Is a low water pickup needed?

[slpcamaross97]

I have a 1993 Starflite with the 24" transom. Bought the boat with a bad lower unit(fluid was not added and cooked the bearings), along with some hack repairs to the currently installed low water pickup(Due to one of the casting ears for the duel hose water pickup being knocked off).

BUT, Kinda got that repaired and removed all the junk but have a water pressure issue when running on plane. I have 8-9 PSI at idle. Pressure drop off as soon as the boat reaches plane.

Im 99.9% sure its a lower unit water inlet problem. But, does the boat really need a low water pickup? Im not running over 70 mph and it came with a factory jack plate. Im trying to find other owners with the same boat hulls that are and are not running low water pickup so i can narrow my lower unit search to factory inlet or do i need to go with a CLE/speedmaster

Engine is a 1993 2.4 efi 200hp xri 20" mid section.

 

[ianz]

depending on how high your running the motor you should be able to get away with std water pickups. A small trick is to plug the top holes either 3 or 4 per side and then open up the lower ones and little wider.

How many PSI do you get when on plane?
where is your gauge getting the reading from? is it the tell-tail or the block for water pressure?

and have you changed the impeller?

 

[wired]

If you want to run the prop centerline over the pad you need a LWPU. If not you dont . That might be too big of a boat/not enough power to run a good surfacing prop on though.

 

[slpcamaross97]

depending on how high your running the motor you should be able to get away with std water pickups. A small trick is to plug the top holes either 3 or 4 per side and then open up the lower ones and little wider.

How many PSI do you get when on plane?
where is your gauge getting the reading from? is it the tell-tail or the block for water pressure?

and have you changed the impeller?

Water pressure on plan falls off to almost zero. temp warning will start to chirp at that time. Water pressure gauge is T-ed into the house between the left and right heads.
Every single gasket, and seal has been double replaced. Has had 3 complete water pump kits installed.

I wanted to add another pressure gauge on the transfer house for the low water pickup but ran out of time and the lake froze.

 

[slpcamaross97]

If you want to run the prop centerline over the pad you need a LWPU. If not you dont . That might be too big of a boat/not enough power to run a good surfacing prop on though.

Thats great info about the center line of the prop over the pad.
Not looking to be a race boat. Just looking to stay on plane longer than 15 seconds.

 

[atc250r]

No pad on that boat. On Flite or Liner with a 200 it's not going to gain you anything running a coned lower and will likely slow you down some. If you can remove it do that, if not find an unmolested lower.

John

 

[ssrstarflite]

The water pressure gauge should be connected to eng. block ,not the hose between the heads that is after the t-stats. On my 2.4 200 it was connected the top of eng. block behind the flywheel. My starflite will run faster with a fishing lower unit than a CLE that has lower water pickup regardless of prop shaft height .

 

[wired]

The water pressure gauge should be connected to eng. block ,not the hose between the heads that is after the t-stats. On my 2.4 200 it was connected the top of eng. block behind the flywheel. My starflite will run faster with a fishing lower unit than a CLE that has lower water pickup regardless of prop shaft height .

Oh yeah. Good catch. The gauge needs to be plumbed into the block , top of the heads or the top of the exhaust divider. Plumbing it into the line between the heads tells you less than nothing.

 

[2tonchevy]

The water pressure gauge should be connected to eng. block ,not the hose between the heads that is after the t-stats. On my 2.4 200 it was connected the top of eng. block behind the flywheel. My starflite will run faster with a fishing lower unit than a CLE that has lower water pickup regardless of prop shaft height .

this topic is something that I have really struggld with on my boat. (not hijacking the thread and hope that this discussion could help find the answer to his question.)

theres a bit of info I havnt been able to get straight answers on:

1)I have always been told if you boat runs under 80 mph (both mine and the thread starters boat do) then a nosecone or cle will slow you down.

2) I have also been told that the higher you can raise your lower unit and maintain water pressure the better.


soooooo....

would a boat that runs under 70 mph run faster with standard lowers running at the maximum weight to still maintain water pressure or would it run faster with cle lowers running on the surface?

I had bobs lowers on my 2800 and have switched to 4 hole cle lowers for this season In an effort to get a more durable lower and hopefully gain a few MPH...... the bobs lowers are ALOT longer and ALOT heavier than the cle....


im not convinced that the CLE are going to help me (or the thread starter).....im almost convinced that any boat under 80 mph will be faster and handle better with a standard lower unit with side pickups. ive not heard one person say that they have gained ANYTHING from switching to a LWP lower unit of any kind and gained speed at less than 80 mph........but the detail that seems to be left out is weather or not they raised the engine up to the maximum level (surface) after they switched from side pickups to a LWP on their sub 80 mph boat.

im pretty sure im not gonna get any performance gain by switching from bobs to cles...(although I will get more durability and save weight)...and am planning on dropping my motors daown and tryin out a set of standard counter rotating side pickup lowers this summer to compare results.


any info or advice on this topic would be great

 

[atc250r]

It differs by hull too. The hull that slp has does not have a pad and needs a prop with a lot of bow lift to get it to fly. If you raise the motor high enough that the coned lower becomes beneficial you have raised UT too high for the prop to get enough bite to lift the boat. A hull like a Hydrostream has will air out without the prop doing so much of the lifting so the motor is run higher and even under 80 the coned set up can work well.

John

 

[2tonchevy]

It differs by hull too. The hull that slp has does not have a pad and needs a prop with a lot of bow lift to get it to fly. If you raise the motor high enough that the coned lower becomes beneficial you have raised UT too high for the prop to get enough bite to lift the boat. A hull like a Hydrostream has will air out without the prop doing so much of the lifting so the motor is run higher and even under 80 the coned set up can work well.

John

I guess the major problem is that I cant find ANY info on how to set up my particular hull due to the scarcity of them.

my boat does have a pad...but its 28 feet long....and I don't kow if the same rules apply. don't get me wrong my boat runs and drives great.....but I just wanna know if im leaving anything on the table....

I cant help but think that a regular set of lowers , maybe with scoops on the sides, could be faster than the LWP lower units....im going to try a set this summer....just to find out.

im running my props as high as I can get em without losing water pressure. I know this through trial and error. I wonder if im causin the props to slip too muchand not get the bow lift I need to really loosen up and get on the pad????

hmmmm......im bored and ready to hit the water ...lol

 

[wired]

this topic is something that I have really struggld with on my boat. (not hijacking the thread and hope that this discussion could help find the answer to his question.)

theres a bit of info I havnt been able to get straight answers on:

1)I have always been told if you boat runs under 80 mph (both mine and the thread starters boat do) then a nosecone or cle will slow you down.

2) I have also been told that the higher you can raise your lower unit and maintain water pressure the better.


soooooo....

would a boat that runs under 70 mph run faster with standard lowers running at the maximum weight to still maintain water pressure or would it run faster with cle lowers running on the surface?

I had bobs lowers on my 2800 and have switched to 4 hole cle lowers for this season In an effort to get a more durable lower and hopefully gain a few MPH...... the bobs lowers are ALOT longer and ALOT heavier than the cle....


im not convinced that the CLE are going to help me (or the thread starter).....im almost convinced that any boat under 80 mph will be faster and handle better with a standard lower unit with side pickups. ive not heard one person say that they have gained ANYTHING from switching to a LWP lower unit of any kind and gained speed at less than 80 mph........but the detail that seems to be left out is weather or not they raised the engine up to the maximum level (surface) after they switched from side pickups to a LWP on their sub 80 mph boat.

im pretty sure im not gonna get any performance gain by switching from bobs to cles...(although I will get more durability and save weight)...and am planning on dropping my motors daown and tryin out a set of standard counter rotating side pickup lowers this summer to compare results.


any info or advice on this topic would be great

The ONLY reason a LWPU coned lower would slow you down is if you used trim like you did before you changed to it. Negative or Positive trim will just give more more drag which would slow you down. Using a LWPU like its designed to be used will give you more speed and thats even under 80 MPH. Just jack it up as high as possible and keep the trim neutral with the prop shaft parallel to the pad or bottom of the "V".

FWIW a properly installed ( fully welded ) Bobs cone will be faster and as durable as a CLE. My bobs cone is fully welded and water tight even before it got epoxy. I got a deal on a custom LWPU nose cone the other day that fit Merc lowers like a glove for $25 from a guy that had 25 surplus units he had made from his mod VP days for sale on scream and fly for $25 a piece. Wish I had bought more. They put the universal Bobs cones to shame.

 

[2tonchevy]

wired:

thanks for the reply!

so why does EVERY "expert" say that under 80 mph cones will slow you down??? are they all over trimming to see the slow down they are talkin about?

theres a guy in this thread that says his boat runs faster with the fishing lower than a cle regardless of prop height?

I know there are exceptions to every rule..

im just tryin to clarify proper set up parameters for v hull boats with outboards in general.

 

[wired]

wired:

thanks for the reply!

so why does EVERY "expert" say that under 80 mph cones will slow you down??? are they all over trimming to see the slow down they are talkin about?

theres a guy in this thread that says his boat runs faster with the fishing lower than a cle regardless of prop height?

I know there are exceptions to every rule..

im just tryin to clarify proper set up parameters for v hull boats with outboards in general.

Because every expert repeats what someone else told him or what they read on the internet . The LWPU exists solely to allow you to use surfacing props and get the side pickups out of the water. If you are running with the prop center under the bottom of the boat it makes no sense to use a LWPU. If you are running higher it makes no sense not to use a LWPU. Ive run my boat with the CLE and with a bobs nose cone and several different blunt face factory lowers including LWPU 3.0's. It handles best with a bobs cone. I cant say it goes faster since I was never able to run it as fast as the motor was capable of running because my steering was crap at the time. I can say that I run 10 MPH faster with a 200/225 than I did with a CLE 260. That has probably zilch to do with the type of lower though. Its just that with the better steering I CAN drive it faster.

 

[2tonchevy]

Because every expert repeats what someone else told him or what they read on the internet . The LWPU exists solely to allow you to use surfacing props and get the side pickups out of the water. If you are running with the prop center under the bottom of the boat it makes no sense to use a LWPU. If you are running higher it makes no sense not to use a LWPU. Ive run my boat with the CLE and with a bobs nose cone and several different blunt face factory lowers including LWPU 3.0's. It handles best with a bobs cone. I cant say it goes faster since I was never able to run it as fast as the motor was capable of running because my steering was crap at the time. I can say that I run 10 MPH faster with a 200/225 than I did with a CLE 260. That has probably zilch to do with the type of lower though. Its just that with the better steering I CAN drive it faster.

yes there are def plenty of parrots on forums that just repeat things that may have no basis in reality or they have simply mis understood. is there any truth at all to the "less than 80 mph the cone will hurt you" theory??

question: what do you make of SSRSTARFLITE'S particular instance where the standard lower is faster than the LWP regardless of prop height?

I know there are no "rules" that count 100% of the time.....so this is all relative.

the nosecone / LWP seems to be one of the most mis understood modifications out there.

 

[wired]

I think theres a lot of variables that go into it. If you have a 28 foot boat and are trying to push it 90 MPH with a 200 HP motor, it doesnt matter what sort of lower unit you are running. Its just not going to happen. Throw a 300 HP motor on there where you might have a fighting chance and I think you will want that prop up as high as possible with a LWPU and a more hydrodynamic nose cone. Prop selection gets more important . Putting a nose cone on and not tuning the rest of the package to take advantage of the nose cone is where people slow down and then they blame the nose cone. The nose cone is just one part of the total package along with prop selection, height in the water , engine horsepower and hull design. On thing is for sure though. Put that nose cone on and forget everything you ever knew about using positive trim to go faster. The prop center needs to be at or above the hull line and the trim needs to be dead neutral.

 

[2tonchevy]

I think theres a lot of variables that go into it. If you have a 28 foot boat and are trying to push it 90 MPH with a 200 HP motor, it doesnt matter what sort of lower unit you are running. Its just not going to happen. Throw a 300 HP motor on there where you might have a fighting chance and I think you will want that prop up as high as possible with a LWPU and a more hydrodynamic nose cone. Prop selection gets more important . Putting a nose cone on and not tuning the rest of the package to take advantage of the nose cone is where people slow down and then they blame the nose cone. The nose cone is just one part of the total package along with prop selection, height in the water , engine horsepower and hull design. On thing is for sure though. Put that nose cone on and forget everything you ever knew about using positive trim to go faster. The prop center needs to be at or above the hull line and the trim needs to be dead neutral.

thanks man! I really appreciate the input!

I love the way my boat runs....and have no complaints....but im always wondering what could be done to improve. I try to learn from the mistakes and trials of others before I run out and spend money. plus.....I like to learn.

so far I have the motors on my boat as high as I possibly could without running hot with the bobs lowers....now with the cle cases it may change. I have tried a set of 26 chopper chopper IIs and a set of 26 hydromotives. the hydros made the boat ride wet and slower (speed and RPM) but man it handled the rough waaaaaaay better. I mean night and day better. Im gnna experiment with the cle cases and see what I can do.

im thinking of switching from twin 200 carb motors to 2.4L 240hp EFI bridgeports......this should put me at or over 80mph when set up correctly...

 

[JUPITER PULSARE]

Ok boys..here's the scoop. You first have to understand what the nose cone does in relation to hydrodynamics. On a stock gearcase...as speed increases, the blunt nose on the gearcase splits the water...until you exceed the design of the gearcase..then the blunt nose will split the water too wide (beyond the diameter of the prop) and the prop will blow out. When you install a nose cone you make the gear case more efficient..but at slower speeds too much water may put pressure on the prop thereby losing rpm and making the boat slower..until you reach a certain speed (which I've seen quoted anywhere from 75-82mph). At that point the nosecone works in your favor with higher motor heights by allowing the water access to the prop without blowout tendancies. Better waterflow to the prop, less drag = more speed.

 

[2tonchevy]

thanks steve

lemme see if I got this right:

so the loss in speed when running a nosecone under speed (75-82 mph)everyone keeps talking about is associated with the nosecone allowing to much water to the prop...and not from the drag of the extra area of the case coming into contact with the water when running a nosecone?

and this can be countered by raising the propshaft up to the surface (allowed by a lwpu) thereby regaining the prop slip and further reducing drag at the same time?

 

[2tonchevy]

I had always been told that the loss in speed was from the drag of the extra area of the nosecone coming in contact with the water...and that's why a fishing lower was faster at speed under 80.....