Intake grate fins

[Tahoe540]

Will these fins hurt top speed or performance? I have not seen them on any other loaders. This is on a Hallett day cruiser.

 

[DarkHorseRacing]

The fins look like they could use a little cleanup but if done right they don't make an appreciable difference unless its a drag boat. What will impact top speed and performance is that rock grate. Need to switch it out for a loader grate but its a trial and error process to find one that's just right (not too much water).

And if you are looking for something more extensive, the intake could be machined for a shoe and ride plate, but I believe it has to come out for that.

 

[mash on it]

The fins give the steering nozzle some 'leverage' while turning.

All of mine have fins. Eliminator day Cruiser, Miller flat deck, Saguaro, double eagle, etc.

The rock jumping aluminum jet hulls delete the fins, for obvious reasons.

What concerns me more is the transition from the hull to the intake housing.
It looks horrible in the pics, and probably worse in person. That transition should be super smooth, and definitely not hanging down a quarter of an inch.

As far as the rock grate, the leading AND TRAILING edges can be 'radiused' or 'knife edged' for some performance improvement. (No performance data, as I did mine when going to a bigger mill) A sport loader wouldn't be a bad idea, depending on where you boat at.

Dan'l

By the way, stainless steel bolts do not belong on a rock grate or loader. Grade 8 anodized is needed here.

 

[Tahoe540]

Thanks for the input on this. It is my first jet boat and learning as I go while upgrading this boat. I have had the jet totally rebuilt with all the goodies (stainless bowl stuffer, A impeller and droop) while the stock 454 was still in the boat. Obviously have not got to the intake. I have read that a basic rock grate is not very performance minded.

You guys have any suggestions on who to talk to about a new loader?

I installed a pretty healthy 555 BBC and it just doesn't have the rpm or speed I was expecting. It will only do a few mph better and the same RPM as the stock 454 it had. It hits a wall at 4800 rpm (same as stock 454) and I am trying to figure things out. I have pulled the motor numerous times checking cam timing, bearings, etc. I did do a compression check and the cylinders are only within 3 lbs between the highest and lowest readings.

 

[J 2]

Good to see some jet boat activity! As mentioned those fins are on all of our jets. Stock rock grate is a good idea for obvious reasons, suck a rock and you'll need a tow in. I personally run my 21' cruiser open, although I'm always very aware of the water depth and bottom conditions. Until you match up your impeller to your engine you won't see much gain. Loaders rarely have a gain that you can feel in the drivers seat unless your really performance minded in your setup, I have a 19' Daytona so yea I can feel that stuff. Not sure where you're located, I like Chris & his guys at B1 Racing. Tom with JBP is on this site quite often, I've talked to and purchased parts from him in the past.

We would need much more detail about your engine & jet to advise. Going with a B impeller will get you more rpm's, will that translate to more speed, maybe, maybe not. Will be quicker. Then again AA impeller could be a possibility too.

This

was in mine when I bought it. The thing about loaders is if they break it will be the most violent feeling you'll ever experience in a jet boat, passengers can get hurt to when the boat makes a sudden stop sideways.

 

[mash on it]

Thanks for the input on this. It is my first jet boat and learning as I go while upgrading this boat. I have had the jet totally rebuilt with all the goodies (stainless bowl stuffer, A impeller and droop) while the stock 454 was still in the boat. Obviously have not got to the intake. I have read that a basic rock grate is not very performance minded.

You guys have any suggestions on who to talk to about a new loader?

I installed a pretty healthy 555 BBC and it just doesn't have the rpm or speed I was expecting. It will only do a few mph better and the same RPM as the stock 454 it had. It hits a wall at 4800 rpm (same as stock 454) and I am trying to figure things out. I have pulled the motor numerous times checking cam timing, bearings, etc. I did do a compression check and the cylinders are only within 3 lbs between the highest and lowest readings.

For comparison purposes only, a stock L31 suburban 350 turned an A impeller at 4600 rpm all day long, ~325 hp absorbed. (55 gps'd)
A warmed over 454 turned an American Turbine AA impeller at ~4900-4950, ~ 505 hp absorbed. (57 gps'd) Both per impeller charts @ JBP. (Both pumps have a shoe, ride plate, and loader.)

With 555 cubes, and some decent hp, should turn an A impeller to 5300? Possibly 5500?

Hope this helps

Dan'l

 

[rivrrts429]

Good to see some jet boat activity! As mentioned those fins are on all of our jets. Stock rock grate is a good idea for obvious reasons, suck a rock and you'll need a tow in. I personally run my 21' cruiser open, although I'm always very aware of the water depth and bottom conditions. Until you match up your impeller to your engine you won't see much gain. Loaders rarely have a gain that you can feel in the drivers seat unless your really performance minded in your setup, I have a 19' Daytona so yea I can feel that stuff. Not sure where you're located, I like Chris & his guys at B1 Racing. Tom with JBP is on this site quite often, I've talked to and purchased parts from him in the past.

We would need much more detail about your engine & jet to advise. Going with a B impeller will get you more rpm's, will that translate to more speed, maybe, maybe not. Will be quicker. Then again AA impeller could be a possibility too. View attachment 919020 View attachment 919021

This View attachment 919023
was in mine when I bought it. The thing about loaders is if they break it will be the most violent feeling you'll ever experience in a jet boat, passengers can get hurt to when the boat makes a sudden stop sideways.

Apparently Starkweather has left a few people without their parts and nobody is at the shop and no return calls.

About the only ones around locally anymore would be...

Jack Mclure (MPD)
Greg Shoemaker (GS Marine)
Tom (Jet Boat Performance)

 

[Tahoe540]

I purchased a rail kit from Tom to install this motor. He is a great guy. I emailed him a few question today and waiting to hear back.

The motor is a 555 BBC that has not been dynoed. The same setup with the same cam (hydraulic roller) and pistons dynoed at 621 HP with 990 iron heads. This combo pushed my single engine 30 ft Advantage to 61 mph at Lake Tahoe (6000 ft elevation) with the BB2 heads and 548 cubic inches.

All the same parts are in this setup except for a new Dart block and Brodix BB2 extra heads with shaft rockers. I was also expecting 5500 rpm with a stainless A. It has a lot of torque down low.

 

[DarkHorseRacing]

Thanks for the input on this. It is my first jet boat and learning as I go while upgrading this boat. I have had the jet totally rebuilt with all the goodies (stainless bowl stuffer, A impeller and droop) while the stock 454 was still in the boat. Obviously have not got to the intake. I have read that a basic rock grate is not very performance minded.

You guys have any suggestions on who to talk to about a new loader?

I installed a pretty healthy 555 BBC and it just doesn't have the rpm or speed I was expecting. It will only do a few mph better and the same RPM as the stock 454 it had. It hits a wall at 4800 rpm (same as stock 454) and I am trying to figure things out. I have pulled the motor numerous times checking cam timing, bearings, etc. I did do a compression check and the cylinders are only within 3 lbs between the highest and lowest readings.

I would have put a pre-impeller on the shaft if you had the pump out and were doing all that stuff. Helps with the holeshot at least (helps load the main impeller).


ETA: I was also going to say it sounds like the pump runs out of water if you're hitting that wall in the same place with both engines. You'll have to get that intake cleaned up and consider a change of grate to get more water into the pump. Also, like someone else said, the change in motor should have probably changed the impeller size due to the increase in HP and torque to match the motor better, but you need to be loading the pump properly, regardless.

 

[Tahoe540]

What do you mean by a "pre-impeller"?

I am attaching the cam specs

 

[DarkHorseRacing]

What do you mean by a "pre-impeller"?

I am attaching the cam specs View attachment 919046

See J 2's middle picture, above. That Jetski looking impeller on the shaft in front of the main impeller is what I'm referring to. I've also heard it referred to as an inducer impeller.

 

[Tahoe540]

The inducer (pre-impeller) was also installed. All parts were purchase through CPPerformance.

 

[Tahoe540]

One more piece of information. It currently has 3/8 line from the tank to carb. I am going to do a test this weekend with an electric pump and 1/2 line and -8 fittings.
It looks fast you think it would be fast LOL

 

[mash on it]

One more piece of information. It currently has 3/8 line from the tank to carb. I am going to do a test this weekend with an electric pump and 1/2 line and -8 fittings.
It looks fast you think it would be fast LOL View attachment 919051

Looks fast.
Can you monitor fuel pressure while underway?

Pulling the rock grate and running it would tell you.

Dan'l

 

[J 2]

That's a big ass jet boat Don't expect to get to much out of that, the size & weight of your hull is why. Is this a 23', 24'? Really cool cruiser.

If you have a fuel problem you would notice engine performance issues, like slowing or hiccups or sounds different.

Post up pics of the pump too. You could experiment with thrust height. Did you go full droop or mini? With a boat of this size I might experiment with moving the thrust back with one of these, AT 6" Extension, I played around with one. Still on my shelf. Based on the size I don't think a loader or rock grate is going to make a difference. If you have good acceleration until you hit the wall then your about as efficient as you're going to get.

 

[Tahoe540]

The boat is a 20.5 BR Hallett. It runs pretty smooth with no hiccups and pulls out of the whole pretty good.

The engine has a 1050 cfm carb with a 4150 base

The jet was totally rebuilt last year in preparation for this motor.

 

[arch stanton]

Size of the boat has no effect on motor rpm it seems like that motor should turn about 5500 rpm or higher with the A impeller
My stock 502/502 crate motor turns a AA impeller at 5100 RPM GPS speed 68 MPH in a 21 shockwave open bow.
I would check a few things is the tach correct
The exhaust may be too restrictive
Is there a rev limiter in the ignition

 

[J 2]

Well 20.5 isn't that big, pic looks bigger than it is. Log exhaust will hold the engine back a bit. Rev limiter is a good thought to check on. Although if you hit a limiter you'd feel it & hear it. Based on what you've stated I don't see a engine issue. Since it runs strong out of the hole then hits a wall at 4800 I'm still leaning pump. I disagree with the size of the boat affecting rpm, if the pump is loading well you hit a wall in every boat out there. The bigger the boat or deeper the V you'll hit that wall sooner.

Is the tach your using the same with both engines? Does it feel the same to you? I've had 21' Eliminator, 18' Rogers, 21' Cobra, 19' Daytona, 21' Rogers all jets and all so very different. The only boat I didn't tear down and rebuild was the Cobra, stock injected 496 with Dominator pump A impeller. This is my long gone Eliminator, I wanted to see the difference in the V, yours is pretty deep. You're pushing a lot more boat, similar to my old Cobra. My Cobra hit the wall about 5000 rpms.

 

[DRYHEAT]

Curious as to how well it breathes with 555 ci. through log style manifolds?

 

[Tahoe540]

I agree on the RPM it should be higher and I don't think the tach is bad. I have done GPS with both motors and the stock 454 did 49 mph once and the new motor at same RPM does 54.

It really feels like it pulling an anchor the whole time. The stock 454 got out of the hole better.

The other thing that changed from the stock motor is the rail kit. I had a shop install it as I did not have a lift (I have one now). When I picked it up the motor was not flat and is angled downward. The drive shaft is straight into the pump. Is this how they are supposed to be installed? The u-joints are perfectly straight no offset. I had to install and angled spacer for the card to make it flat. The back is 1" lower than the front. This also caused the oil pan to be very very close to touching.

 

[Tahoe540]

I have no rev limiter installed. I wish I had to use one. It has a DUI HEI and I have always had good luck with those. I have also ran 2 other HEI's just to check with no change.

I also feel the exhaust is restrictive but not enough to make it lazy.

Looks like a decent V to me.

 

[J 2]

Now I get it, I misunderstood. 1st pic your other boat. I need a reset

 

[J 2]

The shop install looks fine. Yes the front of the engine is always higher and the pan clearance can be really close. Usually there is offset in the u joints, but with the new style you have not so much. As long as it feels smooth without any unusual vibration I would leave it alone. Now I'm reading the engine feels sluggish, how do your plugs look? Troubleshooting via the internet and not by the seat of your pants is difficult

Did you rebuild the pump? Could you turn the shaft by hand from the motor side? I always made sure I could spin mine by hand. Yes you should turn low to mid 5k rpm

 

[Tahoe540]

I did not rebuild the pump. The shop that installed the rail kit also rebuilt the pump. I can turn the shaft by hand on the splines.

There is no vibration from the drive line. Everything is smooth. The plugs look good too.

I am at a loss right now and frustrated. I have been dealing with this since April trying to figure it out. I really expected this motor to perform better than it does or figure out what is causing the issue. I have had many sleepless nights trying to figure this out.

I have built many big blocks (all over 540 cu in) and feel very confident in my build. I built this motor for a friend a week before I built mine. This went into a 25ft Eliminator and hauls ass.

.

 

[arch stanton]

Is there a port on the exhaust were you can get a back pressure reading.
You have gained 6 mph at the same rpm with the rebuilt pump and bigger motor that seems to prove the pump is more efficient so I am going to guess that the exhaust is too restrictive.
My 502 has lighting headers and a Demon 750 you should make more HP and RPM with the A impeller than I do.
I am not sure on the pump loader causing an RPM wall I think if you were not getting enough water it would cavitate and rev higher but that’s a total guess.
On my boat I have a open loader , inducer, ride plate and a jet avatar it has all been tuned and works well.
I have read a bunch about how the bottom of the boat effects speed and how the jets loads but every thing I remembered says a jet has max RPM from a dead stop to top speed with very little difference.
Can you free rev past 4900 dry just for 2 seconds ?

 

[arch stanton]

Had another thought maybe you are getting too much water into the exhaust do you have a regulator on the water inlet to the engine/exhaust that would increase back pressure with rpm from 2 sources

 

[Tahoe540]

I had the pump redone last year so I had one summer with the stock 454 and went to the 555 this year. All my comparisons are same pump different engine. That is why I am so stumped. I thought this motor would be a monster.

I have a gauge on the front of the intake manifold. I have not seen it move much past 0.

I have also cut the tips off my logs and went from 2 7/8 to 3.5 inches. I think that is when it went 54.

I do have a regulator for my inlet. I have it adjusted to run around 180 so not a lot of water going through.

On the hose this thing revs fast and sounds perfect. In the water it does rev when in neutral.

Thanks for trying to help on this issue. I know it is hard to diagnose over the internet.

I am taking it out Sunday for the fuel line change. I will also take out the rock grate.

I will give an update.

 

[arch stanton]

I don’t know if running without a grate or loader just an open hole is good but what the hell give it a try
On the regulator 180 psi seems high but volume of water getting into the logs could cause back pressure.
I think 180 psi is full pump pressure

Regarding the gauge on the intake manifold it should show vacuum at idle and I don’t think it will ever show pressure
I have heard of running a pressure gauge on the jet pump and a gauge on the exhaust/ engine side of water inlet

 

[arch stanton]

So I looked at jet boat performance website and found the information I was talking about try this link

Jet Boat Performance, Jet Boat FAQs diagrams, Impeller charts,

jet boat references, charts, jet drive parts, breakdowns, plumbing diagrams, jet boat header plumbing, jet drive wet logs plumbing,Jetboat impeller charts, electrical wiring diagrams, jet boat information, jet boat

jetboatperformance.biz

On the HP to RPM chart it only takes 375 HP to turn an A impeller at 4900 RPM once you figure out the problem your going to be a happy boater

 

[J 2]

About restricting the water intake, I'm against it. I run cold with no restrictions. This isn't your issue, however my personal experience in doing this is there wasn't enough water coming through the engine to keep from burning holes in the exhaust hose in between the exhaust & transom. This is below the water line and your bilge won't be able to keep up. I did this with my Eliminator. There's also the possibility of getting air pockets inside the motor that will overheat sections, you won't know about this until something fails and you take it apart. My Procharger 468 with 9psi runs about 110 at the gauge, at idle it peaks at 150. I've run all of my jets this way since I learned a hard lesson.

I'm getting a much clearer picture of what your writing about You know what you're doing, solid motor & pump. Engines are air pumps, the more air you can run through them the faster they will go. I'm leaning towards the logs being the wall at this point. I could be wrong, but when I started building performance motors to go fast big exhaust was always part of my equation. They can be pricey, but so is everything else when we decide to go faster. Eddie Marine has some reasonably priced exhaust.

https://www.eddiemarine.com/shop/emi-thunder-exhaust/emi-thunder-exhaust-big-block-chevy

I would post this up in the engine section and ask specifically about the engine set up and exhaust. There's top notch engine builders that will post in that section like Boost Power & Obnoxious. These guys have way more experience with so many different setups.

Good luck and keep us updated

 

[DarkHorseRacing]

Curious as to how well it breathes with 555 ci. through log style manifolds?

I don't have specifics on his log style manifolds but Gale Banks Twin Turbo setups used similar exhaust headers but had up-pipes where the water trap is, up to the turbos. We were able to run a 560cu BBC with Banks TT system (with Dominator carb) and get over 1000hp with log type manifolds. So flowing a NA 555 really shouldn't be too much of an ask on that setup.

You can get Lightening or others to make custom headers that would use tubes that would bolt up to the water traps, or go with a set of CMI E-tops which don't need them and that wouldn't take up much more space.

 

[DarkHorseRacing]

I don’t know if running without a grate or loader just an open hole is good but what the hell give it a try
On the regulator 180 psi seems high but volume of water getting into the logs could cause back pressure.
I think 180 psi is full pump pressure

Regarding the gauge on the intake manifold it should show vacuum at idle and I don’t think it will ever show pressure
I have heard of running a pressure gauge on the jet pump and a gauge on the exhaust/ engine side of water inlet

In his case with the rock grate, taking it off should probably improve water flow into the jet by allowing to follow the curve up into the jet. He's not running a real loader grate where taking that out would cause less volume up into the pump.

 

[Happy Smitty]

Will these fins hurt top speed or performance? I have not seen them on any other loaders. This is on a Hallett day cruiser. View attachment 918957 View attachment 918958

I believe those are referred to as bacon strips or meat curtains. Some boats have them, some don't.

 

[mash on it]

So I looked at jet boat performance website and found the information I was talking about try this link

Jet Boat Performance, Jet Boat FAQs diagrams, Impeller charts,

jet boat references, charts, jet drive parts, breakdowns, plumbing diagrams, jet boat header plumbing, jet drive wet logs plumbing,Jetboat impeller charts, electrical wiring diagrams, jet boat information, jet boat

jetboatperformance.biz

On the HP to RPM chart it only takes 375 HP to turn an A impeller at 4900 RPM once you figure out the problem your going to be a happy boater

On the Impeller power calculator @ Jet Boat Performance,
4900 rpm requires 420 hp, & 450 tq., With an 'A' Impeller.

According to the dyno chart above, at 4900, it's ~590ish hp, and ~635ish tq.

I still am baffled at the 4900 rpm wall.

Dan'l

 

[Tahoe540]

I want to thank everyone for trying to figure this out.

I am done for the year. Almost all of the threaded holes in my heads are stripped for the intake. Probably because it has been off and on quite a few times.

Time for some timeserts in all of them. Also going to get new valves, springs and cam for next year.

If anyone wants my hydraulic roller and really nice lifters they will be ready soon for a good price.

I am also going to try and get my jet intake issues straightened out.

Thanks again for everyones suggestions and internet troubleshooting.

 

[DRYHEAT]

Might I suggest making one change at a time and then analyzing results.

 

[Blackmagic94]

Was the engine dynoed with those exact exhaust manifolds and snails? If not and it was headers there is your hp loss and restriction


Running out of water will not make it lose rpm. It will Cavitate and hit the limiter as there is no load.

 

[jetboatperformance]

sooo much good info here .............. to the OP question those fins help with steering stability and also help keep the jet loaded

 

[Tahoe540]

Pulled the motor to have my heads done and found I have a lean condition.

I have a brand new Proform 1050 with a 4150 base. Only change I did was change the jets for my elevation. I think that was only 2 sizes smaller. I am around 4500 ft.