prop sugg. on a 84 272 ls w/ 5.7 twins?

Reply Subscribe

Thread Tools

09-08-2005 | 08:12 AM

#11

throttleup

Registered

Joined: Mar 2002

Posts: 5,143

Likes: 1

From: Cajun Country

Re: prop sugg. on a 84 272 ls w/ 5.7 twins?

MUCH BETTER!!!!!!!!!!!

You still have 19% slip though. You should be at 15% at a minimum with the 3B Cleavers. You are running right were you should be with the 5.7 L motor at the 4800 RPM at WOT. I think you should try to test some Mirage Plus 21P props and see if they bite a little better.

Julie

09-10-2005 | 12:19 AM

#12

flatout

Thread Starter

Registered

Joined: Jul 2005

Posts: 158

Likes: 0

From: Napa, CA

Re: prop sugg. on a 84 272 ls w/ 5.7 twins?

Can anyone give me some pointers on swithing the gears around in the drives to make the port drive turn LH? I have no Idea how to tear apart a drive though I am very mechanically inclined do most of my own work on my trucks and hot rods. Is it something I should take to a shop?

09-10-2005 | 07:10 AM

#13

BajaRunner

Registered

Joined: Nov 2001

Posts: 3,622

Likes: 2

From: Austin

Re: prop sugg. on a 84 272 ls w/ 5.7 twins?

Quote:

Originally Posted by flatout

You have to buy a counter rotating alpha drive. they are very hard to come by.

09-10-2005 | 10:31 PM

#14

Pat McPherson

VIP Member

Joined: Oct 2002

Posts: 5,246

Likes: 3

From: Ivoryton, CT

Re: ok new #'s

Quote:

Originally Posted by flatout

I got a best of 52.8 on the gps this time at a solid 4800 rpms.

This may sound like a stupid question, but I had a friend that made this mistake last week...
Are you sure your gps is reading mph and not knots/hr?
Your boat should go 60mph with 21p at 4800 engine rpm.
53knots is about 60mph...

__________________
Patrick

09-12-2005 | 03:48 PM

#15

yikes

Registered

Joined: Feb 2003

Posts: 44

Likes: 1

From: Nahant MA, Harrison ME

Re: prop sugg. on a 84 272 ls w/ 5.7 twins?

Just installed a counter rotating drive on my 1986, 24ft Daytona. Went from 20p aluminums to 23P Mirage. Runs straight and handles much better. GPS at 61MPH at 4400 rpm. Have stock 260hp 5.7 w/ alpha I drives. Got a new drive on Ebay for $1600. Now need more power.

09-12-2005 | 04:30 PM

#16

pullmytrigger

Registered

Joined: Jul 2001

Posts: 4,837

Likes: 94

From: oshawa ontario

Re: prop sugg. on a 84 272 ls w/ 5.7 twins?

to make an alpha counter rotate you switch to a counter rotating lower.......you do not have to change the whole drive...............doug

09-12-2005 | 04:54 PM

#17

flatout

Thread Starter

Registered

Joined: Jul 2005

Posts: 158

Likes: 0

From: Napa, CA

Re: prop sugg. on a 84 272 ls w/ 5.7 twins?

Thanks guys I will start searching on ebay for a counter rotating lower.

09-12-2005 | 04:55 PM

#18

pullmytrigger

Registered

Joined: Jul 2001

Posts: 4,837

Likes: 94

From: oshawa ontario

Re: ok new #'s

Quote:

Originally Posted by flatout

My drives are Alpha ones does that limit me? is there any shorty lowers or any performance upgrades for them?

your alphas arnt going to limit you ......they are actually faster than a Bravo due to a smaller gearcase and less mechanical drag from smaller/lighter gears and shafts.......there are no shorty lowers available only a VERY rare "Alpha SS" drive from Mercury that is 2" shorter than a stnd Alpha.....from what I understand (Ive never seen one) you cannot modify a stnd Alpha into an SS they are their own animal ( I could be wrong though)........my very knowagable drive guy said Merc did offer a hardened upper gearset fothem but now the new ones have all been brought up to that spec.......you can have aftermarket nosecones installed and a Simrek drive shower is definatly a high performance modification......they run hot!!!! ........change drive oil often and watch the level.....if it gets even a little bit down you are in trouble