Performance comparison F300 vs 250 SHO

[phallgtown]

I was hoping to get some feed back on which motor would perform better on any particular boat with all things being equal. If either motor were mounted on the same boat in this case fibreglass walleye boat. Boat weight alone is 2630lbs.
both motors are 4.2 litres both have same gear ratio. But the f300 is approx 50+ lbs heavier than the 250SHO. Does SUPER HIGH OUTPUT of the SHO overcome being 50hp less. Never have understood how they can have diff hp ratings.
in a nut shell which motor would have better hole shot and which will get better top end speed. Or is it a wash? Will appreciate the professional input to help me decide which motor to buy.

[rodbolt17]

the SHO motors were typically made to push small light design specific style boats IE bass boats.
typically only made in 20" but some are now 25".
the F300 was designed more for the Deep Vee type of boats typically found for offshore and light inshore style hulls.

[phallgtown]

With that said are you saying the f300 would give me better top end speed?
currently i top out at 50 mph with a 3.3litre f250. Chatting with some guys online with the same boat but the have the f250 4.2 litre and claim to get 56 mph. I have the situation where the boat/hull is being replaced by the factory. The have also redisigned the hull to incorporate a small pad for better performance. The f250 3.3litre gave me a holeshot i was happy with but wanted more speed. I figured a 250 SHO would do that. I dont understand what the difference the motors all being 4.2 except the motor i have at 3.3

[boscoe99]

A motor producing 300 HP at WOT is going to provide more top speed than a motor that only produces 250 HP at WOT.

A VF250 SHO model will therefore not provide a greater top speed than will an F300 Offshore model. In fact, it will be less.

Better that a VF250 SHO model be compared with an F250 Offshore model. If they produce the same HP then they will both provide the same top end speed. But, how they get to the top end speed can be different based upon how the engineers code the engine's computer.

If you are happy with the 3.3L F250 I suspect that you will be overjoyed with either the VF250 SHO or the F250 Offshore models.

The HP difference between the VF200/VF225/VF250 and the F225/F250/F300 Offshore models is the way that the engineers code the engines computer. Via the computer the same block can be made to produce different horse power values. More throttle opening, different ignition timing, different fuel flow rates, different intake cam shaft timing, etc. can all be con*****ed by the engines computer to create more or less HP from the same block.

On what I perceive a Walleye boat to be I would suspect that the SHO would be the best all around choice. Now if you want a bit more top end speed there are companies that can recode the engine's computer so that it outputs 300 HP. Maybe more.

[rodbolt17]

you simply cannot compare the old 3.3L with a 4.2.
other than they both were made by Yamaha and they share 6 cyl that is about all.
like I said the f300 was designed to push a deep vee type hull.
the SHO was designed for hole shot and top end with max jack height and trim.
typically the SHO motors will turn slightly more RPM.

kinda like I want a truck that can haul 9500lbs.
easy.
but I want to get 40 mpg doing it. not gonna happen.

a boat is a comprimise.
that flats boat with a poling platform works well chasing tailing fish on the flats.
not so good for *****ing for rock and useless for minor offshore trips.

that bass boat works wonderfully for lakes and rivers, it totally sucks going after big blues,tuna or stripers 2 miles offshore.

a boat is either purpose built and excels at it or it is a compromise and can do several things ok or really poor at all of it.

[99yam40]

is the new hull going to be rated for a 300hp motor plus its weight?.

did you beat the other hull apart or something else happen to it?

HP is HP,
The more HP, the more prop it can turn, the more speed you can get, that is the way I look at it

[phallgtown]

The boat came with the 3.3L I found the boat slow but lots of power. Top speed was 50 but rarely got there. 48mph was more realistic just didntmatter how the boat was loaded.

The original hull was rated for a 250, so i was planning on switching to the SHO 4.2L from my F250 3.3l
but the new hull has been redesigned for this year and upgraded to 300hp ratings.
i do some local tournaments and some have 250 and under ratings. Why i considered the SHO interested toknow huw many mph i would gain that way and how much i might loose by not going to the f300
I didnt beat the boat but had a couple other issues.

Would the controls on my f250 be the same for f300? I wouldhope so. Would save some money.

Thanks for all the reponses.

[boscoe99]

The 3.3L F250 uses mechanical controls. Throttle and shift.

The 4.2l F300 is electronically con*****ed. Completely different. Nothing much will interchange between the two models. The gauges and that is about it.

The electronic controls will probably add a couple of grand to the overall price.

[pstephens46]

The 3.3L F250 uses mechanical controls. Throttle and shift.

The 4.2l F300 is electronically con*****ed. Completely different. Nothing much will interchange between the two models. The gauges and that is about it.

The electronic controls will probably add a couple of grand to the overall price.

I believe Rodbolt has an opinion on reliability of 3.3 versus 4.2. Maybe he can remind us?

[phallgtown]

Boscoe
you said previously "On what I perceive a Walleye boat to be I would suspect that the SHO would be the best all around choice. "

Can you explain why? I wanted the SHO to be better only as that was my "dream" engine when I thought I wouldn't own anything with a higher horse power rating than 250. But I was having my doubts with all the comments I thought the F300 might have been a better choice if I was to but my bias for the SHO aside.

would appreciate your reasons for leaning to the SHO

[boscoe99]

My perception of a Walleye type boat is that it approximates a lighter weight shallow V hull bass boat/bay boat moreso than it does a heavier weight deep V hull offshore type center console/walkaround boat.

But not knowing all types of Walleye boats I could be completely wrong.

The torque and HP curves for the SHO are different than they are for the Offshore. The bass boaters/bay boaters seem for the most part to be into quick acceleration. The SHO was designed for bass boats/bay boats.

"best" boat is in the eye or the beholder. If you want 300 HP then you need the F300 Offshore. Or as I said, the VF250 with a modified ECU. With either motor you can't go wrong. Heads you win, tails you win.

You can go to Yamaha US' website and look up performance bulletins for Walleye type boats. See all of the different motors installed on different brands and models of Walleye boats. There might be some useful information for you there.

Outboard Performance, Performance Bulletins | Yamaha Outboards

Outboard Performance, Performance Bulletins | Yamaha Outboards

Having looked at Yamaha's website, there are more Walleye type boats with Offshore models on them than SHO's. What in the hell do I know?

[pstephens46]

My perception of a Walleye type boat is that it approximates a lighter weight shallow V hull bass boat/bay boat moreso than it does a heavier weight deep V hull offshore type center console/walkaround boat.

But not knowing all types of Walleye boats I could be completely wrong.

The torque and HP curves for the SHO are different than they are for the Offshore. The bass boaters/bay boaters seem for the most part to be into quick acceleration. The SHO was designed for bass boats/bay boats.

"best" boat is in the eye or the beholder. If you want 300 HP then you need the F300 Offshore. Or as I said, the VF250 with a modified ECU. With either motor you can't go wrong. Heads you win, tails you win.

You can go to Yamaha US' website and look up performance bulletins for Walleye type boats. See all of the different motors installed on different brands and models of Walleye boats. There might be some useful information for you there.

Outboard Performance, Performance Bulletins | Yamaha Outboards

Outboard Performance, Performance Bulletins | Yamaha Outboards

Having looked at Yamaha's website, there are more Walleye type boats with Offshore models on them than SHO's. What in the hell do I know?

Boscoe: About this "modifying the ECU" business......Do you recommend it?
Do you have any experience with or know of anyone that may have tried the "tweak"? The mention made me wonder about the F200TXR V6. My boat is rated for this motor but I feel it could handle the F250. Insurance company would not cover the F250. Of course they would never know of any electronic modifications to a F200TXR.

[boscoe99]

Boscoe: About this "modifying the ECU" business......Do you recommend it?
Do you have any experience with or know of anyone that may have tried the "tweak"? The mention made me wonder about the F200TXR V6. My boat is rated for this motor but I feel it could handle the F250. Insurance company would not cover the F250. Of course they would never know of any electronic modifications to a F200TXR.

No, I don't recommend it. But, that is not to say that I am against it. I don't recommend that it be done and I don't recommend that it not be done.

On a bass boat board that I frequent it seems to be done all of the time. I am not reading a lot of negative feedback from those that had it done.

The F200TXR has mechanical throttle bodies. I don't think an ECU modification will do much for it.

[99yam40]

people can say anything they want about upping HP on motors, but proving it is another story.

Me seeing the dyno runs before and after mods would be the only way I would believe they did any improvements

[boscoe99]

people can say anything they want about upping HP on motors, but proving it is another story.

Me seeing the dyno runs before and after mods would be the only way I would believe they did any improvements

Speaking of dyno runs what do you know about them?

I have been frequenting a dyno website and am wondering about one way to determine torque. That way is to put a load on a propeller shaft with a torque meter between the load device and the propeller shaft. The torque meter provides the torque valve. Run the motor to wide open throttle with a load that will hold it at one RPM. Say 6000. Measure the torque.

Then add more load to reduce the WOT RPM to say 5500 RPM. Measure the torque. Repeat this process adding more load as needed to drop the RPM down in 500 RPM increments until I suppose you are at 1500 RPM.

Now think about having the throttle wide open yet the motor only being able to turn 1500 RPM? Does that not sound like lugging the hell out of the motor? Does that not sound like a recipe for detonation disaster?