HPDI reliability and improvements over 4-Strokes

[asherjackson]

We have had two Etecs and so far so great. I don’t know much about HPDI. Were they reliable? Did the 4 strokes that replaced the HPDIs have functional improvements in power, weight, or torque?


I am not buying anything, just curious.

[David]

Me too. Our Etecs have been great.

What is known is that the Mercury 300R is a lot better than the 300XS Optimax. There are a few dissenting views here, but people who have 300Rs are happy.

Is a the latest 200 Yamaha 4 stroke better than the 200 HPDI? I would love to know. Will the new Mercury 200R outrun my 200XS? I expect yes, albeit with a weight penalty.

[22R]

Me too. Our Etecs have been great.

What is known is that the Mercury 300R is a lot better than the 300XS Optimax. There are a few dissenting views here, but people who have 300Rs are happy.


Is a the latest 200 Yamaha 4 stroke better than the 200 HPDI? I would love to know. Will the new Mercury 200R outrun my 200XS? I expect yes, albeit with a weight penalty.

3.4L vs 2.5L I would hope it would outperform it. If close that tells all you need to know. Imagine if that 2.5l was a 3.4 L 2 stroke.

22R

[David]

At equal cubes and equal level of development, a 2 stroke will smoke a 4 stroke. The AMA for years used a 0.6 factor, which would make 3.4L equivalent to 2L

There are different equivalency estimates out there, but I'd expect the 200R to have better bottom end and mid range. 3.4L is a big motor. It would be mitigated a bit by the higher rev capacity of my 200XS. It will turn 6800 vs the 200R at 6400. So maybe I could run 2" less pitch at the same speed.

For top end, let's assume both the 200R and 200 XS ROS make 200 + 10% HP. Top speed on my SS2000 would then depend upon the gearcase. If the 200R is using the new bigger cases, it's not going to be as fast as the 4.75" sporty on my SS2000.

[Greg G]

The 200XS ROS makes 247hp so it beats the 200R
The 200XS turns 6800rpm so it beats the 200R
The 200XS weighs 80 lbs less so it beats the 200R

Merc missed with the 200R which makes no sense to me. It could have been a V6 layup.

[skialot2]

The 200XS ROS makes 247hp so it beats the 200R
The 200XS turns 6800rpm so it beats the 200R
The 200XS weighs 80 lbs less so it beats the 200R

Merc missed with the 200R which makes no sense to me. It could have been a V6 layup.

Have you put a 200R on a dyno? Then we don't know how much horsepower it really makes. And how much torque does each make?
The 200XS ROS revs 6800 and uses a gear ratio of 1.87. 6800/1.87= 3636.36 prop RPM
The 200R revs 6400 and uses a 1.75 gear ratio. 6400/1.75=3657.14 Prop RPM. The 200R spins the prop 20 rpm more than the 200XS ROS.
Does that 20 prop RPM make up for the 80 lbs.? Maybe.
The 200XS ROS needs high octane fuel to run properly. The 200R runs on cheap 87 octane gas.
What Warranty did the 200XS ROS come with? The 200R comes with an available 8 year warranty.

I think they hit a V6 home run!

[David]

The only dyno curve I have seen for the 200XS showed 238 crankshaft HP, but I don’t know if it was Gen 1 or 2, or if it was corrected for atmospheric conditions.

Gen 2 200XS has 1.75 gears

It cost as much new as the then current 300XS and had no warranty. Not that a warranty matters now. My motor is 9 years old

[David - WI]

Now give the two-strokes 25 more years of advanced machining, computer simulations, manufacturing technology, etc... to make it a fair comparison.

[abdrews013]

Have you put a 200R on a dyno? Then we don't know how much horsepower it really makes.

Legally it can only be 10% over stated power rating, so it's not possible for it to match or exceed 247, or 238 for that matter.

[David - WI]

Legally it can only be 10% over stated power rating, so it's not possible for it to match or exceed 247, or 238 for that matter.

238hp at the crankshaft, why not? That's probably 220hp at the prop.

[abdrews013]

238hp at the crankshaft, why not? That's probably 220hp at the prop.

Aren't all outboards measured at the prop shaft since ~1985?

Edit: ahh, I didn't see that you said 238 at the crank in your original reply. It's certainly possible, then.

[skialot2]

Legally it can only be 10% over stated power rating, so it's not possible for it to match or exceed 247, or 238 for that matter.

Then how can a 200XS ROS be 247HP? That is 23.5% over the stated power rating.

[abdrews013]

Then how can a 200XS ROS be 247HP? That is 23.5% over the stated power rating.

That's a great question and I would love to see an educated answer to it. From what I've read, that law came into the picture well before the 200XS ROS was released. Was that motor sold under contract to be used for racing purposes only? That's the only thing I can think of that would exempt the 200XS ROS from the 10% requirement.

[skialot2]

That's a great question and I would love to see an educated answer to it. From what I've read, that law came into the picture well before the 200XS ROS was released. Was that motor sold under contract to be used for racing purposes only? That's the only thing I can think of that would exempt the 200XS ROS from the 10% requirement.

I think you are right. The 200XS ROS was sold for racing purposes only. If that is true, we are comparing the wrong motors. We should be comparing the 200XS ROS to the 200 APX! That is an actual race motor. Not a consumer series race motor. The description for the 200APX specifically says it was designed to replace the 200XS Optimax.

200APX 3.4 V6 Only 395 Lbs. dry weight. Has 11:1 compression. Runs on 91 octane gas. Revs to 6800RPM. Rated at MORE THAN 200 Horsepower. Mercury already has a 225HP 3.4V6 powerhead in the consumer Fourstroke line. So, it's got to be more than that. It uses a IV Super speed master gearcase with a 1.13 gear ratio. Spins the prop 6017.69 RPM. It has a 12" midsection with trim and built in lift. No jackplate needed. Just does not tilt. It doesn't need to, It's a race motor.

The 200APX also has above water exhaust so it definitely sounds cool.


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[David - WI]

There's no "law" that I'm aware of, the manufacturers had settled with or agreed to the BIA(?) powerhead hp standard... but it was strictly on the "honor system". Later the ICOMIA standard changed it to propshaft +/- 10% of advertised: https://www.screamandfly.com/showthr...77#post3192777