ASD 8 vs #6
 

I've decided I'm not going to run my SSM #4's and I'm going to switch to a set of wet sump 6's or ASD 8's with a drop box. I'm really leaning toward the Arnesons, due to all the reasons guys switch to them, simplicity, efficiency, and reliability.

From what I've read, you need to plan on rebuilding #6's every 250 hours. Is this really true? If so, that right there makes my mind up for me. Other than that, is there anywhere a 6 will out perform an ASD 8 set up? I could careless about dock manners, so that doesn't play into the equation at all.

How much power you plan on running?

Around 1100 hp a side.

ASD8 are rated for 1200hp from twin disc and 1600hp from Rik

ASD6/7&bravo conversion are rated for 600hp from twin disc and 800hp from Rik

Merc dry 6 are about 1175hp, I'm guessing wet are close

All are great drives, and obviously all have been behind more power than rated for

Yes Merc drives require freshening and rebuilds more often than one would think is needed, but they do

Hard to find used AS8 that have reverse rotation, and a pair of new can exceed 100k fast depending on options

Next problem is finding the correct drop box length cause you will have to lower your engines or raise them depending.

Merc #6 you most likely will have to raise your engines

All the drives are designed to surface the prop. None of the Arneson romurs are true lol. There's a skeg and half the prop in the water. The only negatives to the Arnesons are getting them mounted correctly the first time where as the #6 you can mount a little high and space down as needed. Majority of the time an Arneson needs to be mounted as low as possible because the ball socket is aproximently 10" in diameter and the prop is in the center of that, so if you mount the bottom flush with the bottom the prop is still a few inches up. Now there are transom angles to consider etc. But visualizing that helps realize why the ASDs need to be mounted low on the transom.

Half the battle with any upgrade is finding the right prop, sometimes a round ear clever works good.

I would keep your drives, maybe gather gather a spare or 2. Neither conversion is worth the time or money for the average boat! LOL! Now if you are keeping this as your dream boat for many years than go for it!

that notch in your transom, will it help or hurt mounting arnesons ?

going way out on the crazy limb on this one but, w/ drop boxes angled in, as in side by side engines with the
arnesons set @ 20 inch or so centerlines, would a pod built into the notch facilitate mounting the arnesons closer to the bottom ?

the turbine warlock thread, he extended the center pod (straight) for his build.

the pod i'm talking about would be an inch from the bottom and angle up at "X degrees" to cut the depth of the notch in approx
half and be flush w/ the transom so you'd get some benefits from the notch and the close center line drives.

almost don't want to click post quick reply after re-reading this one but i'll take the hits

Yes it's pretty common to fill the notch, sometimes just the shape of the ASD drop box

^^^ zactly what i'm saying. a pod built into the notch for the arnesons not full depth tho maybe half but that's
a spitball guess on my part (have to dummy it up and eyeball it to see)
somebody's done it and knows what they'd do different and why.

post 4 drop boxes angled in maybe not the exact drives but you get the jist
https://www.offshoreonly.com/forums/...4-top-gun.html

https://cimg3.ibsrv.net/gimg/www.off...ba6cd3982e.jpg
Dan-
Your correct in your assumption with filling in the notch just enough for covering the drop box. The ASD 6 on the extension box (ASD 7M) is another option, and while its not rated for the power output I have, I'm sure it could handle it. I know there are guys the have put a 1000 hp to them and they lived. It's a pretty affordable set up, a lot less than ASD 8's. What I would like to do is find a nice set of used asd 8-6's or 8-10's, and rebuild them. That is what I like about Arnesons, most of the parts that wear out are just standard automotive parts, which are cheap.

Kevin, as far as moving my engines, as you can see here, that isn't really a concern. lol.

I think you would be looking for 10 or 16 inch drop box setup. The 6 inch drop will probably require the crankshaft centerline to be so low it won't work or you need to move the engines forward a foot or so to fix the driveshaft angle issue. Unfortunately only the six inch drop box has the counter rotation option.

Kris, your looking at it wrong... The centers are 6" not the crank to bottom of the boat. This puts the engine usually the same as a TRS location or 1" lower than a Bravo at most. (some engines are mounted really high to get the X up but were not addressing a boat like that here)

He should be looking at our #7M Kit... If the boat is not a stagger then there is no concern for a notch issue as the notch ends on the normal 34.5-35" center line.