QC said:
You literally cannot be at peak torque when you are backing off of the throttle...
Yes you can.
The boat is a fictional boat and it really doesn't matter. But in real life single 5.0's MPI's are going into boats as big as 30 feet. With 1 or 2 people the motor and boat performs okay. When the boat is fully loaded with the family, or if you have a mid 20's boat with a single 5.0 MPI and tow with it. They are absolute dogs, and in some cases will not plane with stock props when fully loaded to whatever is stamped on the USCG placard on the boat. This is real life, and I run into this weekly because many a people are either cheap, and buy a boat with the smallest base engine. Or they are mislead by salesmen, promising the 5.0 will deliver good performance on a heavier or highly loaded boat, when it will not. This is a problem I deal with a few times a month.
That "fictional" engine I was hitting rick with earlier was the engine in my truck. It makes 381 HP at 5400 rpms but it makes peak torque of 401 lbs/ft at 3600 rpms. So yes you can be at peak torque at a lower rpm. Some engines make a lot more horsepower than they do torque, like sportbike motorcycle engine, or high reving jetski engines. Other engines make more torque than they do horsepower, like my truck engine or most diesels. Some engines are in the middle of those two extremes, but either favoring horsepower or favoring torque.
Earlier you wrote
qc said:
This is all about the words, and to some of us that matters. A higher peak torque engine develops more horsepower at mid range revs. You can't separate them as most try to do.
Good to see you Jason. Didn't know you were hanging out again
My engine is a peak torque engine, it develops 401 lbs/foot at 3600 rpms and that is the most amount of torque it makes. According to the calculator, at this same 3600 rpms its only about 275 horsepower at this very moment. But if you keep on reving it you can get 381 horsepower at the top of it's rpm range at 5600.
In general, and especially with the GM engines. Most blocks produce more peak horsepower than they do peak torque. But big blocks (and strokers) give you more peak torque than they do peak horsepower.
You have your analogies about hp vs tq. Mine is simply tq is a measurement of how much work an engine can do starting from a dead stop. Hp is how much work an engine can do starting from a rolling start. TQ is how much pulling power you have from a dead stop. For example from a dead stop. If you attach a 1 foot bar at the center of my crankshaft and attach a weight to that bar, and run the engine. It can lift 399 pounds, it can lift 400lbs, and it can lift 401 pounds. But it can not lift 402 pounds. That is the point where the engine would essentially stall. However, once it goes rolling. The engine can still get past its peak torque spot and still develop "overall power" overall if you can spin it faster. Between the flywheel, the crankshaft, and a few other bits you have essentially 100+ pounds of dead weight all spinning to the left. Spinning weight has inertia. Inertia is stored energy. You can add energy to that existing stored energy by spinning that weight faster and faster. And this is horsepower. Horsepower is adding energy to existing energy, torque is creating energy from nothing. The limitation as to which you can add it is 2 fold. 1 mechanical, how fast can you spin it before the mechanical stress becomes to much and it falls apart. And 2, how much energy can you extract from the fuel being consumed. Straight gas has more power in it than E10, or E85. Nitromethane has more power in it than straight gas.
There are 3 types of boaters
1. Lake boaters that consistently run engines to full throttle, all of the time.
2. Ocean boaters that can not run engines to full throttle all of the time because conditions do not allow it
3. Boaters oriented towards towsports, or heavy loading. And they never approach full throttle because most of the time they run the boat in what would be considered for all intents and purposes an overloaded condition. IE - Filling up a ballast bag and towing a wakeboarder.
Maximum HP only really matters if your #1. If your 2 or 3 it doesn't really apply to you.