7.5 tunnel props

Greg Johnson · Sep 26, 2011

Looking for input from those that run 7.5 tunnel. I have two motors that I run a Rossi and a K&B. I design, build and race my own design and have not ever really worked with props all that much. Currently I run X447 sharpened and thinned. I'd like to experiment with some props and am looking for some suggestions on what combinations everyone runs. Can I get some feedback on hull type, OB mfg, prop mfg and what mod's have been made to the prop. I realize that not everyone's props or setup will work on my hull but I do want to experiment.

I just started using the new Rossi on a new hull of mine and am using my K&B setup to get started. Probably not the correct setup but it does give me a baseline to compare against. I'd like to get the most out of this motor. I really like how the hull is working and the motor was worked on by Rod so now I want to take a look at the prop.

lohring · Sep 26, 2011

The modified 1450 has been the standard for years. The 1450 is modified with trailing edge cut back and more cup. Changing the cup and prop depth will adjust your engine to your hull. The H-7, X450 and other similar props are also run.

Lohring Miller

HTV Boats · Sep 26, 2011

The 1450 and H-7 seem to work best on Leecrafts and Hoppers. My setups may be different so the X series are my go to props for heat racing. I like X448's and X450's cut down a bit to 47-48mm diameter. If we are trying to set a needle or making changes in compression I back off to a X447 which will tune easier. Staying with similar profiles allows me to keep height and trim angles fairly constant. I like ABC 47X60 and 47X63's and a Lefluer cut 1914 or 2014 goes very fast. Just need to try different things till you get the handling and speeds you want.

Mic

Greg Johnson · Sep 26, 2011

Lohring, I've tried a stock 1450 but abandoned it as there was too much lift and I just didn't spend time trying to change my set up enough to see if it could work. That particular boat I was trying to keep it in my heat racing setup. Now that I have a second boat I'll go back to that prop and experiment with it.

Mic, where can I learn what the Lefluer cut is?

topfuel443 · Sep 26, 2011

X448's and reduced X450's are the ticket for my Rossi powered 7.5's

HTV Boats · Sep 26, 2011

Ernie Lefluer did props for .45's a few years back and they were ABC castings with his magic knowledge. Kind of unobtanium now as they stay in peoples prop boxes and not sold too often. Like Gabe said X448 & cutdown 50's will do everything you kneed especially if the lift of a 1450 is not what works for your boat. Mark Sholund has cut many of our props that have won heats locally and at national events.

Mic