Can an improperly tuned loader or wrong loader lose rpm's and performance on the water? I believe I have the se loader I trimmed tabs w keel and I'm wondering if I'll see better by taking off more ramp or swapping loaders. I max out at 4500 rpm w an Olds 461 I built and it almost feels the pump runs as well at 3500 I'm almost wondering if I'm overloading the pump?

OK I'll get some.....  btw I'll add it's a 76 brendella pantera delta pad. Pumps a jc w a impeller place divertor and I have over the transom s pipes n logs.... headers are coming soon. Comp cam and 360 offy. Ignitor kit 750 holley dp.

Here's a link to a thread I started on the loader subject, it has some really good info. Hope this helps.

http://www.socaljetboats.com/index.php?topic=24448


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Way valuable info bro! The program for me is choosing what loader is good for my application haa I was hoping someone had a similar hull and could tell me their trial and errors lol I'm thinkin I might trim it a Lil more anyhow haa

Start with five different loaders then narrow it down to one. A good GPS and a vacuum gauge help narrow it down.

GT

Vacuum gauge for my motor? What am I lookin for there?

Manifold vacuum changes in direct correlation with engine load.

Use it with your tach to determine if the power you're making is being used to propel the boat faster against the GPS or just dogging the motor down.

The numerically lower the vacuum, the harder the engine is working. (Oversimplification, but still valid).

GT

I'm relatively sure a healthy engine draws 15 to 20 inches at idle I suppose if I'm topped out and I see more than 5ish 6 I may have some trimming or tuning to do.....

That depends primarily on cam timing events.  The more overlap, the more radical the idle charisterics, the less vacuum the engine will produce at idle.

I'm almost wondering if I'm overloading the pump?

Overloading the pump is a condition where more water is being fed into the pump suction than what the pump can process.  This results in the water being regurgitated back out the intake.  This is actually a good point to find because you know your limits and you can tune accordingly.  It really has nothing to do with "losing RPM."

Our goal is to feed the pump every last drop of water it can process.  The greatest factor in feeding water to the pump is the keel.  The shoe and the loader are basically fine-tuning.  Hull design plays a roll as does intake installation.

First off, I would like to emphasize, you aren't really losing RPM.  The pump is absorbing more power than what the engine can produce.  This is a good thing because the pump is operating more efficiently.  The bad thing is that the engine is no longer operating at peak horsepower.

Our theory is:  make the pump work as hard as it possibly can to absorb every last inch-pound of torque that the engine produces and convert it into useful thrust.

Depriving the pump of water WILL allow the engine to RPM higher, however not all of the power is being used to accelerate the boat.  An extreme example would be, glass entirely over the intake opening so that the impeller is completely sealed.  With the impeller deprived of water and just churning the air, the engine is free to rev to any RPM its breathing capabilities will allow.  Not one pound of thrust was generated.

We feel that it is better to make the entire system efficient and trim the impeller (an inefficiency in itself) to match the power curve of the engine.

In all of this, you can't lose sight of the big picture.  For example, trimming the impeller on a large heavy boat may make it MPH a little better, but at the sacrifice of hole shot and cruise RPM.

At some point, you just need to make more power.

Saving this for later...


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