SV27 vs. UL1 system in a spec Rigger

[Philmunsterman]

I'm running my spec rigger on 4s with the SV27 system. I'm wondering what would be the pros and cons of switching to the UL1 system. Has anyone run both in the same rigger ? Thanks Phil

[Ctonez]

One of our club members started last season with a SV motor in his spec rigger and switched to a UL-1 after a few races.
With the SV motor it wasn't quite on par with the UL-1 boats, now it's just as fast.
Riggers like RPM from what I've observed.
I run an SV motor in LSH in my vac-u-pickle. That boat seems to work well with a bigger prop, and I am pretty much even with UL-1 powered boats.

I'd run a UL-1 if I were running a rigger.

[Hydromaniac]

The rigger may be faster with the UL-1 set up but that is not a given, as the hull is heavier and bigger then a Jae or similar type rigger, The SV-27 motor has higher torque then the UL-1 which may be something you are benniffiting from in the rigger you are running, as you asked for pros and cons, the pros are you may see an increase in speed, may not, the cons are if you don't have the motor already you would need to buy that set up, in order to test but you would have the new motor that can be used in a lot of applications. I have some boats that run well on one type of motor and not another that is very close, sometimes we have to try several different motor and prop combinations to find the sweet spot, then take in to account if you are wanting just the best for all out speed like a Saws type set up or more of an oval type set up with best lap speed and performance. Lots of variables that come in to play.

[Philmunsterman]

I just got back from the lake and the new NeuEnergy 5000 35/80C lipo made a huge difference. I would say I picked up at least 5 to 7 mph and much more run time.

[Fluid]

What prop are you using? I know that the BJ26 motor - similar Kv to the SV27 motor - will swing a relatively huge prop much more slowly than the UL-1 motor will. The SV motor will easily turn an m645 and up, but the UL-1 motor will spin an x637much faster with similar boat speeds. In my own testing the UL-1 is marginally faster than the BJ motor in an LSO cat. Using rigger in a performance program:

SV27 motor, 1750 prop, 21000 rpm = 57 mph
UL-1 motor, 42x66 prop, 27000 rpm = 59 mph

These are comparisons only, but should give relative differences in performance. The boat may not work well at all with the 1750 prop, depending on the hull the prop walk could be terrible. Lifting props can help if you have to use prop down thrust to keep the transom up, "X" props are great where little lift is required.

How do you measure a speed difference? Eyeball doesn't count unless you are running two boats at the same time. 5000 mAh packs will give you 25% longer run time, assuming you can believe the labels. New cells are nice aren't they? ;)



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[Philmunsterman]

I started with the X 445. Temps were all under 100. I have X 447,448. X642, X450-3 blade and a prather stainless 225 ? What would be the next one to try ?

[Jeepers]

The 447

[Hydromaniac]

I would try the X642 next and then the 447, but try short runs first and check temp as the SV -27 ESC is only rated around 50 amps I think.

[Fluid]

I'd start small and work up, but dozens of racers have used rather large props on their SV27 systems in hydros without problems - the ESC is clearly under-rated. That's not a license to be stupid, but don't be surprised if you can pull an x450/2 or more in a properly setup rigger. This isn't a SV27 mono which can't handle a big wheel.



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[Hydromaniac]

I'd start small and work up, but dozens of racers have used rather large props on their SV27 systems in hydros without problems - the ESC is clearly under-rated. That's not a license to be stupid, but don't be surprised if you can pull an x450/2 or more in a properly setup rigger. This isn't a SV27 mono which can't handle a big wheel.



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Boy I agree with the SV-27 ESC being under-rated. I wonder how far they can go in a well set up boat? Haven't really tried to punish one yet.