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Graham
05-02-2007, 10:00 PM
Just got my new (used) boat wet for the first time last weekend! Fun ride, but am wondering if it's as fast as it should be. 1999 Classic 18 350MPI 300 Alpha, 21" pitch, half tank of gas, 220 lbs of people on board, 60 mph on the speedo at WOT. I hear people boasting on this site about near 70 mph speeds from this set-up. Can I expect more and if so, what should I do to get there? Just get a GPS? Thanks for any comments.
BTW, this is a great board, I think I chose a real nice boat largely based on decisions from tons of good info found here. Cheers.

Ed Donnelly
05-02-2007, 10:59 PM
Grham; Is this half tank,gas left over from last season????
If it is,that will be at least part of the problem....Ed

goatee
05-02-2007, 11:14 PM
since we're on topic,,, what about octane?

Cuda
05-02-2007, 11:23 PM
What rpm are you turning?

LKSD
05-03-2007, 12:50 AM
Depending on the drive ratio & altitude you are running at you may be able to get in the low 70's..

I ran a 1999 18 classic with a 1.62 A1 with a tuned 350 mag mpi running a 25p 3 blade Attwood ballistic & turned about 4900 rpms to get real low 70's in ideal situations.. ;) Jamie / Lakeside

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Graham
05-03-2007, 05:22 AM
Prop is actually 23" pitch, which I believe is stock dimension. Yes, old gas, octane unknown. What is CR on this motor and what is recommended octane? I believe tach read 5,000. Does my setup have a rev limiter and when does it kick in?
Jamie, when you say "tuned" what does that mean? Will my motor turn your 25" prop?
I will verify engine speed and drive gearing.
Thanks!

MOP
05-03-2007, 06:19 AM
You need seat time and fresh gas, don't over octane it that will slow you down. You just can't expect to do your best without some practice and having everything perfect in the engine box.

Phil

Pismo
05-03-2007, 07:03 AM
Trim, lots of trim. You also may be up against the rev limiter.

Johntrip
05-03-2007, 07:11 AM
you could wax your hull and gain about 6 mph......!!:lightning :boat: lol!!

glashole
05-03-2007, 07:39 AM
get it into rough water

it will speed up :wink:

LKSD
05-03-2007, 08:40 AM
MOP is right.. Also we had ours on the dyno when tuning it & made sure everything was right on spec wise..

Other than that no magic involved.. If you have a 1.62 ratio & are at roughly sea level & have some seta time you should be able to spin a mirage + or ballistic 25p prop & get similar results.. When I hit those speeds that was without using tabs & boat aired out.. If you are new to it, it may be a little unsettling until you learn how to run the boat like that.. Especially if you have to ride & drive out any chine walking... Also I no longer have the prop.. I kept it when I had my 22c but when I sold that I sold the prop too.. That prop would be too small for my my new ride.. ;) Jamie / Lakeside

Ranman
05-03-2007, 10:58 AM
Are you trimming the drive up at speed?

BigGrizzly
05-03-2007, 12:37 PM
I don't you will see 70. you don't have a mag. With a 1:50 drivve ratio that prop at 5000 rpms puts you about 63-65 mph. The fast people here have much driving experience which is worth about 3 mph, on a good day.

DonCig
05-03-2007, 08:42 PM
I am one of the slower folks on the site with a Classic 18.
Born South of the Mason Dixon line; if you know what I mean.
Have a 1997 Classic 18 with the 300 HP MAG MPI 350 and a Bravo 1 Outdrive with 1:65 gears and a Mirage Plus 25" RH prop. At 600' above sea level I could hit about 66-67 mph. After some expensive teaks I was able to get to 71 mph. After a very expensive engine replacement I could get to 82 mph. Now I just want some cheap gas so I can drive my boat; and no longer work on my boat. Enjoy what you have for as long as you can. I beleive that every day on the water is worth at least 20 days in the shop.

Don

Ed Donnelly
05-03-2007, 09:00 PM
Don,Don, Shame on you.... Enjoy the boat as long as you can before upgrading....He sure came to the wrong site for fuel economy tips..
There are a few Ontario members that would be more than happy to drive his Donzi as fast as it will go,and burn as much $4.50 a gal. gas :wink: :canada: Ed

DickB
05-03-2007, 09:08 PM
Prop is actually 23" pitch, which I believe is stock dimension. Yes, old gas, octane unknown. What is CR on this motor and what is recommended octane? I believe tach read 5,000. Does my setup have a rev limiter and when does it kick in?
Jamie, when you say "tuned" what does that mean? Will my motor turn your 25" prop?
I will verify engine speed and drive gearing.
Thanks!
My boat is identical to yours, with a stock Mirage Plus 23p. It also runs 5K rpms indicated, which is the high end of recommended. I can hit 62 under almost any conditions, but my absolute best (me only, 1/4 tank of gas, moderate chop, 60s air temp) was 64.9 GPS. I haven't duplicated that in 2 years.
A coworker has an older Baja open bow with a modified engine. He has run well in execss of 70. But he started with a modified engine and has tweaked it several times. He blew the engine and had it rebuilt with a bit milder setup. He had the outdrive reworked, rebuilt, or replaced - I forget which - a year or two ago. This spring the outdrive was making noise, and he had to put another $1K+ into it.
I've had my boat for 3+ years now, and it has been rock-solid reliable. No expense short of routine maintenance. It fires up instantly, idles perfectly, and has never left me stranded. I run regular gas (recommended). I've been tempted many times to get a few more mph out of it, but have decided to enjoy it as is. And I do enjoy it.
It sounds to me like you're running in the right ballpark for a stock boat. You can always make it faster, but there is always a cost of some kind. How much are you willing to spend?

DonCig
05-03-2007, 09:10 PM
Don,Don, Shame on you.... Enjoy the boat as long as you can before upgrading....He sure came to the wrong site for fuel economy tips..
There are a few Ontario members that would be more than happy to drive his Donzi as fast as it will go,and burn as much $4.50 a gal. gas :wink: :canada: Ed
Ed, I am sorry!!
I am driving a 2006 Dodge Mega Cab and am crying the gas station blues.
All I was trying to tell the young man was that it does not matter whether you are going 60, 70 or 80 mph. If you are in a Classic on the water; you have no cares or troubles. I know that the speed bug will bite him in time. LOL

Don

Ed Donnelly
05-03-2007, 09:40 PM
Don; I,ll trade vehicles with you any time.. My 2006 Ford F150 Harley Davidson A/W is getting a fuel sipping 10.5 M.P.G. at 65 M.P.H.
Can't wait to see what I get pulling the Criterion..........Ed

DonCig
05-03-2007, 09:47 PM
Don; I,ll trade vehicles with you any time.. My 2006 Ford F150 Harley Davidson A/W is getting a fuel sipping 10.5 M.P.G. at 65 M.P.H.
Can't wait to see what I get pulling the Criterion..........Ed
Ed, that makes me feel better. I am getting 15.7 mph at 73 mph and no wind. I was able to get 14.8 mph at 80 mph; no wind. I am getting 12.5 mpg in town. And if I have a head wind or I am towing a boat I usually get 10-11 mpg.

Thanks,

Don