X'es and R's

[mikesufka]

We have tested the same exact boat (30 Spectre) except for different years with pairs of 250XS, 300X, 300XS with DBR stage 2 and 300R's. The 300R is a torque monster and I am a believer in the Mercury 4 stroke program on larger boats. I would take the 300R over any 2 stroke Mercury made on a twin engine cat application.

What were the results ? That is great info.

MDS

[JPEROG]

Well, I have a 300X on my 21 Daytona, Obsession. I was thinking of a repower and would be disappointed if I put a 300R on and the only thing I would get is an empty wallet. I know the 400R should work because they weigh the same as the blower motors Randy puts on the Liberators. What I want is the ability to blast through the hop zone on glass water and take three people and a cooler over 100mph any place and time. And run 115-120 mph by myself. I don't think a 300R would do it.

Two of them would....

Joe

[skialot2]

I was kind of worried about the weight too. I know my boat has four inches less freeboard, but it has 14.5 inches set back now and I would guess with a 400R it would need to be about 8 inches. Whatever Randy would recommend. That would have to help some. Why can't they make a 400 V8 that runs on premium? I don't think that would be difficult.

Premium? Why premium? The entire R series runs on Regular 87 octane except the 500R. It takes Midgrade 89 octane. None require premium. Even the Verado 600 V12 takes 87 octane.

[Wild Bill]

Because I want 400 HP out of their v8, and a 15-inch shaft too. I want it all, and I know I am not going to get it.

[JPEROG]

Because I want 400 HP out of their v8, and a 15-inch shaft too. I want it all, and I know I am not going to get it.

Be patient my friend. Your dream will become a reality soon. Not all of the parts will be coming from Mercury but it will be an awesome combination.

Joe

[hellbents-10]

My next step will be a 300R with a Motec ECU. Should be fun to see what kind of power we can make on premium pump gas! If that works good then it will be time to find a powerhead to really work on!

[Wild Bill]

Can't wait to hear about that. I am 62 can't wait forever.

[skialot2]

Because I want 400 HP out of their v8, and a 15-inch shaft too. I want it all, and I know I am not going to get it.

I don't think Mercury is going to come out with a consumer outboard that runs on premium. I do think they will have a naturally aspirated 400HP V8 very soon. But, it will run on 87 octane like the rest of Mercury's N.A. motors. There are plenty of 400+Hp N.A. V8's in the automotive world that run on 87. The 15" Mid, that's probably going to have to come from the aftermarket.

[David - WI]

I don't think Mercury is going to come out with a consumer outboard that runs on premium. I do think they will have a naturally aspirated 400HP V8 very soon. But, it will run on 87 octane like the rest of Mercury's N.A. motors. There are plenty of 400+Hp N.A. V8's in the automotive world that run on 87. The 15" Mid, that's probably going to have to come from the aftermarket.

Not very many of them will run "continuously" at 400hp... for very long, like an outboard will.

[skialot2]

Not very many of them will run "continuously" at 400hp... for very long, like an outboard will.

If Mercury's 4.6L V8 can push 500 supercharged horsepower for long enough, It can sure push 400 naturally aspirated horsepower for just as long if not longer.

[David - WI]

If Mercury's 4.6L V8 can push 500 supercharged horsepower for long enough, It can sure push 400 naturally aspirated horsepower for just as long if not longer.

"There are plenty of 400+Hp N.A. V8's in the automotive world that run on 87."

Pretty sure you missed the point.

[skialot2]

"There are plenty of 400+Hp N.A. V8's in the automotive world that run on 87."

Pretty sure you missed the point.

I think you missed the point! My point is that a naturally aspirated V8 can easily produce 400+ horsepower on 87 octane. Premium is not necessary. What is your point? They are not as durable as a 2 stroke? We all know that. But they don't make 2 strokes anymore.

[hellbents-10]

Automotive HP ratings are much different as well. The reason they can post a monster number is with the tuning that they have. As you keep your foot at WOT the power will not stay at max for long it will start to taper off to keep the engine alive. Enrichment vs time, cat over temp, exhaust flange protection, knock enrichment, low octane timing tables, timing vs manifold temp etc. No one would put up with this stuff in a boat, imagine sticks down and you get up to speed then it start falling off.

300hp from a NA v8 on 87 that can sustain that power for a full tank of fuel if you want to is pretty amazing.

[kelvin523]

Agreed; running the 300r at +5K 80% of the time is different application than daily automotive spinning +5k 10% of time. When Mercury puts their talent to work its art; the 300r is just the next generation of better. I'm not sure I agree 2 strokes are more durable; but hey my overall list of favorite outboards still has 2 strokes in the top 2 positions (1500xs, 280ros, 300r)

[David]

My next step will be a 300R with a Motec ECU. Should be fun to see what kind of power we can make on premium pump gas! If that works good then it will be time to find a powerhead to really work on!

are you going to program the ECU yourself?