I have a 1994 Cigarette TOP GUN.
2 blown 605hp motors.
I currently have the large diameter stock 28 pitch maximus props.
I am only hitting 4400rpm and 68mph at WOT.
My motors dyno reads 605hp and 5500rpm.
Something has to change.
What should I do.
Change props, lab my Maximus.

To get 1100 rpms, you are going to need to go to a lot smaller pitch. Probably around a 24 and have them labbed. Have you tried any other props???? I would try set of bravo 1 26's.

When I bought the boat, there were 26 pitch 4 blade hydromotive props. I had new engines built. With the 26 pitch hydromotive props, I hit my mark, 5500rpm, but I did not like them. I had about a 20% prop slip at cruising and I could feel vibration. I went with the Maximus props. Now I don't have vibration. My crusing speed is great, but top end is not. Cigarette racing told me to reduce my Maximus props to 15 1/2 diameter and take half in off the diffuse ring. I don't know what this diameter reduction and diffuse altering will do. As a summary, I had 4 blade hydromotive props, I increased a blade and went up 2 pitches when going to the Maximus, thinking my engines were going to be able to pull it off....I was wrong.

Labbing the 24 or 26 ximus at 15.25 and removing the diff. ring will most likely get you where you want to be. I think testing a Bravo 1 prop is a good idea too.

Let us know if you would like to test some props.

Brett

Can you change a 28 pitch to a 26 pitch? I think a labbed 26 pitch Maximus with the modified diffuse ring is the answer.

that prop is way too far off and you'll never modify it enough to work properly......test some props first if at all possible. There was a set of labbed 26 MAX available awhile ago that would be close.

You said you were at the right rpm with the Hydro 4 blades. You should have gone with 1-2" less pitch in 5 blades to maintain the same rpm with. The increased diameter of the new 5 blades also reduces the rpms.

You need different props. The best thing to do is sell yours and buy some new ones.

Thanks Griff.
Why does Cigarette Racing say to take off the diffuse ring?
What does that do?

I have 2 large diameter non-lab 28 Pitch Maximus Props for Sale.
No nicks or dings.
Anyone Interested?

I have the props in the classified section now.
$1400 or trade for 26 Pitch Maximus.

There is a long story behind the diff ring on the Maximus prop. I was personally involved at Mercury Racing. If you do a search on the prop forum you can find a bunch of information.

Anyway, removal can increase rpm and speed and increase bow lifting capacity.

The diffuser ring helps the boat get on plane easier. Removing it may help some with rpms and speed, but you are too far off to try and modify what you have. With 600hp a 38 TG should run about 75 mph.