High cruising RPM?

[MrHooly]

Recently purchased a 2003 Lavey NuEra 26 MCOB with the standard 496 MAG (non HO) and B1. Overall I'm in love with it, but I was sort of expecting to have lower cruising RPM's, but maybe I just need an adjustment to the setup. Right now 4000 RPM is about 35 mph at Havasu...same as my old 18' VIP with a carbed 4.3L and A1, although I never have to back down to 10-15 mph for afternoon chop anymore. 4200 RPM is about 40 mph, which is where I'd like to cruise at a lower RPM. It's to my understanding that these engines are happiest at 3500. I could be wrong. Also currently running a stock 24P. Would I benefit from switching to a 26, or labbing the 24?

Also boat runs 57 (non GPS speedo, not sure how off that may be) with 3/4 tank, 4 people, full cooler, and a shit ton of life jackets up front. Would like to do the 203 cam, roller rockers, springs, headers, and Whipple stage 2 tune in the future.

 

[LargeOrangeFont]

Labbing the 24 will likely raise the RPM. Try a 25 or 26. Given your info, the 24 is in the ballpark. I don't think it will run any better overall with a bigger prop.

 

[RCDave]

Something ain't right with the setup. That lavey should run much faster with that engine. My former 25 Shockwave tremor cruised at 55mph at 4,000 rpm with a box stock 23 rev 4 and topped out in the low 70's. That Lavey should run close to those numbers....

 

[LargeOrangeFont]

Something ain't right with the setup. That lavey should run much faster with that engine. My former 25 Shockwave tremor cruised at 55mph at 4,000 rpm with a box stock 23 rev 4 and topped out in the low 70's. That Lavey should run close to those numbers....

Its a NON HO 496. About right on for a nearly loaded 26' MCOB. Those are not small or light boats.

 

[spectras only]

Going up one pitch size on the prop would drop rpm by 200 but it would affect your boat getting on plane with the loads you've posted. If you go this route, better get some tabs if you don't already have them.

 

[Bigbore500r]

That's 42% prop slip at 35mph. I don't think that is normal?

At 57 mph your prop slip is down closer to 20%, assuming you're running somewhere around 4600-4800 WOT. That seems like a reasonable slip number

 

[LargeOrangeFont]

That's 42% prop slip at 35mph. I don't think that is normal?

At 57 mph your prop slip is down closer to 20%, assuming you're running somewhere around 4600-4800 WOT. That seems like a reasonable slip number

In the ball park.. Partial throttle has quite a bit of prop slip. I have about 30% at 40MPH and more at 35 MPH.

And none of this is GPS'd so we are shooting in the dark anyway.

A full 26 foot boat closing in on 60 MPH with a standard 496 is around what one could expect. A loaded 23 foot boat with the same engine does mid 60s.

 

[RCDave]

Its a NON HO 496. About right on for a nearly loaded 26' MCOB. Those are not small or light boats.

size and weight wise it might be slightly larger/heavier than a tremor, but wouldnt account for numbers like that. 4000rpm at 35mph is pretty inefficient, The mag has almost the same torque as the HO at that rpm.

Maybe the prop was damaged and repaired at somepoint and the pitch/blade geometry was changed for the worse

 

[LargeOrangeFont]

size and weight wise it might be slightly larger/heavier than a tremor, but wouldnt account for numbers like that. 4000rpm at 35mph is pretty inefficient, The mag has almost the same torque as the HO at that rpm.

Maybe the prop was damaged and repaired at somepoint and the pitch/blade geometry was changed for the worse

Could be a million things. Aren't Lavey's supposed to be heavier boats anyway? How much weight/people and where is it all placed? Without GPS info.. who knows. If the speedo is 10% off (likely) the entire picture changes dramatically.

 

[RCDave]

I'd try a box stock 23P rev4 or 24 bravo 1 and see if improves the performance.

One thing I did notice a 24 bravo requires more cruising rpm versus a 23 rev4. they are not as efficient for cruising

 

[LargeOrangeFont]

I'd try a box stock 23P rev4 or 24 bravo 1 and see if improves the performance.

One thing I did notice a 24 bravo requires more cruising rpm versus a 23 rev4. they are not as efficient for cruising

My Rev 23 was less RPM across the board than my B1 24. It was on the low side of peak RPM with with it. Top speed was about the same.

 

[RCDave]

Yup. I think bravo's are little light on pitch.

 

[spectracular]

How many blades on the stock prop? Go up a blade count but keep the current pitch. Should give more bite for a given rpm.

 

[JDub24]

Paging @lavey jr

 

[FreeBird236]

Does it feel like it's really freeing up when you trim it high? Maybe nose heavy? I lose 3-4 mph with a couple of people up front. Pitot tubes do sometimes register slow with age. Whats your RPM at 57 and WOT? I lose at least 200 RPM in this heat.

 

[02HoWaRd26]

I have a Hydromotive 4 blade 25p your welcome to try.
But i don’t think your numbers are off all that far for a stock mag, I’d try removing the plates from the exhaust manifolds. Of all i did to my 496 ho that was the best seat of the pants dyno increase i saw.

 

[Rbcconst]

Recently purchased a 2003 Lavey NuEra 26 MCOB with the standard 496 MAG (non HO) and B1. Overall I'm in love with it, but I was sort of expecting to have lower cruising RPM's, but maybe I just need an adjustment to the setup. Right now 4000 RPM is about 35 mph at Havasu...same as my old 18' VIP with a carbed 4.3L and A1, although I never have to back down to 10-15 mph for afternoon chop anymore. 4200 RPM is about 40 mph, which is where I'd like to cruise at a lower RPM. It's to my understanding that these engines are happiest at 3500. I could be wrong. Also currently running a stock 24P. Would I benefit from switching to a 26, or labbing the 24?

Also boat runs 57 (non GPS speedo, not sure how off that may be) with 3/4 tank, 4 people, full cooler, and a shit ton of life jackets up front. Would like to do the 203 cam, roller rockers, springs, headers, and Whipple stage 2 tune in the future.

I have a lavey 2750 MCOB with the HO and run a 24P, tried a 26p once and its way to big. The 2750 has a more efficient bottom then the 26 nuera with equal power. My cousin has the lavey 24 nuera open bow walk through with a mag and runs a 22P. You should try a 22P, sounds like you might be over propped. Might also see if someone has a 21P 5 blade, maybe the hill round ear.


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[Runs2rch]

My Rev 23 was less RPM across the board than my B1 24. It was on the low side of peak RPM with with it. Top speed was about the same.

You run a 23 with the 6.2? Pulls it fine?

I run a 23 Rev4. 496ho.

 

[HALLETT BOY]

Pull engine , buy take out 525 , put on blower kit , install 30 pitch Maximus prop ! Walla ! Now you cruise 55-60 at 3500 rpm !

 

[LargeOrangeFont]

You run a 23 with the 6.2? Pulls it fine?

I run a 23 Rev4. 496ho.

Yes and yes. My drive is a 1.62 ratio. I need to get my Rev 4 labbed, and I think it will be perfect.

It actually like a slightly higher pitch than my B1 24 prop. I like the way the boat rides better with the Rev.

 

[BajaMike]

With the current setup and a heavy load can you easily get to red line RPMs (4800 or 4900)? If not your are over propped.

 

[MrHooly]

Pull engine , buy take out 525 , put on blower kit , install 30 pitch Maximus prop ! Walla ! Now you cruise 55-60 at 3500 rpm !

Exactly this in the future...when it's more financially justifiable lol. For next year I'd like to see what the aforementioned Raylar 203 cam and roller rockers, springs, headers (CMI, Dana, etc) and Whipple tune can do. Would the Cool Gap intake with this setup even be remotely worth it with stock heads?

Also for those asking, that 57 was at 4900 - 5000. Gauge once read 60 with a lighter load, but again, none of this is GPS. Stock 24P.

 

[Bpracing1127]

In the ball park.. Partial throttle has quite a bit of prop slip. I have about 30% at 40MPH and more at 35 MPH.

And none of this is GPS'd so we are shooting in the dark anyway.

A full 26 foot boat closing in on 60 MPH with a standard 496 is around what one could expect. A loaded 23 foot boat with the same engine does mid 60s.

67 mph bully

 

[lavey jr]

Exactly this in the future...when it's more financially justifiable lol. For next year I'd like to see what the aforementioned Raylar 203 cam and roller rockers, springs, headers (CMI, Dana, etc) and Whipple tune can do. Would the Cool Gap intake with this setup even be remotely worth it with stock heads?

Also for those asking, that 57 was at 4900 - 5000. Gauge once read 60 with a lighter load, but again, none of this is GPS. Stock 24P.

I don’t have any comment or knowledge on that engine upgrade. The only upgrade I’ve personally tested was CMI headers on a 496HO and it was a great improvement! I assume that same upgrade can be done on the standard 496.

If you’re getting 57 with a loaded up boat like you mentioned, you are right in the ball park of where the speed should be. With that big of a boat and that size of engine, your cruise speed RPM is going to have to be in the 4200 range with the prop you are currently using. If you can I would recommend trying the 26p Bravo1 to see what the boat does. You need to do all this testing with the boat loaded up like you would normally use it to truly know if it’s better or not and to see if you can still get on plane in a good time. If cruising RPM and speed is more of your concern and you’re less worried about the top speed, you should look into a different prop. The Rev4 has great feedback and results for lower and mid range numbers, or possibly try a smaller 5 blade prop. If you go the 5 blade route you’ll have to be easy on the drive getting on plane but once up on plane it’ll be fine

 

[LargeOrangeFont]

67 mph bully

Only in a Cobra.

 

[GRADS]

I have a 26' boat with a 496Mag....speeds sound normal and right on par with mine.

 

[Bpracing1127]

Only in a Cobra.

Paaaaaaleeease. You must also be telling me your boat is worth 65k

 

[SOCALCRICKETT]

Yes and yes. My drive is a 1.62 ratio. I need to get my Rev 4 labbed, and I think it will be perfect.

It actually like a slightly higher pitch than my B1 24 prop. I like the way the boat rides better with the Rev.

How many factory B1 ratios are there? I have 1.50 on a 27 formula, ive seen high hp boats run a 1.32. I always thought there was only 2 options but im no professional by any means.

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[Runs2rch]

I have a 26' boat with a 496Mag....speeds sound normal and right on par with mine.

We don't know what your boat weighs....

 

[GRADS]

We don't know what your boat weighs....

We will tomorrow.

 

[ToMorrow44]

In the ball park.. Partial throttle has quite a bit of prop slip. I have about 30% at 40MPH and more at 35 MPH.

And none of this is GPS'd so we are shooting in the dark anyway.

A full 26 foot boat closing in on 60 MPH with a standard 496 is around what one could expect. A loaded 23 foot boat with the same engine does mid 60s.

I’m right about 30% at cruise speed with a bravo 1 as well.

 

[LargeOrangeFont]

Paaaaaaleeease. You must also be telling me your boat is worth 65k

No of course not. It’s worth 75k.

 

[spectras only]

How many factory B1 ratios are there? I have 1.50 on a 27 formula, ive seen high hp boats run a 1.32. I always thought there was only 2 options but im no professional by any means.

Bravo one drive ratios are 1.36, 1.50,1.65 for single props. Bravo three is 1.81, 2.00, 2.20, 2.43.1
I have 6.2's with Bravo 1 X diesel drives with 1.65 ratios, turning B1 26P labbed and pitched to exact 26P @ 5000WOT.
Before re-pitched the blades from factory [ they're never true 26] I could peg the rev limiter at 5150rpm, but more difficult getting on plane now when loaded. I'll most likely will drop the pitch back to stock.

My boat is pretty heavy for a 24' hull at around 6700lbs dry [ 25'7 with built in swimstep ] but once it's on plane it runs clean

 

[LargeOrangeFont]

Yea I made a typo, I have the 1.65 gearset. That is standard for most small blocks.

 

[LargeOrangeFont]

How many factory B1 ratios are there? I have 1.50 on a 27 formula, ive seen high hp boats run a 1.32. I always thought there was only 2 options but im no professional by any means.

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Just the 3 as stated by Spectras Only. Basically it is to keep most any engine within the same range of props, run more efficiently, etc.

 

[Mandelon]

That 26 is a pretty big boat with only 375 HP behind it. I remember Camire telling me the 26 was slower than the 27 with the same power.

 

[BajaMike]

Exactly this in the future...when it's more financially justifiable lol. For next year I'd like to see what the aforementioned Raylar 203 cam and roller rockers, springs, headers (CMI, Dana, etc) and Whipple tune can do. Would the Cool Gap intake with this setup even be remotely worth it with stock heads?

Also for those asking, that 57 was at 4900 - 5000. Gauge once read 60 with a lighter load, but again, none of this is GPS. Stock 24P.

Also, are you trimming up your drive once you get up to cruise? You’ll pick up a lot of speed as the drive goes up.

 

[MrHooly]

Also, are you trimming up your drive once you get up to cruise? You’ll pick up a lot of speed as the drive goes up.

About as far up as it will go before it starts slowing down again, then just a little back down to where it peaks.

 

[Bigbore500r]

I still think 42% slip at Cruise is damn high. He’s 22% at WOT.

 

[BajaMike]

About as far up as it will go before it starts slowing down again, then just a little back down to where it peaks.

Sounds like you are set up pretty good. I don’t like turbos on a pleasure boat....just some thing else to go wrong. On a none turbo boat, you got an engine and a drive to break. With a turbo, your got an engine and a turbo and a drive to break. The turbo can cost as much as a major engine repair or drive replacement. They give you power and also worry. I’d rather have a bigger engine, no turbo.

 

[02HoWaRd26]

Pull engine , buy take out 525 , put on blower kit , install 30 pitch Maximus prop ! Walla ! Now you cruise 55-60 at 3500 rpm !

With an HO

 

[lavey jr]

That 26 is a pretty big boat with only 375 HP behind it. I remember Camire telling me the 26 was slower than the 27 with the same power.

Yes, that is a true statement. Power for power, the 2750 is faster than the 26

 

[LargeOrangeFont]

I still think 42% slip at Cruise is damn high. He’s 22% at WOT.

It’s a big heavy boat for a 26, and a low HP engine relative to the boat size. Life in the hood.

A magic deck does about 60 on a good day with an HO

 

[mswasey]

I have a 26 Lavey closed bow with a 500efi. Bravo 26 is too big, Bravo 24 runs good, but best all around especially for cruise speed and loaded heavy at Powell is a 4 blade Power Tech 23 that I ended up with. That prop runs 44mph at 3500 and 48mph at 3600, this is loaded heavy and at 3600’ elevation. At Havasu and light load the 24 runs good, the 26 is still a little big. I would really love to try a Max 5 (at Lavey Jr suggestion) if I could ever find one to test.
Hope that helps.

 

[EBT531]

I have a 26 Lavey closed bow with a 500efi. Bravo 26 is too big, Bravo 24 runs good, but best all around especially for cruise speed and loaded heavy at Powell is a 4 blade Power Tech 23 that I ended up with. That prop runs 44mph at 3500 and 48mph at 3600, this is loaded heavy and at 3600’ elevation. At Havasu and light load the 24 runs good, the 26 is still a little big. I would really love to try a Max 5 (at Lavey Jr suggestion) if I could ever find one to test.
Hope that helps.

What top end speed are you getting with the 24P? I have the same motor but a 29 Lavey and the 26P seems too big but thats what the magazines tested it with.

 

[mswasey]

What top end speed are you getting with the 24P? I have the same motor but a 29 Lavey and the 26P seems too big but thats what the magazines tested it with.

Let me just say I completely love my Lavey! It’s a super strong layup and handles great for everything I do.
At Havasu with my Blueprinted Bravo 24 and a light to me load (4 people, 50-60gal of fuel, full cooler, tools, and cleaning supplies) I get 69.0mph at 5100rpm.
I ran a stock 26 Bravo at 66.7mph and 4500rpm wot.
What do you see with your 29/500efi?

 

[GETBOATS]

Forgive me if I missed it, Didn't read all of it. But the first test you need to do is a wide open, loaded the way you normally would run, trimmed the way you normally use it, tabs etc. Your engine has a rated RPM range, ? HP at 4800-5200 rpm maybe, they differ, so do a little homework and find out. preferably in the upper end of that range. Than you have a baseline of where to start moving around with pitch. so if you get 5100, then you would not be advised to drop pitch, on the other hand, if you are only getting 4700, then an increase in pitch is a bad idea. figure about 200 Rpm per inch of pitch. This exercise may solve the problem, then its time to test different ones in that pitch area. unfortunately more times than not lots of money gets spent on the search for the magic prop without the necessary information that free for the taking. test on!!

 

[EBT531]

Let me just say I completely love my Lavey! It’s a super strong layup and handles great for everything I do.
At Havasu with my Blueprinted Bravo 24 and a light to me load (4 people, 50-60gal of fuel, full cooler, tools, and cleaning supplies) I get 69.0mph at 5100rpm.
I ran a stock 26 Bravo at 66.7mph and 4500rpm wot.
What do you see with your 29/500efi?

Well I have'nt had the boat long to try different props, but with a 26P Bravo I, I'm at 63mph and 4800RPM's (GPS). Thats with 3 people and 150 gallons of fuel. I also have a SCX extreme outdrive which is hurting my slip numbers. I have a 24P in the garage I need to try but I'm also thinking I should have the 26 labbed.

Are your speeds GPS or? Your slip numbers are way better than mine. Does the bow carry nicely or does it feel "heavy" or planted?

 

[mswasey]

Well I have'nt had the boat long to try different props, but with a 26P Bravo I, I'm at 63mph and 4800RPM's (GPS). Thats with 3 people and 150 gallons of fuel. I also have a SCX extreme outdrive which is hurting my slip numbers. I have a 24P in the garage I need to try but I'm also thinking I should have the 26 labbed.

Are your speeds GPS or? Your slip numbers are way better than mine. Does the bow carry nicely or does it feel "heavy" or planted?

Seems like you’re pretty close on the prop you’re running, I’m betting you see maybe 1-2mph more with the 24, but obviously you’ll loose a couple on the cruise speed.
My boat likes plenty of trim and the bow carries well, and is still plenty wet that it’s always a solid ride.
My numbers are phone ap and handheld gps, so they should be accurate.
You’ll love your 29. Seanroberts has a beautiful 29 with bigger power, he would likely be a great source for info or questions you might have about yours.

 

[Blackmagic94]

All of the bravo style props I ran on my 238 Carrera would be 11-14% slip at WOT but at cruise they are around 20-25%


I would rather spin a motor slower at the same speed for lower wear