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GT Jets

  • Karma: +192/-0
Re: More jet boat speed
« Reply #25 on: February 17, 2016, 10:18:22 PM »
Consider aftermarket aluminum heads.  The right set will will bump your compression and breathing ability while lowering weight.  You really need to find out what your current compression ratio is.

I'm curious why you are only getting 4400 RPM.

I don't see an intake swap making any positive gain.

With the mentioned budget of $2K, I'm thinking heads will be just a bit out of reach given he really should invest in carburetor, Place Diverter and a loader, not to mention ignition never hurts.

Strictly speaking "Bang for buck".

The next step would be a motor build and if heads are considered that would be the next logical step.

Personally, I don't see him there yet.

As for the 4,400 rpm,  thinking just the tune is likely the culprit unless we are speaking altitude or an AA impeller.

But I like the way you think. 8)


GT

  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

GT Jets

  • Karma: +192/-0
Re: More jet boat speed
« Reply #26 on: February 17, 2016, 10:19:44 PM »
Oh yeah that's right, my "400" hp boat will only go about 30 haha

Fordlover is right though, cruisers are best as just that.


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Sooooooo, thinking out loud here.

You think 400 horses is worth 70?

I would take that bet all day long.
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

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Ray

steves86ta

  • Karma: +41/-0
Re: More jet boat speed
« Reply #27 on: February 18, 2016, 08:37:44 AM »
Sooooooo, thinking out loud here.

You think 400 horses is worth 70?

I would take that bet all day long.

Im making right about 4-450 on motor, and i do 71 on gps :-) lol
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  • Karma: +29/-0
Re: More jet boat speed
« Reply #28 on: February 18, 2016, 08:38:23 AM »
Sooooooo, thinking out loud here.

You think 400 horses is worth 70?

I would take that bet all day long.


Ya know Glenn, a stock ZZ4, 355hp, in the right boat is north of 80...

Dan'l
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steves86ta

  • Karma: +41/-0
Re: More jet boat speed
« Reply #29 on: February 18, 2016, 08:39:46 AM »

Ya know Glenn, a stock ZZ4, 355hp, in the right boat is north of 80...

Dan'l

yep!!! See!!!

butg really in the aspect of this thread. Itll take a LOT more than 400 to see 70 lol
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  • Karma: +29/-0
Re: More jet boat speed
« Reply #30 on: February 18, 2016, 08:54:10 AM »
yep!!! See!!!

but, really in the aspect of this thread. Itll take a LOT more than 400 to see 70 lol

Yep- @ 500 hp+/- , I was at 57-58 in a heavy azz cruiser.

Dan'l
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FordLover

  • Karma: +72/-0
Re: More jet boat speed
« Reply #31 on: February 18, 2016, 08:59:36 AM »
Yep- @ 500 hp+/- , I was at 57-58 in a heavy azz cruiser.

Dan'l

How dare you go against the Yoda(GT) of jet boats!! You will feel his wrath!
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tamsone6

  • Karma: +7/-0
Re: More jet boat speed
« Reply #32 on: February 18, 2016, 09:15:46 AM »

Sooooooo, thinking out loud here.

You think 400 horses is worth 70?

I would take that bet all day long.


No I don't at all GT, FordLover is just poking fun at me because that's what I get for helping him move 6 yards of rock.

I do however agree that with the aforementioned improvements a goal of 60 is reasonable. The last motor in my boat was pretty mild and I ran high 50's. Just adding my opinion on what I would do to grab a few more mph.



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  • Karma: +29/-0
Re: More jet boat speed
« Reply #33 on: February 18, 2016, 09:17:42 AM »
How dare you go against the Yoda(GT) of jet boats!! You will feel his wrath!

I wanted an honest 60 mph out of mine...$2200 just for the roller cam set-up, best of 57-58 mph up river.

Dan'l
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Flusher

  • Karma: +84/-0
Re: More jet boat speed
« Reply #34 on: February 18, 2016, 09:56:48 AM »
The 4400 RPM just doesn't sound right.  Either you have a weak or damaged engine or it is way out of tune.  A 38 year old carburetor and points ignition can be pretty tired by now.  Modernizing with electronic ignition won't necessarily get you any more horsepower but it could allow your engine to operate to its true potential.  Why would start with getting the engine to its peak state of tune.  It needs to run right first!

What intake manifold is on it now that you want to replace with a Torker?

Hardware changes/upgrades really haven't been discussed at this point.  A Place diverted, as mentioned, along with a full-droop, back-cut shoe ride plate will free up a few MPH.  If the engine is in good tune and the pump is still stalling less than 5K,you might consider cutting the impeller (assuming no mechanical issues).

Unless the engine is hurt, tearing into it will be a can of worms and then you will still be restricted by your exhaust.  Hopefully you have the logs that can be opened to the larger outlet.

Speed comes from everything working together and working right.  Overlooked and/or disregarded details will cost you performance.
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  • Karma: +29/-0
Re: More jet boat speed
« Reply #35 on: February 18, 2016, 10:47:26 AM »
The 4400 RPM just doesn't sound right.

Why is this? A stock 460 is about 320 hp, spinning an 'A' would be 4500 or so. Again 38 year old stock motor.

Hardware changes/upgrades really haven't been discussed at this point.  A Place diverter, as mentioned, along with a full-droop, back-cut shoe ride plate will free up a few MPH.

Agreed, hardware is always important.

If the engine is in good tune and the pump is still stalling less than 5K,you might consider cutting the impeller (assuming no mechanical issues).

320hp Will never see 5K with an A.
Cutting the impeller smaller, for a mini cruiser will suffer out of the hole, and will make a minimal difference on top end.


Unless the engine is hurt, tearing into it will be a can of worms and then you will still be restricted by your exhaust.  Hopefully you have the logs that can be opened to the larger outlet.

Logs and snails will support over 500 HP, just not as easy to get there, as with headers.


What intake manifold is on it now that you want to replace with a Torker?


It sounded like a stock 460 cast iron truck manifold. Heavy as an anchor. Any aluminum manifold, especially a single plane would help performance, even more when carb/heads/cam combo is done.


Speed comes from everything working together and working right.  Overlooked and/or disregarded details will cost you performance.


Well said.

Dan'l
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GT Jets

  • Karma: +192/-0
Re: More jet boat speed
« Reply #36 on: February 18, 2016, 11:40:45 AM »
Im making right about 4-450 on motor, and i do 71 on gps :-) lol

On a heavy cruiser?

Not.

GT

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  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

steves86ta

  • Karma: +41/-0
Re: More jet boat speed
« Reply #37 on: February 18, 2016, 11:43:04 AM »
On a heavy cruiser?

Not.

GT

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Yes I know lol I was busting your balls lol

Hence the later "not in the context of this thread" lol
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78millerjet

  • Karma: +0/-0
Re: More jet boat speed
« Reply #38 on: February 18, 2016, 11:48:01 AM »
Meant 4600rpm. I hadn't realized how spendy it was to get from 55 to 65.
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steves86ta

  • Karma: +41/-0
Re: More jet boat speed
« Reply #39 on: February 18, 2016, 11:49:54 AM »
Meant 4600rpm. I hadn't realized how spendy it was to get from 55 to 65.

Yeah. It can be. I'd take some of the advice here and atleast modernize everything.

This way it's new, modern, reliable.

Then you can worry about speed after that. You may gain a bit if your components are a little worn or not in the best of shape

Modernize the ignition, intke, carb and see what happens

I know in a car I gained about a half second in the quarter with a msd 6a and billet distributor  over an old points deal
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78millerjet

  • Karma: +0/-0
Re: More jet boat speed
« Reply #40 on: February 18, 2016, 11:59:58 AM »
Carb was rebuilt last winter. Engine runs good. Will have to look at stock manifold. At this point a full tune up and new ignition are in order. Maybe have the jet looked over. Its all original so its time
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steves86ta

  • Karma: +41/-0
Re: More jet boat speed
« Reply #41 on: February 18, 2016, 12:00:29 PM »
Carb was rebuilt last winter. Engine runs good. Will have to look at stock manifold. At this point a full tune up and new ignition are in order. Maybe have the jet looked over. Its all original so its time
That's your best plan of attack
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GT Jets

  • Karma: +192/-0
Re: More jet boat speed
« Reply #42 on: February 18, 2016, 07:15:13 PM »
Carb was rebuilt last winter. Engine runs good. Will have to look at stock manifold. At this point a full tune up and new ignition are in order. Maybe have the jet looked over. Its all original so its time

Unless I missed it,  I don't see what carburetor it is.

Do you have a list number by chance?

GT

Sent from my SCH-I545 using SoCal Jet Boats mobile app

  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

Flusher

  • Karma: +84/-0
Re: More jet boat speed
« Reply #43 on: February 19, 2016, 10:04:01 AM »
My fault, I missed the this was a cruiser.  With that being said...

I would suggest the Place Diverter HPH over the full droop.  You don't have enough horsepower and the boat is too heavy to take advantage of the full droop.

If your engine is in good condition but only needing carburetor and ignition updates, I would budget for a centrifical supercharger that is capable of up to eight pounds of boost combined with a CSU blow-through carburetor and locked out ignition timing.  Just one pound of boost will net you more power than any performance modification you can make.

Just a thought.

Cheers,

Joe
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FordLover

  • Karma: +72/-0
Re: More jet boat speed
« Reply #44 on: February 19, 2016, 03:28:34 PM »
.
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TEAMSDSU

  • Karma: +1/-0
Re: More jet boat speed
« Reply #45 on: February 21, 2016, 08:41:07 AM »
Did we get any pics of the motor or video links posted yet???

Shawn
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