Like Tree0Likes

Prop Size ? for single engine 454 MPI ?

Reply
Old 05-03-2005, 12:36 PM
  #1
Registered
Thread Starter
 
Join Date: Aug 2003
Location: Dallas, Texas
My Boats: Currently Looking for 25-27 Eliminator
Posts: 40
Default Prop Size ? for single engine 454 MPI ?

I have a 99 Donzi 28ZX with a single 454 mpi engine. It is currently running a Hydromotive 4 blade 20 prop. Does anyone have any recommendations for maybe going to a larger prop to gain a few more MPH ? Thanks
YELLOW7 is offline  
Reply With Quote
Old 05-03-2005, 01:07 PM
  #2
Gone Fishin'
Charter Member
 
Waterfoul's Avatar
 
Join Date: Nov 2000
Location: Grand Rapids/Holland/Grand Haven
My Boats: 1988 Tracker Pro 17, 40 hp Mariner.....1972 Glastron GT 140, Merc 50 power!!!
Posts: 7,408
Default Re: Prop Size ? for single engine 454 MPI ?

Need some more information. How many RPM do you get spinning the 20 Hydro? How fast are you currently going? Does it ride bow high or stern high (hydro's normally carry the stern if I remember correctly)? How is the handling?

Labbing a prop usually gives you another 200 rpm or so... but if you are already at redline with the 20 Hydro, you might have to have them add an inch of pitch when they lab it to bring the rpm's back down, which results in more speed.

There are some merc. dealers who have specially painted (blue) loaner props. Or ask some of your friends with performance boats if you might borrow their prop for one spin around the lake. I'd think that if the 20 hydro works, you might like a 22 Merc. Bravo One prop (especially a labbed one).

'Foul
__________________
[b]M Go Blue.......Gator boots, gator luggage, gator purses... all at cut rate deals!!!!
Waterfoul is offline  
Reply With Quote
Old 05-03-2005, 05:34 PM
  #3
Registered
 
throttleup's Avatar
 
Join Date: Mar 2002
Location: Cajun Country
My Boats: AKA Throttle Up Propellers
Posts: 5,143
Default Re: Prop Size ? for single engine 454 MPI ?

Like Waterfoul said we need a little more infomation about your boat.

What is your WOT RPM and MPH (gps)?
What prop and pitch are you running currently?
What is your gear ratio?

I am sure with a little information we can take a step indialing you in.

Julie
throttleup is offline  
Reply With Quote
Old 05-03-2005, 07:33 PM
  #4
Offshoreonly Advertiser
Offshoreonly Advertiser
 
bbladesprops's Avatar
 
Join Date: Jun 2003
Location: Princeton, Wisconsin
Posts: 3,723
Smile Re: Prop Size ? for single engine 454 MPI ?

We have had great success on ZX's with Lab Finished Bravo 1's

Echoing everyone else, we need to know the current rpm and speed of your rig to determine the correct pitch to work with.
__________________
Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
bbladesprops is offline  
Reply With Quote
Old 05-11-2005, 03:50 PM
  #5
Registered
Thread Starter
 
Join Date: Aug 2003
Location: Dallas, Texas
My Boats: Currently Looking for 25-27 Eliminator
Posts: 40
Default Re: Prop Size ? for single engine 454 MPI ?

Ok, sorry for the delay. I had to get the boat back in the water.

I took it out with 3 people and 90 gallons of fuel and it ran consistently 58mph (speedo) at 5200 RPM's.

Let me know what other information you may need.

Thanks
YELLOW7 is offline  
Reply With Quote
Old 05-11-2005, 03:56 PM
  #6
Gone Fishin'
Charter Member
 
Waterfoul's Avatar
 
Join Date: Nov 2000
Location: Grand Rapids/Holland/Grand Haven
My Boats: 1988 Tracker Pro 17, 40 hp Mariner.....1972 Glastron GT 140, Merc 50 power!!!
Posts: 7,408
Default Re: Prop Size ? for single engine 454 MPI ?

Sounds like you are under propped to me... Need more pitch... possibly a 22" or possibly even a 24" labbed Bravo One. By yourself and with less fuel you are going to be banging the rev limiter...

Also ask yourself, how will you be doing most of your boating? Light fuel? You and one other person? Or will it be heavy fuel, big cooler of refreshements, and several friends? If it is the latter, you are about right on... maybe have your prop tuned down a few hundred rpm to say, 5000 rpm with a loaded boat?? There are several reputable prop shops advertising here on OSO that can "work" your prop for you.

'Foul
__________________
[b]M Go Blue.......Gator boots, gator luggage, gator purses... all at cut rate deals!!!!
Waterfoul is offline  
Reply With Quote
Old 05-11-2005, 05:23 PM
  #7
Registered
 
throttleup's Avatar
 
Join Date: Mar 2002
Location: Cajun Country
My Boats: AKA Throttle Up Propellers
Posts: 5,143
Default Re: Prop Size ? for single engine 454 MPI ?

Assuming that you have a 1.5 gear ratio then it appears that you have 12% slip which is not bad for a 4B propeller. I agree with Foul that you need a taller pitch propeller.

Are you able to put full trim into her as well as full throttle? This will help us to determine exactly how tall of a pitch you may need. Additionallly how is the attitude of the boat? Do you like the way she feels or carries?
What are your goals? This information will help us to provide you with propeller suggestions.

Julie
throttleup is offline  
Reply With Quote
Old 05-11-2005, 06:08 PM
  #8
Offshoreonly Advertiser
Offshoreonly Advertiser
 
bbladesprops's Avatar
 
Join Date: Jun 2003
Location: Princeton, Wisconsin
Posts: 3,723
Smile Re: Prop Size ? for single engine 454 MPI ?

These guys are right. A little more info as to your goals and a prop suggestion can be made.

So far I like Waterfouls suggestion on the 24 Bravo 1 Lab. It has been a good match for your rig in the past.
__________________
Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
bbladesprops is offline  
Reply With Quote
Old 05-12-2005, 11:36 AM
  #9
Registered
Thread Starter
 
Join Date: Aug 2003
Location: Dallas, Texas
My Boats: Currently Looking for 25-27 Eliminator
Posts: 40
Default Re: Prop Size ? for single engine 454 MPI ?

Normally I will have probably (4) people and at least 1/2 a tank of fuel.

Definetly have hit the rev limiter if I try to trim it up all the way. When I have a full tank and 4 people I can trim it up a little more but in only one instance have I been able to trim it up all the way without hitting the rev limiter and that was with a full tank of gas and 5 people.

With (4) people and it trimmed up a little it runs great, gets up on plane quickly....no complaints so far. Just looking for a little more top speed.
YELLOW7 is offline  
Reply With Quote
Old 05-12-2005, 03:51 PM
  #10
Offshoreonly Advertiser
Offshoreonly Advertiser
 
bbladesprops's Avatar
 
Join Date: Jun 2003
Location: Princeton, Wisconsin
Posts: 3,723
Smile Re: Prop Size ? for single engine 454 MPI ?

As the boat sits deeper in the water you could trim it farther.

If you go up in pitch and Lab Finish to regain the rpm, your peed should follow.
__________________
Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
bbladesprops is offline  
Reply With Quote
Reply

Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
articfriends
Wanted
1
09-16-2008 09:31 PM
rangerrick63
General Q & A
9
05-07-2007 10:05 PM
NetGain
General Q & A
12
06-08-2004 09:29 AM
puder
General Q & A
4
04-25-2003 09:40 AM
HyperBaja
General Boating Discussion
3
09-25-2002 05:11 PM



Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 04:45 AM.


Copyright 2011 OffShoreOnly. All rights reserved.