Ammo motor slower than stock?

[7500RPM]

I never claimed my Subi was a " drag race car" just that a 4 cylinder can keep up and pass a v8.( I also get 20+ mpg)
A few years ago I helped a buddy put twin turbos on a 460 with only 7lb of boost and it was around 980hp and 1400lb of torque......remember the hp don't matter if you can't plant it to the pavement!

That is why they invented very large tires ( 14 x 32 w ) and 4 link suspensions, I am not going to debate this.
Top Fuel Dragsters +8000 hp with controlled clutch slippage

[1truckerdan]

I am not arguing with yo bro...I drive my Subi every day on the road I Love it......thats all

[7500RPM]

Who said I was arguing, just stating facts, that is all.

[Darin Jordan]

You need to remember, the higher the KV you go, you need to prop down, regardless if they have the same pole count! the torque is never the same with higher kv motors

Of course, this is true, as Jay and I both stated above... given the same motor dimensions... However, a 2300KV motor with 2-poles, vs. a 2300KV motor with 6, are two completely different animals... The 6-pole will have significantly more torque, and can, therefore, pull a lot more prop than the same KV in 2-Pole... It's the principle that allows our P-Limited motors to achieve such performance...

[7500RPM]

Hi guys,

I've installed a new ammo 2300 motor, and I was dissapointed with the performance, I mean it was noticeably slower
than with my stock setup??

All my batteries, esc, prop setup is the same, i just changed the motor....

this leads me to another question. I solderd on new 5.5mm bullet connectors from the esc and to the motor,
my soldering isn't the best as i'm new to this, so if my soldering wasn't upto standard would the boat run any slower or
would it just not work atall?

My boat does run its just slower.. any ideas guys?

Thanks for any help

Tone

What batteries are you using?

[makin' waves]

Hi guys, I'm using 7 cell nimhs,

They're the same as i've been using with the stock, Also wizard has used the ammo motor and his boat touched just over 50mph...
I'm thinkin i must have been unlucky and got a dud motor..

Tone

[7500RPM]

Hi guys, I'm using 7 cell nimhs,

They're the same as i've been using with the stock, Also wizard has used the ammo motor and his boat touched just over 50mph...
I'm thinkin i must have been unlucky and got a dud motor..

Tone

The problem is the Nimh packs, Unless you are using Matched and Pushed cells this motor Will Not Perform with regular cells, due to the High Peak current demand this motor requires.

[makin' waves]

I'm sure I've heard others say their boats are carzy on 14 cell nimhs with the ammo


there's even a vid of one on youtube

Tone

[Darin Jordan]

I'm sure I've heard others say their boats are carzy on 14 cell nimhs with the ammo


there's even a vid of one on youtube

Tone

OK, what these guys are trying to tell you is that not ALL Nimh cells are created equal... The typical "sport packs" that you can buy these days don't have the voltage retention that a GOOD set of packs will have. They get pulled down under higher amps very quickly and therefore, the motor doesn't have as much RPM...

How about you try using your buddies NiMH cells for a run and see if it's the batteries, or something else...

[makin' waves]

Hi Darin,

The bloke on the vid says his nimhs are IB3600s (14 cells) and I'm using Intellect 5000 mah (14 cells)
therfore i'm thinking my batteries should be faster?
He is using a Cf48 prop, I'm using an X440 which in theory should work better because of the torque loss on the motor?

which is the Ammo 36-50-2300KV and both on stock ESC's
Does that sound right to you mate?

Tone

[Darin Jordan]

Hi Darin,

The bloke on the vid says his nimhs are IB3600s (14 cells) and I'm using Intellect 5000 mah (14 cells)
therfore i'm thinking my batteries should be faster?
He is using a Cf48 prop, I'm using an X440 which in theory should work better because of the torque loss on the motor?

which is the Ammo 36-50-2300KV and both on stock ESC's
Does that sound right to you mate?

Tone

Several things here...

1) Depends on the condition of the cells... In theory, you are correct. The Intellect 5000 cells are good cells. However, the IB's were good cells too. Mah doesn't make one pack "faster" than the other... "Faster Longer", perhaps, but mah alone doesn't necessarily mean more speed. If he has "matched" and "zapped" IB3600s, and you have an Intellect 5000 mah "sport pack" (i.e.: random cells that Intellect had left after they built all their "race" packs), then he may have an advantage. His are lighter as well...

2) The CF48 prop may or may not be faster. Depends on the prep of your X440, how the boat is tuned, etc. On thing CF props are good at is "flattening" out under load. The blades literally lose pitch as they flex under load, which allows the motor to spool up a but faster. Once at speed, they can reform and go... This may or may not be an advantage. It would likely pull less amps under load.

Plus... the CF 48 prop is 48mm... vs only 40mm for yours... That's a BIG difference in blade area. He's got a lot more surface in the water providing thrust, which, in theory, should make the boat faster. BUT, again, where is his strut compared to yours? You can't go from a 48mm prop to a 40mm prop WITHOUT changing the strut height and expect to get a decent comparison. When you change prop diameters, you NEED to adjust the strut accordingly.

I think what I'd suggest is that, if you think you have a problem, try to match his setup and see what yours does. BUT, match it EXACTLY if you are going to directly compare... Trim tab adjustments, strut adjustment, etc., ALL combine to give you your performance. There is so much more to it than just dropping in KV and throwing on a prop.

NOW, personally, I think if you took that X440, properly balanced and sharpened it, and get the strut adjusted correctly, it "should" provide some decent speeds. It might be an issue in hard left-hand turns, do to the small diameter and the offset strut position, but it "should" be capable of laying down some MPH... I think a 42x55 would be a better choice, but with a little tweaking to the pitch on your X440, you should be able to get it to work.

[Darin Jordan]

Just taking a wild stab at an estimate here, using the advertised pitch of the stock X440, and assuming your batteries are REALLY good... maintaining 1.05V/cell under load (NOT very likely... I'm guessing they are .95 or so at best...), here is what I'd expect to see from your boat:

14.7V * 2300KV = 33,810 RPM

(33,810 * 2.198pitch)/1057 *(1- Slip%) = MPH

Assuming about 30% slip for a stock X440 without any tweaking on a mono:

70.30 * (1-.30) = 70.30 * .70 = 49.21mph

In other words... you are going to need to have everything PERFECTLY setup to get 50mph out of this setup with that prop, using NiMH cells...

[7500RPM]

Hi Darin,

The bloke on the vid says his nimhs are IB3600s (14 cells) and I'm using Intellect 5000 mah (14 cells)
therfore i'm thinking my batteries should be faster?
He is using a Cf48 prop, I'm using an X440 which in theory should work better because of the torque loss on the motor?




which is the Ammo 36-50-2300KV and both on stock ESC's
Does that sound right to you mate?




Tone

Do not think just because you have 5000 mah batteries you will be faster, most of these packs I have seen people use have spot welded tabs on them, and are end to end cells. The tab on the end is the first and most critical failure spot on the entire pack. when the cells and tabs get hot it melts the insulation heat shrink on the end cell and shorts out the cell effectivelly killing the cell! The sport packs I have had the most success with are the Duratrax 4200mah side by side cells that come factory with battery bars on them, you will need to change the wire on them as some come with 14 gauge.

[Darin Jordan]

Do not think just because you have 5000 mah batteries you will be faster, most of these packs I have seen people use have spot welded tabs on them, and are end to end cells. The tab on the end is the first and most critical failure spot on the entire pack. when the cells and tabs get hot it melts the insulation heat shrink on the end cell and shorts out the cell effectivelly killing the cell! The sport packs I have had the most success with are the Duratrax 4200mah side by side cells that come factory with battery bars on them, you will need to change the wire on them as some come with 14 gauge.

Exactly! Every off-the-shelf pack I have has spot-welded, VERY thin metal tabs on them... Voltage drop is SEVERE under load...

[7500RPM]

Exactly! Every off-the-shelf pack I have has spot-welded, VERY thin metal tabs on them... Voltage drop is SEVERE under load...

Spot On Darin....no pun intended! There are not many Nimh packs out there that can support the very high peak current demands of FE boats, choose wisely, Battery Bars are a MUST !