CNC Prop for IM 31

[Scooter B]

I've used the search feature and have done a ton of reading on the matter. I've heard alot about M445, ABC 42x55, Grim 42x55, X645 and on and on. I'm leaning hard twords a CNC prop for my stock IM 31.

I've narrowed it down to these two, based on diameter and pitch. I'm wondering if the 45mm would be pushing it too much.

43 mm 2.38" pitch: http://www.offshoreelectrics.com/proddetail.php?prod=cnc-4314250

45 mm 2.52" pitch: http://www.offshoreelectrics.com/proddetail.php?prod=cnc-4514251

If it's not obvious, I don't have the know how or patience to sharpen and balance a prop. I'm just running the boat in my back yard on the weekends while drinking a few beers with my neighbor, so I don't need serious race performance, I just want to go a little faster than stock without burning the thing up. (It doesn't help that his Revolt 30 is quite a bit faster than my Impulse)

Thanks for any help!

[iop65]

i have used the 43 mm cnc with the stock motor on 5s , that was pushing it ( for me ) motor got rather hot
didn't try it on 4s ,would not have been a problem

[Scooter B]

Im running 4s on this set up. Think I'll go 43mm and work up from there. How was the performance over the stock prop?

[BHChieftain]

Hi,
Your stock prop on the impulse has a total pitch of 2.5in. The 2 CNC props you are looking at either have that same pitch or less. The stock setup on the impulse can handle more prop-- I would recommend the Octura X642, total pitch is 2.64in. But I would think about upgrading all your connectors to 5.5mm bullets if you have not done so already.

Note, I like the 42mm props better than the 45mm on this hull-- if the diameter gets too big it can cause handling problems in the corners.

Chief

[iop65]

it was a little faster with the 43 mm cnc 1.4 p then the sharpend and balanced stock prop (40.6 mm 1.6 p)


had to use the gps to notice the difference in speed , but the difference in temp where easier to notice :-)

they are nice props , just sharpend it

[Niky]

Hi everybody, one question;
on 6s with stock setup exept the stock prop., what other prop. will be fine?
I intent to put the upgraded OSE 5mm flex shaft and 5,5 mm bullet connectors between the motor and the esc.
Since I'll go on 6s (the only batt I have), don't want to put the electronics under load with to big prop.
I have x440 and x442 (octura).
Any suggestion will be of big help.
Thanks all, Niky.

[J.W. Pepper]

Hi,
Your stock prop on the impulse has a total pitch of 2.5in. The 2 CNC props you are looking at either have that same pitch or less. The stock setup on the impulse can handle more prop-- I would recommend the Octura X642, total pitch is 2.64in. But I would think about upgrading all your connectors to 5.5mm bullets if you have not done so already.

Note, I like the 42mm props better than the 45mm on this hull-- if the diameter gets too big it can cause handling problems in the corners.

Chief

Hey Chief...
What about x640?? - At 1.6p x 40mm and allowing for manufacturing variance's, it's pretty much the same size as the stock prop.

I ended up keeping my IM-31 - couldn't sell it for anywhere near what I have invested. I've been busy with other projects, so I boxed her up. I want to reinforce the hull & canopy and add some upgrades before the maiden voyage in case anything goes wrong.

Running stock 1800Kv motor (PB not Dynamite), 90A Seaking, 4S power - 2S 5000mAh 30C - x2.

Thanks