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Mercury 450R - any issues ?

Toffen Gunnufsen

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Hi!,

At last I have the possibility to order a V8 450R for my ol Phantom 25. Being a festival promoter has not been easy the last year.. Totally lock down.

The 400R has been a fantastic engine, but this season is the last with warranty.

The 450R has been on the market for a while now. Any issues you know about?

Thanks!


Cheers Toffen
 

McKay

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Some broken lowers is about all I've heard about.
 

prorider

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Lots of broken shafts and lost 6000 dollar cleavers in lake. DCB and Eliminator both putting tabs on boats to help. Mercury has a new shaft now that is supposed to be better.
 

McKay

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Lots of broken shafts and lost 6000 dollar cleavers in lake. DCB and Eliminator both putting tabs on boats to help. Mercury has a new shaft now that is supposed to be better.
I think DCB only put a tab on one with 450’s. Have not been seeing any new models coming out with tabs.
 

BIGRED9158

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I know Elimnator built a 25 with 450r and it was snapping prop shafts almost every time the guy used it the 25 boat did not like that much power that was twins though not a single
 

McKay

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Really. See if they will build you a m33 with 450s and no tab. Nobody likes to talk about it but go ask Barrett marine how many they have fixed.
Ya have a few buddies with 33’s and 450’s. One two doors down. No tabs on them.
 

McKay

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Really. See if they will build you a m33 with 450s and no tab. Nobody likes to talk about it but go ask Barrett marine how many they have fixed.
Show me more than one of the ten or so 33’s built with a tab.

And I’m not saying there isn’t an issue with the lowers. I have been behind the wheel of a 450 boat that broke a lower on me and I was being very easy with it only doing 70 or so.
 

BIGRED9158

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I also know mercury has some lawsuits about people driving at high speeds and breaking prop shafts and people getting seriously hurt and killed that is why you see eliminator not making another 25 with 450r they won’t do it to much of a risk to get sued
 

Sonny

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I just took delivery of a 2021 Statement Cat with 450s.

Hoping someone will explain what effect the tabs have on the lower situation.

Thanks
 

prorider

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I just took delivery of a 2021 Statement Cat with 450s.

Hoping someone will explain what effect the tabs have on the lower situation.

Thanks
A tab helps them roll over easier. Some have lots vibration on takeoff if you give it more than 4000 rpm. They have all that exhaust dumping out around these cleavers which doesn’t help.
 

HighVoltage329

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I believe hull bottom design has helped with some issues.
I just took delivery of a 2021 Statement Cat with 450s.

Hoping someone will explain what effect the tabs have on the lower situation.

Thanks
I think your hull design is going to roll on plane without having to apply much power if it's like my MTI.
 

McKay

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I believe hull bottom design has helped with some issues.

I think your hull design is going to roll on plane without having to apply much power if it's like my MTI.
Agreed, the new lighter, longer cats get on plane so much easier with very little bow rise or cavitation.
 
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Sonny

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Understood. Yes, rolls right over with little to no cavitation. 14.75/15/35s Mercury Props. It did cavitate a little more with the 15.00/15/36s
 

Sonny

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Anyone making a Carbon Fiber Cowl for the 450s yet? With a design to increase air intake?
 

HGP3

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Anyone making a Carbon Fiber Cowl for the 450s yet? With a design to increase air intake?
 

martycar9

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My buddy has an MTI with two 450R's. We noticed there was a decent difference in the coolant temperature and pressure between the two (144 vs 153 and 10PSI vs 14PSI). Does anyone know if this is normal?
 

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lake p.a.l.

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My buddy has an MTI with two 450R's. We noticed there was a decent difference in the coolant temperature and pressure between the two (144 vs 153 and 10PSI vs 14PSI). Does anyone know if this is normal?
I'm no expert on 450s but I did notice the trim is way off between the 2, especially at 68mph
 

McKay

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My buddy has an MTI with two 450R's. We noticed there was a decent difference in the coolant temperature and pressure between the two (144 vs 153 and 10PSI vs 14PSI). Does anyone know if this is normal?
My trim seams to be spot on with my 450's. However yes I have one engine that runs slightly warmer and a little less pressure but only at idle. I have a spare set of lowers so I'm going to try one of my spares to see if there is any difference.

One other thing of note Mercury early this year started using a different prop shaft. There is a date on all of them and the new ones say Revision B.
 

DaveC

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I talked about the prop shaft issue with Eliminator and they said the prop shaft failures are due to severe prop cavitation

The engines are mounted very high for performance. When the boat rolls over while trying to plane they get prop cavitation causing stress on the prop shaft. The prop shaft does not like that vibration and will eventually fail.

If the engine was lower they would have no cavitation but then the boat would be slow.

They put a tab on it to get it to rollover faster reducing cavitation. But that is so the engine can be mounted at the correct height.

In most boats the best MPH is found when the engine is mounted very high. I am told for mine the peak MPH is found with the prop shaft at 2” above the bottom. That is very high.

The other solution is adding a jack plate like mine. I put the engine all the way down until it rolls over then move it up. I have zero cavitation
 
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McKay

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I talked about the prop shaft issue with Eliminator. they said the prop shaft failures are due to severe prop cavitation

The engines are mounted very high for performance. When the boat rolls over while trying to plane they get prop cavitation causing stress on the prop shaft. The prop shaft does not like that vibration and will eventually fail.

If the engine was lower they would have no cavitation but then the boat would be slow.

They put a tab on it to get it to rollover faster reducing cavitation.

The other solution is adding a jack plate like mine. I put the engine all the way down until it rolls over then move it up. I have zero cavitation
I seen STR came out with a version of their engine brackets that adjust. Have not seen them on a boat yet.
 

mbrown2

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The other solution is adding a jack plate like mine. I put the engine all the way down until it rolls over then move it up. I have zero cavitation
This is the route I went....I had a tough time rolling over with more than 2 people in the boat and lots of vibration....I had bobs machine jack installed and it works great...much easier to roll over now.
 

TVMNick

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My buddy has an MTI with two 450R's. We noticed there was a decent difference in the coolant temperature and pressure between the two (144 vs 153 and 10PSI vs 14PSI). Does anyone know if this is normal?
You will see variance widely with water pressure depending on several factors. I would say as stated earlier the variance in the trim setting would be enough to cause that discrepancy in water pressure. Those pressures I would say are normal for that speed, 90+ MPH and those pressures should come up near 20+ sustained.
 

McKay

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You will see variance widely with water pressure depending on several factors. I would say as stated earlier the variance in the trim setting would be enough to cause that discrepancy in water pressure. Those pressures I would say are normal for that speed, 90+ MPH and those pressures should come up near 20+ sustained.
Ya mine is strange. I don’t get hot. But sometimes I’m cruising at a 100 with upper 20s psi and then next time same speed same trim I’m at 15 psi. Need more seat time to figure it out.
 

Flying_Lavey

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Ya mine is strange. I don’t get hot. But sometimes I’m cruising at a 100 with upper 20s psi and then next time same speed same trim I’m at 15 psi. Need more seat time to figure it out.
lighter load allowing the boat to run more out of the water?
 

TVMNick

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Could be? Need to burn a few more tank full’s to get a good feel for it. It has 200 gallons so takes a bit to get through it. Headed to powell next week so much easier to stretch her legs.
I've noticed as I burn off fuel my boat settles on its back steps better and the water pressure comes up, I'm sure with your even bigger tanks you will notice this more than I do! It will be interesting to see if the 18 rake props make a difference as well. I wish I could have ran my 18 rakes at Havasu first for a direct comparison but with the air density difference keeping the bow carrying will be even more important at Powell.
 

HighVoltage329

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I got a set of 18* rakes to try also. Planning one putting them on next week.
 
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