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ConnollyCrew

PSA- Please read! About your engine!

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ConnollyCrew

If you wakeboard or wake surf and load your boat heavily it is critical that your boat is propped appropriately to ensure that your engine gives you the kind of life that you expect. It is critical that the engine is able to turn RPM at wide open throttle within the designated range for your engine. The standard 5.7L engine, Assault 325, 330 … the engines that have the flame arrestor at the top of the engine like a carbureted engine … the WOT RPM range is 4600-4800. The premium 5.7L engine, Assault 340 … the engines that have the flame arrestor at the rear of the engine and a decorative plenum on top … the WOT RPM range is 4800-5200. The 6.0L engines … the LS2 and the L96 … the WOT RPM range is 5200-5600.

What you need to do is load the boat the way you would for whatever activity you are loading it for. If that means all standard ballast full, any extra ballast, 3 cases of cold beverages and 8 friends … load it up. Make sure your fuel tank is full also. You want the boat to be the heaviest that it is ever going to be. Now carefully take the boat up to wide open throttle and see what the maximum engine RPM is. Be careful because the added weight might make the boat handle differently at WOT than it does when lightly loaded. 

If the RPM for your engine is within the WOT RPM range for the engine you are “GOLDEN”. Go wakeboarding … go surfing … have fun! If the engine turns RPM at WOT it means that it will be properly loaded throughout the RPM range. You don’t always have to run the engine at WOT … in fact I don’t recommend that you run at WOT for extended periods of time … it just has to be able to run within that range at WOT. If the engine is not able to turn in the WOT RPM range for your engine, you have two choices … take some weight out of the boat or change the propeller. Every time you run the boat in those same conditions (overloaded) you are risking the longevity of your engine, and if the engine fails under those conditions it is a good chance the failure would not be covered under warranty even though it may be within the warranty period.

If you can’t tolerate reducing the weight in the boat, you will have to re-prop with a smaller pitch/diameter propeller to reduce the load on the engine. I am not a prop expert so I won’t be able to help you select the correct prop. Fortunately, I have some friends who are experts. You can contact the good folks at ACME (www.acmemarine.com) or OJ (www.ojprops.com). Either of those fine companies will be able to help and make propeller suggestions that will get you where you need to be RPM wise.

Once you are propped for the maximum load in the boat, what is going to happen when you run the boat without the load? Not to worry … running the boat under-propped for the load may have an effect on the WOT performance of the boat … it probably won’t go as fast. You won’t have to worry about over-revving the engine though because all of our fuel injected engines have RPM limiters that will not allow the engine to over-rev. It is much better for your engine to be under-propped than it is to be over-propped. If you don’t like the lightly loaded boat performance with the smaller prop, keep your old prop and use it when you are running lightly loaded and switch to the heavy load prop when you use the boat heavily loaded.

Why is this so important? For example, if your engine is only able to turn 4000 RPM at WOT, the engine is running hot and hard but because it cannot turn at the rated RPM, the water pump is not pumping as much water as it should be or that the engine wants when it is working that hard. Also, under those conditions, the throttle settings are telling the ECM/computer to supply fuel to the engine for WOT operation but because the engine is not turning the appropriate RPM, the engine is over-fueled. It may not be able to burn that excess fuel … so now we start washing oil from the cylinder walls which accelerates cylinder wear. And where does that excess fuel go? Some goes past the rings into the oil which dilutes the oil and reduces its ability to properly lubricate the engine … and some goes out through the exhaust. If the engine has catalytic converters, unburned gasoline in the catalysts creates extra heat in the catalyst and with the diminished water flow because of reduced engine RPM we have a hard time keeping the catalysts and manifolds cool which creates more problems.

Bottom line … it is extremely critical that your engine is able to run within the rated RPM range at Wide Open Throttle. If you run your boat heavily loaded and the engine will not turn within the designated RPM range, you are killing your engine and if it dies under those conditions that is considered abuse and abuse is not covered by warranty. 

The Engine Nut has spoken!

Edited by ConnollyCrew

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minnmarker

Good info.  I had not read it - and I seriously doubt that I can get to 4800 rpm with 3,000 lbs of water and 5 people in the boat.  Is there a minimum WOT rpm (not ideal) that is acceptable?

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oldjeep
10 minutes ago, minnmarker said:

Good info.  I had not read it - and I seriously doubt that I can get to 4800 rpm with 3,000 lbs of water and 5 people in the boat.  Is there a minimum WOT rpm (not ideal) that is acceptable?

The minimum WOT is the low number in the WOT range.  This is the same way you pick a prop for anything (ski boat/ tow boat/IO/outboard) regardless of who made the motor.   The danger always is that if you are propping your sunken ship RPM you have to exercise control in not reving out of the WOT range when unloaded.  Some boats have rev limiters and some don't.

Edited by oldjeep

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thtrog

Don't forget to drop the wedge into the equation, if you are considering load. PCM has a chart in their manual with very similar recommendations for load and prop selection.

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Technicallyabu

Over-fueled? Hot?  I don't see a rainbow of fuel on the water from my exhaust or have the engine temp go above 160 degrees.  I change oil at a 30 hr interval.  I'll stick with a prop that is a compromise between top speed and torque even if I have to run the snot out of the engine when surfing.  I understand the engine works hard and will require a rebuild sooner than it would otherwise but whats sooner?  1000 hrs? 1500 hrs?

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surfdude
9 minutes ago, shawndoggy said:

IMHO the reality is that malibu and dealers are not marketing the boats this way.  @DarkSide @UpperleftWake @IXFE @Wakesetter67 @mikeo @nyryan2001 @surfdude @bbattiste247  do you guys make sure that your boat can hit within 400 rpms of redline with all weight and wedge deployed?

Seems like the trend on here is bragging rights about how low your RPMs are at a given surf speed.... Never a mention of being able to hit max rpms in that config...

Yes I can!!

Thought I was being funny one day and had to pick up people from the dock a quarter of a mile away. Loaded for surfing and used the lift mode to get on plane. Boat was at the top rpm line for awhile think I was only going 25-26. I won't do it again though, think it's hard on things!

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95echelon
1 hour ago, oldjeep said:

The minimum WOT is the low number in the WOT range.  This is the same way you pick a prop for anything (ski boat/ tow boat/IO/outboard) regardless of who made the motor.   The danger always is that if you are propping your sunken ship RPM you have to exercise control in not reving out of the WOT range when unloaded.  Some boats have rev limiters and some don't.

I like to time my rev limiter with my drum n bass music.

what-is-love-570898416.gif

12 inch pitch is love, 12 inch pitch is life.

 

Edited by 95echelon

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ConnollyCrew
7 hours ago, 95echelon said:

I like to time my rev limiter with my drum n bass music.

what-is-love-570898416.gif

12 inch pitch is love, 12 inch pitch is life.

 

@ibelonginprison your in the backseat. ??? 

Dont mention me driving or Higgins riding shotgun!

Edited by ConnollyCrew

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DAI

Where do you find WOT RPM ranges (i.e. 2014 MP LS3)?  I've check the engine's literature but can't find it.

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JasonK

Does it matter if it's carb'd or EFI? Does the theory apply to both?

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bbattiste247

I am running a 15X17.75 with a 410 motor and 1.76 tranny ratio. I may be over pitched, now you got me thinking...I doubt if I could get to 3800 rpm's fully loaded. It may be time to get a different prop, but I do like the way the boat handles. It is very smooth even though it takes a little longer to get on plane.

I appreciate the info. Everyone I talked with (Malibu dealer Service Manager and Acme props) all told me there will be no damage to the motor by going with a higher pitch. The explanation I just read make sense.

Edited by bbattiste247

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oldjeep
Just now, JasonK said:

Does it matter if it's carb'd or EFI? Does the theory apply to both?

Different ranges for carb/efi and even different types of EFI but yes WOT operating range is a concept that has been common to all boats for as long as I can recall

 

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ibelonginprison
1 hour ago, ConnollyCrew said:

@ibelonginprison your in the backseat. ??? 

Dont mention me driving or Higgi ma riding shotgun!

Backseat controls the road drinks... I can handle that.

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95echelon
8 minutes ago, DarkSide said:

Absolutely can hit WOT, this was actually a concern.   My 14 couldn't,  even with 2419, 4200 was all she could produce.  The surfer absolutely hits 5000+  

However you are correct in Malibu not marketing towards "those people", of which I one.

I also am starting to believe that the Indmar platform wad not prepared for the usage some of these boats are seeing.   I tried ordering what would be "suited" for my use.  572 LSA, 15x15.5 prop, nothing crazy pitched, or oversized.  

Yet the force involved is still wreaking havoc on the mechanicals.  My engine appears to be solid, I typically am around 3500 RPM, so not totally pushing it, as stated in absolutely can red line it, so not lugging.  However, my tranny blew, my steering tube misaligned, my rudder box cracked, etc.  

On the Malibu call Jack Springer says "wakesurfing is still in its infancy"  I absolutely agree with this,  and as such, they haven't figured everything out yet.   Go back 5 years, 2012 model year very few boats had what is considered minimum now.   The MINIMUM TQ now is 400 and with increased gear ratios, we are stressing the boats significantly more than just 5 short years ago.  I don't believe the drive train has been upgraded to handle this additional load.  Boats are getting heavier, ballast is getting larger, 11,000 pound wake barges are common (boat,ballast,crew).  It's a whole new world, that requires new levels of robustness 

Just my opinion, but....

I have a bit less than 100 hours of wakesurfing on my 340 monsoon, I run 2800 rpm with few people and 3200 with a bunch, also 4k ballast. With the low pitch prop it does extremely well. Time will tell how much my drivetrain takes that abuse, but I think that the main issue people have with surfing is not having the right prop.

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ConnollyCrew
12 minutes ago, DarkSide said:

Absolutely can hit WOT, this was actually a concern.   My 14 couldn't,  even with 2419, 4200 was all she could produce.  The surfer absolutely hits 5000+  

However you are correct in Malibu not marketing towards "those people", of which I one.

I also am starting to believe that the Indmar platform wad not prepared for the usage some of these boats are seeing.   I tried ordering what would be "suited" for my use.  572 LSA, 15x15.5 prop, nothing crazy pitched, or oversized.  

Yet the force involved is still wreaking havoc on the mechanicals.  My engine appears to be solid, I typically am around 3500 RPM, so not totally pushing it, as stated in absolutely can red line it, so not lugging.  However, my tranny blew, my steering tube misaligned, my rudder box cracked, etc.  

On the Malibu call Jack Springer says "wakesurfing is still in its infancy"  I absolutely agree with this,  and as such, they haven't figured everything out yet.   Go back 5 years, 2012 model year very few boats had what is considered minimum now.   The MINIMUM TQ now is 400 and with increased gear ratios, we are stressing the boats significantly more than just 5 short years ago.  I don't believe the drive train has been upgraded to handle this additional load.  Boats are getting heavier, ballast is getting larger, 11,000 pound wake barges are common (boat,ballast,crew).  It's a whole new world, that requires new levels of robustness 

Just my opinion, but....

Agree 100%. 

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ibelonginprison
16 minutes ago, DarkSide said:

11,000 pound wake barges are common

 

Accurate assessment. 

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95echelon
9 minutes ago, ibelonginprison said:

 

Accurate assessment. 

I bet within 5 years we see a small diesel and a 19" prop. On a 25-26 footer. But probably from chaparral.

Edited by 95echelon

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tjklein

I hope it doesn't get too crazy.  If it does you'll start to see restrictions from lake associations on wake boats.  11,000lb barges...which my LSV can cause problems if you don't respect other boaters and the shore. I had a guy go by my lake place a couple weeks ago about 100' offshore and I just shook my head.  Sooner or later enough people will complain and ruin it for me.

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2014Skier
5 hours ago, ConnollyCrew said:

Why is this so important? For example, if your engine is only able to turn 4000 RPM at WOT, the engine is running hot and hard but because it cannot turn at the rated RPM, the water pump is not pumping as much water as it should be or that the engine wants when it is working that hard. Also, under those conditions, the throttle settings are telling the ECM/computer to supply fuel to the engine for WOT operation but because the engine is not turning the appropriate RPM, the engine is over-fueled. It may not be able to burn that excess fuel … so now we start washing oil from the cylinder walls which accelerates cylinder wear. And where does that excess fuel go? Some goes past the rings into the oil which dilutes the oil and reduces its ability to properly lubricate the engine … and some goes out through the exhaust. If the engine has catalytic converters, unburned gasoline in the catalysts creates extra heat in the catalyst and with the diminished water flow because of reduced engine RPM we have a hard time keeping the catalysts and manifolds cool which creates more problems.

Don't really agree with that, if the engine isn't overheating it is getting enough coolant flow.  Yeah sure WOT is hard on engines, maybe piston temp, oil temp etc, but if it's still running at a reasonable temp, the argument doesn't make sense.  Second issue is the over fueling, the ecu, or carb for that matter will not over fuel just because the throttle is pinned and the motor is not turning max rpm.  Fueling is basically a function of manifold pressure/air flow and rpm, the fuel map dictates how much fuel is injected with compensation regarding coolest temp etc.  The target air fuel ratio is always maintained. 

Edited by 2014Skier

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SoulSurfer

So, which is worse - running at 4000 rpm and above basically all the time with the engine pretty freely spinning, with top speed being clearly limited by the rev limiter (quite a bit of throttle left and the boat will do this from sea level to 6500 feet) or having WOT engine speed prop-limited at full weight?  Picking the right prop for these boats is not as simple as it is for most, since the total boat weight can fluctuate so dramatically.  If you're propped for pushing a total weight of 10,000 pounds plus to full WOT range, you are going to be substantially underpropped when the boat weighs 5 or 6,000.  It seems like the application these engines came from (pickup trucks) are an environment where the operators are much more likely to push hard on a higher gear (i.e. lower rpm/higher load) vs. rev the pi$$ out of them in a low gear all the time. 

My boat will hit the top of it's WOT range of 5400 rpm with 2800 pounds of ballast and about 1200 pounds of people on board and I know it will hit 5000 rpm with 4500 pounds of ballast and 1000 pounds of people on board.  However, it also runs at 4000 rpm to cruise at 26 mph unloaded and surf rpm is 4000 - 4200 at 11-11.2 mph.  I can't imagine driving a Ford pickup around at 4000+ rpm all the time and expecting that engine to last very long....but I may be completely off base!

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