With the engine at wot, at whatever rpm that is.............. the output and the load are in a state of stasis.
They are equal. In order for the rpm to change........ something else has to change to allow that to happen.
Either the output or the load.
Since the load curve climbs rather steeply with rpm, in order to raise the rpm from the point of stasis you’ll need to make enough additional power to exceed the rate of change of the load curve.

To lower the rpm, close the throttle some, rpm will drop.

If you closed the throttle say, 1/2 way....... the rpm would drop to the point of the equilibrium between the new 1/2 throttle output and the equivalent pump load.

It’s much the same as the beginning of a dyno pull with a water brake.
Let’s say you want to start the pull at 3000rpm.
You start applying throttle and load together until you get to where you’re at wot, and the engine is steady state at 3000(or just under).
In order for the engine to actually accelerate and make the pull, something has to change, or the engine will just stay at that rpm.
Since you’re already at wot...... you can’t just “make more power”....... so you have to start releasing the load to allow the engine to run at a higher rpm.

With the jet pump, there is no releasing the load........ so if you want the engine/pump to turn faster...... you have to make more power.

To take the analogy a bit further....... once you had the load valve on the dyno set to apply the necessary load to hold the motor at 3000rpm........ you could back the throttle off and the rpm will fall off.
You could keep going to wot over and over again....... but wouldn’t get past 3000rpm because that’s where the power and load are equalized.
So, let’s say that you did that initial load valve setting with the timing 10 degrees less than what’s optimal......... and then you put the correct timing in the motor. Now, that motor makes more power at wot it will go beyond 3000rpm because the output has exceeded the load thats present at 3000rpm.

Good post, I can't explain it any clearer than that 👍

We ran a boat engine on the dyno this morning. 685 ft-lbs at 4500 rpm and 635 hp at 5300 rpm. Very mild hyd roller cam and pump gas compression. Going in a 30 foot cruiser. Should move it right along. I think this boat has a prop but I'm not 100% sure.

Stroker BBC?

Yes, I think it was 568 inches using a Gen VI block and Edelbrock Performer RPM Marine heads. Victor Jr intake with a Braswell 1.59 carb. Cam was only 236/245 hyd roller. Should have great low speed manners but it pulled hard to 5000 rpm.

What headers will be installed in the boat? CMI?

I don't know. I've never seen the boat. I just help with engine design and dyno testing.

Ok, just curious. I've seen a lot of good motors on the dyno, loose 75hp when the owner slaps on a set of stock Mercruiser manifolds when the motor gets installed.

I have used that Lunati cam in a 10.3:1 compression 4.15 stroke 496/440. 950cfm 4-bbl, 2" Super Sucker spacer on a ported Torker II single plane, ported Edelbrock RPM Performer 440 cylinder heads 309 cfm @ .600" lift and our 30" dyno headers 3/4 x 7/8 x 2" step with a 3" collector. 555 torque @ 3,200 rpm, 634 peak torque @ 4,900 rpm and 650 peak horsepower @ 5,800 rpm, 600+ lb-ft of torque from 3,500-5,500 rpm.

Thanks for the feedback 👍But I already had Dwayne spec me a cam, and UPS just delivered it a few days ago., hopefully get it installed in a few weeks.

Please post results, I own a jetboat I would like to make mopar powered!

Got the 2.25" manifolds in, and finished adding 10" of dry pipe to keep the O2 dry with the bigger cam. Off they go for ceramic coating. I will be selling the 1.75" manifolds soon, which will work great for 383-440 cid.

Selling the old 1.75" Hi-Tek manifolds, PM me if interested.

Photo of internal exhaust flapper

Here it is, with Dwayne's 248/248 cam, TFS240 heads, and deep ported Pro Flow XT intake. Also built a new heat exchanger mount, to move it to the front of the engine where it belongs. I ended up installing the 19p/19p impeller stack (developed for the LT4 engine) for more bite and low speed performance, hence the recent decision to go with standard port heads. Gained approx 35-40 ft lbs over the MW-EZ setup, moving the max rpm from 4200 to 4350, slightly more than the KEM LT4.

An interesting note, the datalog now shows about 1.0 kpa pressure difference from MAP to barometer reading with the standard TFS setup. With the MW-EZ setup, it typically showed a 2.5 kpa difference.

Special thanks to Andy and Dwayne for getting this thing lined out, and turned into a TQ monster.