Repower ?

[Sam]

I am thinking about repowering my sixteen, my question is this. How much hp might I need to get in the mid 60's. My current stock 5.7 210-20 hp gives me 56mph (gps). One other thing, I don't want to change my alpha drive.

Sam

[BigGrizzly]

You need another 150, hp minimum to start. A SS lower would be nice. By mid 60's I assume you mean 65+ on GPS. Most guys here will tell you how hard it really is. Some will say it is easy but that's not true. Good luck. I know the guys here will give information freely, so gofor it

Randy

[Dr. Dan]

Sam, there was a gentleman at the Jackson Poker Run this year who had a killer 16', I will look for his card and see if I can't get him on our board here, he had a built 302 or 351,and it moved right there with the big boys until we hit 2' to 3'waves or wakes. I'll let ya know what I come up with...Doc ;)

[Ranman]

Sam, I pull 66mph with my new lab prop. This is on an 18' with 300hp and a Bravo. I know they put 350MAG's in front of Alphas. I dont see why a 350MAG or 300-320hp wouldn't get you there. The alpha would actually run a tad faster than the Bravo. Point is, I bet with 300hp you would run 65+ although that is 80-90hp away. I would think you could either swap your existing engine for a MAG or you could chase the extra power down with heads, cam, intake, and exhaust.

[Barry Phillips]

Sam: I have a 1998 18' with a Bravo 1 drive
swinging a 23" Vengeance prop. My stock 5.7
(350) is only rated at 250hp, (I do have plans
for this motor) but for now it's a nice
running package. I can run 65 to 67 mph on a
good day, and 63-65 all the time. I lose about
2-3 mph in hot humid weather. The Vengeance
dose not like to much trim because it really
begins to slip. I was advised I need to run
another 150hp to get this boat in the low
to mid 70s, which is fast enough for me. I am
not shure about the hull differences between
the 16s and 18s but an honest 100hp at the prop should get you where you want to be. My boat has been checked by radar and both Geoo and Chris have been in it.So it is as fast as
I describe.
good luck
SO-SLO

[CDMA]

Of all the Donzi's I have been in I have to say that Barry's is the one that suprises me the most. I just can't figure how I keep seeing 65.2 on the gun with full fuel and 2 guys out of a 250hp 2 BARREL :eek: 350. Boat really runs well.

Chris

[Sam]

Barry, what kind of rpm's are turning at top end.

Sam

[GEOO]

Chris,

I think Barry must have a sneeky NOS kit!!
No, real he does have the fastest 250hp 18 Donzi. GEOO

[Max]

I have a new 16 with a 5 liter fuel injected mercruiser, alpha 1 generation 2 drive and a 23 pitch Mercury Revolution 4 propeller (Stainless Steel)and I get a steady 62 mph on my gps. I am 150 rpms short of the top recommended rpm at wot but the dealer says that I will reach top rmp and gain a couple of mile per hour once the engine breaks in.

[Barry Phillips]

Sam, Im running 46 to 4800rpm but I'm not
sure how on the VDO tack is. I ordered the
boat in May of 97 with a 4 barrel carb
(275hp) I did not feel the 25hp gained by
MPI mag was worth the S3000.00 price tag.
The boat delivered as a 98 and
the 4 barrel was dropped in favor of a
2 barrel Weber made in house. I am looking
into a Demon marine carb. headwork and a
cam. depending on budget. Does anyone have
any experience with Demon carbs?. Sam you
mentioned that you are makeing 220hp in your
16, are are you shure it's a 5.7 not a 5.0
what year is your boat. The newer V8 16s are
running 305s and 58mph is about right. What
kind of Carb are you running.
SO-SLO


:cool:

[Sam]

Barry, I must admit that I'm not a real gear head. I know enough to get around in the engine commpartment, but to say anything more would be a misnomer. When I bought the boat I knew it had been repowered. I took it to a Mercruiser mechanic and had him give it a physical. He thought is was a 5.7, he did a few minor things and gave it a clean bill of health. He did mention that the motor had very few hours on it based on the hone marks on the cylinder walls. As for the carb I have no idea what make it is, all I know is that it is a 2 brl (shame on me). I have spoken to a few other owners with 5.7's and they have reported the same basic performance as me. With the 21" Stiletto I turn 4400 rpm @ 56 mph (gps). Based on that I have another 400 rpm's that are available to me, I just need to find them. Even if I do I know that it dosen't guarantee me any more speed. If you can share any info regarding this "Demon" carb I would be interested. Are you looking at a 4brl or just a replacment for your current 2brl.

Sam