Originally Posted by IGetWet (Post 4804992)

Hmm. 4.25” should be more boost than 7psi. I have 4.5” on my whippled 525s and I want to say I’m over 8psi. Smaller pulley equals more boost. The way I see it your options are

1. stick with same diameter props but lower pitch and get more rpms, but have same planing and max speed due to lower pitch.
2. Go bigger diameter, but I think 16 7/8” is max on scx, and lower pitch to gain some rpms and help ventilation. And your slip #s are already decent.
3. mess with spacers along with 16.5” diameter props to help with ventilation.

the rabbit hole goes deep. Your trimming to your sweet spot for the WOT runs? How much testing did previous owner do with setup?

Originally Posted by Brad Christy (Post 4806782)

IGetWet,

The question that was asked was about the pulley on the engine. A smaller pulley on the engine would result in less boost, not more.

Thanks. Brad.
Model Machine and Precision LLC
(937)545-8991

Originally Posted by sgett775 (Post 4804986)

4.25 upper, I am looking for some 30 pitch props right now, 7000 dollar gamble.

Originally Posted by Brad Christy (Post 4806782)

IGetWet,

The question that was asked was about the pulley on the engine. A smaller pulley on the engine would result in less boost, not more.

Thanks. Brad.
Model Machine and Precision LLC
(937)545-8991

Originally Posted by IGetWet (Post 4804985)

With 4 ppl and full fuel you’re not far off of 5600. You could see what’s out there for 31” or 30” pitch props. What size pulley do you have on the motors? 4.75”?

Originally Posted by sgett775 (Post 4804986)

4.25 upper, I am looking for some 30 pitch props right now, 7000 dollar gamble.