Null


Pages: [1]

NoRestraint

  • Karma: +0/-0
Sleekcraft SST max 4,000 RPMs on water
« on: June 02, 2012, 07:32:10 PM »
Hi guys! So I didn't get to any of the work I wanted to over the past year because work has been slow. However it's picking up for the summer which means new parts :). Last year we all talked about messing with the secondaries and timing and cleaning the jets etc. I think I found the problem of why I can't get any faster on the water. I'm very poorly educated on engines and jet pumps but I found this chart on the PJB site,

http://www.jetboatperformance.biz/pages/calculator.html

So while I'm trying to become familiar with motors and jets, here is my understanding from this chart, PLEASE CORRECT ME IF I'M WRONG. So I really have no clue which impeller I have but I'm guessing it's an A. For all I know, the motor is a stock 1986 454 which produces 230 HP. It has a Holley marine 715 CFM carb if that info helps at all. While looking at the chart on the PJB site I noticed that the correlation on the chart is 4000 RPMs, around 230 HP with an A impeller. So the way I am understanding this is that this is the highest my boat will perform with the current combination. I appreciate the feedback and any help you guys can offer. I'm trying to get this thing to run around 60-70 mph depending on financial circumstances. Thanks guys!
Logged
  • Boat #1: 1987 Sleekcraft SST
  • Boat #2: 2001 F350 PSD 7.3
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
CG

GT Jets

  • Karma: +192/-0
Re: Sleekcraft SST max 4,000 RPMs on water
« Reply #1 on: June 02, 2012, 11:01:09 PM »
Quote from: NoRestraint on June 02, 2012, 07:32:10 PM
Hi guys! So I didn't get to any of the work I wanted to over the past year because work has been slow. However it's picking up for the summer which means new parts :). Last year we all talked about messing with the secondaries and timing and cleaning the jets etc. I think I found the problem of why I can't get any faster on the water. I'm very poorly educated on engines and jet pumps but I found this chart on the PJB site,

http://www.jetboatperformance.biz/pages/calculator.html

So while I'm trying to become familiar with motors and jets, here is my understanding from this chart, PLEASE CORRECT ME IF I'M WRONG. So I really have no clue which impeller I have but I'm guessing it's an A. For all I know, the motor is a stock 1986 454 which produces 230 HP. It has a Holley marine 715 CFM carb if that info helps at all. While looking at the chart on the PJB site I noticed that the correlation on the chart is 4000 RPMs, around 230 HP with an A impeller. So the way I am understanding this is that this is the highest my boat will perform with the current combination. I appreciate the feedback and any help you guys can offer. I'm trying to get this thing to run around 60-70 mph depending on financial circumstances. Thanks guys!


Unless the cam timing is retarded and there is no advance in the ignition timing, you should easily be in the mid 300's as far as HP.

Something is amiss....Never seen a big block that could not muster at least 4,400 RPM with an A impeller.  :screwy:

A worn out 305 small block with an automotive camshaft, log exhaust and a Quadrajet can make over 230 HP  ;)
Logged
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
Quote from: Brad @ SoCalJetBoats.com on December 22, 2009, 07:40:31 PM
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Quote from: IRRebel on June 11, 2011, 07:30:45 PM
Time to man up and yank it John!  :banghead:
Ray

Willow Wog

  • Karma: +6/-0
Re: Sleekcraft SST max 4,000 RPMs on water
« Reply #2 on: June 03, 2012, 01:41:47 AM »
My worn the hell out 455 in my last boat with a berk and a tight A impeller pulled 5 grand (if i let it) all day long up until its last day on the water with only 7 firing. So somethin aint right bud
Logged
  • Boat #1: 1977 Hawaiian model? southwind splash
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
Coors light dreaming on a Keystone budget...

NoRestraint

  • Karma: +0/-0
Sleekcraft SST max 4,000 RPMs on water
« Reply #3 on: June 03, 2012, 10:07:27 AM »
Thanks guys. I guess its back to troubleshooting everything.
Logged
  • Boat #1: 1987 Sleekcraft SST
  • Boat #2: 2001 F350 PSD 7.3
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
CG

NoRestraint

  • Karma: +0/-0
Sleekcraft SST max 4,000 RPMs on water
« Reply #4 on: June 03, 2012, 10:09:00 AM »
And i think i have it at 12* btdc at idle
Logged
  • Boat #1: 1987 Sleekcraft SST
  • Boat #2: 2001 F350 PSD 7.3
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
CG

GT Jets

  • Karma: +192/-0
Re: Sleekcraft SST max 4,000 RPMs on water
« Reply #5 on: June 03, 2012, 10:36:23 AM »
Quote from: NoRestraint on June 03, 2012, 10:09:00 AM
And i think i have it at 12* btdc at idle

And with all do respect don't mean anything at all...What is the timing at 2500 RPM?  :sly:

If your advance mechanism is not working properly, you could have 12* timing at WOT....BAM, you found your issue... ;)

GT
Logged
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
Quote from: Brad @ SoCalJetBoats.com on December 22, 2009, 07:40:31 PM
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Quote from: IRRebel on June 11, 2011, 07:30:45 PM
Time to man up and yank it John!  :banghead:
Ray

jetjunky101

  • Karma: +5/-0
Re: Sleekcraft SST max 4,000 RPMs on water
« Reply #6 on: June 03, 2012, 11:36:32 AM »
Quote from: GT Jets on June 03, 2012, 10:36:23 AM
And with all do respect don't mean anything at all...What is the timing at 2500 RPM?  :sly:

If your advance mechanism is not working properly, you could have 12* timing at WOT....BAM, you found your issue... ;)

GT
x2 my 454 ran 4500 + rpm's all day "last year" dont know the Mph ...but pretty fast  8) shades required..

but this year...12* at idle and 12* at WOT ...wouldnt go very good at all....new dizzy and all better :thumbup:
and i hope im getting more than 230 HP   :sly:


« Last Edit: June 03, 2012, 11:40:12 AM by jetjunky101 »
Logged
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

NoRestraint

  • Karma: +0/-0
Sleekcraft SST max 4,000 RPMs on water
« Reply #7 on: June 03, 2012, 03:17:43 PM »
Quote from: GT Jets on June 03, 2012, 10:36:23 AM
And with all do respect don't mean anything at all...What is the timing at 2500 RPM?  :sly:

If your advance mechanism is not working properly, you could have 12* timing at WOT....BAM, you found your issue... ;)

GT
i will try to check on that this week, ive got finals monday and tuesday so probably wednesday. I appreciate the help because i dont know where to start!
Logged
  • Boat #1: 1987 Sleekcraft SST
  • Boat #2: 2001 F350 PSD 7.3
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
CG

IRRebel

  • Karma: +16/-0
Re: Sleekcraft SST max 4,000 RPMs on water
« Reply #8 on: June 03, 2012, 03:41:07 PM »
Quote from: NoRestraint on June 03, 2012, 03:17:43 PM
i will try to check on that this week, ive got finals monday and tuesday so probably wednesday. I appreciate the help because i dont know where to start!

GT tells the truth. Total timing after advance rolls in is the only thing that matters. In fact, locked out timing even better, BUT can make the thing a little finicky to start.

The only other thing that is haunting my brain on this is the assumption it's an "A" impeller. Safe assumption normally on most boats, but this is an SST. One of the most modified and raced hulls out there, so I would be pulling the pump and disassembling just to make sure and KNOW what is in there. Could easily be that the pump is set up for the 700+ hp range at much higher rpm or varous combinations thereof.

Good news and bad news. Good news is, you have an SST, one of the most flexible and fun hulls out there! Bad news is, you have an SST, one of the most hot-rodded and raced hulls ever out there!   ;)

Ray 
Logged
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
"Life's journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways totally worn out shouting 'Holy Shit what a ride!"---Crewcheif22 AKA Keith
Pages: [1]
 


Null

SMFPacks CMS 1.0.3 © 2026