to an alpha if it can handle alot of torque. As a mercury enthusiast what is a #8 :confused: I thought a #6 dry sump is the largest drive they make.

Before even starting, let me be clear I'm no expert on this and others will know lots more.

That said, while torque and horsepower are clearly related to each other, the relationship is not a direct proportion at all. (HP = Torque x RPM ÷ 5252, with torque expressed in pound-feet.) So it's not as if the higher the horsepower, the higher the torque. There's a good discussion of the relationship here: http://www.epi-eng.com/piston_engine_technology/power_and_torque.htm You can have engines that rev really high and put out tremendous horsepower, with very little torque.

The engines we're used to in our boats (usually at least) see their greatest torque well below the max recommended RPM. But their greatest horsepower is achieved up at that max recommended RPM. (See graph below, which has HP and torque curves for two smallblocks.)

http://www.dynaformance.com/pics/ChevySBDyno.gif

However, I think to your point, it is generally true that the stronger the engines are that we use in our boats, the greater the peak torque.

But getting beyond all that, however, I think what may be most important here, at least in N2O's analysis, is not purely the engine's peak torque or peak HP. It's the rate of change of of the HP and/or torque and how it is applied. And I think this happens under three basic conditions.

1. First is with gently getting all the gears in contact AND slow changes of power/torque on that drivetrain once the gearing is nicely engaged and loaded.

2. Second is gently getting all the gears are properly in contact and loaded, followed by rapid application/removal of power. Maybe like a manual transmission car, where you have smoothly let the clutch out to finish the shift, and then apply a lot of power quickly.

3. Third is when the slop in the powertrain gets slammed hard into contact under heavy engine load, rather than gently (when power is applied rapidly but not smoothly). Maybe like revving up and popping the clutch.

My instinct is that the worst things you can do in regular use are that third category, where large changes in power/torque are applied rapidly and not smoothly. Slamming into gear, chopping power suddenly, getting air to the prop and slamming back into the water without cutting the throttle back to the right RPM to match the speed, whatever. All much like abusing the clutch in a car.

I am curious about category #2. This is the one where I get confused. My instinct on the math is that if the shifts are smooth and gentle, so that the powertrain is loaded smoothly, then the most the engine can stress the drive gearing is based on the max torque of the engine. So, as long as the application of power is smooth, applying power quickly wouldn't hurt the drive's gears any more than simply running at the RPM of the peak torque would. (It might wear the engine itself more to push it like that, but the gears in the drive would only get pushed as hard as the engine could push.) But my instinct at the helm is to take it easy anyway, and keep everything smooth and pretty gentle unless situations demand otherwise for safety.

A wildcard in this is the resistance/loading that the water puts on the drivetrain. Like a damper, water will resist fast movements far more than slow ones. (With your fist, try a nice hard but smooth shove of a floating chunk of railroad tie down into the water. Then punch it with your fist. Very different feeling.) So, maybe category 1 is best, and both 2 and 3 can beat your drive up a lot, with 3 being worse than 2.

I could be wrong about a bunch of things here--I typed a lot off the top of my head, without revisiting the physics very robustly. Others will know far more off the tops of their heads.

Mike

[Planetwarmer]

An easy way to look at horse power vs torque, is: 1 foot pound of torque is the amount of energy required to move a 1 pound weight 1 foot vertically. Horsepower is, how fast you move that weight.

These are not the engineering definitions, just an easy way to think of the difference between horsepower vs torque. If you want the definitions, Wikipedia them.

[Planetwarmer]

Before even starting, let me be clear I'm no expert on this and others will know lots more.



I could be wrong about a bunch of things here--I typed a lot off the top of my head, without revisiting the physics very robustly. Others will know far more off the tops of their heads.

Mike

You are correct. The constant pressure on the gears is far less than a sudden jolt of pressure on the gears. It is like jumping off of a roof. You don't weigh any more than you do standing on the ground, but the sudden pressure on your knees is far greater when you hit the ground than it was when you were standing.

(In certain situations)With a sudden jolt on the gears, it may be like having a motor with a constant torque value of 1000 ft pounds. That is why the gears or shafts break. In another situation, the sudden force on the drive would be as if your motor had 10000 ft pounds of torque. The situations are endless.

[MOP]

Me just like many others jump to quick to put a Bravo on Oh have to have a Bravo so I can go slower! A Bravo steals a tad over 2 MPH, I went new the $$ I spent on the package could buy at least 4 Alphas. Knowing what I know now there is no way in hell I would I would have switched. I had a fairly new Alpha that now has about 300 more hours on it behind my kids 9,000 lbs. fish boat, talk about feeling stupid! Instead of doing 65.5 I would be tickling 70, and had a bunch more $$ in my pocket! Yes having a SB in front of a Bravo I do have a pretty indestructible package, but much poorer for the mistake!

[Planetwarmer]

Me just like many others jump to quick to put a Bravo on Oh have to have a Bravo so I can go slower! A Bravo steals a tad over 2 MPH, I went new the $$ I spent on the package could buy at least 4 Alphas. Knowing what I know now there is no way in hell I would I would have switched. I had a fairly new Alpha that now has about 300 more hours on it behind my kids 9,000 lbs. fish boat, talk about feeling stupid! Instead of doing 65.5 I would be tickling 70, and had a bunch more $$ in my pocket! Yes having a SB in front of a Bravo I do have a pretty indestructible package, but much poorer for the mistake!

How much HP do you have?

[MOP]

How much HP do you have?

383 375HP 430tq in a 22, mine was built to have torque lower then most. It has a Lunati cam that was designed for a tournament ski boat that was to pull 8 skiers, it has bit more torque then some engines with more HP. Look at all the 22 with BB Alpha setups there are a bunch quite a few with high hours. Trouble is up here you get smoked into thinking you need more than you really do. It is like the header issue setup get little nothing for a fairly large investment! We get up here with the boys and pickup all these heady ideas, instead we should be using our heads!