Fuel comparison of M6 VS LT4?

[hethj7]

On 12/16/2020 at 2:48 PM, cuziluvit said:

We bought a 25LSV with the LT4 in early November, so we don't have a ton of hours on it.  However in the 16 hours we have thrown down, it was getting a workout, lots of surfing and a bit of touring.  We were pushing it to break in the motor on the touring part, varying between 28 and 47MPH, so gas consumption was up there.  Bottom line is, I'm thrilled with it's burn rate.  It's averaging 5 to 5.5 GPH.  Which is basically what I was getting out of my old 383 Hammerhead, but there's a lot more boat to push around, and the power upgrade is astounding.  I never would have believed a boat this size would hole shot so hard.

47 MPH has to be a typo, right?  Even with the LT4.   

[jammer]

48MPH was my experience during a demo in September in a 2021 25LSV w/ LT4 -- the power, speed and quiet operation convinced me to upgrade to the LT4 in a custom-ordered 2021 25 LSV to be delivered in the spring.  And that demo was at an altitude of 5,500 ft. at Deer Creek Reservoir.  The LT4 is legit.

[hethj7]

Wow!   Granted I don’t run a speed prop but didn’t figure the 25 could hit that speed.  Good to know!

[gregtay]

1 hour ago, hethj7 said:

Wow!   Granted I don’t run a speed prop but didn’t figure the 25 could hit that speed.  Good to know!

It is probably easier to get the 25 up that speed vs the shorter boats, length helps you in this case (and it isn't all that much heavier)

[dwc032]

I have the M6 in my 23 MXZ, but I have the LT4 in my ZL1 camaro. That motor is legit, bulletproof as hell solid internals and can produce gobs of power with just minor engine mods. 
 

In my OPINION, the M6 is plenty in all of the Malibu boats and the LT4 is an overkill. With the M6 at a 6K upgrade and the LT4 an 18k price tag, I’d save that money for gas and beer...lol. 
 

We live at 4500 feet, and several of our lakes are in the 5500 6500 range and the M6 has had plenty of power with a full boat and ballast. 

[Outlaw]

On 12/18/2020 at 5:16 PM, jammer said:

48MPH was my experience during a demo in September in a 2021 25LSV w/ LT4 -- the power, speed and quiet operation convinced me to upgrade to the LT4 in a custom-ordered 2021 25 LSV to be delivered in the spring.  And that demo was at an altitude of 5,500 ft. at Deer Creek Reservoir.  The LT4 is legit.

What pitch does the LT4 come with? I’d think with all the extra torque over my M6 you’d be able to run much more pitch at 10.8 mph surf speed. I chose the STD prop for our 2020 23 and glad I did. I’d think M6 and LT4 redlines are about the same so only makes sense to run much more pitch for that top end. I love our M6 but want more top end for some of those grin moments.....  don’t think I need to explain why. Planning for an LT4 in about 2 years to replace our 2020 and want to get smart on LT4 props. Thx

[Tjards]

On 12/18/2020 at 4:16 PM, jammer said:

48MPH was my experience during a demo in September in a 2021 25LSV w/ LT4 -- the power, speed and quiet operation convinced me to upgrade to the LT4 in a custom-ordered 2021 25 LSV to be delivered in the spring.  And that demo was at an altitude of 5,500 ft. at Deer Creek Reservoir.  The LT4 is legit.

That boat we were on had the 3077 which is a 17X15.5. Crazy thing is with the 1773 17x14 we were seeing the same top end speeds. I would like to see how it does with the speed prop to compare.

[gorilla]

Just a comparison, on my 2017 25LSV with the 575 motor, I was running an Acme 3043 17x19 0.075 cup. It originally came with Acme 2805 17x17 0.105 cup. This is a 1.76:1 trans ratio. Fully loaded hard tanks, 750 PNP each rear, 650 bag in the walkway, wedge at 3-4 and it would reach surf speeds easy at 1300' elevation and 6-8 people on board. With that prop, I never found the ceiling for power. I'm sure at Powell that I would have had to run the 17x17 prop, but sold the boat before I ever got up there.

Oh, and I hit 51mph before I let off the throttle. It was starting to get a bit dicey at that point and I still had more RPM left. 

Edited January 3, 2021 by gorilla

[djheywood]

Thanks for all the great replies.  i'm most intrigued about the new top end.  I ordered a 2021 25 LSV and went with the LT4, so once I get the boat in the spring I will report back on fuel burn on an average day vs our 2020 MXZ and top speed at our local lake (about 700 ft above sea level i think) 

[cuziluvit]

On 12/18/2020 at 10:42 AM, gregtay said:

I think some of that has to do with the surfgates and wedge bracket getting in the way of the water stream on our boats  The videos of other manufacture boats with the same thruster do seem to come around much faster.  I know some people have tried use the diverter cowls and that might help a bit more.  There are much larger diverters available (see the ones shown/available on Sidepowers website: https://side-power.com/kategori/2000/sx-serien-ny-2019/, I think the EZDrive guys tested these cowls in the early days but not sure what the result was and/or how well they fit on different Malibu's. When I purchased my unit they had their own smaller diverter power nozzle available but I couldn't get it in black so I went with the normal (straight) power nozzle. The ones below might be a tight fit (they look huge) but I believe people have posted on TMC with them installed (at least on one side) and noted it help increase the turn rate. 

EDIT: I just looked and EZDrive has recently added a few new larger cowls of their own available in 30 and 45 degree angles. Nice! I might have to try one out to see if what the different effects are and if the turn rate improves. The 30 degree one might be just the ticket to divert under the surfgate and the wedge mount.  https://www.ezdrivethruster.com/products/#thruster-parts  Also, it looks like the EZ Drive cowls retain the safety grate while the Sidepower version does not.  I much prefer something there to stop sticks (or my little kiddos hands!) from finding there way to the thruster prop.

 

 

I hadn't looked at that alignment relationship until you pointed it out.  I'm going to try those as well. Thanks for the info!

[andymo]

I have a 2020 M240 with the LT4 and FYI - least season (2020) we surfed a lot and burned about 1200 gals in about 180. The average was closer to 6.75 gals per hour. With a lot of surfing vs cruising. 

[djheywood]

After the first season with the 25 LSV w LT4 it feels to me to use maybe 10% more fuel than the M6 in my 23 MXZ.  All in all it doesn’t feel any worse on fuel.  That is mixed cruising and surfing.  Boat has 50 hours on it now so I feel like I have some basis of comparison.  We were surfing at about 2750-2800 rpms.  
 

and top speed in Tahoe (6500 ft) was 42 mph with the standard 3077 prop.

 

hope that helps.  

[Gene3x]

If you are planning to wakeboard with lots of people or extra weight the newer bigger boats at 6k lbs and up the LT4 is absolutely neccesary if you don't want a ridiculous burn rate.  This is at sea level.  I had a 2021 24MXZ w/ the M6 and when adding more than an extra 800 lbs over stock (this includes people and gear) the boat struggled to get on plane. The ore it struggles to get up to speed the more you will burn through. Plus the rpms run higher on low pitched props causing more burn if it is not in the power band.

[Stevo]

 I’m checking the LT4 box, on the 25.

Altitude was the deciding factor, the 450 loaded with any crew in the Tahoe area, hit the power wall with the 3077 prop, and I would be dumping ballast to fine tune the wave. 

im not big on hitting 35+ generally keep it under 30 , it’s always seemed like a waste of fuel to me.

[djheywood]

You wont be disappointed.  I had 12 people in my 25 LSV in Tahoe, surfed no problem with full ballast, wedge and extra lead and the boat never struggled to get on plane.  It's a no-brainer in my opinion for any 23' boat or larger if you are going to boat in Tahoe.

[Gene3x]

On 9/3/2021 at 3:23 PM, Stevo said:

 I’m checking the LT4 box, on the 25.

Altitude was the deciding factor, the 450 loaded with any crew in the Tahoe area, hit the power wall with the 3077 prop, and I would be dumping ballast to fine tune the wave. 

im not big on hitting 35+ generally keep it under 30 , it’s always seemed like a waste of fuel to me.

Great choice.  Especially for where the boat will be located. 

My understanding is that the transmission is beefed up quite a bit on the LT4 boats also.  I was running across a rough patch of water (10 minute ride) in my 2021 24MXZ with 10 people and no ballast and the boat went into limp mode due to a transmission overheat warning.

[DFW]

Break in fuel consumption (11.1hrs) on my LT4 was 4.2 GPH. We’ll see how she does over the next 20-30hrs with more emphasis on surfing.

 

[Maas]

4.2 gph is a dream, very interested to see fuel burn fully loaded surfing

[Surf4FamFun]

On 9/14/2021 at 12:52 PM, Gene3x said:

Great choice.  Especially for where the boat will be located. 

My understanding is that the transmission is beefed up quite a bit on the LT4 boats also.  I was running across a rough patch of water (10 minute ride) in my 2021 24MXZ with 10 people and no ballast and the boat went into limp mode due to a transmission overheat warning.

Presuming you have lost an impeller wonder if you have a partially blocked cooling channel to the transmission?  

[Surf4FamFun]

Has anyone had troubler finding 91 or higher octane?  Anyone buy an LT4 without 91 octane or higher available on the lake?

[RyanB]

18 hours ago, Surf4FamFun said:

Has anyone had troubler finding 91 or higher octane?  Anyone buy an LT4 without 91 octane or higher available on the lake?

Much different engine, but my LS3 requires premium and the lake we put the most hours on only has 87. I use octane booster and have been fine as long as I use it. The one time I didn’t the engine knocked hard enough to throw a check engine light. 

[boardjnky4]

Be careful with the supercharged engine. Engines with turbo/supercharger are very picky about fuel.

[BarliBear]

On 8/31/2020 at 1:49 AM, Surf4FamFun said:

Looking at moving from a 22 LSV M5 to a 23 MXZ M6.  Any concrete numbers comparing the two, sorry about the hijack.  I can see how going from naturally aspirated to super charged and a big jump in HP and torque would impact fuel consumption but would not seem that the M6 would be that thirsty.  Don't really have a good gph number on the M5, we burn 24-28 gallons a day but have not kept up with the hours per day.

Just moved from a 22LSV with M5 to 25LSV with M6 and the M6 is more efficient. The 17” prop certainly doesn’t hurt 

[Maas]

Every Marina around me has 91 octane only, and with the 96 gallon tank on my new boat, i think i may just trailer it the 5 mins to the gas station to save on fuel costs!!

[Okie8498]

Just purchased a 2022 23LSV with the LT4…..   

will do some calculations after a few runs the next couple months…