Hello, all! Let me preface my first post with a little information about myself. I am a do-it-all employee at the local hobby shop, and as such I fix peoples' toys, sell toys, play with the toys, and occasionally restock the shelves and do inventory. I'm also the go-to guy where I work for advice on electrical systems for RC vehicles of all shapes and sizes.

A customer recently came in and purchased a Traxxas Spartan for it's 50+ claims and then promptly decided that Spartan speed wasn't quite enough. So he ordered a UL-1 Superior and then immediately asked us to put more power into it. My first suggestion was a Hydra 120 with a 1415 motor on 4s, good for a few hundred watts more than the stock setup. While this intrigued him, he wanted more... to which I pondered, "Theoretically, I suppose, you could fit a 1515 or 1521 in it, but..." and I didn't even get to "that would be a bit much and somewhat heavy" before I was told to put one in. I know I could just toss in a motor and batteries and send him on his way (what he originally had planned to do), but I would like to give him the best possible chance at successfully making some speed passes.

My experience in boating is limited, and my experience with sport hydro hulls is virtually nil. If you all would be so kind, I could use some help outfitting the rest of the boat's systems and testing them. I didn't mess around and ordered a Hydra ICE 240 and I'm keeping an eye on weight (Though what's a few more ounces?) to pick out some 65C TP packs. The stock motor mount will fit the motor, without modification I believe.

My motor choices are either the Neu 1521 1Y (1577kV) or the Neu 1527 1.5D (1500kV). I can get cooling jackets for either and the ESC should be able to handle them no problem. My biggest conundrum is picking out a propeller to archive the desired speed of 55+, which I know I have more than enough power to pass like it's standing still. 2 blade, or 3? Metal or carbon? Octura, Prather, Grim Racer... The other is tuning a sport hydro to simply stay on the water at those speeds.

And before you ask, yes both he and I are aware that a UL-1 hull will likely fly apart in a 70 mph crash. I made sure of that. And yes, he still wants to do this. Thank you all in advance for any advice you can give me!

I would run at most a 1515 in that hull. There is absolutely no advantage to the 1521 or the 1527 as the hull will never handle a big enough prop to need them. The boat will run better and faster with the 1515.

I would run that hydra ICE 240 with a 1515-1y on 4s first (shoudl get you close), then 5s if I were out for all-out speed. However, the trick to making that hull go fast is keeping it on the water, not a big motor.

Good to know. I can get a water jacket for the Castle 1515 2200kV as well, which is much more available to me, though I'm sure the Neu 1515 1y is more efficient. However, running on 6s is a desired goal, though not entirely necessary, so a 2.5D motor would be appropriate for that.

Higher kv on 4s will be the hot ticket as long as the esc can take the amps. Running a really big prop on a hydro this size won't work out well.

Whatever you do, keep an eye on the balance point with the heavier parts going in.

1521 1d with an x642 will get you mid 60's easy. Lots of rpms but the guy wants big speed right?

Originally Posted by scorpion1

1521 1d with an x642 will get you mid 60's easy. Lots of rpms but the guy wants big speed right?

Wouldn't it be better to increase RPMs through higher voltage with a lower kV motor rather than using lower cell count on a high KV motor?

If you're putting in a 240a ESC, you've got lots of head room for amps. If you were aiming for 65+ on 120a, you'd want more voltage.

Originally Posted by Back Counter Guy

My motor choices are either the Neu 1521 1Y (1577kV) or the Neu 1527 1.5D (1500kV). I can get cooling jackets for either and the ESC should be able to handle them no problem. My biggest conundrum is picking out a propeller to archive the desired speed of 55+, which I know I have more than enough power to pass like it's standing still. 2 blade, or 3? Metal or carbon? Octura, Prather, Grim Racer... The other is tuning a sport hydro to simply stay on the water at those speeds.

And before you ask, yes both he and I are aware that a UL-1 hull will likely fly apart in a 70 mph crash. I made sure of that. And yes, he still wants to do this. Thank you all in advance for any advice you can give me!

Having owned a UL-1, unless there have been some major design changes you are going to have troubles getting a 1521 under the cowling / hatch. The stock motor end bell comes very close to the flat portion of the main hatch where the little canopy clips on.
Add in the extra weight of 6s packs for the kv you've chosen, the size of a 240 Ice, and you are going to have a nightmare getting everything in the hull.
Handling issues will probably turn into a nightmare as wll.

Originally Posted by bill34207

Having owned a UL-1, unless there have been some major design changes you are going to have troubles getting a 1521 under the cowling / hatch. The stock motor end bell comes very close to the flat portion of the main hatch where the little canopy clips on.
Add in the extra weight of 6s packs for the kv you've chosen, the size of a 240 Ice, and you are going to have a nightmare getting everything in the hull.
Handling issues will probably turn into a nightmare as wll.

Totally agree with Bill I owned one right now i can barely get the two 2s packs in there now runing 40c 5000 very tight fit as far as motor anything bigger than what it comes now , be hard to put in it good luck , also the handling is not that great it bounces it self to death .

If budget isn't an issue for this guy, he'd be MUCH better off with a better starting hull. It won't be off the shelf RTR, but it'll also be much better on the water.

The Insane FE30 is a much better starting point, and will handle lots more speed. Here's one running mid 60's easily:

Insane FE30 running at 64mph (2 min 12 sec)

There's also the ML boatworks P sport hydro:
http://forums.offshoreelectrics.com/...-P-sport-hydro

ML Boatworks GP335 FE P sport hydro (1 min 43 sec)

I had hard time getting my ul1 to stick to the water in the mid 50s. No rtr hull is really best for the speed he wants. Build a boat from a bare hull!

If stuck on the UL1
Like mentioned nothing bigger then a 1515. The boat can get a nice bit of chine walking also, your going to have to mod the sponsons and change the aoa for best performance (JMHO)...

All good to know. I will mention the better hulls to him, however, I believe we will be seeing plenty of chine walking and blow overs. Thank you for all the advice, everyone. I really appreciate it.

Those hulls I posted videos of will run mid 60's in oval trim with other boats in the water all day, a UL-1 in the mid 60's will need dead calm water and a lot of luck to stay on the water.

A newby friend of mine got a Miss Vegas a while back and we fixed it up with a Leopard 2200 4074 on 4s with only an x442 and it really moved out, stable too.................we were kinda proud since I only had an Elam for a short time and he had never owned a hydro.

They are a bit larger at around 33"

He hit mid 50's on the GPS and could have easily hit 60 with an x642

Miss Behavin' 32" Hydro (0 min 54 sec)