Go Back  Offshoreonly.com > Owners Forum > Fountain
Prop help 2002 35 lightning w 730 hp >

Prop help 2002 35 lightning w 730 hp

Notices

Prop help 2002 35 lightning w 730 hp

Old 06-20-2019, 10:03 PM
  #21  
Registered
Thread Starter
 
Join Date: Sep 2016
Posts: 56
Likes: 0
Received 0 Likes on 0 Posts
Default

Thanks Terry and everyone,

Allen I really don't want to break a bunch of drives though lol, if I run the 4 blade and stay away from the 5 blade that should help with that correct?
marcusnapier is offline  
Old 06-21-2019, 09:45 PM
  #22  
Registered
 
Tinkerer's Avatar
 
Join Date: Jan 2002
Location: ALTO, MI
Posts: 4,612
Received 7 Likes on 6 Posts
Default

My 26 Daytona was a totally different problem than you are having.
You are getting on plane and it sounds like you have it pretty much worked out.
I am not up on your X dimensions - How far is your prop shaft below the bottom of your boat?
The 5 blade prop is going to get you on plane faster but is going to cause a lot of transom lift and will not be as fast as a 4 blade.
IF you can get on plane normally ( for a performance boat ) with the 4 blade that is going to be you best all around prop for speed and handling.
The 5 blade causes more transom lift than the 4 blade and may cause ill handling such as bow steer and chine walk.
With my boat being a cat - they don't like transom lift. I did everything to settle the transom that I could.
A few stats
I redid the transom and raised the drive about 1 1/4 inches on the transom.
Than I installed a neutral extension box and mounted an IMCO -3 shorty lower mated to an X drive upper 1.36 ratio ( built by Mr. Gadgets)
This puts my prop shaft right at 2 inches above the lowest point on the bottom of the boat. This is the height that the race guru at Eliminator told me to do.
NOW the issues.
With a stock 28 pitch Bravo 4 blade the boat wouldn't go any faster than 5 MPH and blew out instantly.
My old Glastron had a high X also and to get the boat on plane I modified the trim rams ( shortened the rod 3/4 inch ) this mod allows the rams to collapse farther thus allowing the drive to tuck under farther ( negative trim ) there are other mods that have to be done to the transom assembly also.
I did this to my Daytona and this allowed the boat to get on plane with the 28 and a little better with a 5 blade Maximus. I was still getting too much transom lift so I cut the diffuser ring off both props.( the diffuser ring acts like a ski ) This stopped the excess transom lift but caused a problem getting on plane ( I had to go to 6000 RPM )
As SB said I blocked the exhaust passage at the top of the lower half using a piece of Lexan and 4200 to seal it air tight.
This fixed the problem and I was getting on plane like the diffuser rings were still there.
.I bought a BBlades labbed 28 Bravo and it would get on plane fairly normal for a cat. Prop slips so you just hold the RPM at 5000 and when you get to about 25 MPH you pull the throttle back and than re apply and it hooks up and hang on.
With the stock 28 my best top speed was 107 but most days it was 104 - The labbed 28 did 112 any time. - all props were at 6100 RPM
I am still working with props since my limiter is set at 6500.

Last edited by Tinkerer; 06-21-2019 at 09:47 PM.
Tinkerer is offline  
Old 06-25-2019, 01:49 AM
  #23  
Registered
 
Join Date: Jan 2016
Location: San Tan Valley AZ
Posts: 491
Received 13 Likes on 8 Posts
Default

Originally Posted by SB
Have you guys with cut diffusers with twins that are having a hard time planing blocked the airflow thru the exhaust passage ? A few of us have with single engines with great results. Tinkerer with a Bravo 2"above transon in 26' cat and me to a small boat with alpha ss. Neither of the boats could get on plane with the diffusers cut until blocking the airflow thru the prop.. Oh,both boats thru hull exhaust...so just outside air going thru prop.

I haven't heard of anyone else trying,thus why bringing it up. .We usually bring this up in single engine threads.
I had this same problem/fix last year on my 28 daytona. I went to true value and grabbed 2 rubber plumbing cap and hose clamps and blocked the drives. Before this nothing worked. Tried 5 blades, tunnel tab, and pixie dust. Every time it would blow out once boist on the old engines kicked in. Cap cured it. Wish I would have done it first. Cost alot of money chasing the issue for a $3 repair
mggdoors is offline  
Old 06-25-2019, 07:57 AM
  #24  
SB
Registered
iTrader: (1)
 
Join Date: Nov 2004
Location: On A Dirt Floor
Posts: 13,520
Received 3,090 Likes on 1,392 Posts
Default

Same with me, as I noted above in the Alpha SS case, it took a 2" rubber PVC cap.

What size did you use on the Bravo's ?
As you can see. Tinkerer blocked it another way. He did this so that the drive(s) could have water in them to help cool.
SB is offline  
Old 06-25-2019, 09:36 PM
  #25  
Registered
 
Tinkerer's Avatar
 
Join Date: Jan 2002
Location: ALTO, MI
Posts: 4,612
Received 7 Likes on 6 Posts
Default

Also the joint between the upper and lower is not sealed and can suck in air at that point if you just block the opening at the front of the helmet.
I also sealed this joint above my piece of Lexan to make the exhaust passageway in the upper hold water. when on plane my entire drive is out of the water except for the skag below the bullet.
I have my excess water ( what would normally be going to the exhaust risers on stock exhaust ) dumping onto the top and sides of the upper to help cool it. all this seems to work since There isn't any chalking or discoloring at all.
Tinkerer is offline  
Old 06-25-2019, 10:59 PM
  #26  
Registered
 
Join Date: Jan 2016
Location: San Tan Valley AZ
Posts: 491
Received 13 Likes on 8 Posts
Default

Originally Posted by SB
Same with me, as I noted above in the Alpha SS case, it took a 2" rubber PVC cap.

What size did you use on the Bravo's ?
As you can see. Tinkerer blocked it another way. He did this so that the drive(s) could have water in them to help cool.
I dont remember the size off the top of my head
mggdoors is offline  

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


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.