endeavour32

iTrader: (4)

I've been looking for a pair of -2 drives and I have a line on a pair of Sportmaster -2's. From all the searching on here, it really seems that the Sportmaster is slower on a Straight bottom V than the IMCO. So here is what I have: and '89 Formula 292 that is running around 71 GPS right now with the old school blunt nose bravo lowers. This boat has deep drives and in my opinion could really benefit from a shorter drive to get the X up. That said, the general thought is that the IMCO is faster than the Sportmaster, but seeing that I'm raising the X I would still think it would be a big improvement over my current lowers. I've been digging for at least a year on the Formula section, for info on anyone that has run shorties on an older bird. But there is just lots of talk about it, and from what I can find- nobody has really ever done it. So, has anyone with an old, deep x boat, used sportmaster shorties and seen an improvement in speed? If you've used them, would you post your gains or loss, and what kind of boat you had it on.

BenPerfected

You are on the right track. The IMCO skag is shorter than the Merc so the Sportmaster scrubs 1-2 MPH compared to the IMCO but both will allow you to raise your X. If you drives are currently 5-7" below the bottom, you likely have a + 7-10 MPH opportunity if you are up for a total re-rig of the drive train. The re-rig cost will likely exceed the value of the boat. However, if you do this enough times, I have seen some fools exceed the value of their boat by 10X.

endeavour32

iTrader: (4)

So by re-rig of the drivetrain what exactly are you referring to? I'm not going to go so far as add stand-off boxes but used lowers can be had for some fairly reasonable deals.

BenPerfected

The cost to get your prop shafts 2-3" below the bottom of the boat will likely mean boxes, changing the engine heights which could mean custom hatches or sticking your carbs thru the hatches.....ask me how I know.��
If you just want to install -2" lowers, you can likely get +3 to 4 MPH and the Mirage props will likely still be the best for top end. I doubt you will get much more speed because your drives will still be too deep to pick up significant efficiency. The real speed improvements come from really high X dimensions....like -2" below the below the bottom.

sutphen 30

your going to have to find the shortest drive possible,I like the imco as for the same reasons stated above.

endeavour32

iTrader: (4)

Well I know I'm not going to start moving engines and filling and re-cutting my transom. I don't live in an area anymore where I can do that and my boat is 5 hours away from me. If it's not a bolt on solution then it won't be done. I could raise then engines a good 2" and still keep my hatches. If I can find a good deal on some -2's I may start there, otherwise it sounds like I really may need -3's. Right now I've been running Bravo props. The boat walks on plane like a ski boat. I've tried a variety of 4 blade props but never tried any 3's. It was pretty much agreed on in the Formula section that while you gave up 2 mph the Bravo's and Hydro's, they were superior. When I go up to the boat this weekend, I'm going to get some measurements. I really don't remember what my X is, I just know its deep.

sutphen 30

thats because it was set up for ride comfort and keeping the props planted in the water.
I know first hand ,I take my 2.5" spacers out and my boat gets flighty on every wave,,way more throttling.w/ the drives deeper( a whole 2.5"s) is way smoother,but I do give up about 2-3mph.
whats nice is I can go back and forth in about an hour so,I can runhard and fast during poker runs and then go back to relaxing most weekends.I don't need it on kill all the time.

BGIII

iTrader: (3)

In my experience, ^^^^^^ this is exactly what you can expect except my guess would be 1-2 mph with 2" shorties versus Sutphen's 2-3 mph w/ 2.5" spacers. If you boat on Lake Michigan or are on and off plane frequently, you may not care for the trade offs for such small gains, especially if you are a pleasure boater. Keep in mind that you will have to change props, may have water pressure issues to deal with, boat will not walk on plane anymore and you will have low water pickups, which are more likely to pick up garbage than the side pickups I assume you have right now. I have no scientific facts to back this up, but I believe that deeper drives live longer. IMO, shorties are not magic on the older straight bottom boats, especially if your boat likes a fair amount of trim and if you like the way it handles as is. They can and do work, but are not necessarily the simple bolt on they appear to be. BTW, I was given this same advice several years ago, I'm just adding my .02 and passing it along. LOL

If buying used, it is best to assume it is all junk inside, even if the guy advertises them as having "about 60 hours". He may have inadvertently left out "in both directions" and "on kill the whole time". Lastly, they are not that easy to sell if the experiment fails, everybody wants to pay less than the cost of a new bare case for a complete lower, which is understandable after what I went through.

Good luck with your decision, I personally think the correct path is more horsepower or leave it alone, not shorty lowers.

endeavour32

iTrader: (4)

So do you guys really think there is only 2 mph to gained by switching to a shorter drive? For the 5-6k its going to cost I would rather buy new heads for that money and gain a whole lot more than that. That is the one thing I hate with this idea, is nobody has done this on my boat, so its a pretty expensive test.

class6

Try a set if you can find them. If they are not what you expected. Sell them. They are always for sale on the site. It's only money!