Motor Mystery

[Jeepers]

In order:

I have plenty of props and a tach. Not sure it's worth that much work

Motor was brand new, never mounted or run

I'll give the smaller prop a try. Maybe I was expecting too much. Seems like a m445 should not be too much prop, but maybe it is.

I want the 9XL to be faster than the 10XL. If it takes a smaller prop to go faster, then I am OK with that.

Jeepers, which hull did you have??

Bill I have the older Darkhorse 31" it ran really loose, and I know the Delta Forces are much faster! I got whipped by one that ran a 9XL.

[Steven Vaccaro]

Bill even though you gained rpm, you lost torque. So I'm thinking like the rest that the prop has to go smaller. So now you are back to similar speeds. In a smaller boat going up in rpm will get quicker speeds because there is plenty of left over torque to spare, in your case the df32 is right on the line for a xl. I think you are maxed out for speed with that weight of motor.

[Bill-SOCAL]

I get it, I get it. I just did not think that I lost THAT much torque. Which is why I started at the low end of the props I ran on the 10XL. So I'll go smaller. I ran out of packs on Sunday before I could try that. I have two different cuts of x442, one plain, one modded, to try plus a 440/3, x637 and a 42x55.

Hopefully I can get out today. And hopefully I am on the right track (which it sounds like I am).

As far as the hull size, you may be right. So this will be even more interesting to see.

[Flyguy55]

Bill I have the older Darkhorse 31" it ran really loose, and I know the Delta Forces are much faster! I got whipped by one that ran a 9XL.

Hi Bill
I think I know what DF 33 with a 9XL beat Jeepers ( Grin ) I was running a modded X445. I thought the Dark horse was faster , but the DF handled better .
And Jeepers doesn,t know about the Navajo Shaman LOL LOL LOL
Next time I'll try a X442 :-)

Dick

[Bill-SOCAL]

So a 9XL and 445 worked for you? Interesting. How "modded" was it? Mine is a simple S&B m445. 43 mph with the 9XL, 47 mph with the 10XL.

I am looking forward to running the smaller props to see how they go.

[Flyguy55]

The prop is one I got from " Props 4 You " with some cup, modded for an
OPC tunnel project .
Sorry , I never got a GPS speed , that race was the first time in the water with the 9 XL . For the nationals , I'd go with a NEU . The Rocky Mtn Club has a $150 msrp motor limit for club races.

I built my boat light , just under 4 lbs less lipos with small hardware . That might be a factor too.

Dick

[D. Newland]

Bill, I know bench-testing at full RPM is a no-no. But that's what I would do. Hook up a 2S pack (to keep the rpm's down) to the 10XL on the bench. Rev it up for a quick second and hear the pitch. Do the same w/the 9XL. You should be able to hear the difference in RPM. You won't get above 15,000 rpms unloaded, so nothing is going to get hurt.

Heck, I would even do it on 4S if the 2S test was inconclusive.

And if I saw what you're seeing, I'd be asking the same questions. I've run a 9XL Nemesis w/an X445 detongued and back-cut. Ran terrific. I'll have a spare 9XL with me next week if you have time to run a comparison.

Lastly-Go back to the 10XL. Your boat is running very well with it and I don't want you to get caught up in the "Nat's" moment! Just be sure to give me this same advise when I'm contemplating propping up my N-2 Sport during open water!

[properchopper]

re :

I hub cut the M445; but the X442 runs just the same. Observing your boat run, I'd say you should loosen 'er up some. Shift CG back & maybe raise strut angle some.
Less drag = more straightline speed. I'm heading to the lake shortly; c'mon out & let's see.

[Bill-SOCAL]

You see it running solo most of the time. It is set up for heat racing and runs relatively wet by itself. It loosens up in race water.

This is it running in a heat race with the 10XL

[Flyguy55]

Hi Bill
Did you see Madmike's post on his DF33 , 10XL ? he ran a X450/3 !
It was choppy so he raced it with a $X447/2 .
Looks like you have some testing to do :-)

Dick

[Bill-SOCAL]

I've run up to a 450/3 on my 10XL as well. Usually ran a m445 or m447 for Offshore and a x646 for heat racing. The 10XL did fine with all these props.

But apparently the 9XL has far less torque based on what people are saying here.

I am trying to get out of here for a run up to the lake to run some smaller props.

[Jeepers]

Hi Bill
I think I know what DF 33 with a 9XL beat Jeepers ( Grin ) I was running a modded X445. I thought the Dark horse was faster , but the DF handled better .
And Jeepers doesn,t know about the Navajo Shaman LOL LOL LOL
Next time I'll try a X442 :-)

Dick

Navajo Shaman!!!!! I cant stop laughing!!

When you coming back out Flyguy?

[Bill-SOCAL]

Went out and ran the boat with a x442. Sunday I was getting speeds between 42 and 44 with m445 - m447 props. Today the x442 gave me 38 mph.

So I decided to air it out to where it would be running in heavy race water. Adjusted the trim tabs and strut angle up a bit. The boat as it normally runs is wet in flat solo water. It airs out fine in race water.

After these adjustments (I also moved the cg back a hair) it aired out to the point of being unstable in anything except flat solo running water. I would not race it like this.

Anyhow, it got faster, 44 on the GPS up from 38 with the several changes I made. Assuming that the adjustments would have had the same effect Sunday I could have gotten to 50. But running in race trim I was already at 49 with the 10XL.

Using the same logic, running the boat with a 10XL as loose as it was running today would have gotten me to 55 or 56. So no matter how I slice it, this Feigao 9XL is not pushing the boat as fast as the Nemesis 10XL can. Beats me why not.

Did not get a chance to do any more testing today due to a broken flex.

[DISAR]

I have a Delta Force 36" with a 9xl, 4s1p and tried various props but all I could get is about 40-45 mph in a bit wavy conditions (sea water). I think that the 42mm prop will be too small. I tested various props and the best ones were Graupner 45mm (2317.45), 645, 646.
I also fitted the KB 45 8xl but performance similar, no extra speed probably because of the extra weight of the KB motor.