SoCal Jet Boats
Tech Talk => Hulls => Topic started by: Blue2184 on June 09, 2013, 01:38:48 PM
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guys i have a 18 foot eliminator bubble deck that i baught from tom at jbp. it has a 496 bbc thats about a 10.5-1 motor,about 525hp the pump was redone by ars marine and added the larger bowl to the berk pump witch i also got from tom,it has a droop and a manuel diverter. i am running 72mph on gps, what can i do to pick up any more mph? would love to crack the 75mph mark? i am turnning 5000 maybe 5100 rpms? the pump also has a stuffer and a inducer, im pretty sure the hull was a original ss hull? as it came from the factory with over the tradnsome headers? its a 1976 boat? any tips any help would be great? im running a rpm air gap intake with a quick fuel 850 carb.also has pro comp alum heads. the baot does have a loader but dont know what it is? it was on the boat when i got it from tom? i will help with any info i can! pics info what ever you guys need to try to help me break the 75mph mark?? lol its only 3mph more that i want to get?
thanks for the help all
jason
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It's all based on which impeller it has. If I remember right the A impeller peaks at 5,200 rpm. You may need to go to a stainless impeller
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Jet boat performance has a good chart on it. Tried to upload it, but not sure how to do that yet.
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Wow... I'm running 70 mph on GPS with 78' challenger with a 460 not much done do it. Holley dominator 1050,OT twisties, and good pump. All stock motor otherwise.
Gotta have more in that thing man !
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That was 3 guys full tanks and a ice chest ! Every little bit hurts !
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Pull the droop off and give it a shot
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How bout a pic of it running.
My Saguaro ran 74 with a Clay Smith cam and cleaned up 049 heads on a 454.
-beerjet-
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ill see if i can get a pic of it running, and pretty sure it still has a alum impeller? are thses hulls pretty good for speed? maybe a shoe/ride plate? i know the dominator style bowl we put on the pump is already taped for the ride plate,cause when i first put it on i put it on upside down thinking it was fro the grease fittings..oops and if i remember rite it was like a 8 vaine bowl?
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A shoe and a ride plate would free that thing up a bunch. how far down are the loader ramps hanging below the keel? cutting the ramps to keel or above will help too. jmo
:thumbup:
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i posted a couple pics of the loader,sorry for thw quality that damn trailer is right on the ground!!
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Looks like the loader is a little deep I'd put a straight edge and see how far your biting edge is. Thrust angle pin angle nozzle angle numbers would help to
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A shoe and a ride plate would free that thing up a bunch. how far down are the loader ramps hanging below the keel? cutting the ramps to keel or above will help too. jmo
:thumbup:
Looks like the loader is a little deep I'd put a straight edge and see how far your biting edge is. Thrust angle pin angle nozzle angle numbers would help to
Agreed, check the loader. It looks like it's hanging low. :thumbdown:
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when i get home today i will put a straight edge across it and get a measurement! just electric how do i check the thrust angle and the pin angle?
thanks again for all the help
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also does it matter if i still wave the bowl on upside down? i wouldnt think so? but just a thought? the mounting holes that were for the ride plate witch i thought were the grease fittings are still on the top?
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It's all based on which impeller it has. If I remember right the A impeller peaks at 5,200 rpm. You may need to go to a stainless impeller
This is not true. I spun my stainless "A" to 6000 RPMs all day long.
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also does it matter if i still wave the bowl on upside down? i wouldnt think so? but just a thought? the mounting holes that were for the ride plate witch i thought were the grease fittings are still on the top?
Well if its upside down how do you put oil in the bowel? I'd spin it around the right way
This is not true. I spun my stainless "A" to 6000 RPMs all day long.
Only problem with this statement is you forgot to include your boat was bad@ss and had a beast of a motor
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Of course a stainless impeller will go up 6,000. An aluminum impeller, not so much.
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i was told by tom at jbp that the bowl was water lubricated? what would it take to switch to a stainless impeller? other than $$$
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The aluminum impellers are NOT limited by rpm, but rather HPabsorbed. You don't have enough information in any posts to tell you what needs to be done other than to kick your buddies out of the boat.
Jet boats live and die from weight and weight distribution.
Anything past around 500 HP and I say lose the aluminum impeller.
A shoe and a rideplate may or may not help, but at the same time, if done right, won't hurt either.
You should have enough HP to make the droop work for you, as long as you can fly the bow I say run it.
JMHO
Sent from my SGH-T989 using SoCalJetBoats mobile app
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here is some more pics of the loader..
thanks for the help!!
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The aluminum impellers are NOT limited by rpm, but rather HPabsorbed. You don't have enough information in any posts to tell you what needs to be done other than to kick your buddies out of the boat.
Jet boats live and die from weight and weight distribution.
Anything past around 500 HP and I say lose the aluminum impeller.
A shoe and a rideplate may or may not help, but at the same time, if done right, won't hurt either.
You should have enough HP to make the droop work for you, as long as you can fly the bow I say run it.
JMHO
Sent from my SGH-T989 using SoCalJetBoats mobile app
Well said.
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i can fly the nose of the boat but right at about top speed i do get some bounce in the boat? i do have a three degree up wedge on the pump as well?
and when running the boat trying to check mph its just me with one tank half full..the baot feels like a race car! you get 3 or 4 people in it and you can really tell a diference! just didnt know if a impeller or something else would help me gain a little more mph? my buddy has a taylor with more weight than my boat with a wore out pump and a 505 bbc about the same horse power and he can stay right with me? dont know i guess just thinking spending 3k on a pump it would run a little faster? again ant input is appreciated!!
thanks
jason
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and in the next day or so will see if i can get a pic or a video of the boat running?
thanks guys
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does anybody recognize or know what hull this is?or if it would be good for speed?might have a chance of getting my hands on it?
thanks
jason
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Looks like a southwind tunnel hull and yes that's a fast hull
Sent from my SGH-T999 using SoCalJetBoats mobile app
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im not sure? i dont claim to be an exspert onthis at all? but the ass of the boat looks more like a placecraft
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It's a placecraft tunnel. Basically a southwind tunnel but updated.
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Yep just found out its a 1983 place craft!
Thanks for the help guys!
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The last pic shows the loader hangin WAY down .
Dial in your hardware and then start adding stuff to it.
Gotta know what's slowing you down before you can start speeding up.
-beerjet-
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Thanks beer jet! What's the best way maybe trim a half inch off at a time?
Thanks
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Take a straight edge (like a metal yard stick) and place it front to back of the intake housing, this will give you better perspective of how much is hanging below keel. +/-1/8" is about right.
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ok guys here are some pics of the loader??
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Cut about an inch out of it with a 5 inch grinder. That should help a bit. Tap the intake for pressure and add pressure gauge. That will help with the tuning.
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Cut about an inch out of it with a 5 inch grinder. That should help a bit. Tap the intake for pressure and add pressure gauge. That will help with the tuning.
That might be a bit much
You need to 'sneak up' on it, I'd go about 1/4" shorter to start. It looks like its at about 7/16" then try it, with a gps. Hopefully you have a gps baseline to compare it to. Small changes, ONE at a time, then gps, repeat
Dan'l
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Thanks guys for all the help! Yes I do have a GPS base line one the boat of 72mph I will start slow and sneak up on it. Hope maybe will see a little rpm gain as well?
Thanks again for the help..
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Thanks guys for all the help! Yes I do have a GPS base line one the boat of 72mph I will start slow and sneak up on it. Hope maybe will see a little rpm gain as well?
Thanks again for the help..
You may not see am RPM gain, just making the hull as efficient as possible, with the same amount of thrust
Dan'l
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That might be a bit much
You need to 'sneak up' on it, I'd go about 1/4" shorter to start. It looks like its at about 7/16" then try it, with a gps. Hopefully you have a gps baseline to compare it to. Small changes, ONE at a time, then gps, repeat
Dan'l
that loader looks like it is about a half inch below keel. 1/4 cuts aren't going to help all that much. i would start with 1 inch and the 1/2 inch cuts after that if you need it. a lot of guys these days are running there loaders WAY cut back. JMO
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Ok.. Cutting the loader to raise it a 1/4 inch I will problay have to take of like 3/4 of an inch? Does that sound right? Like If I draw straight line across the loader or imagine the line cutting straight trough were my mark would be off of the straight edge I'm not necessarily going to be cutting a 1/4 inch off to get it to raise the leading edge a 1/4? Does this sound right?
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I guess what I am trying to say in cutting the 1/4 off in hight I will be cutting say maybe 3/4 off in length?
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I guess what I am trying to say in cutting the 1/4 off in hight I will be cutting say maybe 3/4 off in length?
No, you just need to cut the ramps of the loader back. so taking 1/4 inch will be 1/4 inch. start with cutting them back even too keel or 1/4 above keel.
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No, you just need to cut the ramps of the loader back. so taking 1/4 inch will be 1/4 inch. start with cutting them back even too keel or 1/4 above keel.
I'd start at 1/8" Below the keel, and work from there.
I cut mine 3 times and it was still too short.
Dan'l
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ok guys excuse all the questions here just trying not to mess anything up if i dont have to? the top lip on my level in the pic is just about an 1/8 inch thick. so if i mark the loader with a sharpie and cut it even with the mark on the level it should put me about an 1/8 below the keel? witch should give me a good starting point? does this sound about right? then i could start making small cuts from their.
thanks
jason
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Yes that's a good starting point.
Mines ~1/8", maybe less, made a difference over the 3/4"+ it was hanging
Dan'l
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10/4 i will get it trimed today.. and get ready for a test run this weekend, wating on a new o-ring for my steering nozzel as well and will be ready for a test run
thanks all
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I just took another inch out of mine today. 5 inch cutting disk, 5 inch grinder and a 40 grit sanding disk to sharpen and clean it up.
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trying to post some pics of mine but having a little trouble? will try again in a little bit
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does this look better?
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Looks like a good start
Dan'l
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Nice job bud. Looks good