PCM H5 Engine at altitude

[Kevenka]

Does anyone have experience with the PCM H5 engine at 5000+ ft. in altitude? Are there additional settings that have to be made to get maximum performance?

[Kevenka]

Additional question - is this enough power for skiing and wake boarding at altitude?

[JD ski]

The PCM H5 is a naturally aspirated motor producing 355 Hp and 405 Lb. ft. of torque at the crank shaft at sea level at optimal conditions. The higher the altitude the less atmospheric pressure there is resulting in less oxygen for that motor to compress, the spark plug to fire. pushing the piston down, turning the crank shaft, to produce that power. Similar to your heart and lungs at altitude. Between 4500-6000 ft. approximately 28% (give or take) of power is lost on a naturally aspirated motor. On that motor that is about 100 hp. You do not mention what boat this motor is in and for skiing it would be fine for most hulls. If you were going to add 4000 lb. of ballast and want to have a 4 ft. wake behind your boat to jump, the answer is you need more HP. A forced induction motor will only lose about 8% at 5000 ft. such as a XS7 or XR7. It all depends on the boat you are looking at and your expections.
Hope this information helps

[Kevenka]

It is a Nautique 200 OB, but concerned about loss of power due to altitude. I think the weight is listed at 2,800 lbs without people and gear.

[Kevenka]

Thinking the 6.0 may be a better engine, although not fuel injected.

[NautiqueJeff]

Thinking the 6.0 may be a better engine, although not fuel injected.

Um, the 6.0 is certainly fuel injected. Maybe you meant that it isn't supercharged like the XR7/XS7?

[Evening Shade]

Um, the 6.0 is certainly fuel injected. Maybe you meant that it isn't supercharged like the XR7/XS7?

Maybe he meant the 6.0 isn't direct injected.

[Evening Shade]

The PCM H5 is a naturally aspirated motor producing 355 Hp and 405 Lb. ft. of torque at the crank shaft at sea level at optimal conditions. The higher the altitude the less atmospheric pressure there is resulting in less oxygen for that motor to compress, the spark plug to fire. pushing the piston down, turning the crank shaft, to produce that power. Similar to your heart and lungs at altitude. Between 4500-6000 ft. approximately 28% (give or take) of power is lost on a naturally aspirated motor. On that motor that is about 100 hp. You do not mention what boat this motor is in and for skiing it would be fine for most hulls. If you were going to add 4000 lb. of ballast and want to have a 4 ft. wake behind your boat to jump, the answer is you need more HP. A forced induction motor will only lose about 8% at 5000 ft. such as a XS7 or XR7. It all depends on the boat you are looking at and your expections.
Hope this information helps

Help me to understand the physics of how a supercharged engine creates more boost at altitude vs sea level? I don't understand how a supercharged engine only loses 8% power vs 28% power with a naturally aspirated engine. It seems to me the supercharged engine would have to compress air more efficiently at altitude vs sea level for this to happen. The power loss should be similar with all engines that are breathing the same thin air. The only way to partially over come this loss of hp is to go with a higher hp engine, but the hp loss should still be similar. At least that's how it seems to my simple mind.

[JD ski]

Motor on Left is a highly modified naturally aspirated motor approximately 300 hp. Motor on right is a highly modified forced induction "supercharger" with approximately 750 HP

Help me to understand the physics of how a supercharged engine creates more boost at altitude vs sea level? I don't understand how a supercharged engine only loses 8% power vs 28% power with a naturally aspirated engine. It seems to me the supercharged engine would have to compress air more efficiently at altitude vs sea level for this to happen. The power loss should be similar with all engines that are breathing the same thin air. The only way to partially over come this loss of hp is to go with a higher hp engine, but the hp loss should still be similar. At least that's how it seems to my simple mind.

I am a Motorhead not a Physicist.So my answer will be more generic. A naturally aspirated motor draws in air to a cylinder by suction. The more atmospheric pressure there is (sea level) more dense air is moved into the cylinder. Cooler damp air creates even more power, thus "optimal conditions for creating HP ratings, motor dyno test can be different on different days and different altitudes. Same motor at different altitudes will make different amounts of power". Less oxygen less power.

A forced induction motor supercharger, turbo charger, forces the air into the cylinders. At higher altitudes this creates a more consistent cylinder pressure than atmospheric pressure alone can produce. Such as if you throw trash in a garbage can it fills up quick with loose stuff. Now take a trash compactor of the same volume and you will put a lot more garbage into the same area as it get compacted into that same area. On a pulley operated supercharger you can decrease the diameter of the pulley which increases the speed at which the supercharger is spinning and this increases the artificial cylinder pressure. (nothing to play with if you do not know what you are doing)The power loss is similar across naturally aspirated motors and the power loss across forced inductions motors is similar, but the power loss across the two is not. One has compressed air thus the term "forced induction".

[Kevenka]

Well...thanks for the responses. This is interesting stuff. But, my dilemma is still the question of which engine -between the PCM H5 with 355 HP and the PCM 6.0 ZR409 - at 5,000 feet. in a Nautique 200 OB at 2,850 lbs dry weight no tower or ballast tanks. We are primarily skiers, but don't want to be under powered.

[Evening Shade]

I would go with the ZR4 6.0 any day over the H5 regardless if I was at sea level or altitude. It just doesn't make sense to pay more money for less HP. I know the H5 is more fuel efficient, you can buy a lot of fuel for the extra $ you pay for the H5.

[Rogue14]

No experience with that motor but I have 10 years experience with my PCM 330HP motor at 5000 feet. My boat is an SV211 so about 3,500 lbs--heavier than your boat with less HP and it's always pulled me right up on 1 ski. I'm about 175 lb.

[JD ski]

Both motors will ski fine. My Air only has 310 Hp and my Century Resorter has 430Hp. No problem skiing at 4500 ft. with either. If you get more cubic HP for less money, that would be my choice. Ski boats need low end torque not high end HP (above 5250 RPM). The ZR6, 6.0 makes 492 ft. lb of torque and the H5 only makes 409 ft. lbs. That is a HUGE difference in twisting power, ZR6 every day of the week and twice on Sunday.

[jjackkrash]

The 6.0l in the 200 and the 5.3l in the 200 have about the same torque (but the 5.3l has 5 more ft. lbs.), although the 6.0 has 50 or so more HP than the 5.3l.

http://www.nautique.com/models/ski-n...e-200-open-bow

I just took my new 200 OB with a 5.3l out for a spin at around sea level, and that is one impressive engine. I was very impressed. It is very responsive and very snappy. And quiet. And supposedly gets much better fuel economy than older non-GDI engines. I also suspect the direct injection will fair better at altitude than the 6.0l. I would not blink at getting the 5.3l if the other options is the 6.0l as they are very comparable in the 200 and the 5.3l is a more advanced engine and PCM considers it an upgrade over the base 6.0l.

All that said, if you are worried about power at altitude, get the 6.2 (H6DI). It is reportedly a monster in that boat.

[nautiquegeek]

I have experience with both the ZR4 and the H5 at altitude (Lake Tahoe specifically). I have used both the ZR4 and H5 in various Nautique models in high altitude lakes around the 6000ft elevation mark. Most recently in a new 2017 GS20 and 2017 GS22. Hopefully I can give some insight on the new engine and it's performance.

I would say the H5 is the winner at both sea level, high altitude applications and everything in between. Of course this is slightly subjective using my own internal seat of the pants meter. Throttle response is quicker and more precise. Power comes on in a linear fashion compared to the tried and true ZR4. The smooth power delivery of the H5 makes it feel like the boat has another 25 to 50hp over the ZR4 even though its over 50hp less in real world numbers. Power delivery is not only smoother but stays constant throughout the entire RPM band making pulling even the heaviest riders out of the water a smooth transition to your set cruise control speed a breeze.

Keep in mind, torque is one of the most important things in tow boat applications and the H5 does have another 5ftlbs over the ZR4.

Good luck and have fun!