At what point is switching impellers not worth it? For instance I running an A impeller and turning it 5,400 rpm if my engine makes peak power at 5,800 would it be worth switching to a B? Basically to gain a few hundred rpm would it be worth the loss in efficiency of a smaller impeller?
Gonna give you my best possible answer, but first, how sure are you that peak power occurs at 5,800? Do you have a dyno sheet? The reason I ask is because without gained torque, you would be taking a gigantic step backward...
You have two potential problems, if you can call them that...
The first issue you are going to have to deal with, the jet pump will begin to lose efficiency at anything above at or near 5,200 RPM, meaning that it will take "way more HP and RPM to make smaller differences above that point". You can definitely stay ahead of the curve, but instead of 20HP increases to sea a gain, you need 50hp increases...
Second, if your engine really does not make the torque at that higher RPM, it will all be for not.
When I set them up, I do everything in my power to build them to run between 5,200 and 5,600. It is my humble opinion that you will not see the speed change, just the noise... It will potentially lose MPH even though you would gain RPM...
Hope this at least helps.
These are just my observations and opinions.... Your results may vary (although I would be willing to put some skin in the game)...LOL
GT
