86 268 sundancer w/260 merc HELP!!!

[stoney177]

86 268 Sundancer w/50 hrs on 260 engine and 15x15.25 bravo 1 outdrive. Everything is completely stock and it runs very good. 31.5mph wide open throttle at 4400rpm. 3200 cruises at 26. Are there any "simple" modifications to get a little more out of this setup? It still has stock ignition and carb. Coil, plugs, Cam, Prop, any experience is greatly appreciated. I know this setup is weak but I hoped to be able to get 30 & 35 mph out of it. Is it possible? Thank you
Phil

 

[Quint4]

Sounds like good numbers with that set-up...better numbers than others with that set-up...be happy.....do some site searching , this boat / engine / drive combo has been heavily discussed fairly recently....Welcome to CSR.

 

[Sundancer]

I don't think the Bravo was "stock" until around 89 or later? Either way, the cruise looks good at those rpm's. Isn't the suggested WOT a little higher than 4400 RPM's? I think you could drop the pitch an inch or two and see what happens. That will mean your cruise rpms could be higher once on plane.

I think the 454 in that boat MIGHT get you up to 35! It's got a pretty deep V which makes it great in rough water, but requires a little more oomph to get it up and keep it up on plane.

 

[Jimmy Buoy]

I had an 89 268 with a 7.4 Ltr 330 Hp and a Bravo I spinning a Stainless Mirage Prop. Might have done 33MPH on a good day but it did seem stern heavy. Put 24" wide trim tabs to help stabilize the boat since it is relatively top heavy and also to be able to stay on plane at low 20 MPH speeds. Worked well. :grin:

If you want to go FAST there was someone in our area that removed his 268's two 4cyl engines and fitted 2 - 4.3 V6 engines. Uses it for fishing tournaments. Man - that thing runs like a scalded cat!! :wow:

Way too costly to look at changing a single to twins though...:huh:

Sounds like your boat is running pretty well as is. You know what they say "how fast you wanna go, depends on how much you wanna spend the dough!":thumbsup:

 

[lime4x4]

I have the same boat.Except mine has an alpha drive. Numbers are close to what i get. Which took months of tweaking.The boat is a heavy beast.I know for a fact with full load of fuel,water and toys she weighs in at just under 7500 lbs

 

[CaptainH]

I run a 16x16 prop. Any way you look at it that is a lot of boat to push with that motor. I have a cousin from Germany who went out on my boat first time last summer, he was a BMW master mechanic and says he will help me soup up my motor when he comes back this April. He assures me it will have a lot more power, not sure what that means!

 

[mendesb]

I have an 86 268 260 hp 350 with the right prop. A 16x13. it does 19 mph at 3300 rpms. This is all you will get from this set up unfortunatley. I was going to get 383 stroker w/400hp which would help but my mechanic says there is no replacement for displacement meaning a 454 would do a better job with a 15x15 prop. a 454 would cruise at about 26 in my opinion because a 1991 270 cruises at 23 with a 454 and its heavier. Sorry, these these boats are under powered with a 5.7.

 

[mendesb]

Does anybody know the mph cruising speed at say 3400 of an 86 DA with a 7.4

 

[stoney177]

Just an update, Thank yo ufor all the feedback and YES it is an alpha 1 unit. I fould an NOS "Ballistic" 14.875 x 15 stainless prop and reduced the 15.25 x 15 aluminum. The performance change was incredible. Boat gets up on plane in about half the time and top speed went up to 35.2 GPS verified at 4400 RPM. This prop has an odd design. It looks like the prop blades were cut off at the end. I think it will get a little more if I can get the RPM to 4800 but I may need some engine modifications. Once again, this prop setup for this boat made significant improvements. Thanks again:smt038

 

[BonBini]

Stoney177: We have similar boats excect for BIG BLOCK:grin:. Before I sold my 230 I played around with the two differant flame aresters I had at the time. I found that the taller flame arester on the 260 Merc put 3 mph instantly to the wot of the 230. That prop you scored sounds pretty awsom. I'll bet with a high flow flame arester you could be flertin with 37. Btw, 330hp with a cupped 15x15 alum or ss will push my boat 40mph gps. ...Ron