Ken ive allready had her to 68 mph im happy with that to be honest.That was with ridepads the 61 was without,yup made that much difference as Joe told me it would.Dont want to round any tips i need the lift they provide.might try the bigger prop allready on my shopping list,been too busy building boats to be honest to really tweak the rockett much
Mart

If you want to get serious about props, you need the power curve and continuous onboard rpm and speed data. Fortunately, you can have a lot of fun by trying different props and comparing your boat to your buddies'. It's called racing.

We have been getting data in several different ways over the years. Power curves representative of the various Zenoahs can be found in the October 2008 NAMBA Propwash article "The Zenoah from Stock to Outlaw". Your boats speed can be measured with a radar gun, GPS, or a data logger like the Eagle Tree. The engine rpm can be measured with a tach that records peak rpm, a data logger, or from the sound track of a high quality video recording. The speed can be measured from a video as well with either doppler methods or from the time to travel a measured distance. I like the data logger methods the best for serious work, but a peak reading tach and a GPS will give you a lot of information easily.

I think you should prop for peak power coming out of the turn and then let the engine rev as much as it wants down the straight. Speed in the corners is where heat races are won so the power and acceleration there is very important.

Lohring Miller

I forgot to add i used yr old fuel for those runs lol,yea i know but i hate wasting anything .All gone now so time for some new fuel 70 mph here i come lol hehe :dance2: .
Mart

lohring wrote:Bought a Bod Austin 667 saw prop for my Sprint, it was pitched up and rounded tips, the prop ran around 75 mph and the engine pulled it pretty easy, aksed Bob can it run more speed by adding more cup on it, he said send it back to let him add cup, received it back yesterday, tried it again but ran 1.2 mph slower, emailed him about this matter and he let me send it again to take some pitch out to go back to the previous pitch, the previous 667 prop seemed like the correct one for me.

We've run into that problem with SAW boats. There seems to be a wall where more cup just means more slip, not more speed. As I start to run electric spec classes, I'm finding that prop matching is everything. Everybody has the same power, but different props make a huge difference. The situation is similar in gas boats where everyone is running close to the same engine. I bet a lot of the speed differences attributed to the engine are actually in the propeller.

Lohring Miller

lohring wrote:
Lohring .... You & I know this for a fact :dance2:

A quote from Mike Bontoft after he set the new G1 record at 107+ mph," $1500 of props in that box and only one that's worth anything."

Lohring Miller

What a sweet number of 107 mph for the rigg, hats off to all the involved especialy for that fasssssst prop.