New Aritcle - thoughts on a Mercury Racing 3.4-liter R-series engine

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Originally Posted by Rayzor

It sucks that Mercury has "followed the money" and only developed high performance engines for the big multi-engine markets. With the technology we have today, I see no reason why they couldn't build successors to the venerable 2.5/3.0/3.2 models of 280-330HP two-stroke engines that only weighed 375-500#s. I can't imagine that they couldn't build something along the lines of a 2.5L inline 4 w/ a single turbo that wouldn't make at least 350HP on 91 octane and weigh no more than one of the old V6 two-strokes. If GM can do it (2024 2.5L LKO turbo engine, 328hp/326lb-ft) I can't believe Merc can't do it also.

GM 2.5L LK0 I-4 Turbo Engine Info, Uses, Specs, Wiki (gmauthority.com)

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Spot on. :thumbsup:

We have been testing a 200R for Allison and Mercury Racing. It pushes the XB-21 Prosport SUB quite well. :D

Details please!

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Originally Posted by aj06bolt12r

Details please!

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I can't just yet since its an ongoing project but it has crossed the 90 mph threshold.

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Originally Posted by FBM

I can't just yet since its an ongoing project but it has crossed the 90 mph threshold.

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Really.. Thats impressive for a 21

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Originally Posted by aj06bolt12r

Really.. Thats impressive for a 21

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:iagree:

Is the gearcase 4.8 or 5.44? or ?

It sounds very promising. 90 is fast enough for me.

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Originally Posted by David

Is the gearcase 4.8 or 5.44? or ?

It sounds very promising. 90 is fast enough for me.

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5.44 SM w/ 1.75 gears. I have a coned 4.8 TM and a stock 4.8 TM to try but when setup properly the 5.44 SM is fast and extremely stable.

In addition to running the 200R on the SUB into the 90s today, we also ran a 300R on a XB21 2+2 to 104.8 and a XB21 2 seater 450R to 111.3 (boat was loaded, with ultrex quest and 2 12” screens on the bow)

At that rate you could build a new 25 Tuff and run 90+ then! That would be a nice fuel sipping package!

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Originally Posted by FBM

5.44 SM w/ 1.75 gears. I have a coned 4.8 TM and a stock 4.8 TM to try but when setup properly the 5.44 SM is fast and extremely stable.

In addition to running the 200R on the SUB into the 90s today, we also ran a 300R on a XB21 2+2 to 104.8 and a XB21 2 seater 450R to 111.3 (boat was loaded, with ultrex quest and 2 12” screens on the bow)

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That is badass... All of those numbers!... Ya'll have to have the record for the fastest loaded XB21 on the planet.. Also seems already safe to say that the 200R is at least as strong as an old 225 Promax

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Originally Posted by FBM

I can't just yet since its an ongoing project but it has crossed the 90 mph threshold.

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Looks to be adhering to the +10% allowance rule on HP. Do you have a dyno down there to throw the motor on?

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Originally Posted by aj06bolt12r

That is badass... All of those numbers!... Ya'll have to have the record for the fastest loaded XB21 on the planet.. Also seems already safe to say that the 200R is at least as strong as an old 225 Promax

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We do hold the title to all of the XB21 models :cheers::D

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Originally Posted by Greg G

Looks to be adhering to the +10% allowance rule on HP. Do you have a dyno down there to throw the motor on?

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I don't have a dyno unfortunately but I can tell you it will spin a 300HP 32 CNC to 5800 RPM or most any other 30-32 four blade to 6100. I believe when used in the correct application it will be a nice engine. The 5 blade 32 CNC is definitely too big and makes it grunt on the bottom end.

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Originally Posted by FBM

We do hold the title to all of the XB21 models :cheers::D





I don't have a dyno unfortunately but I can tell you it will spin a 300HP 32 CNC to 5800 RPM or most any other 30-32 four blade to 6100. I believe when used in the correct application it will be a nice engine. The 5 blade 32 CNC is definitely too big and makes it grunt on the bottom end.

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That really is impressive... Ive been tentatively considering a 200r for my XB03 but Ive been kind of worried that it would feel a little sluggish compared to my E-Tec.. But judging by this it should do pretty good on a 20ft boat.

FBM what are you doing? You doing your best to outrun that yellow boat on watts bar running a lil motor

FBM you need to hang the little fella on a scale and get a true weight. Not sure what Merc has placed on the tag but the big 300 R weighs 561lbs