P94 6 turn on 4 Cells

[twmaster]

I got my hands on a new P94 6 turn motor I am hoping to use in my 4 cell SAW rigger. I have not pulled it out of the packaging yet but would like to know if the stock brushes and springs are good enough to go fast and live in this hull or do I need to replace these items.

I am also interested in how much timing for this kind of running.

Thanks,

[Paul]

Hello Mike,

I'm guessing direct drive, I would run at least 3/16ths advance with heavy springs. (purple or black) If you want really good brushes give Ed Hughey a call, I couldn't tell you what brushes they are but I do know they work well. I ran a 7 turn double on 6 cells (gearbox) with those brushes and was very surprised at the minimum amount of com wear and arcing.

Paul.

[Patrick]

If it has the double shunt brushes its silver if it the single shunt it copper, I got a conversion kit yesterday and it came with the endbells, and two pairs of brushes, the double shunt is the 4383ep silver compound and the single shunt is the 4380ep copper compound.

[Jay Turner]

Moderator Pat M would be the best source of info - he used this motor to set the 4-cell SAW record at 45+ mph. I believe he used a 6-turn arm ( not a Trinity arm ) in his can. Ed doesn't have the oversized brushes for the P94 - there are a limited number of brushes in this size, with Trinity the major ( perhaps the only? ) supplier.

Comm damage on modern 4-cell motors can be amazingly low, even at very high ( 60+ amps ) current draws. You'll have to experiment, but on my 4-cell Ti motors I need well over 1/4" of timing advance to get real power without comm burning. Start with heavy springs, try going lighter on the negative but watch for arcing damage to the comm if you go too light.

The very low turn 4-cell SAW motors seem to have a narrow rpm band for optimum power....over-prop your motor and it will not produce much power but will suck the current out of the cells real quick! 8)

[Patrick M]

Try 4383 brushes, Trinity purple springs and 30+ degrees of timing with a 1735 prop. Direct drive. That's the 45 mph setup.
You can also try a lighter spring on the negative brush , as Jay suggests, maybe a Trinity red, black may be too light.

Good luck....

[twmaster]

Thanks Patrick and Jay. I will have alook at the motor sometime next week. I am in the middle of cleaning up around here and selling off a bunch of stuff I really don't need. My plan is to have some fresh racing boats for next year so I will be working my hiney off this winter :) As part of my cleanup around here I am setting a whole room aside as my boat workshop!

I am also shooting for the 2 pound or under mark for this 4 cell rigger hull.

[Jay Turner]

That's a good weight target Mike. My most successful 4-cell boats have weighed between 30 and 32 ounces RTR. It is possible to build them a bit lighter, but strength suffers unless you use very high tech mateials and techniques. I doubt that there is any meaningful performance difference between a 30 ounce boat and a 32 ounce boat for most applications.

[Patrick]

Trinity has a ultra silver compound the brush number is 4379 these brush cost about 4.79 at towerhobbies. I have a pair using now my brushes has about 13 runs so far and the brush color has not changed change, also I have extra heavy springs and I am running at 20 degrees of timing and my com don't have any burnning on it, this is with a 12 turn p94.

[Patrick M]

I have some of the 4379's, but haven't had the opportunity to test them. They are purported to make more power than the 4383's though I have not heard much in the way of field results. Their higher silver content may make comm wear an issue for longer runs.